TECHNICAL FIELD

[0001] The present disclosure is directed at methods, systems, and techniques for detecting gas flow.

BACKGROUND

[0002] The ability to measure gas flow may be advantageous in a variety of industries. For example, in the oil and gas industry surface casing vent flow refers to the flow of gas between the surface and production casings of a well. By traveling upwards between the surface and production casings, the gas, which typically comprises a gaseous hydrocarbon, may escape to and pollute the atmosphere. In addition to the inherent harm that this type of pollution represents, government regulations may mandate well monitoring to determine if a well is experiencing surface casing vent flow and, if it is, those regulations may also prescribe that remedial action be taken.

SUMMARY

[0003] In accordance with an illustrative embodiment of the disclosure, there is provided a system for detecting a flow of gas. The system includes a flow meter comprising an inlet for receiving the gas, a vent for venting the gas after having been received by the flow meter, and an analog output that moves proportionally to the volume of the gas flowing through the flow meter. The system also includes a digital encoder having a mechanical, analog input and an electronic, digital output, wherein the digital output outputs an electronic signal that is a digitization of the analog input and wherein the analog input of the digital encoder is coupled to the analog output of the flow meter such that the analog input mirrors the movement of the analog output.

[0004] The analog input of the digital encoder may be directly coupled to the analog output of the flow meter. [0005] The analog output of the flow meter may include a rotatable shaft. The shaft rotates in a first direction when the gas flows into the meter through the inlet and rotates in an opposite, second direction when the gas flows out of the meter through the inlet.

[0006] The encoder may output 1,024 electronic signals for a single rotation of the shaft.

[0007] The system may also include a bypass line coupled to the inlet. The bypass line may have an open and a closed configuration and may be coupled to a second vent. The bypass line directs gas away from the flow meter and to the second vent when the bypass line is in the open configuration.

[0008] The system may also include a solenoid valve having a first port coupled to the flow meter and a second port coupled to the bypass line. The first port is closed and the second port is open when the bypass line is in the open configuration and the first port is open and the second port is closed when the bypass line is in the closed configuration.

[0009] The system may also include a build-up line coupled to the inlet, the buildup line having an open and a closed configuration. The gas collects in the build-up line when the build-up line is in the closed configuration.

[0010] The system may also include a solenoid valve coupled to the flow meter between the build-up line and the flow meter, a bypass line coupled to the build-up line, and a pressure safety valve located on the bypass line. The solenoid valve is closed when the build-up line is in a closed configuration and the pressure safety valve is configured to open if the pressure in the system exceeds a pre-set level.

[0011] The system also includes an input line coupled to the inlet. The input line comprises an air filter for filtering the gas, a pressure transducer for measuring the line pressure, a thermocouple, a pressure regulator for reducing pressure along the line, at least one bypass line with a pressure safety valve for relieving pressure in the system, at least one solenoid valve for controlling gas flow to the flow meter, and a high flow line with a high flow valve coupled to the input line on either side of the solenoid valve for bypassing the solenoid valve.

[0012] In accordance with another illustrative embodiment of the disclosure, there is provided a system for detecting a flow of gas. The system includes a flow meter comprising an inlet for receiving the gas, a vent for venting the gas after having been received by the flow meter, and an analog dial comprising a hand that rotates proportionally to the volume of the gas flowing through the flow meter. The system also includes a pulser comprising a coupler comprising a pair of teeth positioned on either side of the hand to rotatably couple the coupler to the hand and an encoder mechanically coupled to the coupler that outputs electrical pulses in response to rotation of the coupler.

[0013] The hand may rotate in a first direction when the gas flows into the flow meter through the inlet and rotate in an opposite, second direction when the gas flows out of the flow meter through the inlet.

[0014] The flow meter may include a positive displacement meter.

[0015] The flow meter may be selected from the group consisting of a positive displacement flow meter, an orifice flow meter, a turbine flow meter, and a mass flow meter.

[0016] The system may also include a bypass line coupled to the inlet. The bypass line may have an open and a closed configuration and may be coupled to a second vent. The bypass line directs gas away from the flow meter and to the second vent when the bypass line is in the open configuration.

[0017] The system may also include a solenoid valve having a first port coupled to the flow meter and a second port coupled to the bypass line. The first port is closed and the second port is open when the bypass line is in the open configuration and the first port is open and the second port is closed when the bypass line is in the closed configuration.

[0018] The system may also include a build-up line coupled to the inlet, the buildup line having an open and a closed configuration. The gas collects in the build-up line when the build-up line is in the closed configuration.

[0019] The system may also include a solenoid valve coupled to the flow meter between the build-up line and the flow meter, a bypass line coupled to the build-up line, and a pressure safety valve located on the bypass line. The solenoid valve is closed when the build-up line is in a closed configuration and the pressure safety valve is configured to open if the pressure in the system exceeds a pre-set level.

[0020] The encoder may be configured to output a pulse for a detected movement of the gear representing less than 7 mL of gas flow.

[0021] The encoder may be configured to output 1,024 pulses for every rotation of the dial.

[0022] In accordance with another illustrative embodiment of the disclosure, there is provided a method for measuring fluid flow. The method includes receiving fluid flow in a flow meter, detecting, through physical contact with the flow meter, movement of a shaft in the flow meter that moves proportionally to the volume of fluid flowing through the flow meter, and outputting a pulse based on the movement of the shaft.

[0023] The method may also include building up fluid pressure by holding the fluid before the fluid is received in the flow meter.

[0024] The pulse may be output for a 1/1, 024 ^th revolution of an output dial coupled to the shaft.

[0025] The pulse may correspond to 7 mL of fluid flowing through the flow meter. [0026] This summary does not necessarily describe the entire scope of all aspects.

Other aspects, features and advantages will be apparent to those of ordinary skill in the art upon review of the following description of specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the accompanying drawings, which illustrate one or more example embodiments:

[0028] FIG. 1 is a block diagram of a system for detecting gas flow according to a first embodiment;

[0029] FIG. 2 is a schematic drawing of a gas flow meter assembly comprising part of the system of FIG. 1;

[0030] FIGS. 3A, 3B, and 3C are views of a coupler coupled with a faceplate of a flow meter, both of which comprise part of the assembly of FIG. 2;

[0031] FIG. 4 is a flowchart depicting a method for detecting gas flow, according to another embodiment;

[0032] FIG. 5 is a graph showing intermittent flow as measured by the assembly of FIG. 2;

[0033] FIG. 6 is a graph showing slight intermittent flow as measured by the assembly of FIG. 2; and

[0034] FIG. 7 is a graph showing positive and negative flow as measured by the assembly of FIG. 2.

DETAILED DESCRIPTION

[0035] Directional terms such as "top", "bottom", "upper", "lower", "left",

"right", and "vertical" are used in the following description for the purpose of providing relative reference only, and are not intended to suggest any limitations on how any article is to be positioned during use, or to be mounted in an assembly or relative to an environment. Additionally, the term "couple" and variants of it such as "coupled", "couples", and "coupling" as used in this description are intended to include indirect and direct connections unless otherwise indicated. For example, if a first device is coupled to a second device, that coupling may be through a direct connection or through an indirect connection via other devices and connections. Similarly, if the first device is communicatively coupled to the second device, communication may be through a direct connection or through an indirect connection via other devices and connections.

[0036] The ability to detect and measure gas flow may be useful in a number of applications. For example, landfill gas may be monitored in order to ensure compliance with applicable governmental regulations and to facilitate collection of methane for power generation purposes. Similarly, gas generated during industrial processes such as waste water (e.g., sewage) treatment, pulp and paper processing, and mining may be monitored as well. In particular, in the oil and gas industry, monitoring surface casing vent flow ("SCVF") may be a legal requirement and may be useful when attempting to mitigate problems such as pollution and soil contamination.

[0037] Monitoring SCVF may provide useful information about the integrity of a well. Continuous, high resolution monitoring capable of detecting small gas flows may show patterns in, for example, gas flow frequency and volume, that provide information about the effectiveness of an intervention to remediate a well. The volume of gas that a well emits as a result of SCVF may be relatively low, such as on the order of milliliters per year or years. The present disclosure describes embodiments of a method and system for detecting gas flow that is used for monitoring relatively low gas flow volumes and, in the depicted example embodiments, is used to measure SCVF by measuring gas flow exiting or entering a surface casing vent of a well. Gas "exiting" the well is leaving the interior of the well via the surface casing vent and entering the atmosphere, whereas gas "entering" the well is entering the interior of the well via the surface casing vent from the atmosphere.

[0038] In the present disclosure, the system comprises a gas flow meter that is able to detect and measure gas flow in 7 mL increments. The time required for this increment of gas flow to pass through the meter may be as short as on the order of seconds or as long as on the order of years, and as discussed in further detail below the gas flow meter is able to detect both positive flow (i.e., gas exiting the well) and reverse flow (i.e, gas entering the well). Reverse flow may result from changes in barometric pressure, temperature, or other variables such as changes in reservoir or wellbore conditions. Detecting reverse flow may be useful for wells with low flow rates, as the reverse flow may be higher than the positive flow, creating a net or cumulative reverse flow. Flow meters that do not detect reverse flow may measure reverse flow as positive flow leaving the well, providing an inaccurate picture of the well's integrity.

[0039] Referring to FIG. 1, a system 100 for detecting gas flow is shown. In FIG.

1, a well 110 is shown extending through a formation; while not depicted, the well 110 comprises various casings, such as production casing and surface casing. At the top of the well 110 is a wellhead 112 that comprises a vent 114 to which the system 100 is fluidly coupled. The system 100 comprises a gas flow meter assembly 120 and an inlet 210, high pressure vent 215, and low pressure vent 250 each fluidly coupled to the assembly 120. The inlet 210 permits the gas flow meter assembly 120 to exchange gas with the vent 114, while the high and low pressure vents 215,250 are each selectably fluidly couplable to the inlet as discussed in more detail below in respect of FIG. 2. The system 100 also comprises a processor 122 ("system processor 122"), a non-transitory computer readable medium in the form of a memory 124 ("system memory 124"), and a communications interface 126 ("system communications interface 126") for communicating with a computer 150. The system processor 122 is communicatively coupled to each of the system memory 124 and the system communications interface 126. The computer 150 analogously comprises a processor 152 ("terminal processor 152"), a non-transitory computer readable medium in the form of a memory 154 ("terminal memory 154"), a display 158, and a communications interface 156 ("terminal communications interface 156") for communicating with the system 100 via the system communications interface 126. The terminal processor 152 is communicatively coupled to each of the terminal memory 154, the display 158, and the terminal communications interface 156. As discussed in further detail below, the terminal processor 152 may display various graphs, such as those depicted in FIGS. 5 - 7, on the display 158.

[0040] The system 100 of FIG. 1 is designed to detect and measure gas emitted from a well 110 as a result of SCVF in particular, although in different embodiments (not shown) and as discussed above, the system 100 may be used to detect and measure gas flow in other applications, and in particular industrial applications.

[0041] Referring now to FIG. 2, there is shown a schematic drawing of the gas flow meter 252 and a pulser 254 to which the flow meter 252 is connected. The flow meter 252 may be fluidly coupled to the well 110 through any suitable configuration of gas lines and gas measurement and control components, including, for example, filters, safety valves, regulators, thermocouples, check valves, pressure sensors, and solenoid valves. In typical operation, gas from the well 110 enters the assembly 120 via the inlet 210. The gas flows through a number of components before entering the flow meter 252, which is coupled to the pulser 254. A first bypass line 216 is included to vent the gas through a high pressure vent 215 when the incoming gas exceeds a pressure threshold; the first bypass line 216 includes a pressure safety valve 218 rated for that threshold. In some embodiments, the pressure safety valve 218 is rated for 500 pounds per square inch (psi). In certain embodiments, the pressure safety valve 218 may be remotely set to any suitable pressure between 0 to 500 psi for casing depths of 0 to 318m, for example; alternatively, the pressure safety valve 218 may be set to a value selected from the range of 0 to 500 psi regardless of casing depth, or to a value that exceeds 500 psi. If pressure in the inlet line of the assembly 120 is higher than the setpoint for that well 110, such as, for example, 500 psi, the pressure safety valve 218 opens, thereby venting gas to the high pressure vent 215. Once pressure is reduced to less than the input setpoint, the pressure safety valve 218 is reseated and flow continues along the main line towards a filter 219. Examples of suitable pressure safety valves include valves manufactured by Swagelok™ Company.

[0042] The line pressure is kept at or below a maximum pressure of 500 psi in the embodiment of FIG. 2 due to the filter 219 having a maximum pressure rating of 500 psi. In some embodiments, the maximum pressure in the initial portion of the line may be kept below any suitable maximum pressure depending on the devices present along the line. In certain embodiments, there may be no first bypass line 216 and the gas entering the assembly 120 through the inlet 210 proceeds to the filter 219 regardless of its pressure.

[0043] The filter 219 reduces the proportion of contaminates such as oil, water, and dirt in the gas. The gas venting from the well 110 may be dirty or contaminated to an extent that it would damage the flow meter 252; for example, in embodiments in which the flow meter 252 comprises a positive displacement flow meter, the filter 219 prevents liquid from reaching the meter 252. Any suitable filter for filtering the gas to an appropriate level for flowing through the flow meter 252 may be used. For example, high efficiency filters by Headline Filters™ may be used.

[0044] Pressure transducers 220 may be used to measure the line pressure at various points in the assembly 120. For example, in the embodiment shown in FIG. 2, a first pressure transducer 220a is used to measure pressure between the first bypass line 216 and a second bypass line 222. In the depicted embodiment, the first pressure transducer 220 measures pressures up to 3,500 kPa. A second pressure transducer 220b is located downstream of the second bypass line 222 and upstream of a build solenoid 236 and a flow solenoid 237. In the depicted embodiment, the second pressure transducer 220b is rated to measure pressures up to 50 kPa. While the two pressure transducers 220a,b are shown in FIG. 2, in different embodiments (not depicted), the assembly 120 may comprise fewer or more than two transducers, and the transducers 220a,b in different embodiments may also be rated for pressures different than those of the depicted embodiment. For example, the pressure transducers 220a,b may have pressure ratings suitable for various flow conditions. The pressure transducers 220a,b may be selected to operate in harsh conditions. For example, in some embodiments, the UNIK 5000™ series of pressure sensors by General Electric™ may be used.

[0045] A pressure regulator 225 is used to regulate pressure at a point downstream of the inlet 210 to a set pressure point. In the embodiment shown in FIG. 2, the pressure regulator 225 has a setpoint of 30 psi. In other embodiments, any suitable pressure may be used as a setpoint and any suitable pressure regulator may be used. For example, a Fisher™ brand regulator by Emerson™ may be used and set to 30 psi.

[0046] A thermocouple 230 may be used to measure gas temperature in the assembly 120. Any suitable thermocouple 230 may be used. For example, in some embodiments, a Type K thermocouple is used.

[0047] The build solenoid 236 and flow solenoid 237 are used for different operating modes of the assembly 120. A "build-up" mode is used for building up pressure within the assembly 120. In certain embodiments, a build-up line is coupled to the flow meter 252. The build-up line has an open and a closed configuration, wherein the gas collects in the build-up line when the build-up line is in the closed configuration. In the embodiment shown in FIG. 2, energizing the build solenoid 236 stops flow through it; subsequently closing the high flow valve 238 in the high flow line 240 puts the assembly 120 in the build-up mode. In some embodiments, the build-up mode is used for conducting build-up tests, such as an ER Guide 20 test with a rate of 2 kPa/hr over a 6 hour gradient to determine whether the well 110 is stable. The second bypass line 222 with a pressure safety valve 227 may be used to keep the pressure at safe levels. The pressure safety valve 227 may have any suitable pressure setting; in the embodiment shown in FIG. 2, the pressure safety valve 227 opens when the line pressure along the second bypass line 222 meets or exceeds 35 psi. [0048] Alternatively, the assembly 120 may operate in a "bypass" mode. In some embodiments, a bypass line having an open and a closed configuration may be used to direct gas away from the flow meter 252 and to the vent 215 when the bypass line is in the open configuration. In the embodiment shown in FIG. 2, if the assembly 120 is in the bypass mode, both the build solenoid 236 and the flow solenoid 237 are de-energized and a high flow valve 238 is closed, allowing gas to flow to the high pressure vent 215 through a check valve 245.

[0049] The assembly 120 may also operate in a "flow" mode. In the flow mode, the build solenoid 236 is de-energized and the flow solenoid 237 is energized, allowing gas to flow through the flow meter 252 and out of a low pressure vent 250 while blocking flow to the high pressure vent 215 through the flow solenoid 237. For high flow, the high flow valve 238 may also be opened. The high flow valve 238 may be opened, for example, when back flow pressure exceeds the solenoid differential pressure, thereby preventing high differential flow across the solenoids 236,237. A third bypass line 247 containing a pressure safety valve 248 may be coupled to an inlet of the flow meter 252 to vent gas to the high pressure vent 215 if the pressure exceeds a safe pressure for the flow meter 252. For example, in the embodiment of FIG. 2, the pressure safety valve 248 opens if the pressure exceeds 5 psi, although in different embodiments the pressure safety valve 248 may be set to open at a different pressure.

[0050] In some embodiments, the assembly 120 may include a barometer for measuring and outputting barometric pressure. Measuring barometric pressure may allow evaluation of the effect of barometric pressure on well breathing (gas flow into and out of the well 110).

[0051] Any suitable flow meter 252 may be used. For example, a positive displacement flow meter, a turbine meter, an orifice meter, or a mass flow meter may be used as the flow meter 252, depending on the embodiment. In certain embodiments, including the embodiment shown in FIG. 2, the flow meter 252 is a positive displacement flow meter. A positive displacement flow meter measures volumetric flow rates by having the flowing fluid mechanically displace components within the flow meter 252. Fixed amounts of displacement of the components, which may include, for example, gears, pistons, or diaphragms, correspond to certain volumes of fluid. The flow meter 252 in the embodiment shown in FIG. 2 is a positive displacement flow meter using diaphragms to measure fluid flow. For example, an Elster American™ meter class AC- 250 may be used. Fluid enters an inlet side of an oscillating diaphragm and then flows to an outlet; oscillation cycles are then counted to determine the flow rate. A mechanism, including arms and gears, is used to translate the motion of the diaphragms to rotational motion of an output shaft (not shown) for rotating dials on an external face of the flow meter 252, as referenced in FIGS. 3A - 3C below.

[0052] Referring generally to FIGS. 3A - 3C, there are shown various views of a coupler 310 coupled with a faceplate 312 of the flow meter 252 and used to couple the pulser 254 to the flow meter 252. The pulser 254 comprises an encoder 350 and a printed circuit board ("PCB") 352. In the depicted embodiment, the encoder 350 is mechanically coupled to the flow meter 252 through the coupler 310, which comprises a rotating shaft 317 and teeth 315. The rotating shaft 317 represents an analog signal, which the encoder 350 converts to a digital signal and outputs to the PCB 352. The PCB 352 generates pulses from the encoder 310 output. In the depicted embodiment, the PCB 352 comprises the system processor 122. The system processor 122 may be, for example, an Atmel™ ATXMEGA32D4 AU 1343 processor. The system processor 122 permits various other functions, in addition to generating pulses, such as logging, averaging flow rates, and generating serial output rather than pulse output. In some embodiments, the system processor 122 is located away from the PCB 352 and is communicatively coupled to the PCB 352. In certain embodiments, the functions performed by or permitted by the system processor 122 may be performed by a logger in the assembly 120. The logger may be, for example, a DT82i logger.

[0053] In FIG. 3 A, the coupler 310 is shown in an uncoupled position, spaced apart from the faceplate 312 of the flow meter 252. When the pulser 254 is coupled to the flow meter 252, the coupler 310 is positioned to sit overtop a hand 320 of an analog dial on the flow meter's 252 faceplate 312, as shown in FIG. 3B. The coupler 310 is positioned so the teeth 315 extending from the coupler 310 are on either side of the hand 320. As the hand 320 rotates, it pushes against the teeth 315, causing the coupler 310 to rotate with the hand 320. The hand 320 may rotate in one direction for positive flow and in the opposite direction for negative flow. One full rotation of the hand 320 may represent a certain volume of gas flow (e.g., 0.25 ft ), but the sensitivity of the pulser 254 may permit flow to be detected at a higher resolution of, for example, <= 7 mL, and the flow meter 252 may output a pulse for particular increments of detected flow. The pulses are communicated to the computer 150 by the pulser 254. The computer 150 analyzes the pulse data and may produce, for example, a graphical output of flow over a period of time as shown in FIGS. 5 to 7.

[0054] The coupler 310 transmits the rotation of the hand 320 to the encoder 350, which is mounted to the PCB 352. The encoder 350 translates the analog motion of the hand 320 and the coupler 310 into digital data. Each revolution of the hand 320 is encoded by the encoder 350 as multiple data points. In some embodiments, the encoder 350 may be a Bourns™ EMS 22A 1,024 bit encoder 350, which encodes a full revolution of the coupler into 1,024 bits. The PCB 352 may produce a pulse for each data point encoded by the encoder 350, resulting in, for example, 1,024 pulses for each revolution of the hand 320 or one pulse for each 1/1, 024th revolution.

[0055] The pulser 254 may be further coupled to the flow meter 252 using suitable coupling means for maintaining the coupler's 310 position overtop of the hand 320. For example, bolts (not shown) may be used to attach the pulser 254 to the faceplate 312. The bolts may pass through apertures 380 in the PCB 352.

[0056] In some embodiments, the hand 320 may display flow through the flow meter 252 as measured in relatively coarse or low resolution units, such as cubic feet. For example, a full revolution of the hand 320 may represent 0.25 ft ³ of flow. Although a full rotation of the analog dial may represent 0.25 ft ³ of flow, the components being displaced by fluid within the flow meter 252, such as diaphragms, move due to much smaller volumes of fluid flowing through the flow meter 252. These movements are communicated to the hand 320 through an output shaft 355 and a set of gears, causing the hand 320 to rotate proportionally to the volume of the gas flowing through the flow meter 252. Any suitable set of gears with may be used to couple the output shaft 355 to the hand 320.

[0057] In the embodiment shown in FIG. 3C, the output shaft 355 is coupled to a drive gear 360a. The drive gear 360a is engaged to and drives an idler gear 360b. Idler gear 360b is rotationally coupled to idler gear 360c, which in turn is engaged with driven gear 360d. Driven gear 360d is attached to a shaft 361. The hand 320 is also attached to the shaft 361 and rotates as the driven gear 360d rotates. The coupler 310, rotatably coupled to the hand 320 through a pair of teeth 315 positioned on either side of the hand 320 and mechanically coupled to the encoder 350, communicates the analog motion of the hand 320 to the encoder 350. The encoder 350 outputs electrical pulses in response to the rotation of the coupler 310.

[0058] For a single revolution of the hand 320, the encoder 350 may produce multiple points. For example, in some embodiments, the encoder 350 may generate 1,024 points per revolution, or one point for about every 7 mL of gas (6.91 mL +/- 0.2%). In some embodiments, a higher resolution encoder 350 may be used, producing more than 1,024 bits per revolution. A higher resolution output may also be achieved by using additional gearing to multiply the amplification of the measurements made by the flow meter 252.

[0059] In some embodiments, the coupler 310 may be coupled to the output shaft

355 of the flow meter 252 rather than to the hand 320, allowing rotation of the output shaft 355 to be communicated to the coupler 310 without the rotation first being communicated to the hand 320. An opening in the face of the flow meter 252 may allow the output shaft 355 to be coupled to the coupler 310. [0060] In certain embodiments, a system 100 for detecting a flow of gas comprises a flow meter 252 and a digital encoder 350. The flow meter 252 includes an inlet 210 for receiving the gas, a vent 250 for venting the gas after having been received by the flow meter 252, and an analog output that moves proportionally to the volume of the gas flowing through the flow meter 252. The digital encoder 350 has a mechanical, analog input and an electronic, digital output. The digital output outputs an electronic signal that is a digitization of the analog input. The analog input of the digital encoder 350 is coupled to the analog output of the flow meter 252 such that the analog input mirrors the movement of the analog output.

[0061] The assembly 120 may also measure reverse or negative flow rates. In some embodiments, the hand 320 rotates in a first direction when the gas flows into the flow meter 252 through the inlet 210 and rotates in an opposite, second direction when the gas flows out of the flow meter 252 through the inlet 210. In certain embodiments, a cumulative volume may also be quantified by subtracting reverse flow from positive flow.

[0062] The assembly 120 may detect both small volumes of gas flow and low rates of gas flow by detecting small volumes over periods of time up to several years. For example, the assembly 120 may be calibrated to measure <=7 mL/any duration of time (years) at the low end, to 170 m ³ /day at the high end.

[0063] The pulser 254, comprising the coupler 310, the encoder 350, and the PCB

352, may be communicatively coupled to a processor 122 and readable memory 124 for analysing and storing the data produced by the pulser 254. Similarly, other components of the assembly 120, such as, for example, a thermocouple 230 or pressure transducers 220, may also be communicatively coupled to processor 122 and memory 124. In some embodiments, the processor 122 may also be communicatively coupled to a display. The assembly 120 may also include a communications interface 126 for communicating with an external computer 150, such as, for example, a laptop computer. In some embodiments, the processor 122 and memory 124 for analysing and storing the data produced by the pulser 254 may be part of the external computer 150. In certain embodiments, the processor 122 and memory 124 for analysing and storing the data produced by the pulser 254 may be separate from the external computer 150 and may be communicatively couplable to the external computer 150. The assembly 120 may be physically communicatively couplable to an external computer 150 through, for example, wires, or it may be communicatively couplable to the computer through a wireless connection.

[0064] In some embodiments, the pulser 140 may have a protective housing. The protective housing may be an enclosure or a partial enclosure such as a box or a cage with ports for connecting wires. The cover may be constructed of any suitable material, such as, for example, metals, including aluminum alloys and steel, polymers, and composite materials.

[0065] The gas flow meter may be transported long distances and used in harsh environments. It may be left in harsh environments for extended periods of time. In certain embodiments, the assembly 120 may be placed in a protective frame to protect it during transport and in harsh environments. The protective frame may be part of an enclosure, such as a box or cage with access panels or doors and ports for inlets, vent lines, and wires. The enclosure may include components made of metallic parts, such as, for example, steel or aluminum alloys. In some embodiments, the enclosure may also include polymer and/or composite parts.

[0066] In some embodiments, the assembly 120 includes a portable power supply for providing electrical power for the electrical elements of the assembly 120. Any suitable method of supplying electrical power may be used. For example, the power supply may be a battery, such as a rechargeable battery. The batter may be removable so that it can be replaced with a charged battery. In certain embodiments, the assembly 120 includes a solar panel for supplying electrical power. The solar panel may, for example, charge a battery in the assembly 120. In certain embodiments, a diesel or gasoline powered generator may be used to provide power for the assembly 120. In some embodiments, the assembly 120 may include an electrical terminal for connecting the gas flow meter to an external power source through an electrical cord.

[0067] In some embodiments, the assembly 120 may have a connection for uploading data to and downloading data from a satellite. Users may then use the assembly 120 to monitor wells in remote locations without needing to be present at the site.

[0068] Referring to FIG. 4, a method 400 for detecting and measuring vent flow is shown. At block 410, gas from a surface casing of a well enters an inlet of the assembly 120. At block 420, the gas is filtered to reduce the proportion of contaminants in the gas. A pressure safety valve 218 may be used to reduce the pressure to levels safe for the filter 219. At block 420, the pressure of the gas is reduced to a pre-set level. At block 430, the temperature is measured. At block 440, the flow of gas is measured. The gas flows through a flow meter 252. An output shaft 355 in the flow meter 252 moves proportionally to the volume of gas flowing through the flow meter 252. At block 450, movement of the output shaft 355 inside the flow meter 252 is detected. At block 460, a pulse is output based on the movement of the output shaft 355. In some embodiments, the pulse corresponds to <=7 mL of fluid flowing through the flow meter 252 . In certain embodiments, the pulse is output for a 1/1, 024th revolution of an output hand 320 coupled to the output shaft 355.

[0069] In some embodiments, a flow meter 252 may receive fluid flow from an external source, such as a well. A shaft 355 in the flow meter 252 moves proportionally to the volume of fluid flowing through the flow meter 252. The movement of the shaft 355 may be detected by a pulser 254. The pulser 254 includes a coupler 310 and detects movement of the shaft 355 through physical contact of the coupler 310 with the flow meter 252. The pulser 254 outputs a pulse based on the movement of the shaft 355. Results

[0070] Referring to FIG. 5, flow rate 510 and pressure 520 are shown as measured over a month for a well. This well passed the bubble test, which is the regulatory standard as per AER Guide 20 for determining whether or not "vent flow" is present for a well. The measurements shown in FIG. 5 from the assembly 120, however, show that vent flow was present over the month. Relying solely on the bubble test would lead the operator to miss a potential issue.

[0071] Similarly, referring to FIG. 6, flow rate 610, pressure 620, and temperature

630 are shown for a well as measured over a week. Correlations between temperature 630, pressure 620, and flow rate 610 are seen. Additionally, as with the data depicted in FIG. 5, intermittent flow is seen. A well with intermittent vent flow may pass the bubble test despite having vent flow. The assembly 120, by continuously measuring even small amounts of flow over several days or months, is able to provide data that the bubble test may miss, alerting the operator to potential issues with the well.

[0072] Referring to FIG. 7, flow rate 710, barometric pressure 720, and temperature 730 are shown for a well as measured over five days. The assembly 120 shows both negative and positive flow for this well. The flow rate 710 shows that the well is breathing, taking in gas and expelling it based on changes in barometric pressure. The assembly 120 is able to detect and measure this phenomenon due to continuous monitoring and the ability to measure negative flow rates.

[0073] The term "computer", as used herein, is not limited to any particular type of computer system and encompasses servers, desktop computers, laptop computers, networked mobile wireless telecommunication computing devices such as smartphones, tablet computers, as well as other types of computer systems.

[0074] Both the computer 150 and the assembly 120 may comprise one or more processors or microprocessors, such as a central processing unit (CPU) 122,152 which is depicted in FIG. 1. The CPU 122,152 performs arithmetic calculations and control functions to execute software stored in an internal memory 124, 154, such as one or both of random access memory (RAM) and read only memory (ROM), and possibly additional memory (not shown). The additional memory may comprise, for example, mass memory storage, hard disk drives, optical disk drives (including CD and DVD drives), magnetic disk drives, magnetic tape drives (including LTO, DLT, DAT and DCC), flash drives, program cartridges and cartridge interfaces such as those found in video game devices, removable memory chips such as EPROM or PROM, emerging storage media, such as holographic storage, or similar storage media as known in the art. This additional memory may be physically internal, external or both internal and external to the computer 150 and the assembly 120.

[0075] The computer system 150 and the assembly 120 may also comprise other similar means for allowing computer programs or other instructions to be loaded. Such means can comprise, for example, a communications interface 126,156 that allows software and data to be transferred between the computer system 150 (and assembly 120) and external systems and networks. Examples of the communications interface 126,156 comprise a modem, a network interface such as an Ethernet card, a wireless communication interface, or a serial or parallel communications port. Software and data transferred via the communications interface 126, 156 are in the form of signals which can be electronic, acoustic, electromagnetic, optical, or other signals capable of being received by the communications interface 126, 156. Multiple interfaces, of course, can be provided on the computer system 150 and the assembly 120.

[0076] It is contemplated that any part of any aspect or embodiment discussed in this specification can be implemented or combined with any part of any other aspect or embodiment discussed in this specification.

[0077] While particular embodiments have been described in the foregoing, it is to be understood that other embodiments are possible and are intended to be included herein. It will be clear to any person skilled in the art that modifications of and adjustments to the foregoing embodiments, not shown, are possible.