Comprehensive evaluation method and system for determining coal rock gas sweet spot area and drilling target position

Abstract

The invention relates to a comprehensive evaluation method and system for determining a coal rock gas sweet spot area and a drilling target position. The method comprises the following steps that coal rock source rock feature evaluation and coal rock reservoir feature evaluation are conducted on coal rock to be detected; comprehensively evaluating the coal rock quality on the basis of the coal rock source rock characteristic evaluation result and the coal rock reservoir characteristic evaluation result; performing coal rock geological condition evaluation based on a coal rock quality comprehensive evaluation result; performing coal rock dessert zone evaluation based on the coal rock geological condition evaluation result to determine a coal rock dessert zone; and selecting a coal rock drilling target position based on the evaluation result of the coal rock dessert zone. According to the invention, the blank of domestic coal rock gas exploration technology is filled, the reliability and accuracy of the result are improved, and the success rate of exploration is improved.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of oil and gas exploration, and in particular relates to a comprehensive evaluation method and system for determining coal rock gas sweet spots and drilling targets. Background Art

[0002] Previous international research suggests that due to mechanical compaction, coal seams reach a dead end in terms of porosity and permeability with increasing burial depth, meaning that commercial gas flow becomes difficult to generate above 1,786 meters. While there is currently no standard for demarcating coalbed methane (CBM) depths, oil companies generally define 1,500 meters as the boundary between deep and shallow layers. Prior to 2015, guided by CBM theory, domestic CBM development primarily focused on areas with coal seam depths less than 1,500 meters. CNPC conducted deep CBM research and testing in the Daning-Jixian blocks on the eastern edge of the Ordos Basin, and CNOOC conducted deep CBM research and testing in the Linxing-Shenfu blocks on the eastern edge of the Ordos Basin, officially launching China's exploration and development of CBM deeper than 1,500 meters.

[0003] Since 2018, drawing on the practical experience of large-scale volume fracturing of shale oil and gas, domestic oil and gas companies have implemented a number of risky exploration wells with a burial depth of 1,500 to 3,500 meters. The shallow-medium-deep coalbed methane in the Baode block, Daning-Jixian block, and Hancheng block on the eastern edge of the Ordos Basin has achieved a breakthrough in large-scale exploration and development, and the exploration depth has been expanded to 1,500 meters. After 2019, under the guidance of the micro-structural reservoir control mechanism, the "geological-engineering" integrated sweet spot evaluation was guided, and the deep coalbed methane exploration depth exceeded 2,000 meters, breaking through the 1,786-meter boundary. In particular, in 2021, China National Petroleum Corporation deployed a risky exploration well in the Cai 31 well fault anticline structure in the Baijiahai uplift of the Junggar Basin, with the coal seam of the Jurassic Xishanyao Formation as the target layer. The Caitan 1H well used vertical well fracturing and horizontal well fracturing methods, and the gas test achieved a maximum daily production of 5.7×104m 3 , stable daily output of 2×104m 3 The discovery of industrial gas flows has achieved a new breakthrough in the exploration of deep coalbed methane in the basin. This deep coalbed methane has led to the geological concept of "coal rock gas," a new natural gas resource type. This has opened up new areas for exploration in coal-bearing basins and provided new directions for natural gas exploration, which will bring important insights and far-reaching impacts to natural gas exploration in coal-bearing basins.

[0004] China's coal-rock gas accumulation conditions are complex, with poor-quality coal reservoirs and strong heterogeneity, making it difficult to replicate established technologies from abroad. Compared to shallow coal seams, deep coal-rock gas generally exhibits the advantages of high gas content and high saturation, as well as good coal structure and exceptionally low permeability. Production wells are characterized by a short gas-discovery time, high pressure upon gas discovery, and low liquid production after gas discovery. Consequently, deep coal-rock gas differs significantly from shallow coal-rock gas in its accumulation mechanisms, enrichment patterns, and occurrence. Exploration and research into deep coal-rock gas is in its infancy in China, primarily drawing on shale oil and gas exploration and development techniques. Currently, mature theories and technologies to effectively guide production practices are lacking. Summary of the Invention

[0005] The purpose of the present disclosure is to provide a comprehensive evaluation method and system for determining coal gas sweet spots and drilling targets in order to solve the above problems.

[0006] The present disclosure achieves the above objectives through the following technical solutions:

[0007] A comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets includes the following steps:

[0008] Evaluate the source rock characteristics and reservoir characteristics of the coal rock to be tested;

[0009] Comprehensive evaluation of coal rock quality is conducted based on the evaluation results of coal rock source rock characteristics and coal rock reservoir characteristics;

[0010] Evaluate coal rock geological conditions based on comprehensive coal rock quality evaluation results;

[0011] Based on the coal rock geological condition evaluation results, the coal rock sweet spot zone is evaluated to determine the coal rock sweet spot zone;

[0012] Coal and rock drilling targets are selected based on the evaluation results of coal and rock sweet spot zones.

[0013] As a further optimization solution of the present disclosure, the evaluation of the coal source rock characteristics of the coal rock to be tested includes:

[0014] Conduct industrial analysis of the coal rock to be tested, and determine the moisture, volatile matter, ash and fixed carbon content;

[0015] The maturity of the coal rock to be tested is measured, the vitrinite reflectance Ro of the coal rock is measured, and the coal rank is divided according to the Ro value;

[0016] Determination of carbon and hydrogen in the coal rock to be tested; Measure the carbon and hydrogen content in the coal;

[0017] The microscopic components of the coal rock to be tested are measured to determine the percentage of vitrinite, exinite, inertinite and inorganic minerals in the coal.

[0018] As a further optimization solution of the present disclosure, the coal reservoir characteristics evaluation of the coal rock to be tested includes:

[0019] Hand-sample the coal rock to be tested, including hardness, color, luster, coal body structure, cleat and micro-crack development density;

[0020] Conduct routine physical property tests on the coal rock to be tested, and measure gas porosity and permeability;

[0021] Conduct nuclear magnetic resonance experiments on the coal rock to be tested, and judge the distribution of pore size based on the T2 spectrum distribution obtained from the nuclear magnetic resonance experiment;

[0022] Mercury intrusion tests are conducted on the coal rock to characterize the distribution of large pore sizes above 50 nm;

[0023] A nitrogen adsorption experiment was conducted on the coal rock to characterize the distribution of micropores smaller than 2 nm and mesopores between 2 and 50 nm.

[0024] Scanning electron microscopy is used to observe the coal rock microstructure, pore type and morphology, and pore microstructure, and to estimate the surface ratio and inorganic mineral content;

[0025] Industrial CT scanning is performed on the coal rock to display the three-dimensional internal structure of the coal rock and characterize the three-dimensional spatial distribution of pores and fractures.

[0026] As a further optimization scheme of the present disclosure, a comprehensive evaluation of coal rock quality is performed based on the coal source rock characteristic evaluation results and the coal reservoir characteristic evaluation results, including: comprehensively evaluating the quality of coal rock based on the parameters obtained from the source rock characteristic evaluation and the coal reservoir characteristic evaluation, and judging whether it has commercial mining value.

[0027] As a further optimization solution of the present disclosure, the coal rock geological condition evaluation based on the comprehensive coal rock quality evaluation results includes:

[0028] Classification of reservoir-caprock combinations: Based on the lithology of the overlying roof in direct contact with the coal rock, the reservoir-caprock combination types are classified and a reservoir-caprock type range map is drawn. The reservoir-caprock combination types mainly include coal-slime combination with mudstone roof, coal-sand combination with sandstone roof, and coal-ash combination with carbonate rock roof;

[0029] Statistics of coal rock thickness: Based on logging and coring data, the thickness of the thickest single coal rock and the cumulative thickness of coal rocks in the layered system are calculated. Combined with well-logging and seismic data, contour maps of coal rock thickness in the layered system and the contour map of the thickest single coal rock thickness are drawn;

[0030] Determine the structural background: Based on the top or bottom interface of the coal-bearing rock series, combine well-seismic data to draw the structural map of the target layer and determine the structural background of the coal rock.

[0031] Determine maturity: Set a threshold for the number of wells drilled. When the number of wells drilled is less than the threshold, use the measured vitrinite reflectance Ro as a constraint, and use the basin simulation method to calculate the plane distribution map of the Easy%Ro value of the coal rock based on the terrestrial heat flow and burial history. When the number of wells drilled is greater than the threshold, draw a maturity contour map based on the measured vitrinite reflectance Ro.

[0032] Compilation of gas intensity maps: The gas intensity maps are obtained through basin simulation. The gas intensity maps comprehensively reflect the thickness of source rocks, organic matter abundance, organic matter type, maturity and gas conversion rate;

[0033] Draw burial depth map: Draw burial depth contour map of main coal rocks based on structural map and ground topographic map;

[0034] Estimation of resource quantity: Based on the measured gas content C per unit mass of coal, coal rock distribution area S, average thickness H, and coal rock density ρ, the resource quantity G is calculated using the volume method. The calculation formula is: G = 0.01 × S × H × C × ρ.

[0035] As a further optimization scheme of the present disclosure, the evaluation of coal rock sweet spot zones based on the coal rock geological condition evaluation results includes:

[0036] The favorable areas are determined by superimposing the five maps, including:

[0037] The reservoir type range map, the coal rock thickness contour map, the maturity contour map, the burial depth contour map, and the target layer structure map are superimposed to comprehensively divide favorable zones; areas with the best reservoir-cap combination, large coal rock thickness, high maturity, moderate burial depth, structural closure or gentle slope background are divided into sweet spots.

[0038] As a further optimization scheme of the present disclosure, the evaluation of coal rock sweet spot zones based on the coal rock geological condition evaluation results includes:

[0039] The favorable areas are determined by superimposing the four maps, including:

[0040] The reservoir-cap type range map, the gas intensity map, the burial depth contour map and the target layer structure map are superimposed to comprehensively divide favorable zones; areas with the best reservoir-cap combination, high gas intensity, moderate burial depth, structural closure or gentle slope background are divided into sweet spots.

[0041] As a further optimization solution of the present disclosure, the selection of coal rock drilling targets based on the coal rock sweet spot zone evaluation results includes:

[0042] In the sweet spot, surface well target locations are selected at the high point of the structural trap or the flat area of ​​the structure according to the structural map of the target layer.

[0043] A comprehensive evaluation system for determining coal-rock gas sweet spots and drilling targets, including:

[0044] Characteristic evaluation module, used to evaluate the source rock characteristics and reservoir characteristics of the coal rock to be tested;

[0045] Comprehensive quality evaluation module, used to conduct comprehensive evaluation of coal rock quality based on the evaluation results of coal rock source rock characteristics and coal rock reservoir characteristics;

[0046] The geological condition evaluation module is used to evaluate the geological conditions of coal and rock based on the comprehensive evaluation results of coal and rock quality;

[0047] The sweet spot zone evaluation module is used to evaluate the coal rock sweet spot zone based on the coal rock geological condition evaluation results to determine the coal rock sweet spot zone;

[0048] The drilling target selection module is used to select coal and rock drilling targets based on the evaluation results of coal and rock sweet spot zones.

[0049] An electronic device comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0050] Memory for storing computer programs;

[0051] The processor is used to implement a comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets when executing the program stored in the memory.

[0052] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements a comprehensive evaluation method for determining coal-rock gas sweet spots and drilling targets.

[0053] The beneficial effects of the present disclosure are:

[0054] This paper utilizes various experimental techniques to quantitatively evaluate the source rock and reservoir characteristics of coal and comprehensively assess coal quality. It then classifies reservoir-caprock combinations, calculates coal seam thickness, compiles coal burial depth maps, determines maturity, compiles gas generation intensity maps, identifies tectonic settings, and estimates resource quantities. Based on this, five or four maps are superimposed to comprehensively delineate sweet spots. Within Class I sweet spots, drilling targets are selected at structural trap highs or structurally flat areas. This method fills a gap in domestic coal-rock gas exploration technology, improves the reliability and accuracy of results, and increases the success rate of exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a flow chart of the method disclosed herein;

[0056] Figure 2 is a specific method flow chart in an embodiment of the present disclosure;

[0057] Figure 3 is a system structure block diagram in an embodiment of the present disclosure;

[0058] Figure 4 It is a block diagram of the device structure in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0059] The present application is described in further detail below in conjunction with the accompanying drawings. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0060] like Figure 1 As shown, a comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets includes the following steps:

[0061] Evaluate the source rock characteristics and reservoir characteristics of the coal rock to be tested;

[0062] Comprehensive evaluation of coal rock quality is conducted based on the evaluation results of coal rock source rock characteristics and coal rock reservoir characteristics;

[0063] Evaluate coal rock geological conditions based on comprehensive coal rock quality evaluation results;

[0064] Based on the coal rock geological condition evaluation results, the coal rock sweet spot zone is evaluated to determine the coal rock sweet spot zone;

[0065] Coal and rock drilling targets are selected based on the evaluation results of coal and rock sweet spot zones.

[0066] like Figure 2 As shown, in this embodiment, it specifically includes:

[0067] Coal source rock characteristic evaluation technology includes: ① industrial analysis, ② maturity determination, ③ determination of carbon and hydrogen in coal, and ④ measurement of microscopic component content. Specifically:

[0068] ① Industrial analysis: Determine moisture, volatile matter, ash and fixed carbon content according to the industrial analysis method of coal (national standard GB / T30732-2014);

[0069] ② Maturity determination: According to the vitrinite reflectance microscope determination method of coal (national standard GB / T6948-2008), the vitrinite reflectance (R o ), according to R o The coal rank is divided by value;

[0070] ③Determination of carbon and hydrogen: Measure the carbon and hydrogen content in coal according to the determination method of carbon and hydrogen in coal (national standard GB / T476-2008);

[0071] ④Macrochemical component measurement: According to the coal microscopic component grouping and mineral determination method (national standard GB / T8899-2013), the percentage of vitrinite, exinite, inertinite and inorganic minerals in the coal is determined.

[0072] Coal reservoir characteristics evaluation evaluation technology includes: ① hand specimen description, ② conventional physical property measurement, ③ nuclear magnetic resonance experiment, ④ mercury injection experiment, ⑤ nitrogen adsorption experiment, ⑥ scanning electron microscopy, ⑦ industrial CT scanning;

[0073] Specifically: ① Hand specimen description: including hardness, color, gloss, coal body structure, cleats and microcrack density (expressed as number of lines / cm);

[0074] ② Conventional physical properties: Using helium, which has the lowest adsorption capacity, the gas porosity and permeability are measured according to the core analysis method (national standard GB / T29172-2012);

[0075] ③ Nuclear magnetic resonance experiment: The distribution of pore size is determined based on the T2 spectrum distribution obtained from the nuclear magnetic resonance experiment;

[0076] ④ Mercury injection test: Coal rock has low hardness and is suitable for constant-rate mercury injection test, which is used to characterize the distribution of large pore sizes above 50 nm.

[0077] ⑤ Nitrogen adsorption experiment: Low-temperature nitrogen adsorption experiment was used to characterize the distribution of micropore size (less than 2 nm) and mesopore size (2-50 nm);

[0078] ⑥ Scanning electron microscope: used to observe the microstructure of coal rock, pore type and morphology and pore microstructure, and estimate the surface ratio and inorganic mineral content;

[0079] ⑦ Industrial CT scanning: Use core digital CT scanning technology to display the three-dimensional internal structure of coal and rock, and characterize the three-dimensional spatial distribution of pores and fractures.

[0080] The comprehensive evaluation of coal rock quality based on the coal source rock characteristic evaluation results and the coal reservoir characteristic evaluation results includes: comprehensively evaluating the quality of coal rock based on the parameters obtained from the source rock characteristic evaluation and the coal reservoir characteristic evaluation, and judging whether it has commercial mining value.

[0081] After confirming that coal-rock gas has commercial mining value, the following work will be carried out: including ① classification of reservoir-caprock combination types, ② statistics of coal rock thickness, ③ clarification of structural background, ④ determination of maturity, ⑤ compilation of gas intensity map, ⑥ drawing of burial depth map, and ⑦ estimation of resource volume.

[0082] Specifically:

[0083] ① Classification of reservoir-caprock combinations: Based on the lithology of the overlying roof in direct contact with the coal rock, the reservoir-caprock combination types are classified and a reservoir-caprock type range map is drawn. The reservoir-caprock combination types mainly include coal-slime combination (the roof is mudstone), coal-sand combination (the roof is sandstone) and coal-ash combination (the roof is carbonate rock). Among them, the coal-slime combination is the most favorable reservoir-caprock combination.

[0084] ② Count the thickness of coal rocks. Based on the logging and coring data, count the thickness of the thickest single coal rock and the cumulative thickness of the coal rocks in the layered system. Combine well and seismic data to draw the contour map of coal rock thickness in the layered system and the contour map of the thickest single coal rock thickness.

[0085] ③ Clearly define the structural background: Based on the top or bottom interface of the coal-bearing rock system, combine well-seismic data to draw a structural map of the target layer (contour lines are expressed in terms of altitude) to determine the structural background of the coal rock;

[0086] ④ Determine maturity: When the number of wells drilled is small, the actual R o As a constraint, the Easy%R of coal rock is calculated using the basin simulation method according to the terrestrial heat flow and burial history. o Value plane distribution diagram; Under the condition of more drilling wells, according to the measured R o Draw maturity contour maps;

[0087] ⑤ Compile a gas generation intensity map: When conditions permit (abundant data and sufficient time for pre-drilling evaluation), this map can be obtained through basin simulation. This map is a comprehensive reflection of source rock thickness, organic matter abundance, organic matter type, maturity, and gas conversion rate.

[0088] ⑥ Draw a burial depth map: Draw a burial depth contour map of the main coal rocks based on the structural map and the ground topography map. According to the coal rock characteristics and the existing economic and technical conditions, the effective burial depth of coal rock gas is within the range of 1500-5000m;

[0089] ⑦ Estimated resource volume: Based on the measured gas content C per unit mass of coal (unit: m 3 / t), coal rock distribution area S (unit: km 2 ), average thickness H (unit: m), coal rock density ρ (unit: t / m 3 ), use the volume method to calculate the resource volume G (unit: 10 8 m 3 ), the calculation formula is: G = 0.01 × S × H × C × ρ.

[0090] The evaluation of coal rock sweet spot zones based on the coal rock geological condition evaluation results includes: determining favorable areas through the superposition of "five maps" or "four maps", specifically:

[0091] "Five-map" superposition rapid evaluation method: the reservoir and cap type range map (coal mud reservoir and cap combination is the best), coal rock thickness contour map (the maximum thickness of the coal rock single layer is greater than 2m, the greater the cumulative thickness, the better), maturity contour map (R o The favorable zones were comprehensively delineated by overlaying a map of the target stratum structure (favorable structural traps or gentle slopes) with a depth contour map (>0.7%), a target stratum structure (favorable structural traps or gentle slopes) on a single map. Areas with the best reservoir-caprock combinations, thick coal and rock thickness, high maturity, moderate burial depth, and a structural trap or gentle slope background were designated as Class I sweet spots.

[0092] "Four-map" superposition comprehensive evaluation method: Gas intensity map is highly comprehensive. If conditions permit, a gas intensity map should be compiled. Once the gas intensity map is obtained, a four-map superposition comprehensive evaluation can be carried out. That is, the reservoir cap type range map (coal slime reservoir cap combination is the best), gas intensity map (>20×10 8 m 3 / km 2 The authors combined a depth contour map (the larger the better), a depth contour map (depth range: 1500-5000m), and a structural map of the target layer (favorable structural traps or gentle slopes) onto a single map to comprehensively delineate favorable zones. Areas with the best reservoir-caprock combinations, high gas generation intensity, moderate burial depth, and a structural trap or gentle slope background were designated as Class I sweet spots.

[0093] In Class I sweet spots, surface well targets are selected based on the structural map of the target layer, selecting high points in structural traps (anticlines, fault anticlines, fault blocks, etc.) or in flat structural areas (stratum dip angles less than 10°). Because the wave impedance of coal rock is significantly lower than that of the surrounding rock, the amplitude characteristics of the coal rock reflection wave appear as strong amplitude bright spots. Using seismic attribute extraction and inversion techniques, coal rock is described and predicted on the seismic profile, and horizontal well targets are determined based on the thick coal rock development sections shown on the profile.

[0094] like Figure 3 As shown, an embodiment of the present disclosure provides a comprehensive evaluation system for determining coal gas sweet spots and drilling targets, including:

[0095] Characteristic evaluation module, used to evaluate the source rock characteristics and reservoir characteristics of the coal rock to be tested;

[0096] Comprehensive quality evaluation module, used to conduct comprehensive evaluation of coal rock quality based on the evaluation results of coal rock source rock characteristics and coal rock reservoir characteristics;

[0097] The geological condition evaluation module is used to evaluate the geological conditions of coal and rock based on the comprehensive evaluation results of coal and rock quality;

[0098] The sweet spot zone evaluation module is used to evaluate the coal rock sweet spot zone based on the coal rock geological condition evaluation results to determine the coal rock sweet spot zone;

[0099] The drilling target selection module is used to select coal and rock drilling targets based on the evaluation results of coal and rock sweet spot zones.

[0100] The implementation process of the functions and effects of each module in the above system is specifically described in the implementation process of the corresponding steps in the above method, which will not be repeated here.

[0101] For the system embodiment, since it basically corresponds to the method embodiment, the relevant parts can be referred to the partial description of the method embodiment. The system embodiment described above is only schematic, wherein the modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the disclosed solution. Those of ordinary skill in the art can understand and implement it without paying any creative work.

[0102] In the above embodiment, any number of all modules can be combined into one module for implementation, or any one of the modules can be split into multiple modules. Alternatively, at least some of the functions of one or more of these modules can be combined with at least some of the functions of other modules and implemented in one module. At least one of all modules can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation modes of software, hardware and firmware or in a suitable combination of any of them. Alternatively, at least one of all modules can be at least partially implemented as a computer program module, which can perform the corresponding function when the computer program module is run.

[0103] See also Figure 4 The electronic device provided by an embodiment of the present disclosure includes a processor 1110, a communication interface 1120, a memory 1130 and a communication bus 1140, wherein the processor 1110, the communication interface 1120, and the memory 1130 communicate with each other through the communication bus 1140;

[0104] Memory 1130, for storing computer programs;

[0105] The processor 1110 is configured to implement the comprehensive evaluation method for determining coal gas sweet spots and drilling targets as shown below when executing the program stored in the memory 1130 .

[0106] The communication bus 1140 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The communication bus 1140 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, the figure shows only one thick line, but this does not mean that there is only one bus or only one type of bus.

[0107] The communication interface 1120 is used for communication between the electronic device and other devices.

[0108] The memory 1130 may include a random access memory (RAM) or a non-volatile memory, such as at least one disk storage. Alternatively, the memory 1130 may be at least one storage device located away from the processor 1110.

[0109] The above-mentioned processor 1110 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0110] The embodiments of the present disclosure further provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the comprehensive evaluation method for determining coal-rock gas sweet spots and drilling targets as described above.

[0111] The computer-readable storage medium may be included in the device / apparatus described in the above embodiments, or may exist independently and not incorporated into the device / apparatus. The computer-readable storage medium carries one or more programs that, when executed, implement the comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to the embodiments of the present disclosure.

[0112] According to an embodiment of the present disclosure, a computer-readable storage medium may be a non-volatile computer-readable storage medium, such as, but not limited to, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0113] The above-described embodiments merely represent several implementation methods of the present disclosure. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present disclosure. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the scope of the present disclosure, all of which fall within the scope of protection of the present disclosure.

Claims

1. A comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets, characterized by: The following steps are involved: Evaluate the source rock characteristics and reservoir characteristics of the coal rock to be tested; Comprehensive evaluation of coal rock quality is conducted based on the evaluation results of coal rock source rock characteristics and coal rock reservoir characteristics; Evaluate coal rock geological conditions based on comprehensive coal rock quality evaluation results; Based on the coal rock geological condition evaluation results, the coal rock sweet spot zone is evaluated to determine the coal rock sweet spot zone; Coal and rock drilling targets are selected based on the evaluation results of coal and rock sweet spot zones.

2. A comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to claim 1, characterized in that: The evaluation of coal source rock characteristics of the coal rock to be tested includes: Conduct industrial analysis of the coal rock to be tested, and determine the moisture, volatile matter, ash and fixed carbon content; The maturity of the coal rock to be tested is measured, and the vitrinite reflectance R of the coal rock is measured. o , according to R o The coal rank is divided by value; Determination of carbon and hydrogen in the coal rock to be tested; Measure the carbon and hydrogen content in the coal; The microscopic components of the coal rock to be tested are measured to determine the percentage of vitrinite, exinite, inertinite and inorganic minerals in the coal.

3. A comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to claim 1, characterized in that: The coal reservoir characteristics evaluation of the coal rock to be tested includes: Hand-sample the coal rock to be tested, including hardness, color, luster, coal body structure, cleat and micro-crack development density; Conduct routine physical property tests on the coal rock to be tested, and measure gas porosity and permeability; Conduct nuclear magnetic resonance experiments on the coal rock to be tested, and judge the distribution of pore size based on the T2 spectrum distribution obtained from the nuclear magnetic resonance experiment; Mercury intrusion tests are conducted on the coal rock to characterize the distribution of large pore sizes above 50 nm; A nitrogen adsorption experiment was conducted on the coal rock to characterize the distribution of micropores smaller than 2 nm and mesopores between 2 and 50 nm. Scanning electron microscopy is used to observe the coal rock microstructure, pore type and morphology, and pore microstructure, and to estimate the surface ratio and inorganic mineral content; Industrial CT scanning is performed on the coal rock to display the three-dimensional internal structure of the coal rock and characterize the three-dimensional spatial distribution of pores and fractures.

4. A comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to claim 1, characterized in that: The comprehensive evaluation of coal rock quality based on the coal source rock characteristic evaluation results and the coal reservoir characteristic evaluation results includes: comprehensively evaluating the quality of coal rock based on the parameters obtained from the source rock characteristic evaluation and the coal reservoir characteristic evaluation, and judging whether it has commercial mining value.

5. The comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to claim 1, characterized in that: The coal rock geological condition evaluation based on the comprehensive evaluation results of coal rock quality includes: Classification of reservoir-caprock combinations: Based on the lithology of the overlying roof in direct contact with the coal rock, the reservoir-caprock combination types are classified and a reservoir-caprock type range map is drawn. The reservoir-caprock combination types mainly include coal-slime combination with mudstone roof, coal-sand combination with sandstone roof, and coal-ash combination with carbonate rock roof; Statistics of coal rock thickness: Based on logging and coring data, the thickness of the thickest single coal rock and the cumulative thickness of coal rocks in the layered system are calculated. Combined with well-logging and seismic data, contour maps of coal rock thickness in the layered system and the contour map of the thickest single coal rock thickness are drawn; Determine the structural background: Based on the top or bottom interface of the coal-bearing rock series, combine well-seismic data to draw the structural map of the target layer and determine the structural background of the coal rock. Determine maturity: set a threshold for the number of wells drilled. When the number of wells drilled is less than the threshold, the measured vitrinite reflectance R o As a constraint, the Easy%R of coal rock is calculated using the basin simulation method according to the terrestrial heat flow and burial history. o When the number of wells is greater than the threshold, the measured vitrinite reflectance R o Draw maturity contour maps; Compilation of gas intensity maps: The gas intensity maps are obtained through basin simulation. The gas intensity maps comprehensively reflect the thickness of source rocks, organic matter abundance, organic matter type, maturity and gas conversion rate; Draw burial depth map: Draw burial depth contour map of main coal rocks based on structural map and ground topographic map; Estimation of resource quantity: Based on the measured gas content C per unit mass of coal, coal rock distribution area S, average thickness H, and coal rock density ρ, the resource quantity G is calculated using the volume method. The calculation formula is: G = 0.01 × S × H × C × ρ.

6. A comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to claim 5, characterized in that: The evaluation of coal rock sweet spot zones based on the coal rock geological condition evaluation results includes: The favorable areas are determined by superimposing the five maps, including: The reservoir type range map, the coal rock thickness contour map, the maturity contour map, the burial depth contour map, and the target layer structure map are superimposed to comprehensively divide favorable zones; areas with the best reservoir-cap combination, large coal rock thickness, high maturity, moderate burial depth, structural closure or gentle slope background are divided into sweet spots.

7. A comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to claim 5, characterized in that: The evaluation of coal rock sweet spot zones based on the coal rock geological condition evaluation results includes: The favorable areas are determined by superimposing the four maps, including: The reservoir-cap type range map, the gas intensity map, the burial depth contour map and the target layer structure map are superimposed to comprehensively divide favorable zones; areas with the best reservoir-cap combination, high gas intensity, moderate burial depth, structural closure or gentle slope background are divided into sweet spots.

8. A comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to claim 7, characterized in that: The selection of coal rock drilling targets based on the evaluation results of coal rock sweet spot zones includes: In the sweet spot, surface well target locations are selected at the high point of the structural trap or the flat area of ​​the structure according to the structural map of the target layer.

9. A comprehensive evaluation system for determining coal-rock gas sweet spots and drilling targets, characterized by: include: Characteristic evaluation module, used to evaluate the source rock characteristics and reservoir characteristics of the coal rock to be tested; Comprehensive quality evaluation module, used to conduct comprehensive evaluation of coal rock quality based on the evaluation results of coal rock source rock characteristics and coal rock reservoir characteristics; The geological condition evaluation module is used to evaluate the geological conditions of coal and rock based on the comprehensive evaluation results of coal and rock quality; The sweet spot zone evaluation module is used to evaluate the coal rock sweet spot zone based on the coal rock geological condition evaluation results to determine the coal rock sweet spot zone; The drilling target selection module is used to select coal and rock drilling targets based on the evaluation results of coal and rock sweet spot zones.

10. An electronic device, characterized in that: The processor, the communication interface, the memory and the communication bus are connected to each other via the communication bus. Memory for storing computer programs; The processor is configured to implement the comprehensive evaluation method for determining coal gas sweet spots and drilling targets according to any one of claims 1 to 8 when executing the program stored in the memory.

11. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the comprehensive evaluation method for determining coal rock gas sweet spots and drilling targets according to any one of claims 1 to 8 is implemented.

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