Field of the Invention

This invention relates generally to drilling and completing wellbores and more particularly to the use of vibratory and resonance devices downhole for performing selected drilling and completion operations for the production of hydrocarbons from subsurface formations. Background of the Art

To obtain hydrocarbons such as oil and gas, boreholes or wellbores are drilled from surface locations into hydrocarbon-bearing subterranean geological strata or formations. A large amount of current drilling activity involves the drilling of highly deviated or substantially horizontal wellbores.

Often, during the drilling of a wellbore, the drill bit and/or the drill pipe or tubing utilized for drilling the wellbore get stuck downhole, frequently at great distances from the wellbore mouth at the surface location. Additionally, during the completion, production and workover of the wellbores, various devices get stuck that must be retrieved from the wellbore. In many cases the stuck object must be freed and retrieved to continue to drill the wellbore or to continue to perform other operations. In many cases it is more desirable and less expensive to free (dislodge) the stuck object and either continue drilling of the wellbore or retrieve the object to the surface for repair or for substituting such object with a more suitable device than to leave the stuck object downhole. The object to be dislodged and/or retrieved is referred to in the industry as the Tish" and the process of dislodging and/or retrieving is referred to as 'fishing. "

A variety of fishing tools are utilized to free and retrieve stuck objects in

wellbores in the oil and gas industry. A majority of these fishing tools are mechanical devices and do not include any local or downhole intelligence.

Fishing tools utilizing resonance have been used for freeing stuck drill pipes

and other objects in the wellbores. United States Patent No,. 4,815,328,

issued to Albert Bodine and assigned to the assignee of the present invention and which is incorporated herein by reference, discloses a roller-type orbiting mass oscillator for generating resonance downhole. To loosen a drill pipe stuck in a wellbore, the device is attached at a suitable place to a drill pipe and

is vibrated laterally by passing a pressurized fluid therethrough. The vibration rate is controlled by controlling the fluid flow at the surface. Such a device does not provide any positive method to determine when the stuck pipe has achieved resonance, nor any method for sweeping the operating frequency range to determine the optimum operating frequency, nor method to automatically adjust operating parameters such as the fluid flow rate to at

continually or least periodically operate the tool at the optimum frequency.

More recently, surface-operated and surface-controlled resonance tools have been utilized to free stuck tubulars downhole. One such surface tool is available from Baker Hughes Incorporated referred to as the Resonance Tool, Product No. 140-52. It is known that all tubulars exhibit resonant frequencies

that are a function of the free length of the tubular. This resonant tool is

placed at the surface (near the wellhead). It applies acoustic energy to the

stuck point through a work string in order to free the tubular. This tool contains

an oscillator, a hydraulic power pack and a control panel. The control panel

allows for remote control operations of the resonator. Such a tool requires a great amount of power, is large in size and heavy (several thousand pounds), is relatively inefficient because of its great distance from the stuck point and is

expensive to manufacture.

To make a wellbore ready for production of hydrocarbons (i.e., to

complete the wellbore), a liner (which is essentially a tubular string) is inserted into the wellbore with its upper end attached to the casing (previously installed

in the uphole section of the wellbore) with a device known as a liner hanger. Cement is pumped downhole to fill the space (annulus) between the liner and

the wellbore. Frequently the liner is moved up and down and/or rotated during

cementing operations to fill any voids or channels in the annulus and to

generally improve the integrity of the cement bond between the liner and the wellbore. Even using this method, the cement in the annulus in many wellbores includes voids and channels and is not packed as desired. It is

therefore, desirable to have additional and/or alternative methods to improve

the integrity of the cement in the annulus.

The present invention addresses the above-noted and other deficiencies of the prior art resonance devices and provides fishing tools with a downhole resonator, wherein the response of the stuck object to the resonator- induced pulses of mechanical energy is detected by a sensor associated with

the fishing tool. A resonance tool also is provided to aid in the installation of

liners and other cementing operations downhole. A control unit placed at the

surface or in the resonance tool determines the optimum operating frequency

within a range of frequencies and operates the resonator at such determined

frequency. The invention further provides different configurations of the fishing tool for different applications. Additionally, this invention provides certain devices for securing the fishing tool to drill pipes at suitable locations above the stuck point. The fishing tools of the present invention may induce both the lateral and axial vibrations into the stuck object. The present invention also

provides novel devices for latching the resonance tools to tubular members. SUMMARY OF THE INVENTION

In one embodiment, the present invention provides a vibratory and/or resonance device integral to the drill string, which includes a drill bit at its bottom end and a bottom hole assembly uphole from the drill bit for performing downhole measurements during the drilling operations. The vibratory device may be operated at any frequency within a predetermined range of frequencies. The resonator is periodically activated at a selected frequency within a range of frequencies to prevent the drill string from getting stuck.

In another embodiment, a vibratory source is placed in a string utilized for cementing a liner in a wellbore. The liner string includes a liner with a liner hanger attached to its uphole end. A liner hanger running tool is removably attached to the liner hanger for positioning the liner hanger in the casing. A vibratory device is attached above the liner hanger running tool, which is then connected to a drill pipe or a tubing to the surface. The liner hanger is

positioned in place but is not anchored in the casing. During cementing of the wellbore, the vibratory source may be continuously operated or periodically operated to vibrate the liner to improve cementing of the annulus. The liner

hanger is anchored after cementing and the liner hanger running tool is

retrieved from the wellbore.

In an alternative embodiment, a vibratory source is installed in the liner at a predetermined location. The source is operated when the cement and

mud is pumped into the liner during the cementing operations. After cementing, the source is removed from the liner. The fluid flow through the source is set at the surface before installation in the liner to define the frequency of vibration.

The present invention provides a system for freeing an object stuck in a wellbore. The fishing system contains a fishing tool to be conveyed into the wellbore. The fishing tool contains a device for securely engaging the fishing tool to the stuck object. A re of mechanical energy at a number of frequencies within a range of frequencies. A sensor associated with the fishing tool detects the response of the object to the pulses of mechanical energy and generates signals representative of such response. A control circuit within the fishing tool determines the optimum operating frequency for the fishing tool from the sensor signals and causes the fishing tool to operate at the operating frequency to free the object.

In one embodiment, a surface control unit controls the operation of the fishing tool in response to the data transmitted by the fishing tool via a suitable telemetry system. In another embodiment, the control circuit within the fishing tool determines the optimum operating frequency and causes the tool to operate at such frequency.

The resonator may be hydraulically operated by a fluid circulating from a source at the surface, or by a fluid present in the wellbore or by an electro¬ mechanical device, such as a motor or a solenoid or may be a magnetostrictive device. The resonator may produce vibrations radially to the wellbore or along the wellbore axis. Axial vibrations are preferably generated by slugger-type tools. Also, any suitable device may be utilized to engage the resonance tool with the object to be freed. In the case of a stuck drill pipe (object), the resonance fishing tool is anchored within the drill pipe a certain distance above

the stuck point. The resonance is produced in the free length of the drill pipe. In the case of an object that does not have a free pipe section, the resonance fishing tool contains a suitable engagement device at its bottom end and the resonance tool is displaced by an intervening tubular section of a predetermined length, typically about one thousand feet.

The method of freeing an object stuck in a wellbore includes the steps of: (a) conveying a fishing tool in the wellbore, the fishing tool having: a resonator for generating pulses of mechanical energy at a plurality of frequency within a range of frequencies, a sensor associated with the fishing tool for detecting response of the stuck object to the pulses of mechanical energy and for generating signals representative of the response of the drill pipe, and a control circuit for continually or at least periodically determining the optimum operating frequency for the object from the sensor signals and generating corresponding control signals; and (b) securing the fishing tool at the collar; and (c) operating the resonator at the optimum operating frequency to free the dill pipe.

Examples of the more important features of the invention have been

summarized rather broadly in order that the detailed description thereof that

follows may be better understood, and in order that the contributions to the art

may be appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject of the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

For detailed understanding of the present invention, references should

be made to the following detailed description of the preferred embodiment,

taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein:

FIG. 1 shows a schematic illustration of a fishing system for freeing and

retrieving a drill pipe stuck in a wellbore according to one embodiment of the present invention.

FIG. 1A shows an arrangement of certain functional sections of a

downhole resonance tool according to the present invention for use in the

system of FIG.1.

FIG. 1B is an alternative arrangement of certain functional sections of a

resonance tool according to the present invention for use in the system of

FIG.1.

FIG. 2 is a closed-loop block circuit diagram for controlling the

operations of the fishing system of FIG. 1.

FIG. 3 is an alternative closed-loop block circuit diagram for controlling

the operations of the fishing system of FIG. 1.

FIG. 4 shows a hypothetical relationship between the amplitude

response of the stuck object and the frequency of pulses of mechanical energy

generated by a resonance tool.

FIG. 5 is a schematic diagram of a device for anchoring the resonance

tools in a tubular member.

FIG. 6 is a schematic diagram of an alternative device for anchoring the

resonance tool in a tubular member.

FIG. 7 is a schematic illustration of a drill string with a vibratory source

according to one embodiment of the present invention.

FIG. 8 shows a liner string with a vibratory source during the cementing

of a liner in a wellbore with the liner hanger in the open position according to

the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides apparatus and methods utilizing

vibratory and/or a resonance sources for use in performing a suitable

operation in wellbores. Such operations include retrieving an object (fish)

stuck in the wellbore, avoiding getting the drill string from getting stuck during

the drilling operations, freeing a stuck pipe, aiding in the installation of liners

(casings) in the wellbore, and aiding in certain cementing operations

downhole. In general, the system of the present invention contains a

downhole resonance tool that is latched at a suitable place downhole. The

resonance tool includes a pulse generator which generates radial and/or axial

pulses of mechanical energy at different frequencies within a range of frequencies in order to vibrate an object. A control circuit, either placed on the surface or within the resonance tool, monitors the response of the object to the induced mechanical pulses and determines therefrom the natural vibration

frequency for the object that provides the highest transfer efficiency between the resonance tool and the object (also referred herein as the optimum operating frequency). The resonance tool may operate at discrete frequencies within a range of frequencies or may operate to sweep the frequency range. The system then continues to operate the resonance tool at the operating frequency. During operations, the system continuously monitors and determines the optimum operating frequency, which may change as the object is being freed or dislodged from its position.

The use of resonance tools according to the present invention is described by way of examples. Accordingly, FIG. 1 shows a system for freeing

a stuck drill pipe according to the present invention. FIGS. 1A-1B show

examples of embodiments of resonance fishing tool configurations for use in

the fishing system of FIG. 1. FIGS. 2-3 show control circuits for in situ

determination of the response of the stuck object to a resonator and for controlling the operation of the resonator as a function of the response of the object. FIG. 4 shows a hypothetical relationship between amplitude response of the stuck object and the frequency of pulses of mechanical energy generated by a resonance tool. FIGS. 5-6 show embodiments of latching

mechanisms for anchoring the resonance tools to the object to be fished or

retrieved. FIG. 7 shows an embodiment of the drill string incorporating a

resonance device which can be utilized during the drilling of a wellbore to avoid getting the drill stuck in the wellbore. FIG. 8 shows a manner in which the resonance tool of the present invention may be utilized for cementing a liner (casing) in a wellbore.

FIG. 1 is a schematic diagram of a fishing system 10 for freeing and

retrieving a stuck object from within a wellbore 30. As an example and not as

a limitation, the system 10 is shown to free a tubular member, such as a drill

pipe 20, stuck along a zone 22 in an open hole (wellbore) 30. The fishing system 10 includes a rig (typically a workover rig) 15 that includes a rig mast

12 placed on a drilling platform 14. A fluid control unit 16 pumps a desired

fluid 24 into the wellbore 30 via a desired conduit, which depending upon the

application may be a coiled tubing 40 or the drill pipe 20.

A surface control unit 50, preferably placed on the platform 14, controls

the operation of various surface devices including the fluid control unit 16. The surface control unit 50 communicates with a downhole resonance tool 60 (as

described later with reference to FIGS. 2-3) and controls the operation of a

variety of surface and downhole devices according to programmed instruction

associated with the surface control unit 50. The surface control unit 50

includes one or more computers with associated memory, programmed instructions, power supply and a peripheral interface unit. A monitor or display 52, preferably a touch-type monitor, associated with the control unit 50

displays desired information, such as the values of certain operating parameters. A suitable data entry device, such as a key board (not shown),

may be utilized to enter data and instructions to the surface control unit 50.

Alarms, generally denoted herein by numeral 54, are activated by the surface

control unit 50 when certain warning conditions occur during the operation of

the fishing system 10.

Still referring to FIG. 1, the downhole resonance tool 60 is conveyed

into the drill pipe 20 by a suitable conveying member such as coiled tubing 40

or a wireline (not shown). To free the drill pipe 20, the resonance tool 60 is

anchored at a suitable location 64 at a predetermined distance above the stuck

point 22a. The resonance tool 60 may be anchored at additional locations,

such as location 66 within the drill pipe 20. It is known in the art that drill pipes

20 and other objects have a resonance frequency and harmonics thereof that

are a function of the length of the free portion of the drill pipe 20 between the

stuck point 22a and the anchor point 64. Locating the anchor point 64 at a

distance between five hundred feet to one thousand feet is deemed sufficient

to create desired resonance in the drill pipe 20.

FIG. 1A shows an arrangement of certain major functional components

of the resonance tool 60. The resonance tool 60 includes a latching device or

a lower anchor 70 at its lower end and may contain a secondary upper anchor

72 at its upper end. A pulser or resonator 74 disposed above the lower anchor

70, which can operate at any frequency within a predetermined range of

frequencies. Any suitable resonator 74 may be utilized for the purpose of this

invention. One such resonator 74 is disclosed in U.S. Patent No. 4,815,328

issued to Bodine, which is assigned to the assignee of this application and

which is incorporated herein be reference. This patent discloses a roller-type orbiting mass oscillator that generates pulses of mechanical energy in the

radial direction, i.e., orthogonal to the longitudinal axis of the drill pipe 20, when a fluid is passed through this device.

Another resonator 74 is disclosed in the United States Patent No.

4,824,258, issued to Bodine and assigned to the assignee of this application and which is incorporated herein by reference. The U.S. Patent No. 4,824,258 discloses a fluid driven screw type (Moyno) sonic oscillator for generating radial pulses of mechanical energy. Alternatively, the present invention may utilize devices that impart axial pulses of mechanical energy, i.e., along the longitudinal axis of the drill pipe 20. A fluid-driven device that imparts axial vibrations is commercially available from Gefro Oilfield Services a/s of Norway under the trade name "Zeta Tools." The pulse rate (frequency) of the above- noted devices is controlled by controlling the fluid flow through these devices. If a fluid-driven resonator 74 is utilized, the fluid flow may be controlled

at the surface through the fluid control unit 16 (see FIG. 1). In the present

invention, the flow of the fluid 24 is controlled by the surface control unit 50, as

more fully explained later. Alternatively, the fluid flow through resonators 74

may be controlled downhole by the fluid flow control section 76, such as by

directing only the desired amount of fluid 24 through the resonator 74. This

may be done by controllably diverting a portion of the fluid 24 away from the

resonator 74, such as by diverting the fluid 24 into the drill pipe 20 or the wellbore 30 via a control valve (not shown) placed in the fluid path between the

fluid source and the resonator 74. Any suitable flow control device may be

placed in the fluid control section 76 to control the flow of the fluid through the

resonator 74. Such flow control devices are selectively opened and closed to

direct the desired amount of fluid through the resonator 74. The resonance

tool 60 preferably contains a plurality of sensors 68, with at least one such sensor (a resonator sensor) 68a for determining the response of the object or

the drill pipe 20 to the pulses of mechanical energy generated by the resonator

74. An accelerator (not shown) suitably placed in the tool 60 may be utilized

as a sensor 68a for detecting the response of the drill pipe 20 to the resonator

pulses. Alternatively, a plurality of sensors 68 suitably placed in the tool 60

may be utilized for determining the response of the drill pipe 20 to the resonator 74 pulses.

Still referring to FIG. 1A, the resonance tool 60 further includes a

downhole control circuit 78 for continuously monitoring the response of the drill

pipe 20 to the resonator 74 pulses and for controlling the operation of the

resonance tool 60 as a function of such response according to programmed

instruction provided to the downhole control circuit 78. Other sensors 68 such as a pressure sensor, temperature sensor and a fluid flow rate sensor may also be placed in the tool for determining various downhole operating parameters. A two-way telemetry 80 is included in the resonance tool 60 for

communicating data and command signals between the downhole control circuit 78 and the surface control unit 50.

FIG. 1B shows a schematic diagram of an alternative arrangement of the resonance tool 60 configured in a string 90. The string 90 contains the

resonance tool 60 at the upper end of a drill pipe 94 and an engaging device

92 at the bottom end of the drill pipe 94. The engaging device 92 is designed

to latch onto a stuck object (not shown) in the wellbore. The engaging device 92 may be any known engaging device in the art. The engaging device 92 may engage or grab the stuck object at an outer surface or at an inner surface of the stuck object. The engaging device 92 may include a plurality of gripping

members (not shown) which may be independently controlled to move outwardly and inwardly about the tool body. Various types of engaging devices 92 are known in the art and, therefore, are not described in detail

herein.

The resonance tools 60 of the present invention may include a device (not shown) for determining the location of the stuck object, particularly a device for determining the free point of a stuck pipe in a wellbore. Resonance

tools 60 having such devices for determining the free point are useful in that

the resonance tool 60 may be conveyed first to determine the free point and

then anchored at a desired distance above the free point. The resonance tool 60 so used determines the free point and frees the stuck object in a single trip

compared to two trips that will be required if such devices are not integrated into the resonance tool 60.

As noted earlier in FIG. 1, the operation of the fishing system 10,

including the operation of the resonance tool 60 may be controlled by the

surface control unit 50 or by the downhole control circuit 76 associated with the resonance tool 60 or a combination of the two. For simplicity, numeral 60 is

used hereinafter to mean any resonance tool utilized for the purpose of this invention. The operation of the resonance tool 60 controlled by the surface

control unit 50 will be described first while referring to FIGS. 1, 1A, 1B, 2 and

4. The operation of the resonance tool 60 controlled by the downhole control

circuit 78 will be described thereafter while referring to FIGS. 1, 1A, 1B, 3 and

4.

Now referring to FIGS. 1, 1A, 1B, 2 and 4, to free an object (not shown)

stuck in the wellbore 30, the resonance tool 60 is conveyed into the wellbore

30 by any suitable method or device, such as by a wireline, a coiled tubing 40

having a conductor therein or by pumping the resonance tool 60 down into the

wellbore 30 with a fluid 24. In the case of a stuck pipe, the resonance tool 60

is preferably conveyed into the drill pipe 20 via the coiled tubing 40 and

anchored at a predetermined location 64 above the stuck point 22a. In the

case of a stuck object engaging member 92 is securely engaged attached to

the stuck object.

Referring to FIG. 2, once the resonance tool 60 has been properly

engaged with the object to be retrieved, the surface control unit 50 operates

the fluid control unit 16, i.e., pumps the fluid 24 downhole at an initial flow rate

F|_ι. This fluid causes the resonator 74 to generate pulses of mechanical

energy at an initial rate or frequency fi, which causes the stuck object to

vibrate. The resonator sensor 68a detect the response of the object to the

induced pulses of mechanical energy and generate signals that correspond to

the amplitude of the response of the object. The sensor signals are amplified

by an amplifier 108, converted into digital signals by an analog-to-digital

converter (A/D) 110 and fed to a micro-controller 112. The micro-controller

112 may be a general purpose processor, such as a microprocessor, digital

signal processor (DSP) or any other device that can process the required

signals and data from the tool 60. The micro-controller 112 processes the

received sensor signals to determine the amplitude of the response of the

object to the induced pulses or vibrations and further processes such data according to stored instructions (programs) in an associated read only memory

("ROM") 114. The micro-controller 112 stores the computed information in a

downhole memory 116, which may be a random-access-memory ("RAM") and

transmits such data (information) to the surface control unit 50 via the two-way

telemetry 80 over a data bus 118. The surface control unit 50 then changes

the fluid flow rate (and thus the corresponding fluid pressure) by a

predetermined value to F^, which in turn causes the resonator 74 to vibrate at

a corresponding frequency f ₂ . The surface control unit 50 determines the

response of the object at this frequency. This procedure is repeated to sweep

the desired frequency range to determine the optimum or effective operating

frequency. A hypothetical amplitude versus frequency response of the object is

shown in FIG. 4. The local amplitude maxima are shown to occur at points

152, 154, 156 and 158, with the maximum amplitude response occurring at

point 154 and a frequency f ₀ . The surface control unit 50, alone or in

cooperation with the micro-controller 112, adjusts the fluid flow rate to continue

to operate the resonator 74 at the operating frequency f ₀ until the object is

freed. If the effective operating frequency shifts during the operation, the surface control unit 50 can be programmed to continually or periodically adjust

the fluid flow rate so as to operate the resonator 74 at the desired frequency. The above-described operations may be performed by an operator controlling the frequency changes or automatically by the downhole micro-controller 112

and/or the surface control unit 50.

In the case of a stuck drill pipe 20, once the drill pipe 20 is free, the resonance tool 60 is detached and retrieved back to the surface. The drilling

operation is then be continued or the drill pipe 20 is retrieved to either change

the drill pipe 20 and/or to perform some remedial work in the wellbore 30 to

prevent the stuck conditions from recurring. In the case of objects to be retrieved to the surface, the resonance tool 60 is retrieved along with the freed

object.

As noted earlier, the resonator 74 may be a non-fluid operated

resonator 74, such as solenoid operated or electro-mechanically operated. In

such a case, the surface control unit 50 controls the electrical operation of

such devices to operate the resonators 74 at the selected frequencies.

Alternatively, the resonator 74 may utilize a magnetostrictive device, wherein

electrical energy is alternately applied and released in a metal member (not shown) to create acoustic pulses. The frequency of operation is controlled by

varying the rate at which the application of the electrical energy is switched. The resonator 74 may aiso utilize a piezoelectric device (not shown) or any

other device that can generate sufficient energy to vibrate the stuck device.

FIG. 3 is a functional block diagram of a control system which may be

utilized to control the operation of the resonance tool 60 downhole, i.e., by the micro-controller 112. In this system, the micro-controller 112 controls the fluid

flow through the resonator 74 (for a fluid-type resonator) or the electrical energy to the resonator (for an electrically operated resonator), as the case may be, via a resonator control circuit 120. In one embodiment, the resonator

circuit 120 is employed to control a relief valve 121 associated with the

resonance tool 60 in a fluid-operated resonator 74 or the electrical energy supplied to an actuator in an electrically-operated resonator 74, such as

solenoid or motor. The micro-controller 112 also transmits information to the

surface control unit 50. The surface control unit 50 may be programmed to

override operations of the downhole micro-controller 112. Alternatively, an

operator may input instructions to the surface control unit 50 and control the

operation of the system 10 including the downhole resonance tool 60.

As noted above in reference to FIG. 1A, in each of the above-described

systems, other desired sensors 68 are also deployed in the resonance tools

60. The signals from such sensors 68 are amplified and converted by

corresponding amplifiers 108 and A/D converters 112 before being processed

by the micro-controller 112 according to programmed instructions.

FIG. 5 shows a latching device 200 and method for engaging such a

latching device 200 to a tubular member, such as drill pipe 20. During the

drilling operations, one or more landing collars 202, such as lower and upper

collars 202a and 202b, respectively, are installed in the drill pipe 60, where

they are spaced at a selected distance. Two to three such collars 202 are

deemed sufficient for many drilling operations. The spacing between the adjacent collars 202 is preferably between five hundred feet to two thousand

feet. The internal diameter of the successive collars 202 starting from the

lower collar 202a is successively made smaller. As shown in FIG. 5, the

internal diameter of the lower collar 202a is less than the internal diameter of

the upper collar 202b. In this manner, a latching device 200 of suitable external dimensions can be placed at any desired collar 202.

In FIG. 5, the latching device or anchor 200 is shown engaged with the

lower collar 202a. The lower collar 202a has a landing 204 at its upper end

and an internally-threaded section 206 along its internal diameter. The

latching device 200 contains a body 208 having outside dimensions that

enable the latching device 200 to pass through each of the collars 200 that precede (are uphole from) the lower collar 202a. The latching device 200

contains a flange 210 that is designed to rest or seat on the landing 204. The

latching device 200 also has threads 212 along its outer surface. These

threads 212 are designed to engage the internally-threaded section 206 of the

collar 202a. The latching device 200 also includes a spring 214 above the

threads of the internally-threaded section 206 and a plurality of seals 216

between the spring 214 and the flange 210.

To engage the latching device 200 with the collar 202a and, therefore,

the drill pipe 20, the latching device 200 is conveyed into the drill pipe 60 by a

suitable conveying member 40, such as coiled tubing, wireline or by pumping it

downhole by a fluid. Because the outer dimensions of the latching device 200

are smaller than the inside dimensions of any of the collars 202 located above

the lower collar 202a, the latching device 200 will pass all such collars 202

when conveyed downhole. When the latching device 200 reaches the lower

collar 202a, the latching device 200 is securely engaged with the lower collar

202a by engaging the threads 212 with the threads of the internally-threaded

section 206. The spring 214 provides resiliency to the connections and the

seals 216 prevent leakage of fluids around the latching device 200. The

resonance tool 60 may be attached at the bottom end of the latching device

200, as shown in FIG. 5 or above (not shown) the latching device 200. The

resonance tool 60 is retrieved from the wellbore 30 by disengaging the latching

device 200 from the lower collar 202a.

FIG. 6 shows another embodiment of a latching mechanism for

anchoring the resonance tool 60 in a tubular member 20 such as the drill pipe.

A carrier 122 is anchored at a suitable location in the drill pipe 20. The carrier

122 has an inner landing support 124. To anchor the resonance tool 60 to the

tubular member 20, the resonance tool 60 is conveyed into the tubular member

20. The resonance tool 60 has a seat 126 that is designed to rest on the inner

landing support 124. The resonance tool 60 also has an outside threaded

portion 128 that is screwed into the carrier 122. The resonator 74 shown is a

Moyno-type resonator, which includes a rotor 130 whose longitudinal axis Xι-Xι is parallel but offset to the longitudinal axis x-x of the resonance tool 60. The rotor 130, when rotated about the axis X ₁ -X ₁ , generates radial (orthogonal to

the longitudinal axis x-x) pulses of mechanical energy in the tubular member

20. The rotor 130 may be rotated by passing a fluid under pressure along the longitudinal axis, or by an elector-mechanical device, such as a motor (not shown). The operation of the resonator 74 is controlled in the manner

described above with reference to the resonator 74 of FIG. 1.

Alternatively, any commercially available anchor may be utilized for the purpose of this invention. Some such devices are referred to in the oil and gas industry as the liner hangers. A wide variety of liner hangers are sold by a

number of manufacturers, including the assignee of this application. Additionally, any commercially available engagement device may be utilized for applications where the resonance tool is used to engage with any other object stuck in the wellbore. A variety of engagement devices are currently available for engaging fishing tools with the objects to be retrieved.

FIG. 7 is a schematic illustration of a drill string 300 with a vibratory

source (resonance tool) 60 attached to a suitable conveying member, such as

drill pipe 20, at an upper end and to the upper collar 202b at a lower end. The

upper collar 202b is then connected to a bottom hole assembly (BHA) 302,

which preferably includes a plurality of stabilizers 304 connected via the lower

collar 202a to a drill bit 306, to complete the drill string 300.

In a typical drilling operation, the drill bit 306 sometimes becomes stuck

due to such factors as the wβight-on-bit (weight of uphole equipment and drill

pipe 20 on the drill bit 306), the rotary speed of the drill bit 306 and/or the fluid

flow rate. With the preferred embodiment of the present invention, a signal

can be communicated to the resonance tool 60 to start an operation to free the

drill bit 306. As described above, the resonator 74 (FIG. 1) contained within

the resonance tool 60 is activated and a sweep of frequencies is performed to

determine an optimum or effective frequency.

During drilling operations, the vibratory device (resonator) 74 is

operated at a predetermined frequency or at several frequencies to determine the effective frequency. During normal drilling, the vibratory source 74 may be

periodically operated for a predetermined time period. Typically, the resonator

74 is operated during the times when a drill pipe section is added to the drill

string, which usually occurs after the drilling of every 30 or 40 feet. The

vibratory source 74 may be fluid operated, such as by the drilling fluid 24, or

may be an electrically operated device, such as a magnetostrictive device.

The vibratory source 74 may be operated independently of any other device in

the drill string. For fluid operated vibratory source, valves associated with the

source control the fluid flow through the source, thereby controlling the

operating frequency of the source. The source may be operated to sweep the frequency range to determine the most effective frequency and then operated

at such frequency.

Resonator sensors 68a (FIG. 3) transmit signals to either the surface

control unit 50 or the downhole micro-controller 212 and the frequency is then

selected. The resonator 74 is operated at the determined frequency, as

described above, until the drill bit 306 is freed and drilling operations can be

continued. By having the resonance tool 60 downhole as an integral part of

the drill string 300, lost time due to a stuck drill bit 306 can be minimized.

The use of the resonance devices for cementing operations will now be

described while referring to FIG. 8, which shows, by way of an example, a liner

string 320 disposed in the wellbore 30 during a cementing of a liner 322. The

liner string 320 is shown to include the liner 322, a liner hanger 324, a liner

hanger running tool 326 and the vibratory source (resonance tool) 60. The

liner string 320 is detachably connected to a conveying member, such as drill

pipe 20. The liner string 320 is run downhole until the liner hanger 324 is

positioned at a desired location in the wellbore 30.

In prior art operations (not shown), the liner hanger 324 is typically first

anchored in the casing 18. The cement 330 is then circulated through the

annulus between the liner 322 and the wellbore 30. The liner 322 is

sometimes jarred or rotated to obtain more effective cementing in the annulus.

In this preferred embodiment of the present invention, however, the

liner hanger 324 is not anchored prior to cementing. Cement 330 is pumped

downhole through tubing 328 and flows from the bottom of the liner 322 and up

the annulus located between the liner 322 and the wall of the wellbore 30. In

one preferred embodiment, the resonance tool 60 is activated during the

cementing process. In another embodiment, the resonance tool 60 is activated

after circulating a predetermined volume of the cement 330 in the annulus. If a

fluid-operated source is utilized, the slurry of cement 330 used for cementing

the annulus may be used to operate the vibrating source (resonator) 74.

Alternatively, after circulating a predetermined volume of the cement 330 in the

annulus, the resonator 74 may be sealed from the liner hanger 324 by closing

a valve (not shown) between the liner hanger 324 and the resonator 74. The

resonator 74 is then operated at an effective frequency within a predetermined

range of frequencies to vibrate the liner 322, which shakes the cement 330 in

the annulus and causes voids and channels in the annulus to be filled with the cement 330.

The resonator 74 generates pulses of mechanical energy which cause

the liner 322 and the cement 330 to vibrate. These vibrations cause the

cement 330 in the annulus to shift and causes voids and channels in the

annulus to be filled with the cement 330. Once the cementing operation is

completed, the liner hanger 324 is anchored via anchors 338, the liner hanger

running tool 326 is detached from the liner hanger 324 and is retrieved with the

resonance tool 60 back to the surface.

In a similar method involving cementing operations in the wellbore 30, a

vibrating source 74 is integrated into a running tool string and is activated at a

determined frequency, after sweeping the frequencies as described above,

during the cementing operation. One such operation is the sealing of a

juncture (not shown) with cement 330. The vibrations cause the cement 330

around the juncture to shift such that voids and channels will fill with cement 330 as described above.

Thus, the present invention provides apparatus and method for use of

resonance or vibratory devices for performing an operation downhole. The

resonance device may be any suitable device and may include a lateral force generator, an axial force generator, a mechanical force generator, a solenoid- operated force generator, an electro-mechanical device, an inductive device a

fluid-operated device and a magnetostrictive device. The resonator is suitably

placed in the wellbore and operated at an effective frequency selected from a range of frequencies. A sensor associated with the resonator is utilized to detect the response of an object in the wellbore, which is utilized to adjust or

alter the operating frequency of the resonator. The object in the wellbore may be a fish, a stuck tubing, a drill string, a liner, and a member associated with performing a cementing operation in the wellbore or any other suitable element while the selected operation may include fishing, freeing a stuck drill string,

freeing a stuck tubular, installing a liner, cementing a juncture, a general

cementing operation, and drilling of a wellbore.

While the foregoing disclosure is directed to the preferred embodiments of the invention, various modifications will be apparent to those skilled in the art. It is intended that all variations within the scope and spirit of the appended

claims be embraced by the foregoing disclosure.