Shale gas content measurement apparatus and method

Abstract

The present application provides a kind of shale gas content determination device and method, the device includes sample jar, gas volume measurement container, gas collection bottle, vacuum pump and natural gas bottle;Sample jar is provided with first pressure sensor and first temperature sensor;Gas volume measurement container is provided with gas volume measurement chamber, and gas volume measurement container is provided with second pressure sensor and volume measurement sensor component;Sample jar is communicated with gas volume measurement container by first pipeline, and gas volume measurement container is communicated with vacuum pump by second pipeline and third pipeline in turn, and gas volume measurement container is communicated with gas collection bottle by second pipeline and fourth pipeline in turn, and natural gas bottle is communicated with gas volume measurement container by fifth pipeline.It can measure shale gas content, effectively avoid the strict requirement for experimental sample, and the uncertainty caused by loss of time ambiguity, without other parameter calibration, the result is more reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas content determination of cuttings, and particularly relates to a shale formation gas content determination device and method. BACKGROUND

[0002] The shale gas content evaluation experimental methods mainly include core desorption method and isothermal adsorption method. The shale gas content of the core field desorption method is composed of lost gas content, desorbed gas content and residual gas content. The desorbed gas content can be directly measured by experiment, and the residual gas content is measured after the sample is ground to a certain mesh. However, the lost gas content is usually calculated by using the USBM method, Smith Williams method and polynomial curve fitting method established for coalbed methane. The basic principle of the above methods is that the initial desorption amount is proportional to the square root of time, and the lost gas content is restored depending on the loss time. Moreover, the above recovery methods are extrapolation methods, and lack of physical-chemical theoretical basis. The isothermal adsorption method is based on Langmuir isothermal adsorption. Under constant temperature conditions, the adsorption amount of gas under different pressures is tested, and the relationship curve between pressure and adsorption amount is the adsorption isotherm. The relationship model of adsorbed gas content and pressure and humidity is established to obtain the isothermal adsorption equation of the rock sample to the gas. However, the experimental method does not obtain the actual adsorption amount of shale, and the method cannot evaluate the free gas content in shale (Yin Tengyu, 2012; Shen Bojian, 2018).

[0003] Hua Yinchao (2017) analyzed the influencing factors of adsorbed gas and free gas and the corresponding logging parameters based on the laboratory measured free gas and adsorbed gas content, and optimized the logging data related to adsorbed gas and free gas to establish the corresponding logging gas content evaluation model. Xia Hongquan (2019) established a shale gas content calculation model based on conventional logging data by using isothermal adsorption experiment data and a large amount of logging data, and by optimizing the fitting regression method to calculate the key parameters of shale gas content. The calculation of adsorbed gas content by logging method needs to build the relationship between logging curve and TOC, and the calculation of free gas content needs to build the relationship between logging curve and porosity and gas saturation, which all need to use a large amount of measured data for correction or calibration.

[0004] Huang Hexin (2015, application number 201510699029.8) restores the original gas content of shale by adsorbed gas content and pore volume gas content. Adsorbed gas content restoration is based on adsorption potential, dispersion potential energy theory and gas state equation, combined with core column methane isothermal adsorption curve, gas component test data, shale porosity and water saturation, and the adsorbed gas content change of gas between formation temperature and 95℃ desorption process. Pore volume gas content restoration uses porosity and water saturation test data to obtain state equation. This method avoids the uncertainty of empirical formula and can obtain gas composition, but its complex mathematical model still uses methane isothermal adsorption experiment, and the adsorbed gas content evaluation represents the maximum adsorption capacity of the rock.

[0005] The field core desorption method is obviously limited by drilling core and other engineering conditions. Among them, the commonly used USBM method, Smith Williams method and polynomial curve fitting method for restoring lost gas volume all need to accurately judge the loss time, and the desorption sample requires a core; the isothermal adsorption method obtains the maximum adsorbed gas content of shale, which can only evaluate the adsorption capacity of the sample and cannot obtain the free gas volume of the sample; the logging interpretation method often lacks a large number of measured data calibration, and the result reliability is poor; the numerical simulation combined with experimental test uses Langmuir adsorption theory, and the calculated adsorbed gas content is often greater than the actual value. SUMMARY

[0006] Therefore, it is necessary to provide a shale formation gas content measuring device and method aiming at the above technical problems.

[0007] A shale formation gas content measuring device, comprising: a sample tank, a gas volume measuring container, a gas collection bottle, a vacuum pump and a natural gas bottle;

[0008] The sample tank is provided with a first pressure sensor and a first temperature sensor, the first pressure sensor is used to detect the pressure in the sample tank, and the first temperature sensor is used to detect the temperature in the sample tank;

[0009] The gas volume measuring container is provided with a gas volume measuring chamber, and the gas volume measuring container is provided with a second pressure sensor and a volume measuring sensor assembly, the second pressure sensor is used to detect the pressure of the gas volume measuring chamber, and the volume measuring sensor assembly is used to detect the volume of the gas volume measuring chamber;

[0010] The sample tank is communicated with the gas volume measurement container through a first pipeline, the gas volume measurement container is communicated with the vacuum pump through a second pipeline and a third pipeline in sequence, the gas volume measurement container is communicated with the gas collecting bottle through a second pipeline and a fourth pipeline in sequence, and the natural gas bottle is communicated with the gas volume measurement container through a fifth pipeline.

[0011] In one of the embodiments, a first control valve is arranged on the first pipeline, and the first control valve is a waterproof air valve.

[0012] In one of the embodiments, the second pipeline, the third pipeline and the fourth pipeline are respectively arranged as:

[0013] A second control valve is arranged on the second pipeline;

[0014] and / or

[0015] A third control valve is arranged on the third pipeline;

[0016] and / or

[0017] A fourth control valve is arranged on the fourth pipeline.

[0018] In one of the embodiments, the volume measurement sensor assembly comprises a displacement adjuster and a displacement sensor, the displacement adjuster is connected with the gas volume measurement container, the displacement adjuster is used to move in the gas volume measurement container to adjust the volume of the gas volume measurement chamber, and the displacement sensor is used to detect the displacement distance of the displacement adjuster.

[0019] In one of the embodiments, a constant temperature container is further included, a constant temperature cavity is arranged in the constant temperature container, and the constant temperature cavity is used to accommodate the sample tank.

[0020] In one of the embodiments, the sample tank is provided with a screw cap hole, and a sealing gasket screw cap is screwed in the screw cap hole.

[0021] In one of the embodiments, a fifth control valve is arranged on the fifth pipeline.

[0022] A shale formation gas content measurement method is realized by using the shale formation gas content measurement device in any one of the above embodiments, and the shale formation gas content measurement method is characterized in that the shale formation gas content measurement method comprises the following steps.

[0023] In step one, the drilling cuttings are washed clean, the drilling cuttings are filled in the sample tank and compacted, and the sample tank is filled with salt water of a preset saturation degree.

[0024] Step two, turn on the vacuum pump to vacuum the sample tank and the gas volume measuring container to reach a first preset pressure, then stop the vacuum and close the connection between the sample tank and the gas volume measuring container, and close the connection between the gas collecting bottle and the gas volume measuring container;

[0025] Step three, record the pressure value of the first pressure sensor and the temperature value of the first temperature sensor every first preset time interval until the pressure value of the first pressure sensor fluctuates less than a first preset value within a second preset time, record the pressure value of the first pressure sensor at this time as a first pressure value P1, turn on the connection between the sample tank and the gas volume measuring container, adjust the volume measuring sensor assembly until the pressure in the gas volume measuring chamber reaches a second preset pressure, close the connection between the sample tank and the gas volume measuring container, record the volume value of the gas volume measuring chamber detected by the volume measuring sensor assembly at this time as a first volume value V1, turn on the connection between the gas collecting bottle and the gas volume measuring container until the volume value of the gas volume measuring chamber is 0, and close the connection between the gas collecting bottle and the gas volume measuring container;

[0026] Step four, remove the gas collecting bottle and replace it with an empty one, and measure the components in the removed gas collecting bottle;

[0027] Repeat steps three to four, and after repeating a preset number of times, execute step five;

[0028] Step five, pour out the salt water in the sample tank, measure the volume value of the poured out salt water, and record the volume value of the poured out salt water as a salt water volume value V 水 ;

[0029] Step six, execute step two, then turn on the connection between the natural gas bottle and the gas volume measuring container to supply gas from the natural gas bottle to the gas volume measuring container until the volume value of the gas volume measuring chamber detected by the volume measuring sensor assembly is a maximum volume value V max , record the pressure value of the second pressure sensor at this time as a second pressure value P0, close the connection between the natural gas bottle and the gas volume measuring container, turn on the connection between the sample tank and the gas volume measuring container, adjust the volume measuring sensor assembly until the pressure in the gas volume measuring chamber reaches a third preset pressure P 地, closing the communication between the sample tank and the gas volume measuring container, adjusting the volume measuring sensor assembly until the pressure in the gas volume measuring chamber is a second pressure value P0, recording the volume value of the gas volume measuring chamber detected by the volume measuring sensor assembly at this time as a second volume value V0;

[0030] Step seven, taking out the drilling cuttings in the sample tank, drying the drilling cuttings, and weighing to obtain the sample weight G;

[0031] Step eight, calculating the free gas volume value V max , the second volume value V0, the salt water volume value V 水 , the third preset pressure P 地 , and the second pressure value P0 to obtain the free gas volume and the adsorbed gas volume value V 总 ,

[0032] According to the volume value V 总 and the sample weight G, the shale gas content is calculated.

[0033] In one embodiment, it further includes:

[0034] After repeating steps three to four for a preset number of times n, a plurality of first pressure values P1 to P n and a plurality of first volume values V1 to V n are obtained, according to the plurality of first pressure values P1 to P n and the plurality of first volume values V1 to V n , a linear relationship between the stable pressure and the free gas volume desorbed after reaching the stable pressure is obtained, according to the linear relationship and the third preset pressure P 地 , the volume V 游离 of the free gas at standard atmospheric pressure is calculated;

[0035] According to the volume V 游离 of the free gas at standard atmospheric pressure and the sample weight G, the free gas volume per unit mass of shale is calculated.

[0036] In one embodiment, it further includes:

[0037] According to the free gas volume and the adsorbed gas volume value V 总 and the volume V 游离 of the free gas at standard atmospheric pressure, the volume V 吸附 of the adsorbed gas at standard atmospheric pressure is calculated;

[0038] According to the volume V 游离 of the free gas at standard atmospheric pressure and the volume V 吸附The ratio of free gas volume to adsorbed gas volume was calculated.

[0039] The aforementioned apparatus and method for measuring the gas content of mudstone and shale formations can effectively avoid the stringent requirements on experimental samples and the uncertainties caused by the ambiguity of time loss. No other parameter calibration is required, and the results are more reliable. The aforementioned apparatus and method can be applied to the identification of gas-rich shale layers and the evaluation of resource potential, and play a very important role in shale gas exploration.

[0040] Furthermore, the aforementioned device and method for measuring gas content in shale formations are applicable to core drilling or cuttings sampling, are independent of time loss, and can simultaneously obtain total gas content, free gas content, and adsorbed gas content. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a device for measuring the gas content of mudstone and shale formations in one embodiment.

[0042] Figure 2 In one embodiment, the experimental equilibrium pressure P and the desorbed free gas V are used to calculate the equilibrium pressure at each stage of the experiment. 游离 Relationship diagram. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] Example 1

[0045] In this embodiment, as Figure 1As shown, a shale gas content measuring device is provided, which comprises a sample tank 03, a gas volume measuring container, a gas collecting bottle 15, a vacuum pump 01 and a natural gas bottle 17; the sample tank 03 is provided with a first pressure sensor 04 for detecting the pressure in the sample tank 03 and a first temperature sensor 06 for detecting the temperature in the sample tank 03; the gas volume measuring container is provided with a gas volume measuring chamber 16, a second pressure sensor 05 for detecting the pressure in the gas volume measuring chamber 16 and a volume measuring sensor assembly for detecting the volume of the gas volume measuring chamber 16; the sample tank 03 is communicated with the gas volume measuring container through a first pipeline, the gas volume measuring container is communicated with the vacuum pump 01 through a second pipeline and a third pipeline in sequence, the gas volume measuring container is communicated with the gas collecting bottle 15 through a second pipeline and a fourth pipeline in sequence, and the natural gas bottle 17 is communicated with the gas volume measuring container through a fifth pipeline.

[0046] In this embodiment, the sample tank 03 is used to contain shale cuttings, when the sample tank 03 is communicated with the gas volume measuring container, the gas in the sample tank 03 enters the gas volume measuring container through the first pipeline, so that the position of the volume measuring sensor assembly in the gas volume measuring container changes, thereby changing the volume of the gas volume measuring chamber 16 in the gas volume measuring container. The gas collecting bottle 15 is used to collect the gas discharged from the gas volume measuring chamber 16, and the vacuum pump 01 is used to vacuum the sample tank 03, the gas volume measuring container and the gas collecting bottle 15. The natural gas bottle 17 is used to supply gas to the gas volume measuring container.

[0047] In one embodiment, a first control valve is arranged on the first pipeline, and the first control valve is a waterproof air valve 07.

[0048] In this embodiment, the first control valve, i.e. the waterproof air valve 07, is used to control the conduction and cutoff of the first pipeline, so as to control the conduction and cutoff between the sample tank 03 and the gas volume measuring container, and the waterproof air valve 07 can prevent water from entering the first pipeline, so that gas can enter the gas volume measuring container through the first pipeline.

[0049] In one embodiment, the second pipeline, the third pipeline and the fourth pipeline are respectively arranged as follows: a second control valve 09 is arranged on the second pipeline; and / or a third control valve 10 is arranged on the third pipeline; and / or a fourth control valve 08 is arranged on the fourth pipeline.

[0050] In the embodiment, the second pipeline is provided with a second control valve 09, which is used to control the on and off of the second pipeline. The third pipeline is provided with a third control valve 10, which is used to control the on and off of the third pipeline. The fourth pipeline is provided with a fourth control valve 08, which is used to control the on and off of the fourth pipeline. When the second pipeline and the third pipeline are off, the communication between the gas volume measuring container and the vacuum pump 01 is closed. When the second pipeline and the third pipeline are on, the communication between the gas volume measuring container and the vacuum pump 01 is on. When the second pipeline and the fourth pipeline are off, the communication between the gas volume measuring container and the gas collecting bottle 15 is closed. When the second pipeline and the fourth pipeline are on, the communication between the gas volume measuring container and the gas collecting bottle 15 is on. In the embodiment, the second pipeline, the third pipeline and the fourth pipeline are communicated through a three-way pipe. When the second control valve 09, the third control valve 10 and the fourth control valve 08 are opened, the second pipeline, the third pipeline and the fourth pipeline are communicated, and the vacuum pump 01 can be communicated with the gas volume measuring container and the gas collecting bottle 15 respectively.

[0051] In one of the embodiments, the volume measuring sensor assembly comprises a displacement adjuster 14 and a displacement sensor 13. The displacement adjuster 14 is connected with the gas volume measuring container, and is used to move in the gas volume measuring container to adjust the volume of the gas volume measuring chamber 16. The displacement sensor 13 is used to detect the displacement distance of the displacement adjuster 14.

[0052] In the embodiment, when the volume of the gas in the gas volume measuring container changes, the displacement adjuster 14 is adjusted to move in the gas volume measuring container to change the volume of the gas volume measuring chamber 16. The displacement distance of the displacement adjuster 14 moving in the gas volume measuring container is monitored by the displacement sensor 13, and the volume of the gas volume measuring chamber 16 can be calculated according to the displacement distance. In one of the embodiments, the computer reads the displacement distance of the displacement adjuster 14 detected by the displacement sensor 13, and calculates the volume of the gas volume measuring chamber 16.

[0053] In one of the embodiments, the shale gas content measuring device further comprises a constant temperature container, and a constant temperature cavity 02 is arranged in the constant temperature container, which is used to accommodate the sample tank 03.

[0054] In the embodiment, the constant temperature cavity 02 is used to place the sample tank 03, and constant temperature circulating oil is injected into the constant temperature cavity 02 to keep the sample tank 03 at constant temperature. The constant temperature cavity 02 is used to simulate the formation temperature, so that the formation temperature is maintained in the sample tank 03.

[0055] In one of the embodiments, the sample tank 03 is provided with a screw cap hole, and a sealing gasket screw cap 12 is screwed in the screw cap hole.

[0056] In this embodiment, the screw hole is used to let the excess liquid in the sample tank 03 out, and the screw hole is sealed by the sealing washer screw cap 12.

[0057] In one embodiment, a fifth control valve 11 is provided on the fifth pipeline.

[0058] In this embodiment, the fifth control valve 11 is used to control the on and off of the fifth pipeline, when the fifth pipeline is off, the communication between the natural gas cylinder 17 and the gas volume measuring container is closed, when the fifth pipeline is on, the communication between the natural gas cylinder 17 and the gas volume measuring container is open.

[0059] Embodiment two

[0060] In this embodiment, a shale gas content determination method is provided, which is realized by using the shale gas content determination device in any of the above embodiments, comprising:

[0061] Step one, wash the drilling cuttings clean, fill the sample tank 03 with drilling cuttings and compact, fill the sample tank 03 with salt water of a predetermined saturation degree.

[0062] In this embodiment, the predetermined saturation degree is 5% to 10%. In this step, first wash the drilling cuttings clean, fill the sample tank 03 with drilling cuttings and compact, fill the sample tank 03 with salt water of a saturation degree of 5% to 10%, tighten the sample tank cover, excess salt water seeps out from the screw hole 12, wipe the sample tank 03 clean, tighten the sealing washer screw cap 12, and place the sample tank 03 in the constant temperature chamber 02.

[0063] Preparation before experiment. Before the experiment, check whether the pipeline connection of the equipment is normal, and whether all the valves are in the closed state, i.e. the first control valve, the second control valve, the third control valve, the fourth control valve and the fifth control valve are in the closed state. Start the display panel and start the computer. Check the instrument readings on the display panel, if the readings of the first pressure sensor 04 and the second pressure sensor 05 are not zero at this time, manually zero. Start the constant temperature oil bath, set the oil bath circulating temperature to the formation temperature (T), and inject constant temperature circulating oil into the constant temperature chamber 02. The displacement regulator is also called the tightening displacement adjustment device 14, adjust the displacement sensor 13 to zero, i.e. the reading on the display panel is zero.

[0064] Step two, open the vacuum pump 01, and vacuumize the sample tank 03 and the gas volume measuring container, so that the pressure in the sample tank 03 and the gas volume measuring container reaches a first preset pressure, then stop vacuumizing the sample tank 03 and the gas volume measuring container, close the communication between the sample tank 03 and the gas volume measuring container, and close the communication between the gas collecting bottle 15 and the gas volume measuring container.

[0065] In this embodiment, the first preset pressure is -0.10 MPa. In this step, the system is vacuumized. Open the first control valve 07, the second control valve 09, and the fourth control valve 08, open the vacuum pump 01, open the third control valve 10, and vacuumize to about -0.10 MPa of the first pressure sensor 04 and the second pressure sensor 05, for about 1-3 min. Then close the first control valve 07, the second control valve 09, the third control valve 10, and the fourth control valve 08.

[0066] Step three, record the pressure value of the first pressure sensor 04 and the temperature value of the first temperature sensor 06 every first preset time, until the fluctuation of the pressure value of the first pressure sensor 04 in a second preset time is less than a first preset value, record the pressure value of the first pressure sensor 04 at this time as a first pressure value P1, open the communication between the sample tank 03 and the gas volume measuring container, adjust the volume measuring sensor assembly until the pressure in the gas volume measuring chamber 16 reaches a second preset pressure, close the communication between the sample tank 03 and the gas volume measuring container, record the volume value of the gas volume measuring chamber 16 detected by the volume measuring sensor assembly at this time as a first volume value V1, open the communication between the gas collecting bottle 15 and the gas volume measuring container until the volume value of the gas volume measuring chamber 16 is 0, and close the communication between the gas collecting bottle 15 and the gas volume measuring container.

[0067] In this embodiment, the first preset time is 5 min, the second preset time is 30 min, and the second preset pressure is 0.1 MPa.

[0068] In this step, the temperature sensor 06 on the display panel is recorded every 5 minutes; the pressure sensor 04 on the display panel is recorded by the computer every 5 minutes, until the reading is nearly constant within the last 30 minutes, and the pressure at this time, i.e. the equilibrium pressure P1, is manually input or recorded by the computer; the waterproof air valve 07 is opened, and the gas slowly enters the gas volume measuring chamber 16 through the pipeline; the displacement adjusting device 14 is slowly adjusted, and the reading of the pressure sensor 05 on the display panel is observed until the reading is 0.1 MPa, the displacement adjusting device 14 is stopped, and the waterproof air valve 07 is closed; the displacement of the displacement sensor 13 at this time is manually recorded by the computer, and the volume V1 of the gas volume measuring chamber 16 is automatically calculated by the computer and recorded; the control valves (08, 09) are opened, and the displacement adjusting device 14 is tightened until the reading of the displacement sensor 13 on the display panel is zero, i.e. the volume of the gas volume measuring chamber 16 is zero, and the natural gas desorbed in this stage is all introduced into the gas collection bottle 15.

[0069] In step four, the gas collection bottle 15 is removed, an empty gas collection bottle 15 is replaced, and the components in the removed gas collection bottle 15 are measured.

[0070] In this step, the control valves (08, 09) are closed, the gas collection bottle 15 is removed and sent to the laboratory for component and isotope testing; a new gas collection bottle 15 is replaced; and the experiment in this stage is terminated.

[0071] Steps three to four are repeated, and after a predetermined number of repetitions, step five is performed.

[0072] In this embodiment, the predetermined number of repetitions is five. Therefore, steps three to four are performed a total of six times. The above experimental process is repeated, and the equilibrium pressures (P2, P3, P4, P5, P6) and (V2, V3, V4, V5, V6) in each experimental stage are manually input or recorded by the computer.

[0073] In step five, the salt water in the sample tank 03 is poured out, the volume value of the poured-out salt water is measured, and the volume value of the poured-out salt water is recorded as the salt water volume value V 水 .

[0074] In step six, step two is performed, and then the communication between the natural gas bottle 17 and the gas volume measuring container is turned on, so that the natural gas bottle 17 supplies gas to the gas volume measuring container, until the volume value of the gas volume measuring chamber 16 detected by the volume measuring sensor assembly is the maximum volume value V max, the pressure value of the second pressure sensor 05 at this time is recorded as the second pressure value P0, the communication between the gas cylinder 17 and the gas volume measuring container is closed, the communication between the sample tank 03 and the gas volume measuring container is opened, the volume measuring sensor assembly is adjusted until the pressure in the gas volume measuring chamber 16 reaches a third preset pressure P 地 , the communication between the sample tank 03 and the gas volume measuring container is closed, the volume measuring sensor assembly is adjusted until the pressure in the gas volume measuring chamber 16 reaches a second pressure value P0, and the volume value of the gas volume measuring chamber 16 detected by the volume measuring sensor assembly at this time is recorded as a second volume value V0.

[0075] In this embodiment, the third preset pressure P 地 is the formation pressure.

[0076] In this step, after repeating steps three to four for a preset number of times, the gas collecting bottle (15) is removed, and the control valves (08, 09) are closed.

[0077] The sealing gasketed nut 12 is unscrewed, the sample tank 03 is inverted, and the brine enters the measuring cylinder (not shown in the figure) from the flow guide pipeline until no brine flows out of the flow guide pipeline, and the brine volume V 水 is input on the display panel. The flow guide pipeline is removed, and the sealing gasketed nut 12 is screwed tightly.

[0078] The control valves (07, 09) are opened, the vacuum pump 01 is started, the control valve 10 is opened, and the pressure sensor (04, 05) is extracted to about -0.10 MPa, and the time is about 30 min. Then the control valves 07, 09, and 10 are closed.

[0079] The control valve 11 is opened, gas is supplied to the gas volume measuring chamber 16 through the pipeline; the displacement sensor 13 is adjusted to the maximum value on the display panel through the displacement adjusting device 14, that is, the volume of the gas volume measuring chamber 16 is the maximum V max = 0.5 L, and the pressure sensor 05 is recorded on the display panel at this time P0.

[0080] The control valve 11 is closed, the water-proof air valve 07 is opened, the displacement adjusting device 14 is slowly screwed, and the pressure sensor 04 is observed on the display panel until the value is equal to the formation pressure P 地 , and there is no change for 12 h; the water-proof air valve 07 is closed, the displacement adjusting device 14 is loosened, and the pressure sensor 05 is observed on the display panel until the value is P0, the displacement amount of the displacement sensor 13 at this time is recorded manually, the computer automatically calculates the volume V0 of the gas volume measuring chamber 16 according to the displacement amount, and records it.

[0081] During the experiment, the pressure sensor 04 should be observed several times. If the reading is lower than the formation pressure P 地 , the displacement adjusting device 14 should be tightened again to make the pressure sensor 04 show the formation pressure P 地 . After the last adjustment, the pressure sensor 04 should always show the formation pressure P 地 12h, no obvious change, the experiment is over. The time required for the experiment is 48-120h.

[0082] System emptying: close the 410 constant temperature oil bath; connect the waste gas tank 15 (note that 15 is connected to the gas collection bottle during the evaluation experiment, and is connected to the waste gas tank during emptying); open the control valve (08, 09), tighten the displacement adjusting device 14, and make the displacement sensor 13 show zero on the display panel; remove the waste gas tank 15. Figure 1

[0083] Step seven: take out the drilling cuttings in the sample tank 03, dry the drilling cuttings, and weigh to obtain the sample weight G.

[0084] In this step, the cuttings sample is weighed: take out the sample tank 03, pour out the cuttings sample, and weigh G after drying on a special sample plate.

[0085] Step eight: calculate the free gas volume and adsorbed gas volume V max in the shale cuttings original pore according to the maximum volume value V 水 , the second volume value V0, the salt water volume value V 地 , the third preset pressure P 总 , and the second pressure value P0; and calculate the shale gas content according to the volume value V 总 and the sample weight G.

[0086] The gas measurement chamber volume at the beginning of the experiment is V max =0.5L, the gas volume measurement chamber volume at the end of the experiment is V0, the gas volume measurement chamber pressure is P0, and the temperature is room temperature 20℃. The volume of natural gas injected into the sample tank is V max -V0; the space volume between the cuttings and the cuttings is V 水 (equivalent to the salt water volume); therefore, the actual volume of the free gas volume and the adsorbed gas volume injected into the shale cuttings original pore is V max -V0-V 水 ×(P 地 / P0).

[0087] The volume converted to standard atmospheric pressure is V 总 =(V max -V0-V 水 ×(P 地 ​The volume is calculated as / P0))×(P0 / 0.1), which represents the gas content of shale under formation temperature and pressure conditions at standard atmospheric pressure and room temperature (20℃). Therefore, the gas content per unit mass of shale is V. 总 / G.

[0088] In one embodiment, the method further includes the step of repeating steps three to four a preset number of times n to obtain multiple first pressure values ​​P1 to P2. n and multiple first volume values ​​V1 to V n According to multiple first pressure values ​​P1 to P n and multiple first volume values ​​V1 to V n A linear relationship is obtained between the stable pressure and the amount of free gas desorbed after reaching the stable pressure. Based on the linear relationship and the third preset pressure P, 地 Calculate the volume V of free gas under standard atmospheric pressure. 游离 Based on the volume V of free gas under standard atmospheric pressure 游离 The amount of free gas per unit mass of mudstone and shale was calculated using the sample weight G.

[0089] In the above embodiments, six stages of experiments were carried out. The experimental parameters for each stage are shown in Table 1: the experimental temperature was kept constant at the formation temperature T (°C), the equilibrium pressures for each experimental stage were P1, P2, P3, P4, P5, and P6, and the volumes of natural gas in a free state after reaching the equilibrium pressure in each experimental stage were V1, V2, V3, V4, V5, and V6, respectively.

[0090] The derivation of the free gas volume calculation process is as follows:

[0091] The stable pressure (P) in the six experimental stages showed a good linear relationship with the amount of free gas desorbed (V) after reaching the equilibrium pressure: V = aP + b. Figure 2 As shown. Based on this formula, the formation pressure P of the rock cuttings sample can be calculated. 地 The volume V of free gas contained under standard atmospheric pressure at certain temperature conditions. 游离 Therefore, the free gas content per unit mass of mudstone and shale is V. 游离 / G.

[0092] In one embodiment, it further includes: based on the volume values ​​V of free gas and adsorbed gas. 总 And the volume V of free gas under standard atmospheric pressure 游离 The volume V of the adsorbed gas under standard atmospheric pressure was calculated. 吸附 Based on the volume V of free gas under standard atmospheric pressure 游离 and the volume V of adsorbed gas under standard atmospheric pressure 吸附 The ratio of free gas volume to adsorbed gas volume was calculated.

[0093] The gas content V of the mudstone 总 Mainly includes free gas volume V 游离 and adsorption gas volume V 吸附 Based on this, the formation pressure P of the rock cuttings sample can be calculated. 地 The volume V of adsorbed gas under standard atmospheric pressure at the specified temperature conditions. 吸附 =V 总 -V 游离 .

[0094] Because a small amount of the original adsorbed gas still remained in the rock fragment sample after multiple desorption processes and 30 minutes of vacuuming, the above-mentioned V... 总 It should be less than the original gas content of the rock cuttings sample, therefore, through V 吸附 =V 总 -V 游离 The calculated adsorbed gas volume only represents the minimum adsorption capacity of the rock fragment sample. However, with the more desorption cycles in the "Free Gas Evaluation System Experiment" and the longer the vacuum time in the "Shale Gas Content Evaluation Experiment," the less original adsorbed gas remains in the rock fragment sample, i.e., the experimentally measured V... 总 The closer the gas content is to the original gas content of the rock cuttings sample, the better the gas content can be obtained through V. 吸附 =V 总 -V 游离 The closer the calculated amount of adsorbed gas is to the actual amount of adsorbed gas in the rock cutting sample, the better.

[0095] Therefore, the amount of gas adsorbed per unit mass of mudstone and shale is V. 吸附 / G.

[0096] Calculation of the ratio of free gas to adsorbed gas: V can be obtained through "Calculation of free gas volume in shale" and "Calculation of adsorbed gas volume in shale". 游离 and V 吸附 Based on this, the ratio of free gas to adsorbed gas can be calculated as V. 游离 V 吸附 .

[0097] Example 3

[0098] The following is in conjunction with the appendix Figure 1 The experimental process of the device of the present invention, as well as the calculation of shale gas content, free gas content, and the ratio of free gas to adsorbed gas, are explained.

[0099] (1) Sample loading. Quickly rinse the drilling cuttings clean, fill the sample container 03 with the cuttings and compact it as much as possible; fill it with brine with a saturation of 5% to 10%; tighten the sample container lid, and let the excess brine seep out from the nut hole 12; wipe the sample container 03 clean and tighten the nut 12 with the sealing gasket; put the sample container 03 into the constant temperature chamber 02.

[0100] (2) Preparation before experiment. Check the pipeline connection of the equipment, make sure that all the valves (07, 08, 09, 10, 11) are closed. Start the display panel and the computer. Check the reading of the panel, if the reading of the pressure sensor (04, 05) is not zero, manually reset the zero. Start the constant temperature oil bath, which is not shown in the figure, set the circulating temperature of the oil bath to the formation temperature T, and inject the constant temperature circulating oil into the constant temperature cavity 02. Tighten the displacement adjusting device 14, and adjust the displacement sensor 13 to zero, that is, the reading on the display panel is zero.

[0101] (3) System vacuumization. Open the control valves (07, 08, 09), start the 01 vacuum pump, open the 10 control valve, and vacuumize to about -0.10 MPa of the pressure sensor (04, 05), which takes about 1-3 min. Then close the 07, 08, 09, 10 control valves.

[0102] (4) Free gas evaluation system experiment:

[0103] ① First stage experiment: the computer automatically records the reading of the temperature sensor 06 on the display panel every 5 min; the computer automatically records the reading of the pressure sensor 04 on the display panel every 5 min, until the reading is nearly unchanged in the last 30 min, manually input or control the computer to record the pressure at this time, that is, the equilibrium pressure P1; open the waterproof air valve 07, and the gas slowly enters the gas volume measuring chamber 16 through the pipeline; slowly adjust the displacement adjusting device 14, and observe the reading of the pressure sensor 05 on the display panel until the reading is 0.1 MPa, stop adjusting the displacement adjusting device 14, and close the waterproof air valve 07; manually control the computer to record the displacement of the displacement sensor 13 at this time, and the computer automatically calculates the volume V1 of the gas volume measuring chamber 16 according to the displacement and records it; open the control valves 08, 09, and tighten the displacement adjusting device 14 until the reading of the displacement sensor 13 on the display panel is zero, that is, the volume of the gas volume measuring chamber (16) is zero, and the natural gas desorbed in this stage experiment all enters the gas collection bottle (15); close the control valves (08, 09), and remove the gas collection bottle 15 to send to the laboratory for component and isotope testing; replace the new gas collection bottle 15; this stage experiment is terminated.

[0104] ② Second, third, fourth, fifth, and sixth stage experiments: repeat the above experimental procedures, and manually input or control the computer to record the equilibrium pressures P2, P3, P4, P5, P6 and the volumes V2, V3, V4, V5, V6 of each experimental stage.

[0105] The total time required for the above six stage experiments is 24-72 h.

[0106] (5) Mud shale total gas content evaluation experiment:

[0107] After the sixth stage of the experiment is completed, remove the gas collecting cylinder 15 and close the control valves (08, 09).

[0108] Unscrew the nut 12 with the sealing gasket, replace the guide tube (not shown in the diagram), invert the sample container 03, and let the brine enter the metering cylinder (not shown in the diagram) through the guide tube until no brine flows out of the guide tube. Manually input the brine volume V on the display panel. 水 .

[0109] Remove the guide tube and replace it with nut 12 with a sealing gasket and tighten it.

[0110] Open control valves (07, 09), start vacuum pump 01, open control valve 10, and pump until the pressure sensor (04, 05) reads approximately -0.10 MPa, which takes about 30 minutes. Then close control valves (07, 09, 10).

[0111] Open control valve 11 to supply gas to gas volume measuring chamber 16 through pipeline; adjust displacement sensor 13 to the maximum reading on display panel via displacement adjustment device 14, i.e., the maximum volume V of gas volume measuring chamber 16. max =0.5L, manually instruct the computer to record the reading P0 of pressure sensor 05 on the display panel at this time.

[0112] Close control valve 11, open waterproof and breathable valve 07, slowly tighten displacement adjustment device 14, and observe the reading on the display panel of pressure sensor 04 until the reading equals the formation pressure P. 地 And there is no change after 12 hours; close the waterproof and breathable valve 07, loosen the displacement adjustment device 14, observe the reading of the pressure sensor 05 on the display panel until the reading is P0, manually command the computer to record the displacement of the displacement sensor 13 at this time, and the computer automatically calculates the volume V0 of the gas volume measuring chamber 16 based on the displacement and records it.

[0113] During this experiment, the reading of pressure sensor 04 needs to be observed multiple times. If the reading is lower than the formation pressure P... 地 Tighten the displacement adjustment device 14 again so that the pressure sensor 04 reads the formation pressure P. 地 Until the final adjustment, the reading of pressure sensor 04 was kept constant at the formation pressure P. 地 After 12 hours, no significant changes were observed, and the experiment was concluded. The required time for this experiment is 48–120 hours.

[0114] (6) Voiding the experimental system: Close the 410°C constant temperature oil bath; connect the waste gas tank 15 (Note: attached) Figure 1 In step 15, the gas collection bottle is connected during the evaluation experiment, and the waste gas tank is connected during venting; open the control valves (08, 09), tighten the displacement adjustment device 14, and make the reading of the displacement sensor 13 on the display panel zero; remove the waste gas tank 15.

[0115] (7) Weighting of the cuttings sample: take out the sample jar 03, pour out the cuttings sample therein, place it on a special sample tray to dry, and then weigh G.

[0116] (8) Calculation of total gas content in shale

[0117] According to the "evaluation experiment of total gas content in shale", the volume of the gas measuring chamber at the beginning of the experiment is V0 max = 0.5 L, the volume of the gas measuring chamber at the end of the experiment is V0, the pressure of the gas measuring chamber is P0, and the temperature is room temperature 20℃. The volume of the natural gas injected back into the sample jar is V max -V0; the space volume between the cuttings and the cuttings is V 水 (equivalent to the volume of salt water); therefore, the actual volume of the free gas and the adsorbed gas injected into the original pore of the shale cuttings is V max -V0-V 水 ×(P 地 / P0).

[0118] The volume under the standard atmospheric pressure is V 总 =(V max -V0-V 水 ×(P 地 / P0))×(P0 / 0.1), which is the volume of the gas content in shale under the conditions of formation temperature and pressure under the standard atmospheric pressure and room temperature 20℃. Therefore, the gas content per unit mass of shale is V 总 / G.

[0119] (9) Calculation of free gas content in shale

[0120] According to the "evaluation experiment of free gas content", six-stage experiments were carried out, and the experimental parameters of each stage are shown in Table 1: the experimental temperature is constant at T℃, the equilibrium pressure of each experimental stage is P1, P2, P3, P4, P5, and P6, respectively, and the volume of the natural gas in the free state under the standard atmospheric pressure after desorption at each experimental stage is V1, V2, V3, V4, V5, and V6, respectively.

[0121] Table 1: Parameters of each experimental stage

[0122]

[0123]

[0124] The calculation process of free gas content is derived as follows:

[0125] The six experimental stages have a good linear relationship between the stable pressure P and the free gas content V after reaching the equilibrium pressure V=aP+b, please refer toFigure 2 According to the formula, the volume of free gas in the rock sample under the formation pressure P 地 and temperature conditions under standard atmospheric pressure V 游离 can be calculated.

[0126] Therefore, the free gas content of unit mass of shale is V 游离 / G.

[0127] (10) Calculation of shale adsorbed gas content

[0128] The shale gas content V 总 mainly includes free gas content V 游离 and adsorbed gas content V 吸附 . According to this, the volume of adsorbed gas in the rock sample under the formation pressure P 地 and temperature conditions under standard atmospheric pressure V 吸附 = V 总 -V 游离 can be calculated.

[0129] Because there is still a small amount of original adsorbed gas in the rock sample after multiple desorptions in the "free gas evaluation system experiment" and 30 minutes of vacuum pumping in the "shale gas content evaluation experiment", the above V 总 should be less than the original gas content of the rock sample in the "shale gas content evaluation experiment", and thus the adsorbed gas content calculated by V 吸附 = V 总 -V 游离 only represents the minimum adsorbed amount of the rock sample. However, the more the number of desorptions in the "free gas evaluation system experiment" and the longer the vacuum pumping time in the "shale gas content evaluation experiment", the less the original adsorbed gas remaining in the rock sample, that is, the closer the V 总 measured by the experiment to the original gas content of the rock sample, and the closer the adsorbed gas content calculated by V 吸附 = V 总 -V 游离 to the true adsorbed gas content of the rock sample.

[0130] Therefore, the adsorbed gas content of unit mass of shale is V 吸附 / G.

[0131] (11) Calculation of free gas and adsorbed gas ratio

[0132] V 游离 and V 吸附 can be obtained through "calculation of shale free gas content" and "calculation of shale adsorbed gas content", and according to this, the ratio of free gas to adsorbed gas is V 游离 : V 吸附 .

[0133] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiments of the methods can be included. Any reference to memory, storage, databases, or other media in the embodiments provided by the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0134] The technical features of the above embodiments can be combined in any way. In order to make the description simple, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the present application.

[0135] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of the patent protection of the present application should be subject to the appended claims.

Claims

1. A device for measuring the gas content of mudstone and shale formations, characterized in that, include: Sample containers, gas volume measuring containers, gas collecting bottles, vacuum pumps, and natural gas cylinders; The sample container is equipped with a first pressure sensor and a first temperature sensor. The first pressure sensor is used to detect the pressure inside the sample container, and the first temperature sensor is used to detect the temperature inside the sample container. The gas volume measuring container is provided with a gas volume measuring chamber. The gas volume measuring container is provided with a second pressure sensor and a volume measuring sensing component. The second pressure sensor is used to detect the pressure of the gas volume measuring chamber, and the volume measuring sensing component is used to detect the volume of the gas volume measuring chamber. The sample container is connected to the gas volume measuring container via a first pipeline. The gas volume measuring container is connected to the vacuum pump via a second pipeline and a third pipeline in sequence. The gas volume measuring container is connected to the gas collecting bottle via a second pipeline and a fourth pipeline in sequence. The natural gas cylinder is connected to the gas volume measuring container via a fifth pipeline. The volume measurement sensing component includes a displacement adjuster and a displacement sensor. The displacement adjuster is connected to the gas volume measurement container and is used to move within the gas volume measurement container to adjust the volume of the gas volume measurement chamber. The displacement sensor is used to detect the displacement distance of the displacement adjuster.

2. The apparatus according to claim 1, characterized in that, A first control valve is installed on the first pipeline, and the first control valve is a waterproof and breathable valve.

3. The apparatus according to claim 1, characterized in that, The second pipeline, the third pipeline, and the fourth pipeline are respectively configured as follows: A second control valve is installed on the second pipeline; and / or A third control valve is installed on the third pipeline; and / or A fourth control valve is installed on the fourth pipeline.

4. The apparatus according to claim 1, characterized in that, It also includes a temperature-controlled container, which has a temperature-controlled cavity inside, and the temperature-controlled cavity is used to contain the sample container.

5. The apparatus according to claim 1, characterized in that, The sample container has a nut hole, and a sealing gasket nut is screwed into the nut hole.

6. The apparatus according to claim 1, characterized in that, A fifth control valve is installed on the fifth pipeline.

7. A method for determining the gas content of shale formations, implemented using the gas content determination device for shale formations as described in any one of claims 1-6, characterized in that, include: Step 1: Rinse the drilling cuttings clean, fill the sample container with the drilling cuttings and compact it, and fill the sample container with salt water of a preset saturation level. Step 2: Turn on the vacuum pump to evacuate the sample canister and the gas volume measuring container so that the pressure inside the sample canister and the gas volume measuring container reaches the first preset pressure. Then, stop evacuating the sample canister and the gas volume measuring container, close the connection between the sample canister and the gas volume measuring container, and close the connection between the gas collecting bottle and the gas volume measuring container. Step 3: Record the pressure value of the first pressure sensor and the temperature value of the first temperature sensor at first preset time intervals until the fluctuation of the pressure value of the first pressure sensor within a second preset time interval is less than the first preset value. Record the pressure value of the first pressure sensor at this time as the first pressure value P1. Connect the sample canister and the gas volume measuring container. Adjust the volume measuring sensor component until the pressure in the gas volume measuring chamber reaches the second preset pressure. Close the connection between the sample canister and the gas volume measuring container. Record the volume value of the gas volume measuring chamber detected by the volume measuring sensor component at this time as the first volume value V1. Connect the gas collecting bottle and the gas volume measuring container until the volume value of the gas volume measuring chamber is 0. Close the connection between the gas collecting bottle and the gas volume measuring container. Step 4: Remove the gas collecting bottle, replace it with an empty one, and measure the components inside the removed gas collecting bottle. Repeat steps three and four a preset number of times, then proceed to step five. Step 5: Pour out the brine from the sample container, measure the volume of the poured brine, and record the volume value as the brine volume value V. 水 ; Step six, execute step two, and then connect the natural gas cylinder to the gas volume measuring container so that the natural gas cylinder supplies gas to the gas volume measuring container until the volume of the gas volume measuring chamber detected by the volume measuring sensor component is the maximum volume value V. max Record the pressure value of the second pressure sensor at this time as the second pressure value P0. Close the connection between the natural gas cylinder and the gas volume measuring container, open the connection between the sample tank and the gas volume measuring container, and adjust the volume measuring sensor component until the pressure in the gas volume measuring chamber reaches the third preset pressure P. 地 Close the connection between the sample container and the gas volume measuring container, adjust the volume measuring sensor component until the pressure in the gas volume measuring chamber is the second pressure value P0, and record the volume value of the gas volume measuring chamber detected by the volume measuring sensor component at this time as the second volume value V0. Step 7: Remove the drilling cuttings from the sample container, dry the drilling cuttings, and weigh them to obtain the sample weight G; Step 8, based on the maximum volume value V max Second volume value V0, saline volume value V 水 The third preset pressure P 地 The volumetric values ​​V of free gas and adsorbed gas injected into the primary pores of shale fragments were calculated based on the second pressure value P0. 总 , Based on the volume value V 总 The gas content of the mudstone and shale was calculated based on the sample weight G.

8. The method according to claim 7, characterized in that, Also includes: After repeating steps three and four a preset number of times n, multiple first pressure values ​​P1 to P2 are obtained. n and multiple first volume values ​​V1 to V n According to multiple first pressure values ​​P1 to P n and multiple first volume values ​​V1 to V n A linear relationship is obtained between the stable pressure and the amount of free gas desorbed after reaching the stable pressure. Based on the linear relationship and the third preset pressure P, 地 Calculate the volume V of free gas under standard atmospheric pressure. 游离 ; Based on the volume V of free gas under standard atmospheric pressure 游离 The amount of free gas per unit mass of mudstone and shale was calculated using the sample weight G.

9. The method according to claim 7, characterized in that, Also includes: Based on the volume values ​​V of free gas and adsorbed gas 总 And the volume V of free gas under standard atmospheric pressure 游离 The volume V of the adsorbed gas under standard atmospheric pressure was calculated. 吸附 ; Based on the volume V of free gas under standard atmospheric pressure 游离 and the volume V of adsorbed gas under standard atmospheric pressure 吸附 The ratio of free gas volume to adsorbed gas volume was calculated.

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