Underground in-situ gas content testing device and method for lamina-containing or interlayer-containing rock

Abstract

The invention relates to an underground in-situ gas content testing device and method for lamina-containing or interlayer rock, the device comprises a connecting rod and a plurality of identical testing units which are connected with the connecting rod and can slide up and down along the connecting rod, and each testing unit is composed of a positioning system, a detection system and a metering system. The gas content of different lithology of the lamina-containing or interlayer rock is obtained based on each test unit, and the contribution proportion of different lamina, interlayer and lithology in the rock to the gas content of the whole gas-containing layer section can be analyzed. The device provided by the invention is used for drilling different layers of an underground stratum, collecting gas in the stratum, and calculating the gas content of the underground in-situ stratum according to the relation of temperature, volume and pressure, so that the relation of the gas content of different layers under the actual stratum temperature and pressure environment is obtained, and evaluation parameter support is provided for exploration and development of natural gas in different lithologic reservoirs.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field exploration and development technology, specifically to a downhole in-situ gas content testing device and method for lamellar or interbedded rocks. Background Technology

[0002] my country's natural gas reservoirs exhibit diverse lithologies, primarily consisting of shale, sandstone, volcanic rocks, and mixed sedimentary rocks. Oil and gas drilling has confirmed the strong heterogeneity of underground rocks, characterized by widespread development of laminae and interlayers across different lithologies. These characteristics are closely related to sedimentary environments, diagenesis, and tectonic activity. Shale reservoirs are typically characterized by millimeter-scale laminae; for example, the Longmaxi Formation shale in the Fuling shale gas field exhibits horizontal and micro-bedding, with significant differences in organic carbon content and porosity among different types of laminae. Sandstone reservoirs are dominated by argillaceous and physical property interlayers. For instance, the Upper Paleozoic sandstone in the Sulige gas field features alternating layers of argillaceous interlayers and sand bodies. These interlayers divide the reservoir into multiple flow units, controlling gas distribution and enrichment. The lamination and fractures in volcanic reservoirs are dominated by the eruptive environment, lithofacies differentiation, and subsequent alteration. Mixed sedimentary reservoirs, on the other hand, exhibit complex interlayering due to the alternating deposition of multiple lithologies. For example, in the Da'anzhai section of the Puguang gas field, carbonate rocks and silty mudstones are thinly interbedded, while in the Longdong area of ​​the Ordos Basin, bauxite and coal seams are interbedded. The development of laminations and interlayers poses a challenge to understanding the gas-bearing capacity of subsurface rocks, making it difficult to distinguish the gas content in reservoirs of different lithologies and their contribution to the overall gas-bearing capacity of the entire stratum.

[0003] Existing testing devices and methods have limitations in analyzing reservoir gas content distribution. They cannot accurately test the in-situ downhole gas content of rocks with laminar or interbedded layers. Theoretical calculations only determine gas content under ideal conditions and are difficult to verify with actual cases. Furthermore, different logging methods have different resolutions for reservoir identification, which can interfere with the calculation results.

[0004] Therefore, there is an urgent need for a downhole in-situ gas content testing device and method for lamellar or interbedded rocks to solve the above problems. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a downhole in-situ gas content testing device and method for lamellar or interbedded rocks. This device can drill into different layers of underground strata, collect gas from the strata, and then calculate the downhole in-situ gas content using the relationship between temperature, volume, and pressure. This provides the gas content relationship of different layers under actual formation temperature and pressure conditions, and offers evaluation parameters to support the exploration and development of natural gas in reservoirs of different lithologies.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The downhole in-situ gas content testing device for layered or interbedded rocks of the present invention comprises: The connecting rod contains a cable that powers the test unit. A test unit, wherein several test units are respectively disposed on the connecting rod and are movably connected to the connecting rod via threaded collars, so that the test units can slide freely along the length direction of the connecting rod; The test unit includes a positioning system, a detection system, and a measurement system. The positioning system is mounted on the connecting rod, the measurement system is located below the positioning system and mounted on the connecting rod, and the detection system is connected to the measurement system. The positioning system is used to monitor radioactive signals of different lithologies. The radioactive signals are converted into lithological information by a data processor. Based on the lithological information, the system locates different parts of the lamellar or interbedded rocks by the differences in radioactivity of different lithologies. The detection system is used to drill rock fragments and collect the rock fragments and gas from the rock strata, and to record the initial temperature and initial pressure; The metering system is used to collect the gas that has been filtered by the detection system through rock debris and enters the metering system, and to measure the temperature and pressure of the gas.

[0007] The downhole in-situ gas content testing device for layered or interbedded rocks, preferably, includes a positioning system comprising a radioactivity intensity detector and a data processor. The radioactivity intensity detector and the data processor are arranged sequentially from top to bottom on the connecting rod; The radioactivity intensity detector is used to monitor the radioactivity of different lithologies; The data processor is used to convert radioactive signals into lithological information, and based on the lithological information, locates different parts of the lamellar or interbedded rocks by the radioactive differences of different lithologies.

[0008] The downhole in-situ gas content testing device for layered or interbedded rocks, preferably, includes the following detection system: a auger bit, a solid collection chamber, a one-way filter, a gas collection chamber, a thermometer, and a pressure gauge; One end of the auger bit is connected to the solid collection chamber, the solid collection chamber is connected to and communicates with the gas collection chamber, and a one-way filter is provided at the connection between the solid collection chamber and the gas collection chamber; The gas collection chamber is equipped with a thermometer and a pressure gauge; The thermometer is used to measure the initial temperature of the gas after it has been filtered through rock debris and enters the gas collection chamber, and the pressure gauge is used to measure the initial pressure of the gas after it has been filtered through rock debris and enters the gas collection chamber.

[0009] The downhole in-situ gas content testing device for layered or interbedded rocks, preferably, includes a metering system comprising a metering chamber, a temperature sensor, and a pressure sensor. The metering chamber is connected to the gas collection chamber, and a valve is installed between the two. The metering chamber is equipped with temperature and pressure sensors. The temperature sensor is used to detect the temperature of the gas entering the metering chamber, and the pressure sensor is used to detect the pressure of the gas entering the metering chamber.

[0010] This invention also provides a downhole in-situ gas content testing method for rocks containing laminae or interlayers, comprising the following steps: The testing device is placed in the wellbore of the target layer in the oil and gas well. The positioning system slides up and down along the connecting rod to detect the formation radioactivity. Based on the difference in radioactivity, it locates the rock parts of different lithologies with different layers or interlayers. The detection system is activated, and the auger drill bit is inserted into different rock types. The drilled rock fragments and gas simultaneously enter the solid collection chamber. The gas, after being filtered through a one-way filter to remove the rock fragments, enters the gas collection chamber. At this point, the initial gas content in the gas collection chamber is... The thermometer and pressure gauge record the initial temperature. and pressure Once the thermometer and pressure gauge readings have stabilized, open the valve. When the valve is opened, gas from the gas collection chamber enters the metering chamber, where temperature and pressure sensors measure the temperature. and pressure Once the temperature and pressure sensor readings stabilize, close the valve. Determining in-situ gas content in wells based on the gas state equation Based on the gas content of different lithologies of lamellar or interbedded rocks obtained from each test unit, the contribution ratio of different lamellars, interbeds, and lithologies in the rocks to the gas content of the entire gas-bearing stratum is analyzed.

[0011] The aforementioned testing method, preferably, involves the gas entering the gas collection chamber after the gas has passed through a one-way filter to remove rock debris. At this point, the gas in the gas collection chamber satisfies the gas state equation, as follows:

[0012] When the gas enters the metering chamber through the valve, the gas in the metering chamber satisfies the gas law, as follows:

[0013] Where n and R are constants; According to formulas (1) and (2), we can obtain:

[0014] Furthermore, we can obtain:

[0015] in, The initial pressure of the gas; The initial temperature of the gas; The pressure of the gas entering the metering chamber; The temperature of the gas entering the metering chamber.

[0016] The present invention has the following advantages due to the adoption of the above technical solutions: (1) This invention uses a threaded steel connecting rod and several identical test units connected to the connecting rod by threaded collars, which can slide freely up and down along the connecting rod. The test units slide up and down along the connecting rod to detect the radioactivity of the formation through the positioning system. Based on the radioactivity differences of different lithologies, the test units locate different parts of the lamellar or interlayered rocks. Based on the gas content of different lithologies of the lamellar or interlayered rocks obtained by each test unit, the contribution ratio of different lamellars, interlayers and lithologies in the rock to the gas content of the entire gas-bearing section can be analyzed. This invention breaks through the limitations of traditional whole-section testing, which cannot evaluate the gas content of lamellars or interlayers, and avoids defects such as "interlayer interference" or "missed effective reservoirs" in heterogeneous reservoirs.

[0017] (2) This invention innovatively uses a spiral drill bit for drilling and solid-gas filtration and separation to obtain natural gas samples under the temperature and pressure conditions of the well in situ reservoir. This overcomes the defect that traditional wellbore coring tools cannot obtain natural gas samples. It also overcomes the defects of traditional perforation testing technology, such as changes in downhole temperature and pressure conditions, fluid leakage leading to reservoir depressurization, and downhole liquid pollution caused by high-energy jets penetrating the casing and reservoir.

[0018] (3) The present invention achieves non-destructive sampling by “spiral drill bit drilling + in-situ pressure holding gas collection”, which completely preserves the original composition and occurrence state of natural gas. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a schematic diagram of the downhole in-situ gas content testing device for layered or interbedded rocks as described in this invention.

[0020] The labels for the attached figures are as follows: 1-Connecting rod; 2-Radioactivity intensity detector; 3-Data processor; 4-Temperature sensor; 5-Pressure sensor; 6-Metrology chamber; 7-Valve; 8-Gas collection chamber; 9-Solid collection chamber; 10-Auger bit; 11-Cable; 12-Wellbore; 13-Thermometer; 14-Pressure gauge; 15-One-way filter. Detailed Implementation

[0021] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0022] This invention provides a downhole in-situ gas content testing device for lamellar or interbedded rocks, comprising a connecting rod and several identical testing units connected to and sliding up and down along the connecting rod. Each testing unit consists of a positioning system, a detection system, and a metering system. Based on the gas content of different lithologies of lamellar or interbedded rocks obtained from each testing unit, the contribution ratio of different lamellars, interbeds, and lithologies in the rock to the gas content of the entire gas-bearing section can be analyzed. Using the device of this invention, boreholes are drilled at different strata in the underground formation to collect gas from the formation. Then, the downhole in-situ formation gas content is calculated using the relationship between temperature, volume, and pressure, obtaining the gas content relationship of different strata under actual formation temperature and pressure conditions, providing evaluation parameter support for the exploration and development of natural gas in reservoirs of different lithologies.

[0023] like Figure 1 As shown, the in-situ downhole gas content testing device for layered or interbedded rocks provided by the present invention includes: a connecting rod 1, which has a cable 11 installed inside for powering the testing unit; a testing unit, in which several testing units are respectively mounted on the connecting rod 1 and movably connected to the connecting rod via threaded collars, so that the testing units can slide freely along the length of the connecting rod; the testing unit includes a positioning system, a detection system, and a metering system, the positioning system being mounted on the connecting rod 1, the metering system being located below the positioning system and mounted on the connecting rod 1, and the detection system being connected to the metering system; the positioning system is used to monitor radioactive signals of different lithologies, convert the radioactive signals into lithological information through a data processor, and locate different parts of the layered or interbedded rocks based on the radioactive differences of different lithologies based on the lithological information; the detection system is used to drill rock fragments and collect the rock fragments and gas from the rock formation, and record the initial temperature and initial pressure; the metering system is used to collect the gas that passes through the rock fragments from the detection system and enters the metering system, and measure the temperature and pressure of the gas.

[0024] In the above embodiments, preferably, the positioning system includes a radioactivity intensity detector 2 and a data processor 3; the radioactivity intensity detector 2 and the data processor 3 are arranged sequentially from top to bottom on the connecting rod 1; the radioactivity intensity detector 2 is used to monitor the radioactivity of different lithologies; the data processor 3 is used to convert the radioactivity signal into lithological information, and based on the lithological information, locate different parts of the lamellar or interbedded rocks by the radioactivity differences of different lithologies.

[0025] In the above embodiment, preferably, the detection system includes: a auger drill bit 10, a solid collection chamber 9, a one-way filter 15, a gas collection chamber 8, a thermometer 13, and a pressure gauge 14; one end of the auger drill bit 10 is connected to the solid collection chamber 9, the solid collection chamber 9 is connected to and communicates with the gas collection chamber 8, and a one-way filter 15 is provided at the connection between the solid collection chamber 9 and the gas collection chamber 8; a thermometer 13 and a pressure gauge 14 are provided in the gas collection chamber 8; the thermometer 13 is used to measure the initial temperature of the gas after filtering rock debris entering the gas collection chamber 8, and the pressure gauge 14 is used to measure the initial pressure of the gas after filtering rock debris entering the gas collection chamber 8.

[0026] In the above embodiment, preferably, the metering system includes a metering chamber 6, a temperature sensor 4, and a pressure sensor 5; the metering chamber 6 is connected to the gas collection chamber 8, and a valve 7 is provided between the two; the metering chamber 6 is equipped with a temperature sensor 4 and a pressure sensor 5; the temperature sensor 4 is used to detect the temperature of the gas entering the metering chamber 6, and the pressure sensor 5 is used to detect the pressure of the gas entering the metering chamber 6.

[0027] This invention also provides a method for testing the in-situ gas content in downhole rocks containing laminar or interlayered layers, comprising the following steps: S1. The testing device is placed in the wellbore 12 of the target layer in the oil and gas well. The positioning system slides up and down along the connecting rod 1 to detect the formation radioactivity. Based on the difference in radioactivity, the system locates the rock parts with different lithologies of different laminated or interbedded rocks. The detection system is activated, and the auger bit 10 drills into different rock types. The drilled rock fragments and gas simultaneously enter the solid collection chamber 9. The gas, after being filtered by the one-way filter 15 to remove the rock fragments, enters the gas collection chamber 8. At this point, the initial gas content in the gas collection chamber is... Thermometer 13 and pressure gauge 14 record the initial temperature. and pressure Once the readings of thermometer 13 and pressure gauge 14 have stabilized, open valve 7. When valve 7 is opened, gas in gas collection chamber 8 enters metering chamber 6, where temperature sensor 4 and pressure sensor 5 measure the temperature. and pressure Once the readings of temperature sensor 4 and pressure sensor 5 stabilize, close the valve. Determining in-situ gas content in wells based on the gas state equation Based on the gas content of different lithologies of lamellar or interbedded rocks obtained from each test unit, the contribution ratio of different lamellars, interbeds, and lithologies in the rocks to the gas content of the entire gas-bearing stratum is analyzed.

[0028] In the above embodiments, preferably, when the gas enters the gas collection chamber after being filtered by a one-way filter to remove rock debris, the gas in the gas collection chamber satisfies the gas state equation, as follows:

[0029] When the gas enters the metering chamber through the valve, the gas in the metering chamber satisfies the gas law, as follows:

[0030] Where n and R are constants; According to formulas (1) and (2), we can obtain:

[0031] Furthermore, we can obtain:

[0032] in, The initial pressure of the gas; The initial temperature of the gas; The pressure of the gas entering the metering chamber; The temperature of the gas entering the metering chamber.

[0033] It should be noted that the unidirectional filter in this invention is a mature component that can be directly purchased on the market, and its specific structure will not be described in detail here.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A downhole in-situ gas content testing device for layered or interbedded rocks, characterized in that, include: The connecting rod contains a cable that powers the test unit. A test unit, wherein several test units are respectively disposed on the connecting rod and are movably connected to the connecting rod via threaded collars, so that the test units can slide freely along the length direction of the connecting rod; The test unit includes a positioning system, a detection system, and a measurement system. The positioning system is mounted on the connecting rod, the measurement system is located below the positioning system and mounted on the connecting rod, and the detection system is connected to the measurement system. The positioning system is used to monitor radioactive signals of different lithologies. The radioactive signals are converted into lithological information by a data processor. Based on the lithological information, the system locates different parts of the lamellar or interbedded rocks by the differences in radioactivity of different lithologies. The detection system is used to drill rock fragments and collect rock fragments and gas from the rock strata, and to record the initial temperature and initial pressure; The metering system is used to collect the gas that has been filtered by the detection system through rock debris and enters the metering system, and to measure the temperature and pressure of the gas.

2. The downhole in-situ gas content testing device for layered or interbedded rocks according to claim 1, characterized in that, The positioning system includes a radiation intensity detector and a data processor; The radioactivity intensity detector and the data processor are arranged sequentially from top to bottom on the connecting rod; The radioactivity intensity detector is used to monitor the radioactivity of different lithologies; The data processor is used to convert radioactive signals into lithological information, and based on the lithological information, locates different parts of the lamellar or interbedded rocks by the radioactive differences of different lithologies.

3. The downhole in-situ gas content testing device for layered or interbedded rocks according to claim 1, characterized in that, The detection system includes: a auger bit, a solid collection chamber, a one-way filter, a gas collection chamber, a thermometer, and a pressure gauge; One end of the auger bit is connected to the solid collection chamber, the solid collection chamber is connected to and communicates with the gas collection chamber, and a one-way filter is provided at the connection between the solid collection chamber and the gas collection chamber; The gas collection chamber is equipped with a thermometer and a pressure gauge; The thermometer is used to measure the initial temperature of the gas after it has been filtered through rock debris and enters the gas collection chamber, and the pressure gauge is used to measure the initial pressure of the gas after it has been filtered through rock debris and enters the gas collection chamber.

4. The downhole in-situ gas content testing device for layered or interbedded rocks according to claim 3, characterized in that, The metering system includes a metering chamber, a temperature sensor, and a pressure sensor; The metering chamber is connected to the gas collection chamber, and a valve is installed between the two. The metering chamber is equipped with temperature and pressure sensors. The temperature sensor is used to detect the temperature of the gas entering the metering chamber, and the pressure sensor is used to detect the pressure of the gas entering the metering chamber.

5. A testing method for an in-situ downhole gas content testing device based on any one of claims 1 to 4, characterized in that, Includes the following steps: The testing device is placed in the wellbore of the target layer in the oil and gas well. The positioning system slides up and down along the connecting rod to detect the formation radioactivity. Based on the difference in radioactivity, it locates the rock parts of different lithologies with different layers or interlayers. The detection system is activated, and the auger drill bit is inserted into different rock types. The drilled rock fragments and gas simultaneously enter the solid collection chamber. The gas, after being filtered through a one-way filter to remove the rock fragments, enters the gas collection chamber. At this point, the initial gas content in the gas collection chamber is... The thermometer and pressure gauge record the initial temperature. and pressure Once the thermometer and pressure gauge readings have stabilized, open the valve. When the valve is opened, gas from the gas collection chamber enters the metering chamber, and the temperature and pressure sensors measure the temperature. and pressure Once the temperature and pressure sensor readings stabilize, close the valve. Determining in-situ gas content in wells based on the gas state equation Based on the gas content of different lithologies of lamellar or interbedded rocks obtained from each test unit, the contribution ratio of different lamellars, interbeds, and lithologies in the rocks to the gas content of the entire gas-bearing stratum is analyzed.

6. The test method according to claim 5, characterized in that, When the gas enters the gas collection chamber after being filtered by a one-way filter to remove rock debris, the gas in the gas collection chamber satisfies the gas law, as follows: When the gas enters the metering chamber through the valve, the gas in the metering chamber satisfies the gas law, as follows: Where n and R are constants; According to formulas (1) and (2), we can obtain: Furthermore, we can obtain: in, The initial pressure of the gas; The initial temperature of the gas; The pressure of the gas entering the metering chamber; The temperature of the gas entering the metering chamber.

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