Description

Acoustic Generator for Measuring Distances by Echoes

Technical Field

[1] Since the late 1930s the so-called acoustic sounding, or echometering, method has been used in the oil industry for taking distance measurements in an oil well or borehole, see U.S. Pat. No. 2,927,301, Booth, Measurement of liquid levels in wells. The acoustic sounding method involves sending a short, sharp, clear, loud bang sound down an oil well or borehole and using a transducer to listen' to the echoes reflected back. The signal from the transducer is usually recorded for analysis which is usually performed by a separate device: see U.S. Pat. 2,209,944, Walker, Method of measuring location of obstructions in deep wells, and U.S. Pat. 2,232,476, Ritzmann, Method and apparatus for measuring depth in wells.

Background Art

[2] As explained in these patents and other literature, the acoustic sounding method not only determines the distances between the source of the sound and the causes of the echoes, but also determines the physical nature of the causes of the echoes based on the frequency, amplitude, and other attributes of the sound being reflected back. For example, in its application in oil wells the acoustic sounding method can not only determine the distance to the 'bottom' of the well, i.e. the fluid level of the well, but it can also determine other attributes and anomalies, such as wax, scale, or gas build-up and other obstructions, encountered down the well based on the nature of the echoes received at the wellhead by the transducer.

[3] One common method for generating the sound needed for the acoustic sounding method is to use an air or gas pressurized chamber which is discharged at or near the wellhead or the void to be analyzed. As described in U.S. Pat. 4,750,583 and 4,646,871, Wolf, Gas-Gun for Acoustic Well Sounding (hereinafter "WoIf) the sound generated by the pressurized chamber comes from the energy released by the equilibration of the different pressures between the chamber and the wellhead or the void. A different, earlier method for generating the sound needed for the acoustic sounding method was to fire a blank cartridge from a firearm at the wellhead. Accordingly the oil industry has coined the term 'sound gun ¹ , 'echo gun ¹ , 'acoustic gun', or simply 'gun' to generally describe devices that produce the sound needed for the acoustic sounding method. Disclosure of Invention

Technical Problem

[4] Although acoustic generators, acoustic guns using a pressurized gas chamber, have been used for many years, these acoustic generators have failed to address a number of issues in their use and have failed to yield the full benefits of the acoustic sounding method as an analytical tool for measuring distances and analyzing physical attributes.

Technical Solution

[5] The current invention is the application of the acoustic sounding method by using a fully automatic acoustic generator. [6] The current invention is also a component of a real time control system for oil well pumping operations. The objective of the real time control system being to optimize oil production from an oil field. The current invention is a key component to this real time control system because it provides a practical method for providing the oil field operator real time information and feedback about the fluid level status and other physical statuses of the wells in their oil field.

Advantageous Effects

[7] The benefits of the current invention include, but are not limited to:

[8] a device for automatically setting gas pressures in various chambers for numerous uses and applications including, but not limited to, setting the pressures for the various chambers in an acoustic generator; [9] a mechanism for automatically setting the gas pressures of various chambers in a device based on a control gas pressure for numerous uses and applications including, but not limited to, a mechanism for automatically setting the gas pressures for the various chambers of an acoustic generator based upon the void gas pressure; [10] a unique differential regulator that is used in a mechanism for automatically setting the gas pressures of various chambers in a device based on a control gas pressure; [11] an acoustic generator with the ability to automatically set the pressure chamber of the acoustic generator to any desired pressure; [12] an acoustic generator with the ability to automatically set the pressure chamber of the acoustic generator to a suitable pressure with respect to the void pressure for firing the acoustic generator in either the explosion mode or implosion mode; [13] an acoustic generator with the ability to automatically set the pressure chamber of the acoustic generator to a gas pressure difference that is relative to, and based upon, the void gas pressure at the time of automatic setting; [14] an acoustic generator with the ability to automatically set the pressure chamber of the acoustic generator to a gas pressure difference that is relative to, and based upon, the void gas pressure for any void gas pressure; [15] an acoustic generator with the ability to automatically set the pressure chamber of the acoustic generator to a gas pressure difference that is relative to, and based upon, the void gas pressure for any gas pressure difference; [16] an acoustic generator with the ability to fire the pressure chamber of the acoustic generator at any pressure setting; [17] an acoustic generator with the ability to fire the pressure chamber of the acoustic generator for any pressure difference between the pressure chamber and the void; [18] an acoustic generator with the ability to fire the pressure chamber of the acoustic generator for any void gas pressure;

[19] an acoustic generator with the ability to automatically set the arming and firing mechanism of the acoustic generator; [20] an acoustic generator with a firing mechanism that will fire for any pressure in the pressure chamber; [21] an acoustic generator with a firing mechanism that will fire the pressure chamber for any void gas pressure; [22] an acoustic generator with a firing mechanism that will fire for any gas pressure difference between the pressure chamber and the void; [23] an acoustic generator with an automated mechanism for controlling the timing of the arming and firing of the acoustic generator; [24] an acoustic generator with a unique outlet or portal design from the pressure chamber for the efficient and effective generation of the desired sound needed for the acoustic sounding method; [25] an acoustic generator with a unique design and configuration of the microphone element and unit for the efficient and effective detection of echoes from the void; and [26] an acoustic generator that produces a shorter, sharper, and clearer sound wave than any prior art acoustic generator.

Description of Drawings [27] Figure Ia is a cross sectional view of the Acoustic Generator with Main Body

Housing (Portable Unit) in a preferred embodiment of the current invention. [28] Figure Ib is a cross sectional view of the Main Body Housing (Stationary Unit) in a preferred embodiment of the current invention. [29] Figure 2 is a cross sectional view of the internal module of the Acoustic Generator in a preferred embodiment of the current invention. [30] Figure 2a is a cross sectional view of two different versions of the Stable Pressure

Regulator Shaft used in preferred embodiments of the current invention. [31] Figure 2b is a cross sectional view of three different versions of the Nub Bobbin and Piston used in preferred embodiments of the current invention. [32] Figure 2c is a rear face view of two different versions of the Piston Section used in preferred embodiments of the current invention. [33] Figure 2d is a side and cross sectional view of two different versions of Pressure

Chamber Sleeves used in preferred embodiments of the current invention. [34] Figure 2e is a side view of the Stable Pressure Regulator Spring Guide Spacer used in a preferred embodiment of the current invention. [35] Figure 2f is a side view of the Fire Bobbin Spring Guide Spacer used in a preferred embodiment of the current invention. [36] Figure 2g is a perspective view of the microphone element and microphone wires used in a preferred embodiment of the current invention. [37] Figure 2h is a cross sectional view of the microphone element and microphone wires used in a preferred embodiment of the current invention.

[38] Figure 3 is a cross sectional exploded view of the internal components of the

Acoustic Generator in a preferred embodiment of the current invention. [39] Figure 3a is a cross sectional exploded view of the components of the Stable

Pressure Regulator used in a preferred embodiment of the current invention. [40] Figure 3b is a cross sectional exploded view of the components of the Differential

Regulator used in a preferred embodiment of the current invention. [41] Figure 3 c is a view of the components of the Microphone Area of the Acoustic

Generator used in a preferred embodiment of the current invention. [42] Figure 4a is a view of the rear of the Top Section in a preferred embodiment of the current invention with the figures denoting the locations of the components placed in the Top Section. [43] Figure 4b is a view of the front of the Top Section in a preferred embodiment of the current invention with the figures denoting the locations of the components as placed in the Top Section. [44] Figure 4c is a view of the rear of the Piston Section in a preferred embodiment of the current invention with the figures denoting the locations of the components as placed in the Piston Section. [45] Figure 4d is a view of the front of the Piston Section in a preferred embodiment of the current invention with the figures denoting the locations of the components as placed in the Piston Section. [46] Figure 5 is an exploded view of the rear of the Piston Section used in a preferred embodiment of the current invention showing components as placed in the Piston

Section. [47] Figure 6a is a schematic depiction of the components, chambers and passages of an embodiment of the Acoustic Generator in the armed position (explosion mode). [48] Figure 6b is a schematic depiction of the components, chambers and passages of an alternative embodiment of the Acoustic Generator in the armed position (explosion mode). [49] Figure 7a is a schematic depiction of the components, chambers and passages of an embodiment of the Acoustic Generator in the standby/fired position (explosion mode). [50] Figure 7b is a schematic depiction of the components, chambers and passages of an alternative embodiment of the Acoustic Generator in the standby /fired position

(explosion mode). [51] Figure 8a is a schematic depiction of the components, chambers and passages of an embodiment of the Acoustic Generator in the armed position (implosion mode). [52] Figure 8b is a schematic depiction of the components, chambers and passages of an alternative embodiment of the Acoustic Generator in the armed position (implosion mode). [53] Figure 9a is a schematic depiction of the components, chambers and passages of an embodiment of the Acoustic Generator in the standby/fired position (implosion mode).

[54] Figure 9b is a schematic depiction of the components, chambers and passages of an alternative embodiment of the Acoustic Generator in the standby/fired position

(implosion mode). [55] Figure 10 is a face view of a Surveyor Unit in a preferred embodiment of the current invention. [56] Figure 11 is a flowchart depicting the instructions executed by the signal processor, main processor, and i/o processor of a Surveyor Unit in a preferred embodiment of the current invention. [57] Figure 12 is a block diagram depicting the components of a Surveyor Unit in a preferred embodiment of the current invention. [58] Figure 13 (Omitted).

[59] Figure 14a is a view of the setup between the wellhead, Acoustic Generator,

Compressed Gas Source, and Surveyor Unit in applying the acoustic sounding method in a preferred embodiment of the current invention. [60] Figure 14b is a view of the Surveyor Unit and a programmed computer for downloading the data collected by the Surveyor for offsite analysis of the data collected in the acoustic sounding method in a preferred embodiment of the current invention. [61] Figure 15 is a graph depicting the sound generated by a preferred embodiment of the current invention at 10Hz under the benchmark test conditions described herein. [62] Figure 16 is a graph depicting the sound generated by a preferred embodiment of the current invention at 20Hz under the benchmark test conditions described herein. [63] Figure 17 is a graph depicting the sound generated by a preferred embodiment of the current invention at 40Hz under the benchmark test conditions described herein. [64] Figure 18 is a graph depicting the sound generated by a preferred embodiment of the current invention at 70Hz under the benchmark test conditions described herein. [65] Figure 19 is a graph depicting the sound generated by a SONOLOG D-6C2 at 10Hz under the benchmark test conditions described herein. [66] Figure 20 is a graph depicting the sound generated by a SONOLOG D-6C2 at 20Hz under the benchmark test conditions described herein. [67] Figure 21 is a graph depicting the sound generated by a SONOLOG D-6C2 at 40Hz under the benchmark test conditions described herein. [68] Figure 22 is a graph depicting the sound generated by a SONOLOG D-6C2 at 70Hz under the benchmark test conditions described herein. [69] Figure 23 is a graph depicting the sound generated by an ECHOMETER

COMPACT GAS GUN at 10Hz under the benchmark test conditions described herein. [70] Figure 24 is a graph depicting the sound generated by an ECHOMETER

COMPACT GAS GUN at 20Hz under the benchmark test conditions described herein. [71] Figure 25 is a graph depicting the sound generated by an ECHOMETER

COMPACT GAS GUN at 40Hz under the benchmark test conditions described herein.

[72] Figure 26 is a graph depicting the sound generated by an ECHOMETER COMPACT GAS GUN at 70Hz under the benchmark test conditions described herein.

Best Mode

[73] The following table is a list of the various components that are used in a various preferred embodiments of the current invention as described herein. Note that some of the components listed are optional or are used in some preferred embodiments of the current invention but not in other preferred embodiments:

[74]

Table 1 - List of Components

Mode for Invention

[75] Configuration of the Acoustic Generator and Surveyor Unit

[76] As depicted in Figure 14a, in a preferred embodiment of the current invention the

Acoustic Generator (0) is connected to the well annulus at the wellhead by a 1/2 inch (12.7 mm) NPT Modified Female Quick Connect (8) on the Main Body Fitting (Portable Unit) (Ia). A 2 inch (50.8 mm) pipe threaded end is normally used for an Acoustic Generator (0) with a Main Body Fitting (Stationary Unit) (Ib). For either the portable or stationary configurations the Acoustic Generator (0) is connected to a Compressed Gas Source (99) via the Male Quick Connect (66) using a hose or mounting. The Male Quick Connect (66) is connected to the Top Section Gas Inlet (66c) in the Acoustic Generator (0).

[77] The Surveyor Unit (100) is electronically connected to the Acoustic Generator (0) via a Data Cable (60c) and controls all of the automatic functions of the Acoustic Generator (0).

[78] In a preferred embodiment of the current invention the connections between all the components can be completed prior to installing the Acoustic Generator (0) to the well annulus thus allowing single-hand installation of the Acoustic Generator (0).

[79] As explained above acoustic soundings for oil wells are normally made within the inside wall of the casing pipe and the exterior of the production tubing string hanging within the casing pipe. The casing pipe is normally cemented in place within the oil producing borehole. The production tubing is normally formed from relatively uniform sections of steel tube screwed together using joints known as collars. As explained herein, the average distance between collars and the echoes created by the collars are used to calibrate readings obtained by an acoustic generator.

[80] Acoustic Generator

[81] In a preferred embodiment of the current invention, the Acoustic Generator (0) has two static positions, the fired/standby position and the armed position. In operation the Acoustic Generator (0) is initially at rest in the fired/standby position, is moved to the armed position, and is fired to return to the fired/standby position.

[82] As depicted in Figure Ia in a preferred embodiment of the current invention the

Acoustic Generator (0) is made of an internal module, see Figure 2, which is placed inside a Housing (1) and secured by a Lock Ring (10) at the rear of the Acoustic Generator (0).

[83] The Acoustic Generator (0) also has several alternative embodiments and optional parts depending on the needs of the acoustic sounding for a particular well or void. As

explained above and shown in Figure Ia and Figure Ib, the Acoustic Generator (0) has alternative housings for alternative configurations and connections at the wellhead. Further as shown in Figures 2a to 2h inclusive, Figures 6a to 9b inclusive, and as explained further herein, several components in the Acoustic Generator (0) have alternative designs depending on the needs of the acoustic sounding method being applied. Also, as explained further herein, there are several optional components with the Acoustic Generator (0) to assist in use and operation, such as the Filter Spacer/Tool (28) which is used for disassembling and reassembling the Acoustic Generator (0) for maintenance and repair purposes.

[84] In addition, unless stated otherwise, the components in the preferred embodiments of the Acoustic Generator (0) are made of high quality stainless steel and the O-rings identified are of Buna-N. Also stainless steel E-clips, screws, and springs have been used in preferred embodiments of the current invention. However, the Acoustic Generator (0) can use alternative comparable materials and alternative comparable components that provide the same functions as O-rings, E-clips, valves, screws, springs, flanges and stops. For example, in a preferred embodiment of the current invention, the four springs used in the Acoustic Generator (0) are all commercially available but can easily be replaced by alternative components that produce the same function and performance. In a preferred embodiment of the current invention the specifications of the springs are as follows:

[85]

[86] * MSDivisions, a division of Commercial Communications LLC of Middletown,

NY

[87] As depicted in Figure Ia, in a preferred embodiment of the current invention the

Acoustic Generator (0) is cylindrical in shape and can be viewed as having three distinct areas (moving from the rear to front): the Pneumatic Computer area, the Pressure Chamber area, and the Microphone Cavity area. These three areas can be loosely associated with the three basic functions of the Acoustic Generator (0), i.e. arming a pressure chamber, firing the pressure chamber, and detecting the echoes received, but as explained herein each area of the Acoustic Generator (0) plays a role in each of the three basic functions.

[88] Pneumatic Computer area

[89] In a preferred embodiment of the current invention the Pneumatic Computer (90) not only controls the arming and firing of the acoustic generator's Pressure Chamber (80) but also controls of the functions of gas pressure regulation, control, timing, delivery, and evacuation for the other chambers, cylinders, channels and passages in a preferred embodiment of the Acoustic Generator (0). As shown in Figures 3, 4a to 4d, and 5, in a preferred embodiment of the current invention the Pneumatic Computer (90) area contains most of the components of the Acoustic Generator (0).

[90] Top and Piston Sections

[91] As shown in Figure 3, in a preferred embodiment of the current invention the two largest components of the Pneumatic Computer (90) are the Top Section (21) and the Piston Section (20). As shown in Figures 3, 4a to 4d, and 5, in a preferred embodiment of the current invention the Top Section (21) and the Piston Section (20) are joined together by three Cap Screws (65) located in the Cap Screw Receivers (69) in the Top Section (21) and the Piston Section (20). The three Cap Screws (65) are accessible, and can be removed from, the rear of the Top Section (21). When the Cap Screws (65) are removed, the Top Section (21) and Piston Section (20) spring apart as a result of the spring pressure that exists between the various components of the Pneumatic Computer (90).

[92] In separating the Top Section and Piston Section the first noticeable aspect of the interior of the Pneumatic Computer (90) is that there are no tubes, pipes, or other fallible connections. The pneumatic connections in the body of the Pneumatic Computer (90) are all made by machined cross channels, holes, and cylinders which are conjoining each other within the Top Section (21) and Piston Sections (20). Figures 6a through 9b schematically depict the components and the relationship between the chambers, cylinders, channels and passages used in two preferred embodiments of current invention.

[93] Where the Top Section (21) and Piston Section (20) face together there are five O- rings (49), (67),(75), (71a) and (71b) to seal the pressure channels between the two Sections. A Piston Cylinder O-ring (49) is set around a raised Piston Cylinder Guide

(82) and used to seal the Fire Piston Cylinder (72). The other four O-rings (67), (71a), (71b) and (75) seal the rest of the pneumatic passages in between the Top Section (21) and the Piston Section (20). This assembly configuration of a preferred embodiment of the Pneumatic Computer (90) allows the components and working parts of the Pneumatic Computer (90) to be removed, replaced, or cleaned quickly. When the two Sections are apart, every component and working part can be removed from the Top Section (21) and Piston Section (20) by hand. In disassembly there may be working parts or components in either Section, but generally all will remain with the Piston Section (20).

[94] As shown in Figure 3b, on the front side of the Top Section (21) are Spring Holes

(91a-c) for the springs over several components, and O-ring slots for the various O- rings. There is also a machined Solenoid Wire Channel (64) for the control wires coming from the Solenoid (70) and going over to the Data Cable (61) in the Top Section (21). In the Top Section (21), there are two small machined Vent Channels (81b) and (81c) being attached to various component Spring Chambers (91b) and (91c) and over to the outer edge of the Top Section (21). The Vent Channels allow the gas from the internal components to be dissipated into an Edge Bevel (89) surrounding 180 degrees around the outer circumference of the rear end edge of the Piston Section (20). In a preferred embodiment of the current invention a flat surface of the Edge Bevel (89) can be between 0.03 inches (0.76 mm) to 0.30 inches (7.62 mm) with a bevel angle of 30 to 60 degrees, with 0.085 inches (2.16 mm) and a 45 degree Edge Bevel (89) working the best. This is a safety feature of a preferred embodiment of the current invention as gas pressure released from the two Vent Channels (81b) and (81c) to the atmosphere is rendered harmless by being bled down through the Edge Bevel (89) and disbursed into the space that is left between the outer diameter of the Top Section (21) and the inside diameter of the Lock Ring (10).

[95] Pneumatic Computer Components

[96] The following is a description of the components present in a preferred embodiment of the current invention starting with the components in the Top Section (21).

[97] Piston Nub

[98] As shown in Figure 1, in a preferred embodiment of the current invention inside the center of the Top Section (20) is a Nub Bobbin (29). In a preferred embodiment of the current invention the Nub Bobbin (29) is about ¹ A inch (13mm) diameter. The Nub Bobbin (29) acts as a pressure compensation bobbin for the Piston Shaft (22). The Nub Bobbin (29) pushes down on the top of the Piston Shaft (22) with the same void pressure entering into the front of the Acoustic Generator (0). In a preferred embodiment of the current invention the void pressure that might affect the operation of the instrument is balanced and neutralized against itself by utilizing the Nub Bobbin (29). The nub pressure comes directly from the void pressure to equalize and compensate for the well pressure entering the front of the Acoustic Generator (0) and

pressuring the front of the Piston Shaft (22). This compensation or equalizing allows the Piston Shaft (22) to be operated with a separate Stable Pressure gas driven firing system as described herein.

[99] As shown in Figure 2b there are three alternative versions of the Nub Bobbin (29) for various preferred embodiments of the current invention. In Version A, the Nub Bobbin (29) is solid and completely free and separate from the Piston Shaft (22). In Version A the void pressure is fed to the rear the Nub Bobbin (29) through the Pneumatic Computer (90). This is achieved by using Version A of the Piston Section

(20) as shown in Figure 2c, which links the inlet from the Pressure Transducer (77) to the Nub Port (29c). Schematically this is depicted in Figure 6a which shows the inlet from the void to the Pressure Transducer (77) being continued to the rear of the Nub Bobbin (29). Version B and Version C as shown in Figure 2b work by connecting a Nub Bobbin (29) with a passageway as an extension of a Piston Shaft (22) with a passageway, the passageways of the Piston Shaft (22) and Nub Bobbin (29) allowing the void gas to pass through the Piston Shaft (22) to the rear of the Nub Bobbin (29). As the void gas does not need to pass through the Pneumatic Computer (90) in this arrangement, the channel from the Pressure Transducer (77) to the Nub Port (29c) is omitted, as depicted in Version B of the Piston Section (20) as shown in Figure 2c and schematically depicted in Figure 6b.

[100] In a preferred embodiment of the current invention the Nub Bobbin (29) may be removed for maintenance or Nub O-ring (14) replacement with the same Filter Screen/ Tool (28) threaded tool that is used for removing the Filter Screens as described herein.

[101] Wire Components

[102] As shown in Figures 1 and 5, in a preferred embodiment of the current invention the Pneumatic Computer (90) has a commercially available Pressure Transducer (77) to read the void pressure at any given time. The Pressure Transducer (77) sends its results through its wires to any electronics in sync with its specifications. The Pressure Transducer (77) may be easily removed from its Seat (77s) and replaced after the Top Section (21) and the Piston Section (20) have been separated and the Pressure Transducer Wires (79) have been disconnected from the Data Connector (60). The Top Section (21) has a Data Channel (62) on the outer edge of the Data Connector Receiver (6Or). The Data Cable (61) which includes the Pressure Transducer Wires (79), the Microphone Wire (58), and the Solenoid Wire (59) can be brought out through the Data Channel (62) after the Data Connector Set Screw (68) is unscrewed from the Data Connector (60) and released. This allows the sections to be moved further apart without unduly disturbing the wiring. The only wire still attached to the Top Section

(21) is the Solenoid Wire (59) which is coiled into the open wiring compartment space around the Data Connector (60) when assembled.

[103] Piston Section Components

[104] As shown in Figure 5, in a preferred embodiment of the current invention the major components that are housed in the Piston Section (20) will be described as viewed in order clockwise beginning at the Filter Screen/Tool (28).

[105] Note although it is a component in the Piston Section (20) as depicted, the Piston Shaft (22) is more fully described in the Pressure Chamber area.

[106] Filter Screen/Tool and Filter Screens

[107] In a preferred embodiment of the current invention the Pneumatic Computer (90) houses a Filter Screen/Tool (28) which is a spacer for the Filter Screen (35b) below it. It also has a threaded shaft on one end which is used as a removal tool for the Filter Screens, (35a) and (35b), and the Piston Nub (29) which is located inside the Top Section (21). The threaded shaft of the Filter Screen/Tool (28) is used to remove the Filter Screens (35a) and (35b) by inserting it into the exposed end of the Filter Screen, turning the tool clockwise and pull up and out to remove. Pulling the stainless steel Filter Screen (35b) out for cleaning is also the first step for a complete breakdown of the Acoustic Generator (0). This enables the sections to be submerged in solvent and the channels within the Top and Piston Sections cleaned in total. The Filter Screen (35a) filters the Stable Pressure gas from the Stable Pressure Regulator (48) into the center or feed of the Solenoid (70).

[108] Differential Regulator

[109] A component within the Pneumatic Computer for a preferred embodiment of the current invention is the Differential Regulator (45), as shown in Figure 3b. In a preferred embodiment of the current invention the Differential Regulator (45) is an assembly of components that is a little over an inch (25.4 mm) in length. The Differential Regulator (45) consists of a Center Shaft (25) with shoulders or stops at both ends and the following assembled components, starting from the rear moving to the front: a small Relief Spring (47) resting on the rear shoulder of the Center Shaft (25) with the front end of the Relief Spring (47) compressing against the rear end of a Slide Bobbin (24b). Against the front end of a Slide Bobbin (24b) is the rear end of a Differential Pressure Spring (51) which has another identical but inverted Slide Bobbin (24c) on its front end and an E-clip (57b) or other similar stop holding the assembly to the front end of the Center Shaft (25). The Slide Bobbins have holes through their centers and are used as valves in conjunction with O-rings (54a), (54b) on the Center Shaft (25). The Slide Bobbins also have external O-rings (38b), (38c) which will allow the bobbins to be used as valves when the Differential Regulator (45) is inside the Differential Regulator Chamber (45c). The Differential Regulator Chamber (45c) having two inlets: a front inlet for the void and a rear inlet for the Compressed Gas Source (99). The Differential Pressure Spring (51) determines the pressure differential in the Pressure Chamber (80) in relation to the void pressure, and the Relief Spring (47) holds the whole assembly in place and rapidly moves air by moving the assembly's components before their intended usage. The Relief Spring (47) also holds the front

Slide Bobbin (24c) down, using O-ring (54b) as a closed valve awaiting pressure movement. In a preferred embodiment of the current invention there are two outlet or feed channels connected to the Differential Regulator Chamber (45c). The front channel feeds the Stable Pressure Regulator (48) and the rear channel feeds the Pressure Chamber (80). As the regulator is shifted from front to rear and vise versa, the gas pressure flowing into these feed channels is shifted from one source to another. In this configuration of a preferred embodiment of the current invention the Differential Regulator (45) is able to perform several different functions in the operation of the Acoustic Generator (0).

[110] Automated explosion vs. implosion mode selection function

[111] As shown in Figures 6a through 9b, one function of the Differential Regulator (45) is that of assessing the operations of the Acoustic Generator (0) for explosion or implosion mode. Depending on the void pressure, a gas pressurized acoustic generator can be armed and fired in one of two modes: the explosion or implosion mode. The explosion mode requires an external source of gas pressure to arm the gun's chamber to a pressure above the void pressure. In firing the gun the sound is generated by the higher pressure gas in the chamber entering the void. Alternatively, the implosion mode sets the gun's chamber to a pressure below the void pressure. In firing the gun the sound is generated by the higher gas pressure in the void entering the chamber. [112] In a preferred embodiment of the current invention the question of whether to arm the Acoustic Generator (0) in the explosion or implosion mode is automatically determined by the Pneumatic Computer (90) through the Differential Regulator (45) which responds to the source of the greater pressure: the void pressure at the front or the Compressed Gas Source (99) at the rear of the Differential Regulator (45). In a preferred embodiment of the current invention the Compressed Gas Source (99) also provides the preset gas pressure used to charge the Pressure Chamber 80 in the explosion mode. When the rear of the Differential Regulator (45), at Slide Bobbin (24b), is subjected to a greater pressure than the front of the Differential Regulator (45), at Slide Bobbin (24c), the entire Differential Regulator (45) acts like a shuttle valve and shifts forward in the Differential Regulator Chamber (45c). As shown in Figure 6a, with the Differential Regulator (45) in the forward position, the gas from the Compressed Gas Source (99) can flow into the Pressure Chamber and into the Stable Pressure Regulator Chamber (48a). When the gas pressures are reversed with respect to each other, i.e. void pressure at the front is greater than the Compressed Gas Source (99) pressure at the rear, the Differential Regulator (45) will move to the rear to a position where the Slide Bobbin (24b) is restrained from further movement by the front face of the Top Section (21). As shown in Figure 8a, in this position the pressure feed for both channels shifts. The feed channel for the Pressure Chamber (80) is now positioned to feed or vent from the center section of the Differential Regulator (45). The feed channel for the Stable Pressure Regulator (48) is now in front of the entire

Differential Regulator (45) allowing the void pressure to flow freely into this feed channel.

[113] As explained herein, in a preferred embodiment of the current invention the

Compressed Gas Source (99) provides the basis for a preset gas pressure from which the automatic determination of explosion or implosion mode is made. The Compressed Gas Source (99) can also provide a predetermined gas pressure to charge the Pressure Chamber to in the explosion mode.

[114] Implosion mode differential regulation function

[115] The next function in a preferred embodiment of the current invention is the differential regulator function that occurs in the implosion mode. The Differential Regulator (45) maintains a regulated differential pressure between the void and the Pressure Chamber (80) for firing in the implosion mode. In a preferred embodiment of the current invention the Pressure Chamber (80) is ported by the Differential Regulator (45) through Slide Bobbin (24b) to maintain a constant balance pressure difference between the Pressure Chamber (80) and the void. This regulation is accomplished by the opposing pressures being applied on Slide Bobbin (24c) when the Differential Regulator (45) is at the rear of the Differential Regulator Chamber (45c) in the implosion mode as explained above. With the Differential Regulator (45) in this position the void pressure on the front side of Slide Bobbin (24c) is opposed by the combined pressure of the Pressure Chamber (80) and the Differential Regulator Spring (51) on the rear Slide Bobbin (24c). In this function the compression resistance of the Differential Regulator Spring (51) determines the relative pressure of the Pressure Chamber (80) to the void. In a preferred embodiment of the current invention, in this function the Differential Regulator Spring (51) can be selected to produce pressure in the Pressure Chamber (80) of 25 pounds per square inch (psi) (1.75 kilograms per square centimeter (kg/cm ² ), or 1.70 atmospheres (arm)) up to the maximum rated working pressure of the Acoustic Generator (0), with a range of 50 psi (3.5 kg/cm ² , 3.40 atm) to 2,000 psi (140.8 kg/cm ² , 136.1 arm) being good and sufficient for acoustic soundings for most oil wells. In a preferred embodiment of the current invention one guide for setting the Pressure Chamber (80) is to set it at a pressure difference of 100 psi (7.0 kg/cm ² , 6.80 atm) plus 10 psi (0.7 kg/cm ² , 0.68 atm) per 1,000 feet (304.8 meters) of well. In a preferred embodiment of the current invention a pressure difference of approximately 150 to 300 psi (10.5 kg/cm ² (10.2 atm) to 21.0 kg/cm ² (20.4 atm) ) less than the void pressure is found to be the optimum pressure difference for an acoustic sounding of an average oil well. In circumstances when the void pressure is higher than 1000 psi (70.3 kg/cm ² , 68.05 atm), the chamber pressure area can also be reduced in size using either Version A or Version B of the Pressure Chamber Sleeves shown in Figure 2d and the differential pressure between the void and the chamber area can be varied anywhere from 150 psi (10.5 kg/cm ² , 10.2 atm) up to the void pressure.

[116] Implosion mode pressure chamber setting function

[117] As shown in Figure 9a or 9b, in the standby/fired position in the implosion mode of a preferred embodiment of the current invention the Pressure Chamber (80) is open and has the same gas pressure as the void. In the implosion arm cycle the pressure in the Pressure Chamber (80) needs to be reduced with relationship to the void. This is done by releasing an appropriate amount of gas through the center valve of Slide Bobbin (24b) into a suitable containment area. In a preferred embodiment of the current invention, as shown in Figure 1, the Pressure Chamber (80) is armed in the implosion mode by the Piston Shaft (22), which has a Piston Flange (73) and Piston Valve (12), moving forward to close the Fire Tube Valve (84). As the Piston Shaft (22) moves forward the Piston Valve (12) opens allowing the gas pressure in the Pressure Chamber (80) to equalize with the gas pressure that exists between the Slide Bobbins (24b) and (24c) in the Differential Regulator (45). When the gas pressure between the Slide Bobbins, along with the pressure from the Differential Spring (51) and the Relief Spring (47), spreads the two Slide Bobbins (24b) and (24c) sufficiently apart the front Slide Bobbin (24c) meets the Differential Regulator E-clip (57b) on the Center Shaft (25). This draws the Center Shaft (25) forward opening the O-ring (54a) from inside the rear Slide Bobbin (24b) allowing gas to escape through this channel and the Male Quick Connect (66). When a sufficient amount of gas from the Pressure Chamber (80) has escaped gas pressure along with the compression tension of both the Differential Spring (51) and the Relief Spring (47), moves the O-ring (54a) into Slide Bobbin (24b) thus closing the path for the escaping gas.

[118] In an alternative preferred embodiment of the current invention by restraining the movement of the Center Shaft (25) when the Differential Regulator (45) is in its rearmost position in the armed position any backward movement of the front Slide Bobbin (24c) caused by an increase in void pressure enables additional gas to enter between the Slide Bobbins (24b) and (24c) to the Pressure Chamber (80). Accordingly in this alternative preferred embodiment of the current invention the difference between the pressure in the Pressure Chamber (80) and the void is constantly maintained even if the void pressure suddenly increases or decreases during the arming cycle.

[119] Implosion mode differential regulator pressure function

[120] In a preferred embodiment of the current invention, when the gas pressure in

Pressure Chamber (80) is reduced for firing in the implosion mode, there is also a slight pressure difference between the two Slide Bobbins (24b) and (24c) of the Differential Regulator (45) and the Pressure Chamber (80) due to the presence of the Relief Spring(47). The additional tension of the Relief Spring (47) to the tension of the Differential Regulator Spring (51) will determine the release pressure at which the Differential Regulator Chamber (45c) gas is allowed to equalize with the Pressure Chamber (80). In a preferred embodiment of the current invention a range difference

of 2 to 50 psi (0.14 kg/cm ² (0.14 atm) to 3.5 kg/cm ² (3.4 atm)) is a possible difference, with a range difference of 3 to 15 psi (0.21 kg/cm ² (0.20 atm) to 1.05 kg/cm ² (1.02 atm)) being good, and a range difference of 5 to 10 psi (0.35 kg/cm ² (0.34 atm) to 0.70 kg/cm ² (0.68 atm)) being the best. The presence of this gas pressure between the two Slide Bobbins (24b) and (24c) is sufficient to prevent any chattering effect and to prevent any pressure blast from the Compressed Gas Source (99) from moving the rear Slide Bobbin (24b) and closing its center passage at an inappropriate time.

[121] Safety bleed function

[122] Another function of the Differential Regulator (45) in a preferred embodiment of the current invention is that of a safety bleed function. If the Acoustic Generator (0) needs to be removed from the well annulus and either the void pressure, i.e. the gas pressure in the chamber around the front of the Microphone Section (74), and/or the Pressure Chamber (80) is above atmospheric pressure, then either excess pressure can be relieved by putting a rod or other similar device into the Male Gas Quick Connect (66) inlet and gently pushing on the top of the Differential Regulator (45). This will relieve the excess pressure after the well is shut off and before the Acoustic Generator (0) is removed from the well annulus. This bleed function is important for proper safety and operation of the Acoustic Generator (0).

[123] An alternative way to bleed off unwanted gas pressure is to simply fire the Acoustic

Generator (0) when the void pressure is at atmospheric pressure or when the Well Depth is set to ¹ OOO' on the Surveyor Unit (100). As explained herein because the firing mechanism is an independent mechanism, the Acoustic Generator (0) can be fired at anytime to equilibrate any gas pressure differences.

[124] Stable Pressure Regulator

[125] As shown in Figure 5, moving clockwise from the Differential Regulator (45) in the

Piston Section (20) is the Stable Pressure Regulator (48). In a preferred embodiment of the current invention the Stable Pressure Regulator (48) is depicted in Figure 3 a. The Stable Pressure Regulator (48) is housed in the Pneumatic Computer (90) in a Stable Pressure Regulator Chamber (48a), the top of which is vented through the Pneumatic Computer (90) to outside atmospheric air pressure. A Stable Pressure Regulator Spring (52) is placed on the rear of the Stable Pressure Regulator (48) in the Stable Pressure Regulator Chamber (48a). The Stable Pressure Regulator Spring (52) may also use an optional Stable Pressure Regulator Spring Guide Spacer (52g), at Figure 2e, for adjusting its spring tension accordingly.

[126] In a preferred embodiment of the current invention the Stable Pressure Regulator

(48) provides a consistent stable gas pressure for operation of the internal processes in the Acoustic Generator(O). This stable gas pressure can be from 25 to 1000 psi (1.76 kg/cm ² (1.70 atm) to 70.30 kg/cm ² (68.05 atm)), with 70 to 500 psi (4.9 kg/cm ² (4.8 atm) to 35.2 kg/cm ² (34.0 atm)) being better, and 70 to 150 psi (4.9 kg/cm ² (4.8 atm) to 10J kg/cm ² (10.2 atm)) being optimum for most of the time. In disassembling the

Pneumatic Computer (90), the Stable Pressure Regulator Shaft (26) along with the Slide Bobbin (24a) may be removed, as with previous items, by simply grasping the upper portion of the stem and pulling them straight out of the Piston Section (20). The Stable Pressure Regulator Shaft (26) has two identical exposed O-rings: one spaced near the center (56b), and the other (56c) spaced near the front of the Stable Pressure Regulator Shaft (26).

[127] In a preferred embodiment of the current invention the O-ring (56b) regulates the air from the high pressure source to the Stable Pressure system by sealing off incoming gas pressure when the O-ring (56b) meets the Stable Pressure Regulator Seat (27). The O-ring (56c) located at the front end of the Stable Pressure Regulator Shaft (26) goes into a Stable Pressure Regulator Valve Cylinder (48c) located underneath the Seat (27), As shown in Figure 2a, the O-rings can be either single or doubled as there is a slight improvement in performance using doubled O-rings. The other end of the Stable Pressure Regulator Valve Cylinder (48c) is vented through the Pneumatic Computer (90) to the outside atmospheric air pressure. Because of this configuration with the venting of the Stable Pressure Regulator Chamber (48a) and the Stable Pressure Regulator Valve Cylinder (48c) the rear and front ends of the Stable Pressure Regulator Shaft (26) are at the same atmospheric pressure. The front and rear ends of the Stable Pressure Regulator Shaft (26) being at the same atmospheric pressure, and isolated from the higher pressures that exist in the Acoustic Generator (0) during its operation, enable the accurate control of the Stable Pressure Regulator Shaft (26) by the Stable Pressure Regulator Spring (52). In a preferred embodiment of the current invention, this same pressure compensation technique is used on the Piston Nub (29).

[128] In a preferred embodiment of the current invention there is an O-ring (56a) underneath the Slide Bobbin (38a) which provides the Stable Pressure Regulator Shaft (26) flexibility in operation by allowing it to self align with its respective seats that are further inside the Piston Section (20). The Slide Bobbin (24a) is held in position over this O-ring (56a) by an E-clip (57a) around the Stable Pressure Regulator Shaft (26).

[129] In front of the Stable Pressure Regulator Shaft (26) and Slide Bobbin (24a) in the

Stable Pressure Regulator Chamber (48a) is the Stable Pressure Regulator Seat O-ring (53) which sits on Stable Pressure Regulator Seat (27).

[130] In a preferred embodiment of the current invention the Stable Pressure Regulator

(48) works by taking any higher gas pressure from the void or from the Compressed Gas Source (99) and reduces it to the working pressure for the Solenoid (70), Fire Bobbin (23), and the Piston Shaft 22. The Stable Pressure gas system created by the Stable Pressure Regulator (48) can be from 25 to 1000 psi (1.76 kg/cm ² (1.70 arm) to 70.30 kg/cm ² (68.05 ami)) , with 70 to 200 psi (4.9 kg/cm ² (4.8 arm) to 14.1 kg/cm ² (13.6 arm)) being better, and 70 to 150 psi (4.9 kg/cm ² (4.8 arm) to 10.5 kg/cm ² (10.2 arm)) being optimum.

[131] As shown in Figure 2a, in one preferred embodiment of the current invention single

O-rings can be used for each of the 3 sections on the Stable Pressure Regulator Shaft (26). However, it is found that when the front section uses two O-rings, as shown in Figure 2a, there is a slight improvement in operation.

[132] In a preferred embodiment of the current invention the Stable Pressure Regulator

Seat (27) has a Screwdriver Slot (76) for ease of removal and replacement for maintenance.

[133] In a preferred embodiment of the current invention some of the components in the

Pneumatic Computer (90) are identical. For example, the Slide Bobbins ((24a), (24b), and(24c)) in the Differential Regulator (45) and Stable Pressure Regulator (48) are identical, as are O-rings on the shafts of both regulators and as are the O-rings on the Slide Bobbins.

[134] Fire Bobbin

[135] As shown in Figure 5, moving clockwise on the Pneumatic Computer (90) the next component in a preferred embodiment of the current invention is the Fire Bobbin (23). In the preferred embodiment of the current invention the Fire Bobbin (23) is a little over an inch (2.54 cm) long and has 3 sections of O-rings (11). Although single O- rings can be used for each of the 3 sections on the Fire Bobbin it is found that when the top two sections have two O-rings, as shown in Figure 5, there is a slight improvement in operation.

[136] The Fire Bobbin (23) is spring loaded at its rear end by a Fire Bobbin Spring (50) which fits in the center of the Fire Bobbin (23) and protrudes out above the Fire Bobbin (23). The preferred embodiment of the current invention also permits an optional Fire Bobbin Stable Pressure Regulator Spring Guide Spacer (5Og) at Figure 2f to be used for adjusting the tension of the Fire Bobbin Spring (50) as needed.

[137] On the front end of the Fire Bobbin (23) is a nub that is designed to allow Stable pressure to pass around it quickly in the arming process. The nub also suspends the Fire Bobbin (23) away from the blunt end of the Fire Bobbin Cylinder (23c) as an antijamming feature. In a preferred embodiment of the current invention the Fire Bobbin (23) can be removed from the Pneumatic Computer (90) using any shaft of appropriate size to dislodge and remove the Fire Bobbin (23). This is accomplished by inserting the end of the shaft into the hole where the Fire Bobbin Spring (50) was removed and, with a small side pressure to create some resistance, pulling the Fire Bobbin (23) out of the Fire Bobbin Cylinder (23c).

[138] Solenoid

[139] In the preferred embodiment of the current invention moving clockwise on the

Pneumatic Computer (90) the next component is the Solenoid (70) which is located on the rear end of the Acoustic Generator (0) secured to the Top Section (21). This Solenoid (70) is used to initiate both the arming and firing of the Acoustic Generator (0). In a preferred embodiment of the current invention the Solenoid (70) has two positions to control the Acoustic Generator (0). In the off-position the internal valve in

the Solenoid (70) is closed and Acoustic Generator( 0) is in the fired/standby mode. In the on-position the internal valve in the Solenoid (70) is open allowing the various gases to enter the Acoustic Generator (0) to switch it to the armed mode. Several benefits arise from this arrangement. One benefit is safety as the Acoustic Generator (0) can only become armed when an electrical signal from an outside source activates the magnetic field in the Solenoid (70) to open the internal valve in the Solenoid (70). This means that if no electrical signal is sent to the Solenoid (70) the Acoustic Generator (0) will remain in the fired/standby position and the electrical connection is only needed when the Acoustic Generator (0) needs to be armed and fired. As shown in Figure 14 there are several potentially hazardous connections to be made in order to set up the Acoustic Generator (0). Many prior art acoustic generators use the opposite configuration, i.e. the solenoid is to remain on at all times and only turned off to fire the acoustic generator. Other prior art acoustic generators were even more hazardous by requiring the operator to first charge the pressurized chamber and then set up the connections as depicted in Figure 14.

[140] As shown in Figures 6a to 9b, when activated the valve in the Solenoid (70) allows the Stable Pressure gas from the Stable Pressure Regulator (48) through the Solenoid Channel (70c) and Filter Screen (35a) to the nub end of the Fire Bobbin (23). Because the rear end of Fire Bobbin (23) is vented to atmospheric pressure in the fired/standby mode the Fire Bobbin (23) is pushed backward which allows Stable Pressure gas from the Stable Pressure Regulator (48) to be directed to exhaust port of the Piston Cylinder (72) and the rear face of the Fire Piston Flange (73) which is pushed forward closing the Fire Tube Valve (84) between the Pressure Chamber (80) and the void as the Piston Shaft 0-ring (16) seals inside the Fire Tube (30). When the Solenoid (70) is closed the gas pressure is released through the solenoid vent, the Fire Bobbin Spring (50) pushes the Fire Bobbin (23) down, which redirects the Stable Pressure gas to the pressure supply port of the Piston Cylinder (72) and the front face of Fire Piston Flange (73) pulling the connected Piston Shaft (22) to the rear and the Piston Shaft O- ring (16) out of the Fire Tube (30) and opening the Pressure Chamber (80) to the void for rapid pressure equalization.

[141] As further shown schematically in Figures 6a to 9b, the firing mechanism is the same regardless of the gas pressures that exist in the Pressure Chamber (80), void, or Compressed Gas Source (99).

[142] The Solenoid (70) can easily be removed by disconnecting the Solenoid Wire (59) and unscrewing the unit while the Top Section (21) is separated from the Piston Section (20). With the sections separated O-rings (49), (67), (71a), (b), and (75) can be removed or replaced.

[143] Pressure Chamber Area

[144] As shown in Figure 1, in a preferred embodiment of the current invention the

Pressure Chamber (80) is formed between the Piston Section O-ring (19) and the Fire

Tube O-ring (39) sealing against the inside diameter of the Acoustic Generator Housing (1). As shown in Figure 1 the Pressure Chamber (80) also has Support Tubes (40) and the Piston Shaft (22) running through its length from rear to front. The Piston Shaft (22) with its Piston Shaft O-ring (16) forms the Fire Tube Valve (84) and seals the Pressure Chamber (80) from the void when the Piston Shaft (22) is inserted into the Fire Tube (30). The Support Tubes, which are used as a conduit for the wire components and to provide atmospheric pressure to the inside of the Microphone Unit, as further described herein, have O-rings (43) on both of their ends to seal the Pressure Chamber (80), and are suspended between the Piston Section (20) and the Fire Tube (30), which has a flange plate at the rear. In alternative embodiments of the current invention Support Tubes (40) may have Support Tube Sleeves (41) and may be held in position at either end by an E-clip or Anchor Set Screw (42). The use of Anchor Set Screws (42) at the front end of the Support Tube (40) for securing to the Fire Tube (30) eliminates the need for Support Tube Sleeves (41) and O-rings on the set screw ends.

[145] As the Pressure Chamber area is the main portion associated with the firing mechanism of the Acoustic Generator (0), the following not only describes the various components in the Pressure Chamber area in a preferred embodiment of the current invention, but also describes the firing mechanism of the Acoustic Generator (0).

[146] Firing Mechanism

[147] As described in Wolf, a gas pressurized acoustic generator works by isolating a chamber from the wellhead or void, changing the gas pressure in the chamber to be different than the void pressure, and connecting the chamber to the void to equilibrate the pressure difference. The energy released in the gas pressure equalization process generates the sound needed for making the echoes from the borehole.

[148] Without being bound by any theory or hypotheses the sharpness, duration, clarity, and intensity of the sound made by a gas pressured acoustic generator are related to the time taken for the gas pressure difference to equilibrate. Essentially, the shorter the time to equilibrate the better the sharpness, duration, clarity, and intensity of the gunshot sound for acoustic sounding purposes. The preferred embodiment of the current invention is designed to use a number of systems to improve time taken for the gas pressure difference to equilibrate.

[149] One of the systems used in a preferred embodiment of the current invention is the firing mechanism, which is an actuating system that uses a separate force, other than the force created by the unequal gas pressures, to continue to open the firing valve past the initial moment the unequal gas pressures meet, i.e. past the moment the firing valve is cracked open.

[150] By using this actuating system, the current invention does not use nor rely upon the gas pressure difference between the pressure chamber and the void in order to effectuate a quick time to equilibrate. In fact the actuating system is designed not only

to be independent of the pressures of the pressure chamber, void and external source but also to reduce the effects of any force created between the pressure chamber and void when firing the Acoustic Generator (0).

[151] Accordingly the actuating system will operate regardless of the pressure chamber, the void, the external gas source, and the pressure difference between the pressure chamber and the void. As a direct outcome of using this actuating system, the current invention removes any effects of the difference in gas pressures on the firing mechanism. As a result the current invention can produce a suitable sound at any pressure within the device's physical limitations. As the actuating system is not dependent on the pressure difference, the current invention can be used in either explosion or implosion mode. Further the magnitude of the unequal gas pressures can be made very high for deep wells, or very low for an acoustic sounding of the top of a well or for shallow wells.

[152] In the preferred embodiment of the current invention the actuating system is driven by the Stable Pressure gas system as defined herein. This is a gas-powered pneumatic system, but it is not the only type of system that can provide the actuating force. The actuating force could be provided by hydraulic, electromechanical, or any other type of mechanism that could provide an actuating force to open the pressure chamber to the void.

[153] Further, as shown herein, the independent firing mechanism is just one of the systems used in a preferred embodiment of the current invention to eliminate, reduce or offset the effects that the unequal gas pressure force has on the time taken for the gas pressures to equilibrate. As shown in the Benchmark Test results herein, the interesting and unexpected phenomena of the current invention is that the preferred embodiment of the current invention not only produces an equilibration time shorter than any prior art gas pressurized acoustic generator but also produces a sharper, shorter, clearer, and more intense sound for acoustic soundings than all prior art gas pressurized acoustic generators.

[154] Firing Mechanism Components

[155] The following describes the components that make the firing mechanism in a preferred embodiment of the current invention.

[156] Piston Shaft

[157] The Piston Shaft (22) provides the platform for several functions in the pressure chamber setting and firing mechanisms. As shown in Figure 2b there are alternative embodiments of the Piston Shaft depending on the path for providing void gas to the rear of the Nub Bobbin (29) as described herein. In Figure 2b, Version A of the Piston Shaft (22) is solid and the rear of the Nub Bobbin (29) is set to the void pressure by gas sent through the Pneumatic Computer (90) as described herein. In Figure 2b, Versions B and C of the Piston Shaft (22) show the rear of the Nub Bobbin (29) being set to the void pressure by gas sent through passageways in both the Piston Shaft (22)

and the Nub Bobbin (29). In both versions the Piston Shaft (22) has a filter screen on the front of the channel to prevent material from the void entering the Acoustic Generator (0). The difference between Versions B and C being the connection between the Piston Shaft (22) and the Nub Bobbin (29) which can be temporary by using a hollow Piston Nub Set Screw (37s) or permanent by machining the Piston Shaft (22) and Nub Bobbin (29) together as a single unit.

[158] Piston Cylinder

[159] In a preferred embodiment of the current invention as shown in Figure Ia, the

Piston Cylinder (72), which is a part of the firing mechanism, is at the rear of the Piston Section (20). As shown in Figures 2 and 3 in a preferred embodiment of the current invention the Piston Cylinder (72) is of a size and diameter so as to utilize an actuating force created by the Stable pressure system created in the Pneumatic Computer (90) in order to drive the Piston Flange (73) and the Piston Shaft (22) forward and backward at a very high rate of speed. In a preferred embodiment of the current invention the Piston Cylinder (72) has an exhaust port and a pressure supply port fed through the Fire Bobbin (23). In a preferred embodiment of the current invention the Piston Cylinder (72) cavity can be from 0.5 (13mm) to 1.5 inch (38mm) diameter and 0.2 inch (5mm) to 1.5 inch (38mm) depth with a 0.850 inch (21.6mm) diameter by 0.850 inch (21.6mm) depth working well and a 1.0 inch (25.4mm) diameter by 0.750 inch (19.0mm) depth working the best.

[160] Piston Shaft

[161] In a preferred embodiment of the current invention as shown in Figure 1, with the

Top Section (21) and the Piston Section (20) separated the Piston Shaft (22), which has a Piston Flange (73) and Piston Valve (12), may be removed by pushing the Piston Shaft (22) up through the Piston Section (20) to exit the rear of the Piston Section (20).

[162] Piston Flange

[163] In a preferred embodiment of the current invention the Piston Flange (73), which sealed against Piston Cylinder (72) wall by an O-ring (73 a) is moved by the differences and changes in gas pressure on either side of the Piston Flange (73). The changes in the gas pressure on either side of the Piston Flange (73) in turn moves Piston Shaft (22) between the fired/standby and armed positions. In the fired/standby position the Piston Flange (73) is to the rear of the Piston Cylinder (72) as the result of a higher gas pressure being applied to the front face of the Piston Flange (73). As described herein by moving to the armed position the pressures on the exhaust and pressure supply channels to the Piston Cylinder (72) are reversed, with the higher gas pressure on the rear face of the Piston Flange. This moves the Piston Flange and Piston Shaft forward closing the Fire Tube Valve (84) isolating the Pressure Chamber (80) from the void and enabling the Pressure Chamber (80) to be charged to the appropriate pressure via the Piston Valve (12) which is now open to the Differential Regulator (45). The forces on the Piston Flange (73) provide a power stroke when pushing the

Piston Shaft (22) forward to close the Fire Tube Valve (84) and a speed stroke when moving the Piston Shaft (22) back to release the pressure wave created between the Pressure Chamber (80) and the void. The size and diameter of the entrance and exit passages directly relates to the power and speed strokes. A small diameter is used to create a back pressure brake for the power stroke and a larger diameter passage is used for the speed stroke. This prevents damage to the internal parts and alleviates any unwanted sounds from metal contact.

[164] As further described herein, in a preferred embodiment of the current invention the void pressure that might affect the operation and firing of the Acoustic Generator (0) is offset against itself by utilizing the Nub Bobbin (29) which sits behind the Piston Flange (73) in the Pneumatic Computer (90) as described herein. The nub gas pressure comes directly from the void pressure to equalize and compensate for the void pressure entering the front of the Acoustic Generator(O) and pressuring the front of the Piston Shaft (22). This compensation or equalizing allows the Piston Shaft (22) to be operated with the separate Stable Pressure gas system as described herein.

[165] Piston Valve

[166] As shown in Figure 2 and 5, in a preferred embodiment of the current invention there is a Piston Valve (12) on the Piston Shaft (22). The Piston Valve (12) is the link between the firing mechanism and chamber pressure setting mechanism in the Acoustic Generator (0). The function of the Piston Valve (12) is to open the Pressure Chamber (80) to the Differential Regulator (45) in order for the Pressure Chamber (80) to be automatically set to the appropriate pressure for firing. In a preferred embodiment of the current invention the Piston Valve (12) is formed by a curved indent completely around a portion of the Piston Shaft (22).

[167] In a preferred embodiment of the current invention when moving from the fired/ standby position to the armed position the Piston Shaft (22) moves forward and closes the Fire Tube Valve (84) resulting in the Pressure Chamber (80) being isolated from the void. After the Fire Tube Valve (84) closes the Piston Shaft (22) continues to move forward opening the Piston Valve (12). The opening of the Piston Valve (12) allows gas to flow past the Piston Section O-ring (17a) to gaseously link the void-isolated Pressure Chamber (80) to the Differential Regulator (45). As described herein the Differential Regulator (45) performs either one of two functions in setting the pressure of the Pressure Chamber (80). In the implosion mode, excess gas will follow from the Pressure Chamber (80) through the Differential Regulator (45) to the appropriate lower pressure as determined by the mechanisms of the Differential Regulator (45) as explained herein. In the explosion mode, gas from the Compressed Gas Source (99) will follow to the Pressure Chamber (80) via the Differential Regulator (45) as explained herein.

[168] In a preferred embodiment of the current invention the indent of Piston Valve (12) allows required gas to flow either in or out, depending on the mode of firing, around

and past the O-ring (17a) to fill or empty the Pressure Chamber (80). When the Piston Shaft (22) is pulled backward, i.e. to fire the gun and return to the fired/standby position, the shaft portion without the indent, seals against the Piston Section O-ring (17a) and the Piston Valve (12) is closed.

[169] In a preferred embodiment of the current invention the radius of the cut for the

Piston Valve (12) can be from 0.1 inch (2.5mm) to 0.4 inch (10.1mm) we have found 0.25 inch (6.4mm) to work well with 0.261 inch (6.63mm) being best. The depth of this machine cut radius can be from O.Olinch (0.25mm) to 0.5 inch (12.7mm) ; it has been found that 0.350 inch (8.9mm) works well and 0.339 inch (8.61mm) works the best. In a preferred embodiment of the current invention the Piston Valve (12) curve completely encompasses the Piston Shaft (22) in order to disperse the gas uniformly, to reduce turbulence, and to prevent any tendency to lift out of place or pit the Piston Section O-ring (17a).

[170] Fire Tube Valve

[171] As shown in Figure 1, in a preferred embodiment of the current invention the Fire

Tube Valve (84) is inside the rear of the Fire Tube (30) and is formed when the Piston Shaft O-ring (16) at the front of the Piston Shaft (22) seals inside the rear of the Fire Tube (30). In a preferred embodiment of the current invention the Piston Shaft (22), with Piston Shaft O-ring (16), is propelled forward by the Piston Flange (73) so as to insert the front end, approximately ¹ A inch (6.4 mm) in a preferred embodiment of the current invention, into the Fire Tube (30) center shaft hole at the flange end completely sealing off and isolating the Pressure Chamber (80) from the void. When the Piston Flange (73) is propelled backward the Piston Shaft (22) and Piston Shaft O-ring (16) are extracted from the Fire Tube (30) and the valve is opened. As described herein in the explosion mode the Pressure Chamber (80) is charged with pressurized gas from an outside gas source, the Fire Piston Flange (73) is fired, pulling the Piston Shaft (22) and the Piston Shaft O-ring (16) out of the Fire Tube (30) opening the Fire Tube Valve (84) and expelling the pressured gas charge into the void. As described herein in for the implosion mode the Pressure Chamber (80) is set to a pressure lower than the void, the Fire Piston Flange (73) is fired, pulling the Piston Shaft (22) and the Piston Shaft O-ring 16 out of the Fire Tube (30) instantly opening the Fire Tube Valve (84) and allowing the higher pressure void gas to fill the Pressure Chamber (80).

[172] The firing mechanism operation is shown in Figures 6a to 9b. The figures show the various components, channels, passageways, and gas pressures at the fired/standby and armed positions for both the explosion and implosion mode in two alternative embodiments of the current invention. There are differences in position of various components in the explosion and implosion mode due to the Pressure Chamber (80) pressure setting mechanism. But the firing mechanism for both modes is the same and is not influenced by the pressures in the Pressure Chamber (80), Compressed Gas Source (99), void, or any part of the Pressure Chamber (80) pressure setting

mechanism.

[ 173] In a preferred embodiment of the current invention the time of the firing mechanism to be set from the fired/standby to armed position is determined by an electrical supply that is sent through the Data Cable (61) to the actuating side of the Solenoid (70). This electrical supply opens the internal valve in the Solenoid (70). In a preferred embodiment of the current invention the electrical supply is left on for 1/2 to 5 seconds duration, with 2 seconds being optimum. During this time the Stable Pressure gas from Stable Pressure Regulator (48) then travels through the Solenoid (70) and into the Pneumatic Computer (90) to apply pressure to the actuating end of the Fire Bobbin ( 23) which in turn compresses the Fire Bobbin Spring (50) located inside the opposite end of the Fire Bobbin (23). The movement of the Fire Bobbin (23) reverses the exhaust and pressure supply ports which are applied to the rear and front of the Piston Cylinder (72) respectively, the exhaust port being increased from atmospheric to the Stable pressure, the pressure supply port being decreased from the Stable pressure to atmospheric. This pressure difference moves the Piston Flange (73) with its Piston Shaft (22) forward to seal off the Pressure Chamber (80) from the void by utilizing the Piston Shaft O-ring (16) seated inside the rear end of the Fire Tube (30) creating the High Pressure Fire Valve (84). When the Fire Valve (84) closes the Piston Valve (12) opens and the Pressure Chamber (80) is then set to the appropriate pressure as determined by the Pneumatic Computer (90) as described herein.

[174] In a preferred embodiment of the current invention when the electrical supply is shut off to the Solenoid (70) the pressure supply to the passageway for the actuating end of the Fire Bobbin (23) vents to atmospheric pressure. The compressed Fire Bobbin Spring (50) pushes the Fire Bobbin (23) forward which in turn reverses the pressures in the exhaust and the pressure supply ports of the Piston Cylinder (72), the exhaust port returns to atmospheric pressure and the pressure supply port is increased from atmospheric pressure to the Stable pressure. This change in pressure moves to the Piston Flange (73) back to its original fired/standby position pulling the Piston Shaft (22) with the Piston Shaft O-ring (16) out of the Fire Tube (30) to close the Piston Valve (12) and open the Fire Valve (84) thus enabling the pressure difference between the Pressure Chamber (80) and the void to equilibrate. In a preferred embodiment of the current invention the complete cycle time is just over 2 seconds.

[175] Microphone Cavity area

[176] In a preferred embodiment of the current invention the Microphone Cavity area at the front of the Acoustic Generator(O) contains the Fire Tube (30) which sends the sound into the void, and the Microphone unit ((32), (33), and (34)) which receives echoes from the well and sends the appropriate electrical signal to the Surveyor Unit (100).

[177] As mentioned before in a preferred embodiment of the current invention there are systems used to eliminate, reduce or offset the effects that the unequal gas pressure

force has on the time taken for the gas pressures to equilibrate. This includes the portal structure design and the design of the components in the Microphone Cavity area which are made for the efficient and effective firing of sound and the accurate recording of the echoes generated.

[178] Fire Tube

[179] As shown in Figure 1 in a preferred embodiment of the current invention the Fire

Tube (30) is set in its position against the Housing (1) at the front of the Pressure Chamber area and is sealed from the void by the Fire Tube O-ring (39). The rear flange plate of the Fire Tube (30) and the Housing (1) form the front wall of the Pressure Chamber (80). As shown in Figure 2 in a preferred embodiment of the current invention the rear flange plate of the Fire Tube (30) also secures the Support Tubes (40).

[180] Without being bound by any theory or hypotheses due to the design of the Acoustic

Generator (0) in a preferred embodiment of the current invention the barrel or portal of the Fire Tube (30) has a number of features which shorten the time taken for the gas pressure difference to equilibrate.

[181] First, in a preferred embodiment of the current invention the diameter of the barrel or portal of the Fire Tube (30) is as large enough so as to shorten the time to equilibrate and yet not too large so as to create unwanted or excess turbulence. In a preferred embodiment of the current invention the opening has an area of 0.1 to 2.5 square inches (0.64 to 16.1 square centimeters).

[182] Second, in a preferred embodiment of the current invention the portal of the Fire

Tube (30) is in the center of the front face of the Pressure Chamber (80). In a preferred embodiment of the current invention the front face of the Pressure Chamber (80) is symmetrical with the Fire Tube (30) in the center to ensure a symmetrical release of the gases when the Acoustic Generator (0) is fired.

[183] Third, in a preferred embodiment of the current invention barrel of the Fire Tube

(30) is a hollow cylinder which provides a straight shot of the sound wave into the void. In a preferred embodiment of the current invention when the Piston Shaft (22) is pulled back to fire the Acoustic Generator (0) the sound generated is directly channeled by the barrel of the Fire Tube (30) into the void.

[184] Another option for a preferred embodiment of the current invention is for the barrel of the Fire Tube 30 to be rifled, i.e. to have cut or machined in any number if spiral grooves to the inside surface.

[185] Microphone Unit and Wave Guide

[186] As shown in Figure 2 and 3 c, in a preferred embodiment of the current invention the Microphone unit ((32), (33),and (34)) is a hollow cylindrical design that is fits over the barrel of the Fire Tube (30) and is secured into place with the Wave Guide Nut

(31) screwed on to the front end of the Fire Tube (30). The Wave Guide Nut (31) is further locked down from unscrewing with a Set Screw (36). As shown in Figure 2, in

a preferred embodiment of the current invention the Microphone Element (34) is parallel to the barrel of the Fire Tube (30) and perpendicular to the front of the barrel. The Wave Guide Nut (31) has a symmetrical bevel on the front so as to correspond and be parallel to the angle of the internal symmetrical bevel of the Housing (1). The Wave Guide Nut (31) is larger in diameter than the outside surface of the Microphone Element (34). This design allows any incoming pressure waves that might affect the signals from the Microphone unit to be deflected around the Wave Guide Nut (31) into the main part of the Microphone Cavity (46) area as they ricochet against the rear flat side of the Wave Guide Nut (31). This design permits the Microphone Unit to be extremely sensitive in order to enhance and improve the quality of the echoes detected. In a preferred embodiment of the current invention the bevel of the Wave Guide Nut (31) can be 20 to 45 degrees, depending on other internal characteristics of the Acoustic Generator(O) and microphone. Thirty degrees works well but twenty-five degrees works the best for acoustic sounding purposes.

[187] In a preferred embodiment of the current invention the Microphone unit itself consists of a Microphone Element (34) made of a cylindrical Ceramic Piezo material which is suspended between the Microphone Holder (32) and the Microphone Cap (33) with Microphone O-rings (86) on the ends and inside diameter. There are alternative embodiments for the Microphone Element (34). As shown in Figures 2g and 2h one embodiment has two separate oppositely charged conductive coatings on the inside of the Microphone Element (34) with the outer surface having a neutral coating. A Lead Wire, (58a) and (58b), is connected to each of the conductive coatings on the inside.

[188] As shown in Figure 3c in another embodiment the Microphone Element (34) has two separate oppositely charged conductive coatings, one on the outside and the other on the inside with both Lead Wires (58a) and (58b) being connected to the inside coating through a Zener Diode (87) and a Resistor (88) respectively.

[189] For either embodiment of the Microphone Element (34) described the Lead Wires,

(58 a) and (58b), run through a Support Tube (40) to the Data Channel (61) as shown in Figure 1. The Microphone unit ((32), (33) and (34)) is assembled with specific torque specifications for resonant frequency response and sufficient sensitivity. The cavity made in the Microphone unit by its three components is air-tight but is constantly at the atmospheric pressure due to the air passageway through the Support Tube to the rear of Acoustic Generator (0). Maintaining atmospheric pressure in the cavity of the Microphone unit maintains the quality of the echoes received regardless of the void gas pressure.

[190] Sound Quality

[191] In addition to the ability to automatically set and fire itself remotely, another significant achievement of the current invention is its superior Sound Quality.

[192] In order to function well, an acoustic generator needs to generate a sound that

enables the microphone in the gun, or a separate transducer, to detect a clear range of echoes from the entire borehole. For the acoustic sounding method the sound to be generated by the gun should be similar to that of a gunshot, i.e. a loud sharp short bang. This is oversimplifying the situation, but the phrase loud sharp short bang' is useful because it relates to the three measurable qualities of the sound's effectiveness in the acoustic sounding method: intensity (loud), the face angle (sharp), and the elapsed time (short). In addition to these criteria there is a fourth factor in determining the effectiveness and quality of the sound generated for the acoustic sounding method: clarity. One measurement of clarity is determine whether or nor interference is present. Interference is a fourth measurement of a sound's effectiveness in the acoustic sounding method because it takes into consideration the effects that any interfering secondary sounds may have with the primary sound wave generated by the gun.

[193] Intensity

[194] Intensity is the initial power release rated in decibels (dB) which are easily measured with readily available electronic instruments and programs, such as a pressure transducer calibrated in a linear scale converted to millivolts and sent to a digital readout. But decibels are not an empirical measurement unit as the decibel value depends on the agreed upon reference . The decibel scale is a base 10 logarithmic scale, so from any given starting point it takes 10 times an increase in sound power to increase the dB readings by 10. As an example to increase 150 dBs to 160 dBs it takes 10 times greater power needed then at 150 dBs. To the average person a 10 dB increase in sound level is perceived as a doubling in loudness.

[195] So although intensity is rated in decibels, intensity is related to pressure amplitude.

Pressure amplitude being a measure of the size of the variation in air pressure caused by a sound wave. In particular, the energy in a sound wave is proportional to the square of the pressure amplitude. As an example, if the pressure amplitude of a sound wave is doubled then the energy carried by that wave is quadrupled. In pure silence there is a constant pressure-atmospheric pressure. It is fairly simple to understand how a calibrated measurement of the pressure amplitude can be made using a microphone to convert the pressure variations into an electrical signal. By applying known pressure variations to the microphone the electrical signal can be calibrated to directly measure the air pressure variations. With suitable processing this pressure variation can be converted into the pressure amplitude. This function is performed by Sound Pressure Level (SPL) meters .

[196] Elapsed Time

[197] The second is elapsed time. This equates to the exact amount of time measured in milliseconds from the first recordable pressure wave created by this rapid equalization to the end of any equalization activity which will create distortion in the echo return. The end of the equalization activity being defined as the point when the amplitude drops back to Odb and does not produce a secondary wave afterwards, i.e. does not

produce a subsequent positive reading of 155dB or more.

[198] Face Angle

[199] The third factor determining the effectiveness of a sound wave intended for acoustic sounding purposes is the flatness of the front wave face. For the purposes of benchmarking, this is measured from the graph results as being the angle of the front wave face as compared to a horizontal line in sync with the base line of the wave trace.

[200] Secondary Wave

[201] The fourth factor to be determined is the clarity of the sound. The presence or absence of a secondary wave being an indicator of the clarity of the sound. To be effective the primary sound wave, i.e. the largest sound wave generated by the acoustic generator when fired must not encounter interference created by a secondary wave or a ripple in the primary or first wave. For the purposes of benchmarking, a secondary wave is defined as a second positive reading of 155dB or more produced from the acoustic generator during the initial firing of the generator for at least one-half of the firings at the particular setting. A ripple is defined as a sharp dip or fall off in the front face of the first primary wave so as to separate the front face into two or more angles (see Sonolog Figs 19, 20, and 21).

[202] Test Methodology

[203] A preferred embodiment of the current invention was tested with two commercially available pressurized chamber acoustic generators, the SONOLOG D-6C2 from Keystone Development Corporation as described in Wolf and the COMPACT GAS GENERATOR from the Echometer Corporation. Each of the three generators was attached to a one meter long, two inch (5.0 centimeter) diameter stationary pipe with a threaded end at one end for attaching the generator. The generators were fired at room temperature using an external gas pressure source in the explosion mode and the sounds emitted from the generators were detected at the other end of the pipe by a Honeywell 30 psig microphone. The microphone output being sent to a computer programmed with a standard audio signal analysis program with the results being plotted on a graph such as the one shown in Figure 15 with time (in seconds) on the x- axis and the decibel (dB) logarithmic scale for the y-axis.

[204] In the oil industry the acoustic sounding method uses very low audio to sub-audio sound wave frequencies. These sound frequencies can range from 100 Hz to 1 Hz, with a range of 80 Hz to 10 Hz being the norm. The different frequencies within these ranges are used to detect different attributes in the well, for example, collars are usually detected at the 80 Hz to 40 Hz range, whereas the fluid level is detected in the 30 Hz to 1 Hz range. Accordingly the results from the microphone were detected at 10, 20, 40 and 70 Hz for each firing to determine the sound generated by each generator at each frequency.

[205] Further for the purposes of benchmarking the different generators, the generators were fired with their pressure chambers set at 150 psi (10.5 kg/cm ² , 10.2 arm) and 100

psi (7.0 kg/cm ² , 6.80 atm) to determine any change in performance at these different pressures and each generator was fired at least ten (10) times at each pressure setting for statistical accuracy.

[206] Sound Quality Benchmark Results [207] Figures 15 through 26 show the results produce at 10, 20, 40 and 70 Hz from firing of each generator. The following are the benchmark results for the three gas pressu rized acoustic generators:

[208]

Table 4 - SONOLOG D-6C2 - Benchmark Results

[209]

Table 5 - ECHOMETER INC. COMPACT GAS GENERATOR - Benchmark Results

[210]

Table 6 - Preferred embodiment of the current invention - Benchmark Results

[211] From the results in the following tables there are similarities and differences in the generators. All generators increased in both intensity and face angle with an increase in the chamber gas pressure. Also all generators increased in both intensity and face angle with an increase in the frequency of the sound.

[212] The change in chamber pressure had a different effect on the elapsed time for the prior art gas pressurized generators when compared to a preferred embodiment of the current invention, providing proof of the effect of the different mechanisms and systems used in the current invention to speed up the equilibration time. For the SONOLOG D-6C2 and the ECHOMETER COMPACT GAS GENERATOR the elapsed time for a pressure chamber set to 150 psi (10.5 kg/cm ² , 10.2 atm) was less than the elapsed time for a pressure chamber set to 100 psi (7.0 kg/cm ² , 6.80 atm). This result supports the theory that the performance of these gas pressurized acoustic generators is linked to the pressure difference between the chamber and the void.

[213] The preferred embodiment of the current invention produced the opposite result in testing. An increase in the pressure chamber produced an increase in the elapsed time. But regardless of this trend, the preferred embodiment of the current invention produced significantly shorter elapsed times than the prior art gas pressurized acoustic generators for all chamber pressures at all frequencies measured. Industrial Applicability

[214] As explained above, the acoustic sounding method is used to calculate distances and physical properties of fluids or objects by analyzing the echoes created from the generation of a loud sharp short bang sound.

[215] As explained above one industrial applicability of the current invention is to calculate the distances and physical properties of fluids or objects in a borehole. As further explained above, and as shown in Figure 14a, for acoustic soundings in oil well

boreholes, the sounding is normally made within the inside wall of the casing pipe and the exterior of the production tubing string hanging within the casing pipe. As explained herein, the average distance between collars and the echoes created by the collars are used to calibrate readings obtained by an acoustic generator in order to calculate the distances and physical properties of fluids or objects in the borehole. Further the acoustic sounding method itself has other distance measuring and obstruction analysis applications beyond its use in oil wells. As an example, an early application of the acoustic sounding method was used by the postal service in New York City in the early 1900s to locate mail bags stuck in mail transportation tubes.