Shale reservoir gas-bearing property evaluation device and method

Abstract

The application provides a shale reservoir gas content evaluation device and method, wherein the shale reservoir gas content evaluation device comprises a sample containing assembly, a crushing assembly, an exhaust assembly, a gas collecting assembly and a gas chromatograph, the sample containing assembly comprises a sealed tank and a baffle, the baffle is movably arranged in the sealed tank and can control the upper containing cavity and the lower containing cavity to be communicated or closed, the crushing assembly is arranged at the bottom of the lower containing cavity, the exhaust assembly comprises a sealed cover, a gas flow meter and a one-way valve, the gas inlet end of the gas collecting assembly is communicated with the gas outlet end of the one-way valve, and the gas inlet end of the gas chromatograph is communicated with the gas outlet end of the gas flow meter. Thus, desorption gas measurement and residual gas measurement can be carried out in one container without transfer, and the operation is simpler. Meanwhile, the problem that a part of desorption gas escapes in the transfer process of the shale sample is solved, the measurement precision is improved, and the shale reservoir gas content evaluation result is more accurate.

Description

Technical Field

[0001] This invention belongs to the field of shale gas exploration and detection technology, specifically relating to a device and method for evaluating the gas content of shale reservoirs. Background Technology

[0002] Unconventional oil and gas refers to resources such as coalbed methane and shale gas. With the scarcity of conventional oil and gas resources and the improvement of extraction technologies, the exploration and extraction of unconventional oil and gas have gradually gained attention, with shale gas becoming a global energy hotspot. Shale gas exists within shale reservoirs. Before extracting shale gas from these reservoirs, it is necessary to evaluate the gas content of the shale reservoirs through which the shale gas well passes, understand parameters such as shale gas resource quantity, reserves, and recoverable quantity, and assess its economic development value.

[0003] Shale gas content refers to the natural gas content in shale reservoirs, usually expressed as the amount of natural gas per unit volume of shale. The gas content of a shale reservoir can be evaluated by measuring the gas content of a shale sample. Gas content can be obtained through in-situ desorption experiments on the sample. Based on the gas volume obtained at different stages of the desorption experiment, shale gas content is divided into three parts: desorbed gas volume, residual gas volume, and lost gas volume. Desorbed gas volume is the volume of gas desorbed from the shale sample in the desorption container. Lost gas volume refers to the volume of gas released from the moment the drill bit encounters the rock formation until the shale sample is loaded into the desorption container. Residual gas volume measures the volume of gas remaining in the shale sample after desorption has ceased.

[0004] The accuracy of shale gas content assessment hinges on the accuracy of desorbed gas and residual gas measurement. In existing technologies, the desorbed gas and residual gas are measured separately in different containers. During sample transfer, some desorbed gas may escape, which can affect the measurement results. Summary of the Invention

[0005] This invention provides a device and method for evaluating the gas content of shale reservoirs, aiming to solve the problem in the prior art that transferring samples during the measurement of residual gas volume can cause errors in the measurement results. This invention helps to improve the accuracy of the measurement results and makes the evaluation results of the gas content of shale reservoirs more accurate.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a device for evaluating the gas content of shale reservoirs, comprising:

[0008] A sample receiving assembly includes a sealed container, a baffle, and a first driving mechanism. The sealed container has an upper receiving cavity and a lower receiving cavity connected vertically. The baffle is movably disposed in the sealed container. The first driving mechanism is connected to the baffle to drive the baffle to switch between a closed posture and an open posture. When the baffle is in the closed posture, the baffle separates the upper receiving cavity and the lower receiving cavity. When the baffle is in the open posture, the upper receiving cavity and the lower receiving cavity are connected vertically.

[0009] A crushing assembly is located at the bottom of the lower receiving cavity;

[0010] The exhaust assembly includes a sealing cap, a gas flow meter, and a one-way valve. The sealing cap covers the top opening of the upper receiving cavity and has an outlet communicating with the upper receiving cavity. The inlet of the gas flow meter is connected to the outlet, and the outlet of the gas flow meter is connected to the inlet of the one-way valve.

[0011] A gas collection assembly, wherein the inlet of the gas collection assembly is connected to the outlet of the one-way valve; and

[0012] A gas chromatograph, wherein the gas inlet of the gas chromatograph is connected to the gas outlet of the gas flow meter.

[0013] In one possible implementation, the side wall of the sealed container is provided with a clearance opening in the horizontal direction, one end of the baffle is slidably engaged with the clearance opening, and the other end is provided with a rack;

[0014] The first driving mechanism includes:

[0015] A drive motor is located in the sealed container; and

[0016] A gear is located on the motor shaft of the drive motor and meshes with the rack for transmission.

[0017] In one possible implementation, the sealed container has a heating jacket arranged circumferentially along the upper and lower receiving cavities.

[0018] In one possible implementation, the breaking component includes:

[0019] A tray is located at the bottom of the lower receiving cavity;

[0020] A second drive mechanism, located in the sealed container, is used to drive the tray to rotate about a vertical axis; and

[0021] Multiple broken balls are rotatably disposed on the tray.

[0022] In one possible implementation, the gas collection assembly includes:

[0023] Gas collection bottle;

[0024] The air inlet pipe has one end connected to the outlet end of the one-way valve and the other end extending into the gas collection bottle.

[0025] The drain pipe has one end connected to the bottom of the gas collection bottle and the other end extending out of the gas collection bottle;

[0026] A water outlet valve is located on the drain pipe;

[0027] The air pressure detection mechanism includes an internal air pressure sensor located inside the gas collection bottle, and an atmospheric air pressure sensor located outside the gas collection bottle; and

[0028] The control module is communicatively connected to the water outlet valve, the bottle internal pressure sensor, and the atmospheric pressure sensor.

[0029] Compared with existing technologies, the beneficial effects of the shale reservoir gas-bearing evaluation device provided by this invention are:

[0030] The shale reservoir gas-bearing evaluation device provided by this invention includes a sample containing component, a crushing component, an venting component, a gas collection component, and a gas chromatograph. In use, the shale sample is placed in the sample containing component for desorption. The gas generated by desorption passes through a sealing cap, a gas flow meter, a one-way valve, and other components before entering the gas collection component for collection and storage. The gas collection component can collect the desorbed gas and residual gas generated by the shale sample for other tests, such as gas isotope analysis. After the desorbed gas volume measurement is completed, the crushing component can crush the shale sample, releasing the residual gas and allowing for the measurement of the residual gas volume. During the measurement of desorbed and residual gas, the gas chromatograph can sample the desorbed and residual gas, and the measurement results are corrected by analyzing the oxygen content, which helps improve the reliability and accuracy of the measurement results.

[0031] The sample containing assembly of this invention includes a sealed container, a baffle, and a first driving mechanism. The baffle divides the sealed container into an upper containing chamber and a lower containing chamber. The upper containing chamber is used for desorbed gas measurement, and the lower containing chamber is used for residual gas measurement. This configuration allows desorbed gas and residual gas measurements to be performed within a single container without the need for transfer, simplifying the operation. It also solves the problem of some desorbed gas escaping during shale sample transfer, thus contributing to improved measurement accuracy.

[0032] In this invention, a crushing component is installed at the bottom of the lower receiving chamber. After desorption is completed, the baffle is adjusted to an open position, allowing the shale sample to fall into the lower receiving chamber. The crushing component crushes the shale sample, releasing the gas remaining in the shale sample. During the crushing of the shale sample, the baffle can be kept in a closed position to prevent dust and other particles generated during crushing from spreading into the gas pipeline.

[0033] In a second aspect, the present invention provides a method for evaluating the gas content of shale reservoirs, implemented using a shale reservoir gas content evaluation device as described in any of the above embodiments, comprising the following steps:

[0034] The amount of desorbed gas was measured, and the desorbed gas content V per unit mass of shale sample was calculated based on the amount of desorbed gas. d ;

[0035] The residual gas volume was measured, and the residual gas content V per unit mass of shale sample was calculated based on the residual gas volume. r ;

[0036] Calculate the gas loss volume, and based on the gas loss volume, calculate the gas loss content V per unit mass of shale sample. l ;

[0037] The total gas content V per unit mass of shale sample is calculated using the formula: V = V0 d +V l +V r .

[0038] In one possible implementation, the amount of desorbed gas is measured, and the desorbed gas content V per unit mass of shale sample is calculated based on this amount. d Includes the following steps:

[0039] With the baffle in a closed position, the shale sample to be tested is placed into the upper containment cavity, and the desorbed gas generated by the shale sample enters the gas collection assembly through the gas flow meter.

[0040] The volume and rate of the desorbed gas flowing through the gas flow meter are detected. The measurement of the desorbed gas volume ends when the rate of the desorbed gas flow is less than 0.5 ml / h.

[0041] During the detection of the rate of desorbed gas passing through the gas flow meter, when the gas flow meter detects that the rate of desorbed gas passing through is uniform, the gas chromatograph is started, so that a portion of the desorbed gas enters the gas chromatograph as the desorbed sample gas.

[0042] The components of the desorbed sample gas were obtained by gas chromatography analysis, and the percentage coefficient of O2 in the desorbed sample gas content was obtained.

[0043] according to The total volume V of desorbed gas measured by the gas flow meter m1检测 Calculate the total volume of oxygen in the desorbed gas. The calculation formula is:

[0044]

[0045] By proportionally subtracting the air mixed in with the desorbed gas using the volume relationship between nitrogen and oxygen in the air, the total amount of desorbed gas V actually generated in the shale sample can be calculated. m1 The calculation formula is:

[0046]

[0047] Based on the actual total desorbed gas V produced by the shale sample m1 The desorbed gas volume V under standard atmospheric conditions was calculated. s The calculation formula is:

[0048] In the formula V s p is the volume of desorbed gas under standard atmospheric conditions. m1 V is the air pressure inside the containment cavity of the sealed container. m1 T represents the total amount of desorbed gas actually produced by the shale sample. m1 The temperature inside the sealed container;

[0049] Based on the desorption volume V under standard atmospheric conditions s The desorbed gas content V per unit mass of shale sample was calculated. d The calculation formula is:

[0050] In the formula, m is the mass of the shale sample.

[0051] In one possible implementation, the residual gas volume is measured, and the residual gas content V per unit mass of shale sample is calculated based on the residual gas volume. r Includes the following steps:

[0052] Switch the baffle from the closed position to the open position to allow the shale sample to fall into the lower receiving cavity. Then switch the baffle from the open position to the closed position and start the crushing component to fully crush the shale sample.

[0053] After the crushing is completed, the control baffle switches from the closed position to the open position. The volume and rate of the residual gas flowing through are detected by the gas flow meter. When the gas flow meter detects that the measured rate of the residual gas is less than 0.5 ml / h, the measurement of the residual gas volume ends.

[0054] During the monitoring of the residual gas flow rate by the gas flow meter, when the flow rate of the residual gas is detected to be uniform, the gas chromatograph is started, allowing a portion of the residual gas to enter the gas chromatograph as a sample gas. The composition of the sample gas is then analyzed by the gas chromatograph, and the percentage coefficient of O2 in the sample gas content is obtained.

[0055] according to The total volume V of residual gas measured by the gas flow meter m2检测 Calculate the total volume of oxygen in the residual gas. The calculation formula is:

[0056]

[0057] By proportionally subtracting the air mixed in with the residual gas from the volume relationship of nitrogen and oxygen in the air, the total amount of residual gas V actually generated in the shale sample can be calculated. m2 The calculation formula is:

[0058]

[0059] Based on the actual total residual gas V generated by the shale sample m2 The residual gas volume V under standard atmospheric conditions was calculated. R The calculation formula is:

[0060] In the formula V R p represents the residual gas volume under standard atmospheric conditions. m2 V is the air pressure inside the lower cavity of the sealed container. m2 T represents the total amount of residual gas actually generated by the shale sample. m2 The temperature inside the sealed container;

[0061] Based on the residual gas volume V under standard atmospheric conditions R The residual gas content V per unit mass of shale sample was calculated. r The calculation formula is:

[0062] In the formula, m is the mass of the shale sample.

[0063] In one possible implementation, calculating the gas loss and obtaining the gas loss content per unit mass of shale sample based on the gas loss includes the following steps:

[0064] The computer is connected to the gas flow meter to automatically record the volume change of the desorbed gas during the desorption process. The computer automatically calculates and corrects the volume of the desorbed gas. The desorption curve is established with the square root of time as the x-axis and the corrected gas volume as the y-axis.

[0065] The gas loss V was calculated using linear fitting. L The calculation formula is:

[0066] In the formula V L The absolute value of the lost gas is taken; k is the slope of the straight line segment of the desorption curve; t0 is the dissipation time of the lost gas; t is the desorption time of the desorbed gas.

[0067] Calculate the gas loss V per unit mass of shale sample. l The calculation formula is:

[0068] In the formula, m is the mass of the shale sample.

[0069] In one possible implementation, the sealed container is heated using a heating mantle before the step of detecting the volume and rate of the desorbed gas flowing through it by a gas flow meter.

[0070] After the desorbed gas volume measurement is completed and before the residual gas volume measurement is performed, the heating jacket is turned off to allow the sealed container to cool down.

[0071] After the crushing components are activated to fully crush the shale sample, and before the volume and rate of the residual gas flowing through it are detected by a gas flow meter, the sealed container is heated using a heating jacket.

[0072] Compared with existing technologies, the beneficial effects of the shale reservoir gas-bearing evaluation method provided by this invention are:

[0073] The shale reservoir gas-bearing evaluation method provided by this invention can measure the desorbed gas volume and residual gas volume, calculate the gas loss volume, determine the gas composition of the desorbed gas and residual gas using gas chromatography, and mathematically correct the gas desorption data using the detected oxygen content, thereby improving the reliability and accuracy of the desorption data and greatly facilitating user operation. It helps to rationally evaluate the gas-bearing capacity of shale reservoirs, understand parameters such as shale gas resources, reserves, and recoverable quantities, and accurately assess its economic development value. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the process for measuring the gas content of shale using the desorption method;

[0075] Figure 2A schematic diagram of the structure of a shale reservoir gas-bearing evaluation device provided in one embodiment of the present invention;

[0076] Figure 3 This is a schematic diagram of the structure of the sample containing assembly, the crushing assembly, the venting assembly, and the gas collecting assembly in one embodiment of the present invention;

[0077] Figure 4 This is a schematic diagram of the structure of a gas chromatograph in one embodiment of the present invention;

[0078] Figure 5 This is a schematic diagram of the structure of the crushing component in another embodiment of the present invention.

[0079] Explanation of reference numerals in the attached figures:

[0080] 1. A device for evaluating the gas content of shale reservoirs;

[0081] 10. Sample receiving assembly; 11. Sealed container; 12. Baffle; 13. First drive mechanism; 131. Drive motor; 132. Gear;

[0082] 20. Crushing assembly; 21. Pallet; 22. Second drive mechanism; 23. Crushing ball;

[0083] 30. Exhaust assembly; 31. Sealing cap; 32. Gas flow meter; 33. Check valve; 34. Three-way valve;

[0084] 40. Gas collection assembly; 41. Gas collection bottle; 42. Inlet pipe; 43. Drain pipe; 44. Water outlet valve; 45. Internal pressure sensor; 46. Atmospheric pressure sensor;

[0085] 50. Gas chromatograph; 51. Sample injection system; 52. Carrier gas system; 53. Chromatographic column; 54. Detection system;

[0086] 60. Controller;

[0087] 70. Computer. Detailed Implementation

[0088] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0089] It should be noted that when an element is referred to as "fixed to," "fixed," or "attached" to another element, it can be directly on the other element or may have an intervening element. When an element is referred to as "connected to" or "connected to" another element, it can be directly connected to the other element or may have an intervening element. When an element is referred to as "set on" or "located on" another element, it can be directly on the other element or may have an intervening element. "Multiple" refers to two or more items. "At least one" refers to one or more items. "Several" refers to one or more items.

[0090] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0091] Please refer to the following: Figures 1 to 5 The following describes the shale reservoir gas content evaluation device 1 and method provided in the embodiments of the present invention.

[0092] Please see Figures 1 to 5 In a first aspect, embodiments of the present invention provide a shale reservoir gas-bearing evaluation device 1, comprising a sample containing assembly 10, a crushing assembly 20, an exhaust assembly 30, a gas collection assembly 40, and a gas chromatograph 50. The sample containing assembly 10 includes a sealed container 11, a baffle 12, and a first driving mechanism 13. The sealed container 11 has an upper containing cavity and a lower containing cavity connected vertically. The baffle 12 is movably disposed within the sealed container 11. The first driving mechanism 13 is connected to the baffle 12 to drive the baffle 12 to switch between a closed state and an open state. When the baffle 12 is in the closed state, it separates the upper containing cavity and the lower containing cavity; when the baffle 12 is in the open state, the upper containing cavity and the lower containing cavity are connected vertically. Component 20 is located at the bottom of the lower receiving cavity; the exhaust assembly 30 includes a sealing cover 31, a gas flow meter 32, and a one-way valve 33. The sealing cover 31 covers the opening of the upper receiving cavity and has an outlet communicating with the upper receiving cavity. The inlet end of the gas flow meter 32 is connected to the outlet end, and the outlet end of the gas flow meter 32 is connected to the inlet end of the one-way valve 33. The inlet end of the gas collection assembly 40 is connected to the outlet end of the one-way valve 33. The inlet end of the gas chromatograph 50 is connected to the outlet end of the gas flow meter 32.

[0093] Compared with the prior art, the beneficial effects of the shale reservoir gas content evaluation device 1 provided in this embodiment of the invention are:

[0094] The shale reservoir gas content evaluation device 1 provided in this embodiment of the invention includes a sample containing component 10, a crushing component 20, an exhaust component 30, a gas collection component 40, and a gas chromatograph 50. In use, the shale sample is placed in the sample containing component 10 for desorption. The gas generated by desorption passes through components such as a sealing cap 31, a gas flow meter 32, and a one-way valve 33, and enters the gas collection component 40 for collection and storage. The gas collection component 40 can collect the desorbed gas and residual gas generated by the shale sample for other tests, such as gas isotope analysis. After the desorbed gas volume measurement is completed, the crushing component 20 can crush the shale sample, releasing the residual gas and allowing for the measurement of the residual gas volume. During the measurement of desorbed and residual gas, the gas chromatograph 50 can sample the desorbed and residual gas, and correct the measurement results by analyzing the oxygen content, which helps improve the reliability and accuracy of the measurement results.

[0095] In this embodiment of the invention, the sample containing assembly 10 includes a sealed container 11, a baffle 12, and a first driving mechanism 13. The baffle 12 divides the sealed container 11 into an upper containing chamber and a lower containing chamber. The upper containing chamber is used for desorbed gas measurement, and the lower containing chamber is used for residual gas measurement. This arrangement allows desorbed gas measurement and residual gas measurement to be performed within a single container without the need for transfer, simplifying the operation. It also solves the problem of some desorbed gas escaping during shale sample transfer, thus contributing to improved measurement accuracy.

[0096] In this embodiment of the invention, a crushing component 20 is provided at the bottom of the lower receiving cavity. After desorption is completed, the baffle 12 is adjusted to an open position, and the shale sample falls into the lower receiving cavity. The crushing component 20 crushes the shale sample, releasing the gas remaining in the shale sample. When the shale sample is crushed, the baffle 12 can be kept in a closed position to prevent dust and other particles generated during crushing from spreading into the gas pipeline.

[0097] In this embodiment of the invention, the sealed container 11 can be made of stainless steel, glass, or other materials. The baffle 12 is movably disposed within the sealed container 11. Optionally, the baffle 12 can be rotatably disposed within the sealed container 11 along a horizontal axis, in which case the first driving mechanism 13 is a motor. Alternatively, the baffle 12 can also be slidably inserted into the sealed container 11 along a horizontal direction (the baffle 12 can specifically be the valve plate of a slide valve), in which case the first driving mechanism 13 can be a cylinder, a hydraulic cylinder, a motor, or the like.

[0098] The baffle 12 can control the upper and lower receiving cavities to be separated or connected. When the desorbed gas volume is measured, the baffle 12 is in a closed state and is used to support the shale sample. After the desorbed gas volume measurement is completed, the baffle 12 switches to an open state, allowing the shale sample it supports to fall into the lower receiving cavity and come into contact with the crushing component 20. The crushing component 20 crushes the shale sample to facilitate the measurement of the residual gas volume.

[0099] It should be noted that, in order to prevent gas leakage, the mating surface between the baffle 12 and the sealed container 11 must be sealed regardless of whether the baffle 12 is in a closed or open position. Specifically, this can be achieved by using sealing gaskets, sealing rings, or other methods at the mating surface; this embodiment of the invention does not impose any limitations on this approach.

[0100] The crushing component 20 is used to crush the shale sample. The crushing component 20 can be a rotating crushing blade, grinding roller, etc., as long as it can crush the shale sample.

[0101] The exhaust assembly 30 connects the sealed container 11, the gas collection assembly 40, and the gas chromatograph 50, guiding the desorbed gas into the gas collection assembly 40 or the gas chromatograph 50. The sealing cover 31 is closable and can be installed at the opening of the upper receiving cavity, achieving a seal using sealing elements such as sealing rings to prevent gas leakage. The sealing cover 31 and the sealed container 11 can be connected by bolts, snap-fit ​​connections, or other methods. The gas flow meter 32 measures the volume of gas passing through; an electronic gas flow meter 32 can be used for more accurate measurement, precisely detecting the amount of shale gas flowing through. Its onboard sensor module connects to the computer 70 (computer), allowing for direct reading of the corresponding values, making operation more convenient. It can also be used to calculate gas loss in subsequent steps. The gas collection assembly 40 collects and stores the desorbed gas; the gas collection assembly 40 can be a vacuum bag, collection bottle, etc.

[0102] like Figure 2 and Figure 3 As shown, a three-way valve 34 can be installed at the outlet of the gas flow meter 32. The three-way valve 34 has one inlet and two outlets. The inlet is connected to the outlet of the gas flow meter 32, one outlet is connected to the inlet of the one-way valve 33, and the other outlet is connected to the inlet of the gas chromatograph 50. The three-way valve 34 can control the flow of gas from the gas flow meter 32 to the one-way valve 33, or allow the gas to flow from the gas flow meter 32 to the gas chromatograph 50. The three-way valve 34 can be a manual valve or an electrically controlled valve.

[0103] It should be noted that the sample containing assembly 10, the crushing assembly 20, the venting assembly 30, the gas collecting assembly 40, and the gas chromatograph 50 can be mounted on support structures such as brackets, bases, and boxes to form an integrated structure, facilitating transportation and field use. All pipeline interfaces can be connected using rubber hoses for easy assembly in the field.

[0104] In some possible embodiments, the side wall of the sealed container 11 has a clearance opening in the horizontal direction, one end of the baffle 12 is slidably fitted into the clearance opening, and the end of the baffle 12 adjacent to the first drive mechanism 13 has a rack along its own length direction. The first drive mechanism 13 includes a drive motor 131 and a gear 132. The drive motor 131 is located in the sealed container 11; the gear 132 is located on the motor shaft of the drive motor 131 and meshes with the rack for transmission.

[0105] In this embodiment, the first drive mechanism 13 is a motor with a gear 132. The motor drives the gear 132 to rotate, which in turn drives the rack to move, thereby causing the baffle 12 to switch between a closed posture and an open posture.

[0106] In some possible embodiments, the baffle 12 has a through hole running vertically through the cavity. When in the open position, the through hole is located inside the receiving cavity and can connect the upper and lower receiving cavities. When in the closed position, the through hole and the receiving cavity are offset vertically, and the baffle 12 isolates the receiving cavity into two receiving cavities.

[0107] In this embodiment, the baffle 12 is slidably disposed in the horizontal direction, and during the sliding process, the upper and lower receiving cavities can be connected or closed. The first driving mechanism 13 may be a cylinder, an electric telescopic rod, or the like connected to the baffle 12.

[0108] In some possible embodiments, the sealed container 11 has a heating jacket arranged circumferentially along the upper and lower receiving cavities. This embodiment, by circumferentially arranging the heating jacket, can increase the temperature of the sealed container 11, promoting rapid desorption of shale gas. The rapid desorption time is short, facilitating field use. The heating jacket can be a resistance wire wound around the sealed container 11, utilizing the heat generated by energizing the resistance wire to heat the sealed container 11. Alternatively, the heating jacket can be a thick-film heater; this embodiment is not limited to this. The heating jacket can generate a stable temperature up to 200°C, with a heating rate of 3°C / min, meeting the usage requirements.

[0109] Please see Figure 2 , Figure 3 and Figure 5 In some possible embodiments, the crushing assembly 20 includes a tray 21, a second drive mechanism 22, and a plurality of crushing balls 23. The tray 21 is located at the bottom of the lower receiving cavity; the second drive mechanism 22 is located in the sealed container 11 and is used to drive the tray 21 to rotate about a vertical axis; the plurality of crushing balls 23 are respectively rotatably disposed on the tray 21.

[0110] This embodiment uses a ball milling method to measure residual gas. When the shale sample falls onto tray 21, the second drive mechanism 22 drives tray 21 to rotate. The rotation of tray 21 causes the crushing balls 23 on it to roll, colliding with the shale sample and gradually pulverizing it. Tray 21 can be made of materials such as steel, glass, or ceramic, while the crushing balls 23 can be made of materials such as stone, steel, or cast iron. The second drive mechanism 22 can be an electric motor, a hydraulic motor, or other power device capable of outputting rotational motion.

[0111] The tray 21 can be disc-shaped, funnel-shaped, cylindrical, etc. In order to increase the probability of collision with the shale sample and make the shale sample crushed quickly, the inner wall of the tray 21 can be provided with collision protrusions.

[0112] Multiple crushing balls 23 are provided, and the diameters of the multiple crushing balls 23 can be the same or different. Multiple crushing balls 23 have multiple different diameter specifications, which can fully grind the shale sample to be tested until it is crushed to below 0.2464mm (60 mesh), so as to facilitate the full release of shale gas.

[0113] It should be noted that the operation of components such as the first drive mechanism 13, the second drive mechanism 22, the gas flow meter 32, and the heating jacket can be controlled by the controller 60. The controller 60 has a built-in STM32 chip, but other chips can also be used.

[0114] Please see Figure 2 and Figure 3 In some possible embodiments, the gas collection assembly 40 includes a gas collection bottle 41, an inlet pipe 42, a drain pipe 43, a water outlet valve 44, a pressure detection mechanism, and a control module. The gas collection bottle 41 contains saturated brine or other liquids incompatible with alkane gases. One end of the inlet pipe 42 is connected to the outlet of the one-way valve 33, and the other end extends into the gas collection bottle 41. One end of the drain pipe 43 is connected to the bottom of the gas collection bottle 41, and the other end extends outside the gas collection bottle 41. The water outlet valve 44 is located on the drain pipe 43. The pressure detection mechanism includes an internal pressure sensor 45 located inside the gas collection bottle 41 and an atmospheric pressure sensor 46 located outside the gas collection bottle 41. The control module is communicatively connected to the water outlet valve 44, the internal pressure sensor 45, and the atmospheric pressure sensor 46, respectively.

[0115] In this embodiment, the gas collection component 40 uses a water displacement method to collect the shale gas generated by desorption. The gas collection bottle 41 can be a glass bottle, and it is equipped with graduations to indicate the volume of gas collected. The inlet pipe 42 is connected to the outlet of the one-way valve 33 to prevent liquid backflow.

[0116] The working principle of the gas collection component 40 is as follows: the control module is communicatively connected to the water outlet valve 44, the bottle internal pressure sensor 45, and the atmospheric pressure sensor 46. The water outlet valve 44 is a solenoid valve, which is controlled to open and close by the control module. The gas desorbed from the shale sample enters the gas collection bottle 41 after passing through the gas flow meter 32, the one-way valve 33, and the inlet pipe 42. This causes the pressure inside the gas collection bottle 41 to be higher than the external atmospheric pressure. The control module controls the water outlet valve 44 to open, allowing some water to be discharged through the drain pipe 43 to maintain the pressure inside the bottle and the external pressure, ensuring that the desorbed gas can smoothly enter the gas collection bottle 41.

[0117] Please see Figure 4 In some possible embodiments, the gas chromatograph 50 includes an injection system 51, a carrier gas system 52, a chromatographic column 53, and a detection system 54. The inlet of the injection system 51 is connected to the outlet of the gas flow meter 32; the outlet of the carrier gas system 52 is connected to the injection system 51; the inlet of the chromatographic column 53 is connected to the outlet of the injection system 51; and the detection system 54 is connected to the outlet of the chromatographic column 53.

[0118] The gas chromatograph 50's injection system 51 is connected to the chromatographic column 53, carrier gas system 52, and gas flow meter 32. The detection system 54 includes a detector, which is connected to the chromatographic column 53 and computer 70. The carrier gas system 52 includes a carrier gas tank and a pressure regulating valve. During operation, the carrier gas flows out from the carrier gas tank (high-pressure steel cylinder), is reduced to the required pressure by the pressure reducing valve, passes through a purification and drying tube, and then flows through the vaporization chamber of the injection system 51 at a stable pressure and constant speed after passing through the pressure regulating valve. It is fully mixed with the sample gas and then carried into the chromatographic column 53 for separation. The separated components enter the detection system 54 with the carrier gas. The detector converts the concentration or mass change of the substance into a certain electrical signal, which is amplified and recorded on the recorder to obtain the chromatographic elution curve. This facilitates qualitative analysis of the content of each substance in the gas sample by the operator or computer 70.

[0119] In this embodiment, the chromatographic column 53 is a packed column, which can be made of metal, polytetrafluoroethylene tubing, or glass. Its inner diameter is generally 2-4 mm, and its length is 1-10 meters. The column shape can be U-shaped or spiral, with the ratio of the spiral diameter to the column inner radius generally ranging from 15:1 to 25:1. The detector is a thermal conductivity detector, which has advantages such as low noise, small size, fast response, and responsiveness to various substances. The computer 70 can receive signals from the gas flow meter 32, view the amount of shale gas flowing through it, process the electrical signals from the detection system 54 of the gas chromatograph 50, and display the results on a monitor.

[0120] In a second aspect, embodiments of the present invention provide a method for evaluating the gas content of shale reservoirs, implemented using the shale reservoir gas content evaluation device in any of the above embodiments, comprising the following steps:

[0121] The amount of desorbed gas was measured, and the desorbed gas content V per unit mass of shale sample was calculated based on the amount of desorbed gas. d ;

[0122] The residual gas volume was measured, and the residual gas content V per unit mass of shale sample was calculated based on the residual gas volume. r ;

[0123] Calculate the gas loss volume, and based on the gas loss volume, calculate the gas loss content V per unit mass of shale sample. l ;

[0124] The total gas content V per unit mass of shale sample is calculated using the formula: V = V0 d +V l +V r .

[0125] In some possible embodiments, the amount of desorbed gas is measured, and the desorbed gas content V per unit mass of shale sample is calculated based on the amount of desorbed gas. d Includes the following steps:

[0126] With the baffle 12 in a closed position, the shale sample to be tested is placed into the upper containment cavity, and the opening of the containment cavity is sealed by the sealing cover 31, so that the desorbed gas generated by the shale sample can enter the gas collection assembly 40 through the gas flow meter 32.

[0127] The volume and rate of the desorbed gas flowing through the gas flow meter 32 are detected. When the gas flow meter 32 detects that the rate of the desorbed gas is less than 0.5 ml / h, the measurement of the desorbed gas volume ends.

[0128] During the period when the rate of the desorbed gas passing through the gas flow meter 32 is detected to be uniform, the gas chromatograph 50 is started, so that a portion of the desorbed gas enters the gas chromatograph 50 as the desorbed sample gas.

[0129] The components of the desorbed sample gas were obtained by gas chromatography-mass spectrometry (GC-MS), and the percentage coefficient of O2 in the desorbed sample gas was obtained. Combined with the total volume V of the desorbed gas measured by gas flow meter 32 m1检测 Calculate the total volume of oxygen in the desorbed gas. The calculation formula is:

[0130] In the formula V m1检测 and The units are all in ml;

[0131] By proportionally subtracting the air mixed in with the desorbed gas using the volume relationship between nitrogen and oxygen in the air, the total amount of desorbed gas V actually generated in the shale sample can be calculated. m1 The calculation formula is:

[0132] In the formula V m1 The unit is ml;

[0133] Based on the actual total desorbed gas V produced by the shale sample m1 The desorbed gas volume V under standard atmospheric conditions was calculated. s The calculation formula is:

[0134] In the formula V s The volume of desorbed gas under standard atmospheric conditions is expressed in cm³. 3 ;p m1 V represents the air pressure inside the containment cavity of the sealed container 11, expressed in kPa. m1 The total amount of desorbed gas actually produced by the shale sample, in cm³. 3 ;T m1 The temperature inside the sealed container 11 is expressed in °C.

[0135] Based on the desorption volume V under standard atmospheric conditions s The desorbed gas content V per unit mass of shale sample was calculated. d The calculation formula is:

[0136] In the formula, m is the mass of the shale sample, in grams;

[0137] In some possible embodiments, the residual gas volume is measured, and the residual gas content V per unit mass of shale sample is calculated based on the residual gas volume. r Includes the following steps:

[0138] Switch the baffle 12 from the closed position to the open position to allow the shale sample to fall into the lower receiving cavity. Then switch the baffle 12 back to the closed position and start the crushing component 20 to fully crush the shale sample.

[0139] After the crushing is completed, the control baffle 12 switches from the closed position to the open position. The gas flow meter 32 detects the volume and rate of the residual gas flowing through it. When the gas flow meter 32 detects that the measured rate of the residual gas is less than 0.5 ml / h, the residual gas measurement ends.

[0140] During the period when the flow rate of the residual gas detected by the gas flow meter 32 is constant, the gas chromatograph 50 is started, allowing a portion of the residual gas to enter the gas chromatograph 50 as a sample gas. The composition of the sample gas is obtained by analyzing it with the gas chromatograph 50, and the percentage coefficient of O2 in the sample gas content is obtained.

[0141] according to The total volume V of residual gas measured by gas flow meter 32 m2检测 Calculate the total volume of oxygen in the residual gas. The calculation formula is:

[0142] In the formula V m2检测 and The units are all in ml;

[0143] By proportionally subtracting the air mixed in with the residual gas from the volume relationship of nitrogen and oxygen in the air, the total amount of residual gas V actually generated in the shale sample can be calculated. m2 The calculation formula is:

[0144] In the formula V m2 The unit is ml;

[0145] Based on the actual total residual gas V generated by the shale sample m2 The residual gas volume V under standard atmospheric conditions was calculated. R The calculation formula is:

[0146] In the formula V R The residual gas volume under standard atmospheric conditions is expressed in cm³. 3 ;p m2 V represents the air pressure inside the containment cavity of the sealed container 11, expressed in kPa. m2 This represents the total amount of residual gas actually produced by the shale sample, expressed in cm³. 3 ;T m2 The temperature inside the sealed container 11 is expressed in °C.

[0147] Based on the residual gas volume V under standard atmospheric conditions R The residual gas content V per unit mass of shale sample was calculated. r The calculation formula is:

[0148] In the formula, m is the mass of the shale sample, in grams;

[0149] The calculation of the total gas content V per unit mass of shale sample includes the following steps:

[0150] According to the formula: V = V d +V l +V r The total gas content V per unit mass of shale sample was calculated.

[0151] Compared with existing technologies, the beneficial effects of the shale reservoir gas-bearing evaluation method provided in this invention are:

[0152] The shale reservoir gas-bearing evaluation method provided in this invention can measure the desorbed gas volume and residual gas volume, calculate the gas loss volume, determine the gas composition of the desorbed gas and residual gas using a gas chromatograph 50, and mathematically correct the gas desorption data using the detected oxygen content, thereby improving the reliability and accuracy of the desorption data and greatly facilitating user operation. It helps to rationally evaluate the gas-bearing capacity of shale reservoirs, understand parameters such as shale gas resources, reserves, and recoverable quantities, and accurately assess its economic development value.

[0153] It should be noted that the measurement and calculation of desorbed gas content V per unit mass of shale sample involves... d Measurement of residual gas volume, and calculation of residual gas content V per unit mass of shale sample. r Calculate the gas loss volume and the gas loss content V per unit mass of shale sample. l Steps such as calculating the total gas content V per unit mass of shale sample can be performed manually or automatically using a computer to calculate and output the results.

[0154] The shale reservoir gas content evaluation method provided in this invention can achieve integrated measurement and calculation of desorbed gas, residual gas, and lost gas. It uses a computer (PC) for automatic calculation and result output. After loading the shale sample, no additional operation is required to achieve automated, integrated, and intelligent measurement of gas content. This reduces experimental errors caused by human intervention and yields more accurate results.

[0155] This invention introduces a gas chromatograph 50 to determine gas components, and uses oxygen component data to mathematically correct gas desorption data, thereby improving the reliability and accuracy of desorption data and greatly facilitating user operation.

[0156] It should be noted that the shale reservoir gas-bearing evaluation method provided in this invention is not limited to any specific region and can be used both domestically and internationally. Furthermore, it is not limited by strata or lithology; in addition to shale gas, it can be used for gas-bearing rocks in reservoirs such as coalbed methane and tight sandstone gas. Overall, the applicability and scope of the shale reservoir gas-bearing evaluation method provided by this invention are stronger and broader than existing methods.

[0157] In some possible embodiments, calculating the gas loss and determining the gas loss content per unit mass of shale sample based on the gas loss includes the following steps:

[0158] The computer 70 is connected to the gas flow meter 32. The computer 70 automatically records the volume change of the desorbed gas during the desorption process and automatically calculates and corrects the volume of the desorbed gas. The desorption curve is established with the square root of time as the abscissa and the corrected gas volume as the ordinate.

[0159] The gas loss V was calculated using linear fitting. L The calculation formula is:

[0160] In the formula V L The amount of gas lost is expressed as an absolute value, in cm³. 3 ; k is the slope of the straight line segment of the desorption curve; t0 is the dissipation time of the lost gas, in min; t is the desorption time of the desorbed gas, in min;

[0161] Calculate the gas loss V per unit mass of shale sample. l The calculation formula is:

[0162] In the formula, m is the mass of the shale sample, in grams.

[0163] In this embodiment, computer 70 automatically calculates and records the corrected desorbed gas volume, and establishes a desorption curve with the square root of time as the x-axis and the corrected gas volume as the y-axis. Subsequently, the loss gas volume is calculated using the USBM method. This part of the operation can be completely completed automatically by computer 70, with a high degree of automation.

[0164] The principle behind the USBM method used in this embodiment to estimate the gas loss of shale samples is as follows: the shale sample is cylindrical, and during diffusion, the temperature and diffusion rate are constant. At the start of diffusion, the surface concentration is zero, and the change in gas concentration from the particle center to the surface is instantaneous. According to diffusion simulation, in the initial stage of desorption, the total desorbed gas volume changes linearly with the square root of time. Therefore, by extrapolating the desorption readings from the first few hours to the starting point of the timing, the gas loss V can be derived using linear fitting. L Dividing by the mass of the shale sample gives the gas loss V per unit mass of the shale sample. l The calculation formula is: In the formula V L (Absolute value) represents the gas loss volume, in cm³. 3; k is the slope of the straight line segment; t0 is the time of gas loss, i.e., the time from when the drill bit encounters the rock layer to when the shale sample is loaded into the desorption container, in min; t is the desorption time of the desorbed gas, in min; m is the mass of the shale sample, in g.

[0165] In some possible embodiments, the sealed container 11 is heated by a heating jacket before the step of detecting the volume and rate of the desorbed gas flowing through the gas flow meter 32; after the desorbed gas volume measurement is completed and before the residual gas volume is measured, the heating jacket is turned off to allow the sealed container 11 to cool down; after the crushing assembly 20 is started to fully crush the shale sample and before the volume and rate of the residual gas flowing through the gas flow meter 32 are detected, the sealed container 11 is heated by a heating jacket.

[0166] This embodiment utilizes a heating jacket to heat the sealed container 11, which helps to rapidly desorb shale, improves detection speed, and shortens waiting time when used in the field.

[0167] It is understood that the parts in the above embodiments can be freely combined or deleted to form different combined embodiments. The specific contents of each combined embodiment will not be repeated here. After this description, it can be considered that the present invention specification has recorded each combined embodiment and can support different combined embodiments.

[0168] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for evaluating gas content of a shale reservoir, characterized in that, The shale reservoir gas-bearing property evaluation device comprises: a sample containing assembly, including a sealed tank, a baffle and a first driving mechanism, the sealed tank has an upper containing cavity and a lower containing cavity connected in sequence, the baffle is movably arranged in the sealed tank, and the first driving mechanism is connected with the baffle to drive the baffle to switch between a closed posture and an open posture; when the baffle is in the closed posture, the baffle separates the upper containing cavity and the lower containing cavity; when the baffle is in the open posture, the upper containing cavity and the lower containing cavity are communicated in the up-down direction; a crushing assembly arranged at the bottom of the lower containing cavity, the crushing assembly comprises a tray, a second driving mechanism and a plurality of crushing balls; the tray is arranged at the bottom of the lower containing cavity; the second driving mechanism is arranged in the sealed tank and used for driving the tray to rotate around a vertical axis; and the plurality of crushing balls are rollably arranged on the tray; an exhaust assembly, including a sealing cover, a gas flow meter and a one-way valve; the sealing cover is arranged on the top opening of the upper containing cavity and has a gas outlet communicated with the upper containing cavity; the gas inlet end of the gas flow meter is communicated with the gas outlet; and the gas outlet end of the gas flow meter is communicated with the gas inlet end of the one-way valve; a gas collecting assembly, the gas inlet end of the gas collecting assembly is communicated with the gas outlet end of the one-way valve; and a gas chromatograph, the gas inlet end of the gas chromatograph is communicated with the gas outlet end of the gas flow meter.

2. The apparatus of claim 1, wherein, The side wall of the sealed tank is provided with a relief opening in the horizontal direction, one end of the baffle is slidingly fitted in the relief opening, and the other end of the baffle is provided with a rack; the first driving mechanism comprises: a driving motor arranged in the sealed tank; and a gear arranged on the motor shaft of the driving motor and engaged with the rack to drive.

3. The apparatus of claim 1, wherein, The sealed tank is provided with a heating jacket arranged along the circumferences of the upper containing cavity and the lower containing cavity.

4. The apparatus of claim 1, wherein, The gas collecting assembly comprises: a gas collecting bottle; a gas inlet pipe, one end of which is communicated with the gas outlet end of the one-way valve, and the other end of which extends into the gas collecting bottle; a drain pipe, one end of which is communicated with the bottom of the gas collecting bottle, and the other end of which extends out of the gas collecting bottle; a water outlet valve arranged on the drain pipe; a gas pressure detection mechanism, including an in-bottle gas pressure sensor arranged in the gas collecting bottle and an atmospheric gas pressure sensor arranged outside the gas collecting bottle; and a control module, which is respectively communicatively connected with the water outlet valve, the in-bottle gas pressure sensor and the atmospheric gas pressure sensor.

5. A method for evaluating gas content of a shale reservoir, characterized by, The shale reservoir gas-bearing property evaluation device is used to realize the following steps: The amount of desorbed gas is measured, and the desorbed gas content of the shale sample per unit mass is calculated from the amount of desorbed gas ; measuring the residual gas amount, and calculating the residual gas content per mass of the shale sample from the residual gas amount ; The lost gas amount is calculated, and the lost gas content of the shale sample per unit mass is calculated according to the lost gas amount ; The total gas content V of the shale sample per unit mass is calculated, and the calculation formula is: .

6. The method for shale reservoir gas-in-place evaluation of claim 5, wherein, The amount of desorbed gas is measured, and the desorbed gas content of the shale sample per unit mass is calculated from the amount of desorbed gas comprising the steps of: the baffle is in the closed posture, the shale sample to be tested is put into the upper containing cavity, and the desorption gas generated by the shale sample enters the gas collecting assembly through the gas flow meter; the volume and the passing rate of the desorption gas flowing through the gas flow meter are detected, and the desorption gas measurement is ended when the passing rate of the desorption gas is lower than 0.5 ml / h. During the step of detecting the rate of the desorbed gas passing through the gas flow meter, when the speed of the desorbed gas passing through the gas flow meter is uniform, the gas chromatograph is started so that a part of the desorbed gas enters the gas chromatograph as a desorbed sample gas; The components of the desorbed sample gas are obtained by gas chromatography analysis to obtain the percentage coefficient of O2 in the desorbed sample gas ; According to and the total volume of desorbed gas measured by the gas flow meter , the total volume of oxygen in the desorbed gas is calculated , and the calculation formula is: ； The total amount of desorbed gas actually produced in the shale sample is calculated by proportionally deducting the air mixed in the desorbed gas according to the volume ratio of nitrogen and oxygen in the air , and the calculation formula is: ； The total amount of desorbed gas actually produced from the shale sample The volume of desorbed gas at standard atmospheric conditions is calculated The formula is: wherein is the volume of desorbed gas at standard atmospheric conditions; is the pressure of the gas in the holding chamber on the sealed canister; is the total amount of desorbed gas actually produced by the shale sample; is the temperature in the sealed canister; Desorbed gas volume according to standard atmospheric conditions The desorbed gas content of the shale sample per mass unit is calculated , with the following formula: where m is the mass of the shale sample.

7. The method for shale reservoir gas-in-place evaluation of claim 5, wherein, measuring the residual gas amount, and calculating the residual gas content per mass of the shale sample from the residual gas amount comprising the steps of: The baffle is switched from the closed posture to the open posture so that the shale sample falls into the lower accommodating cavity, and then the baffle is switched from the open posture to the closed posture, the crushing assembly is started, and the shale sample is fully crushed; After the crushing is completed, the baffle is controlled to be switched from the closed posture to the open posture, the volume and the rate of the residual gas passing through the gas flow meter are detected, and when the gas flow meter detects that the measured rate of the residual gas passing through is lower than 0.5 ml / h, the residual gas measurement is completed; During the detection of the rate of the residual gas passing through by the gas flow meter, when the speed of the residual gas passing through detected by the gas flow meter is uniform, the gas chromatograph is started so that a part of the residual gas enters the gas chromatograph as a sample gas, the components of the sample gas are obtained by analysis through the gas chromatograph, and the percentage coefficient of O2 in the content of the sample gas is obtained ; According to and the total volume of residual gas measured by the gas flow meter , the total volume of oxygen in the residual gas is calculated , the calculation formula is: ； The total amount of residual gas actually produced by the shale sample is calculated by proportionally deducting the air mixed in the residual gas according to the volume ratio of nitrogen and oxygen in the air The calculation formula is: ； The total amount of residual gas actually produced from the shale sample The residual gas volume at standard atmospheric conditions is calculated The formula is: , wherein is the volume of the residual gas under standard atmospheric conditions; is the gas pressure in the containment chamber under the sealed tank; is the total amount of residual gas actually produced by the shale sample; is the temperature in the sealed tank; Residual gas volume according to standard atmospheric conditions The residual gas content of the shale sample per unit mass is calculated , and the calculation formula is: where m is the mass of the shale sample.

8. The method for shale reservoir gas-in-place evaluation of claim 5, wherein, The loss gas amount is calculated, and the loss gas content of the shale sample per unit mass is calculated according to the loss gas amount, which includes the following steps: The computer is communicatively connected with the gas flow meter, the volume change of the desorbed gas during the desorption process is automatically recorded by the computer, and the obtained volume of the desorbed gas is automatically calculated and corrected, so as to establish a desorption curve with the square root of time as the horizontal coordinate and the corrected gas volume of the desorbed gas as the vertical coordinate; The loss gas amount is calculated by linear fitting The calculation formula is: wherein is the amount of lost gas, and is taken as the absolute value; k is the slope of the linear portion of the desorption curve; is the time of loss of the gas; t is the desorption time of the desorption gas; Calculating the amount of gas lost by a unit mass of shale sample The formula is: where m is the mass of the shale sample.

9. The method for shale reservoir gas-in-place evaluation of claim 8, wherein, Before the step of detecting the volume and the rate of the desorbed gas passing through the gas flow meter, the sealing tank is heated by the heating jacket; After the desorbed gas measurement is completed, and before the residual gas measurement, the heating jacket is turned off so that the sealing tank is cooled and cooled down; After the crushing assembly is started to fully crush the shale sample, and before the volume and the rate of the residual gas passing through the gas flow meter are detected, the sealing tank is heated by the heating jacket.

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