Honeycomb type coalbed methane exploration and development well pattern deployment method

Abstract

The invention discloses a cellular coalbed methane exploration and development well pattern deployment method, which comprises the following steps: step 1, carrying out geological exploration and analysis, and determining the distribution, reservoir characteristics and geological conditions of coalbed methane; 2, according to occurrence characteristics and geological conditions of the coal bed gas, a honeycomb type well pattern layout is designed; step 3, accurately arranging a well position: optimizing the well position by utilizing a geographic information system and a computer simulation technology; 4, drilling operation is conducted, specifically, in the drilling process, a directional and horizontal drilling technology is adopted, and it is ensured that drilling is conducted according to the preset track and angle; 5, fracturing operation is conducted, specifically, fracturing fluid is injected into the well through a high-pressure pump, cracks are formed, and the permeability of the coal seam is improved; and step 6, carrying out production testing and monitoring. According to the method, the honeycomb structure is simulated, the mining wells are evenly distributed on the coal seam, the coal seam area can be covered to the maximum degree, comprehensive covering and efficient development of coal seam gas resources can be achieved, and the recovery rate of coal seam gas is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of coalbed methane development, relates to earthquake geology, drilling engineering, coalbed methane exploration and development, and specifically is a honeycomb coalbed methane exploration and development well network deployment method. Background Art

[0002] The deployment of coalbed methane development well networks at home and abroad has its own characteristics, which are mainly affected by factors such as geological conditions, resource distribution, technological development level and policy orientation.

[0003] In China, the deployment of coalbed methane development wells usually follows the following pattern: first, determine the distribution and reserves of coalbed methane resources through geological exploration; second, design the well network layout according to the occurrence characteristics and development goals of coalbed methane; then, carry out development operations such as drilling and fracturing; finally, transport the coalbed methane to the user end or processing plant through the ground gathering and transportation system. China focuses on scale and intensiveness in well network deployment to improve development efficiency and economic benefits.

[0004] Internationally, especially in the United States, the deployment of coalbed methane development well networks also attaches great importance to geological exploration and resource assessment, but its well network density and development model may vary from region to region. The United States has a long history of coalbed methane development and relatively mature technology. The well network deployment is often more flexible and can be adjusted according to different geological conditions and market demands. For example, the Barnett shale gas field in the United States adopts a high-density well network deployment to increase the single well production and overall development effect.

[0005] In general, whether at home or abroad, the deployment of coalbed methane development wells emphasizes scientific planning and technological innovation to achieve efficient development and utilization of resources. At the same time, environmental protection and safe production are also important factors that must be considered in the deployment of wells.

[0006] The current coalbed methane development well network mainly includes vertical wells, horizontal wells, multi-branch wells, and cluster well networks. Vertical wells are the most common well type, mainly used for preliminary exploration and development; horizontal wells can increase the contact area with the coal seam and improve the recovery rate of coalbed methane; multi-branch wells further increase branches on the basis of horizontal wells to increase the control area and gas recovery efficiency of the well network. In addition, there are special well types such as inclined wells and fishbone wells, which are selected and used according to specific geological conditions and development needs.

[0007] Multi-branch wells are a technology that is further developed on the basis of horizontal wells. It forms a well pattern structure similar to fishbone or tree by drilling multiple branch wellbores in the horizontal section. This well type can further increase the contact area with the coal seam and improve gas production efficiency. At the same time, multi-branch wells can also achieve more extensive coalbed methane development in a limited surface area and reduce the occupation of land resources. However, the construction difficulty and cost of multi-branch wells are higher, requiring more sophisticated drilling and completion technologies.

[0008] The cluster well network is formed by concentrating multiple wells in a certain area to improve the efficiency and economic benefits of coalbed methane extraction. This well network layout can effectively reduce the footprint of ground facilities and reduce development costs. It is also beneficial to protect the environment and improve resource utilization. When implementing the cluster well network for coalbed methane development, it is necessary to comprehensively consider factors such as geological conditions, coal seam characteristics, and mining technology to ensure the safety and economy of mining. The design and implementation of the cluster well network for coalbed methane development involves multiple key links. First, geological exploration is carried out to accurately understand the key parameters such as the distribution, thickness, permeability, and reservoir pressure of the coal seam, which is the basis for formulating a reasonable well network layout. Through three-dimensional geological modeling technology, the spatial morphology and geological structure of the coal seam can be intuitively displayed, providing a scientific basis for well network design.

[0009] In terms of cluster well pattern layout, factors such as well spacing, well type, and well depth need to be considered. Reasonable well spacing can ensure that each well can effectively cover the coal seam and improve the recovery rate; while the selection of well type and well depth needs to be determined according to the characteristics of the coal seam and the requirements of mining technology. For example, for coal seams with low permeability, horizontal wells or directional wells can be used to increase the contact area between the wellbore and the coal seam, thereby improving the desorption and seepage efficiency of coalbed methane.

[0010] The main disadvantages of cluster well patterns and multi-branch well patterns in coalbed methane development include:

[0011] 1. Geological adaptability limitations: Cluster well networks and multi-branch well networks have high requirements on geological conditions. Not all coalbed methane reservoirs are suitable for this development method.

[0012] 2. Inter-well interference: In a cluster well network, since multiple wells are concentrated in the same area, there may be mutual interference between the wells, affecting the production capacity of a single well and the efficiency of the entire well network. This interference may include pressure transmission, changes in fluid flow direction, etc.

[0013] 3. Limited effect of drainage and pressure reduction: In coalbed methane mining, drainage and pressure reduction are key steps to increase production. However, in cluster well networks and multi-branch well networks, due to the interference between wells and the complexity of fluid flow, the effect of drainage and pressure reduction may not be as expected, thus affecting the production capacity of the entire well network.

[0014] 4. Increased difficulty in monitoring: In order to ensure the stable operation of cluster well networks and multi-branch well networks, comprehensive monitoring is required. However, due to the complexity of the well network structure, the difficulty of monitoring may increase, and more advanced monitoring technologies and equipment are required.

[0015] In summary, although cluster well patterns and multi-branch well patterns have some advantages in coalbed methane development, their disadvantages cannot be ignored. In practical applications, it is necessary to comprehensively consider the specific geological conditions, economic conditions and technical conditions to select the most suitable development method. Summary of the invention

[0016] The purpose of the present invention is to provide a honeycomb type coalbed methane exploration and development well network deployment method, which can better solve various problems in geophysical data interpretation, geological design, and drilling engineering in the ultra-deep well design process in Shunbei area, control drilling risks, improve drilling rate, and maximize benefits with high quality, speed and low cost.

[0017] To achieve the above object, the technical solution adopted by the present invention is: a honeycomb coalbed methane exploration and development well pattern deployment method, which includes the following steps:

[0018] Step 1: Conduct geological exploration and analysis to determine the distribution, reservoir characteristics and geological conditions of coalbed methane;

[0019] Step 2: Design a honeycomb well pattern layout based on the occurrence characteristics and geological conditions of coalbed methane, including determining the density of the well pattern, the well spacing, and the arrangement of the wells;

[0020] Step 3: Accurately arrange the well locations: Use geographic information systems and computer simulation technology to optimize the well locations to achieve the best mining results;

[0021] Step 4: Drilling: During the drilling process, directional and horizontal drilling techniques are used to ensure that the drilling is carried out according to the predetermined trajectory and angle to meet the layout requirements of the honeycomb well pattern;

[0022] Step 5: Perform fracturing operations: inject fracturing fluid into the well through a high-pressure pump to form cracks and increase the permeability of the coal seam;

[0023] Step 6: Conduct production testing and monitoring.

[0024] Furthermore, in step 1, detailed geological information is obtained by means of seismic exploration and coring.

[0025] Furthermore, in step 2, planning the honeycomb well location deployment to ensure the well pattern density and distribution uniformity includes:

[0026] (1) Detailed analysis of the geological characteristics of the coalbed methane reservoir, including the thickness, permeability, gas content, and stress state of the coal seam;

[0027] (2) Determine the well pattern density based on the development objectives of the coalbed methane reservoir and determine the optimal well spacing through simulation and optimization.

[0028] (3) Select a honeycomb well site deployment mode: Use a hexagonal grid, with each well site located at the center of the hexagon, and the lines connecting adjacent well sites form a honeycomb structure.

[0029] Furthermore, in step 4, directional drilling is to drill along a predetermined trajectory by the drill bit to reach a specific position of the coal seam, and by controlling the direction and angle of drilling, it is ensured that the drill bit penetrates a predetermined area of ​​the coal seam to achieve precise penetration of the coal seam. Directional drilling uses a guidance system to monitor the drilling path in real time and adjust it according to geological data.

[0030] Furthermore, in step 4, horizontal drilling is used to expand the contact area of ​​drilling. After reaching the coal seam, the drilling path is changed to a horizontal direction and drilling is performed along the layer of the coal seam; and horizontal drilling uses a multi-section drilling tool combination to maintain the stability and directionality of drilling.

[0031] Furthermore, in step 5, the fracturing operation includes:

[0032] (1) Preparation and injection of fracturing fluid: Prepare fracturing fluid suitable for the characteristics of the coal seam, and inject the fracturing fluid into the well through a high-pressure pump. The liquid enters the coal seam under high pressure, causing cracks in the coal seam;

[0033] (2) Fracture formation and expansion: After the fracturing fluid forms the initial fracture in the coal seam, as the fluid is continuously injected, the fracture will expand to the surrounding area, forming a complex fracture network. Then proppant is injected into the fracture to prevent the fracture from closing and keep the fracture open.

[0034] (3) Fracture monitoring and optimization: Use microseismic monitoring or pressure monitoring to monitor the formation and expansion of fractures in real time, and adjust the fracturing parameters based on the monitoring results to optimize the morphology and distribution of the fracture network to improve the fluidity and recovery rate of coalbed methane;

[0035] (4) Gas extraction and post-processing: After fracturing is completed, the coalbed methane begins to flow from the cracks and is extracted to the ground through the wellbore. The extracted coalbed methane is then dehydrated and desulfurized to meet the standards for transportation and use.

[0036] Furthermore, in step 6, the wellhead pressure, production, and gas composition parameters are monitored in real time, and the pressure, temperature, and permeability geological parameters of the coalbed methane reservoir are regularly evaluated, and production parameters are adjusted in a timely manner through data monitoring and analysis.

[0037] Furthermore, during the development process, the use and treatment of fracturing fluids can be controlled, and ground subsidence monitoring can be implemented to reduce the impact on the environment.

[0038] The technical problems to be solved by the present invention and the beneficial effects thereof are:

[0039] 1. Enhanced flexibility: According to the specific characteristics of the coalbed methane reservoir and the mining requirements, the honeycomb well pattern can be flexibly adjusted and optimized to adapt to different mining conditions and goals;

[0040] 2. Compared with traditional mining methods, the honeycomb well pattern can more accurately control the mining range and reduce interference between wells;

[0041] 3. Optimize pressure management: Reasonable honeycomb well spacing deployment helps maintain the pressure balance in the coal seam, avoids coal seam stability problems caused by excessive local pressure drop during drainage pressure drop, and is also conducive to improving the fluidity and mining efficiency of coalbed methane. ;

[0042] 4. The application of real-time monitoring technology of honeycomb well pattern is also key. By installing more advanced sensors and monitoring equipment, key parameters such as coal seam pressure and gas flow rate can be obtained in real time, providing data support for adjusting mining strategies and optimizing production.

[0043] In summary, the honeycomb coalbed methane exploration and development well network of the present invention is an efficient coalbed methane mining layout method, which imitates the structure of a honeycomb and evenly distributes the mining wells on the coal seam. This layout method can maximize the coverage of the coal seam area, achieve comprehensive coverage and efficient development of coalbed methane resources, and maximize the recovery rate of coalbed methane; it can reduce interference between wells, increase the output of a single well, and thus reduce the unit coalbed methane mining cost; the layout of the honeycomb well network makes production management more centralized and efficient, facilitates monitoring and adjustment of the production process, improves production efficiency, reduces the impact on the surface and groundwater environment, is conducive to environmental protection, and promotes the innovation and development of related technologies, promotes the rapid development of the coalbed methane industry, increases the proportion of coalbed methane in the energy structure, and promotes the optimization and diversification of the energy structure. At the same time, with the continuous advancement of technology and the further reduction of costs, the coalbed methane industry is expected to achieve more sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of a honeycomb coalbed methane exploration and development well pattern platform;

[0045] Figure 2 This is a schematic diagram of the transportation location of the Fukang mining area;

[0046] Figure 3 It is a schematic diagram of the regional structural location;

[0047] Figure 4 It is a regional geological map;

[0048] Figure 5 This is the structural map of the top boundary of the T1 coal seam of the Jurassic Xishanyao Formation in the footwall of the Fukang Fault in the well area.

[0049] Figure 6It is the overall distribution map of the honeycomb development well network. DETAILED DESCRIPTION

[0050] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] A honeycomb coalbed methane exploration and development well pattern deployment method, comprising the following steps:

[0052] Step S1: According to the geological characteristics and development objectives of the coalbed methane reservoir, the honeycomb well location deployment is rationally planned to ensure the density and uniformity of the well pattern. This method is an efficient coalbed methane development method, and its core lies in simulating the honeycomb structure to achieve uniform distribution of well locations and maximize coverage.

[0053] (1) It is necessary to conduct a detailed analysis of the geological characteristics of the coalbed methane reservoir, including the thickness, permeability, gas content, stress state, etc. of the coal seam.

[0054] (2) Determine the well pattern density based on the development objectives of the coalbed methane reservoir, such as improving recovery, reducing development costs, and reducing environmental impact. The determination of the well pattern density requires comprehensive consideration of the geological conditions and economic factors of the coal seam, and the optimal well spacing is determined through simulation and optimization.

[0055] (3) Select an appropriate well layout pattern. Honeycomb well deployment usually adopts a hexagonal grid, with each well located at the center of the hexagon, and the lines connecting adjacent wells form a honeycomb structure. In actual deployment, factors such as topography, existing infrastructure, and land use restrictions need to be considered to make appropriate adjustments to the ideal honeycomb structure.

[0056] (4) After the well layout pattern is determined, the specific well planning is carried out. This step includes determining the precise location of each well and the specific distance between wells. Geographic Information System (GIS) and computer simulation technology are used to assist planning to ensure uniform distribution of wells and maximize coverage.

[0057] Step S2: Use advanced technologies such as directional drilling and horizontal drilling to achieve precise penetration of the coal seam and maximize the contact area to increase the production of a single well.

[0058] (1) Directional drilling technology uses a drill bit to drill along a predetermined trajectory to reach a specific location in the coal seam. By precisely controlling the direction and angle of drilling, it can ensure that the drill bit penetrates the predetermined area of ​​the coal seam and achieves accurate penetration of the coal seam. Directional drilling usually requires the use of a guidance system, such as a rotary guidance system or geo-steering technology, which can monitor the drilling path in real time and make adjustments based on geological data.

[0059] (2) Horizontal drilling technology further expands the contact area of ​​drilling. After reaching the coal seam, the drilling path can be changed to a horizontal direction and drilled along the coal seam. In this way, the contact area of ​​drilling is greatly increased, thereby increasing the production of a single well. Horizontal drilling usually requires the use of a multi-section drilling tool assembly, including a drill bit, drill collar, stabilizer, etc., to maintain the stability and directionality of the drilling.

[0060] (3) In order to maximize the contact area, geological models and geophysical data are used to optimize the drilling trajectory. The best drilling path is designed by analyzing parameters such as the thickness, inclination, and fracture development of the coal seam. In addition, during horizontal drilling, drilling fluid and mud systems are used to maintain the stability of the wellbore wall and prevent wellbore collapse, thereby ensuring the safety and efficiency of the drilling process.

[0061] Step S3: Increase the permeability of the coal seam through hydraulic fracturing and other technical means to form an effective fracture network, thereby improving the fluidity and recovery rate of coalbed methane.

[0062] (1) Preparation and injection of fracturing fluid: Fracturing fluid suitable for the characteristics of coal seams is prepared, usually including water, sand (proppant), chemical additives, etc. The fracturing fluid is injected into the well by a high-pressure pump. The liquid enters the coal seam under high pressure, causing cracks in the coal seam.

[0063] (2) Crack formation and expansion: After the fracturing fluid forms the initial cracks in the coal seam, as the fluid continues to be injected, the cracks will expand to the surrounding area, forming a complex crack network. Proppants (such as sand particles) are injected into the cracks to prevent the cracks from closing and keep them open.

[0064] (3) Fracture monitoring and optimization: Use microseismic monitoring, pressure monitoring and other technical means to monitor the formation and expansion of fractures in real time. Adjust the fracturing parameters based on the monitoring results to optimize the morphology and distribution of the fracture network to improve the fluidity and recovery rate of coalbed methane.

[0065] (4) Gas extraction and post-processing: After fracturing, coalbed methane begins to flow from the cracks and is extracted to the surface through the wellbore. The extracted coalbed methane is dehydrated, desulfurized and other post-processing to meet the standards for transportation and use.

[0066] Step S4: According to the dynamic changes and production data of the coalbed methane reservoir, the honeycomb well pattern layout is continuously adjusted and optimized to adapt to the changing needs during the development process.

[0067] (1) Collect and analyze the dynamic data of coalbed methane reservoirs, including changes in parameters such as pressure, temperature, gas content, and permeability. These data help to understand the production status of gas reservoirs and the distribution of remaining resources.

[0068] (2) Use production data, such as gas production, water production, bottom hole pressure, etc., to evaluate the production efficiency of the existing well network. By analyzing production data, high-yield wells, low-yield wells, and non-productive wells can be identified to determine the well locations that need to be adjusted. For low-yield wells, production-increasing measures such as fracturing and acidizing can be considered; for non-productive wells, plugging or converting them to gas injection wells can be considered.

[0069] (3) According to the characteristics of coalbed methane reservoirs, numerical simulation technology is used to simulate the production conditions under different well network layouts. Through the simulation results, the production effects of different adjustment plans are predicted, so as to select the optimal adjustment plan. In the adjustment process, factors such as well network density, well spacing, and well type should be considered to ensure that the adjusted well network layout can improve the recovery rate and economic benefits of the gas reservoir.

[0070] (4) Fully consider the heterogeneity of coalbed methane reservoirs. Due to the heterogeneity of coal seams, the fluid flow and pressure distribution in the gas reservoir may be uneven. Therefore, when adjusting the well pattern layout, the well pattern should be adapted to this heterogeneity as much as possible, such as by adjusting the well position to improve the fluid flow path and improve the development effect of the gas reservoir.

[0071] (5) Regularly monitor and evaluate the adjusted well pattern layout to ensure the effectiveness of the adjustment measures. Through continuous monitoring and evaluation, new problems can be discovered in a timely manner, and the well pattern layout can be continuously optimized based on new production data and dynamic changes to adapt to changing needs during the development process.

[0072] Step S5: Environmental protection: During the development process, take effective measures to reduce the impact on the environment, such as controlling the use and treatment of fracturing fluids and implementing ground subsidence monitoring.

[0073] Step S6: Monitoring and evaluation system: Establish a comprehensive production monitoring and evaluation system, including real-time monitoring of parameters such as wellhead pressure, production, gas composition, and regular evaluation of geological parameters such as pressure, temperature, and permeability of coalbed methane reservoirs. Through data analysis, timely discover and solve problems in production and optimize production strategies.

[0074] The honeycomb coalbed methane development well network deployment method is a complex system engineering, the core of which is to achieve effective development of coalbed methane resources through scientific and reasonable well network layout. First of all, geological conditions are the basis, and detailed exploration and analysis of the depth, thickness, inclination, coalbed methane content, permeability, etc. of the coal seam are required. Through geological exploration data, the occurrence state and distribution law of coalbed methane are determined to provide a basis for well network design.

[0075] Secondly, coal seam characteristics are crucial to well pattern deployment. The physical and chemical properties of different coal seams, such as the solidity, porosity, and adsorption of coal seams, will directly affect the difficulty and effectiveness of drilling, fracturing, and other operations. Therefore, it is necessary to conduct in-depth research on coal seam characteristics to optimize well pattern design and improve coalbed methane recovery.

[0076] Economic factors are the key to determining the feasibility of honeycomb coalbed methane development well network deployment. When designing the well network, drilling costs, fracturing costs, operating costs, and expected economic returns must be considered. Through cost-benefit analysis, the most economical well network density and layout method are selected to ensure the economic rationality of the project.

[0077] Environmental protection is an important factor that cannot be ignored in modern energy development. Honeycomb coalbed methane development must follow environmental protection principles, reduce pollution to surface and groundwater bodies, and reduce damage to the ecosystem. During the well network deployment process, measures need to be taken to reduce waste generated during drilling and fracturing, and effectively control gas leakage, water pollution and other problems that may occur during the mining process.

[0078] The following mainly uses the coalbed methane exploration and development of Block 4 in Fukang Mining Area on the southern edge of the Junggar Basin as an example.

[0079] (I) Basic overview of Fukang mining area

[0080] 1. Geographical location

[0081] The Xinjiang Fukang Mining Area Coalbed Methane Exploration Project is located in Fukang City. The work area is located about 11km southeast of Chengguan Town, Fukang City, and about 4km south of Ganhezi Town. The administrative division is under the jurisdiction of Sangonghe Township, Shanghugou Township, and Ganhezi Town of Fukang City. The western boundary is Shuimo River, the eastern boundary is about 4km east of Huangshan River, the southern boundary is Yaomoshan Fault (F4), and the northern boundary is Fukang Reverse Fault (F1). It is about 56km long from east to west, 3-10km wide from north to south, and has a total area of ​​about 260km 2 .

[0082] The work area is about 9km away from Beijing-Xinjiang Expressway G7 and about 5km away from National Highway G335 in the north, with convenient transportation. The townships and coal mines in the area are connected by simple roads or sandy roads, with basic traffic conditions (see Figure 2 ).

[0083] The Fukang mining area has a long history of coal exploration. According to incomplete statistics, there are more than 50 exploration projects. The exploration blocks are distributed throughout the area, and the geological results are rich. The coal-bearing strata, coal-bearing structures, coal seam divisions, main coal seam distribution, coal rock and coal quality characteristics, roof and floor characteristics, hydrogeological conditions, and mechanical properties of coal rocks and roof and floor plates in the entire area have been basically identified, laying a solid foundation for coalbed methane exploration in the area.

[0084] Coalbed methane research in the Fukang mining area began in the 1980s, and geological exploration work began in 2012. The main projects carried out include the following coalbed methane research, coalbed methane exploration, and coalbed methane development pilot projects.

[0085] Through years of coalbed methane exploration in Fukang mining area, we have a general understanding of the distribution law of coalbed methane, which provides parameters for the estimation of coalbed methane reserves in Fukang mining area. For the convenience of description, the coalbed methane reserve estimation range is divided into three blocks according to the structural division and coal-bearing strata of Fukang mining area, from west to east:

[0086] The Shuimohe well area in western Fukang is located between Shuimohe and Sangonghe. The coal-bearing structures are Fukang syncline, South Fukang anticline, South Fukang syncline, Qidaowan anticline, etc. The coal-bearing stratum is the Xishanyao Formation of the Middle Jurassic.

[0087] The Sigonghe well area in western Fukang is located between the Sangong River and the Sigong River. The coal-bearing structure is the eastern uplift end of the Fukang syncline, and the coal-bearing stratum is the upper section of the Badaowan Formation of the Lower Jurassic System.

[0088] The Wugong-Dahuangshan mining area in the central and eastern part of Fukang is located east of the Sigong River to the eastern uplifted end of the Huangshan-Ergong River syncline. The main coal-bearing structure is the northern wing of the Huangshan-Ergong River syncline, and the coal-bearing strata are the middle and lower sections of the Badaowan Formation of the Lower Jurassic System.

[0089] Considering that the exploration depth of coalbed methane in Xinjiang is generally shallower than 1500m, the coal seam depth of a small number of gas-producing wells in Fukang mining area is between 1500-2000m. Drawing on the fact that the maximum development depth of coalbed methane in the mainstream coalbed methane fields in China, such as the southern Qinshui Basin and the eastern edge of the Ordos Basin, has exceeded 2000m, it is preliminarily determined that the maximum depth for calculating coalbed methane reserves in Fukang mining area is 2000m.

[0090] The total controlled and predicted geological reserves of coalbed methane in Fukang mining area are 93.34×10 8 m 3 , of which the controlled geological reserves are 64.83×10 8 m 3 The predicted geological reserves are 28.51×10 8 m 3 The distribution of reserves at different burial depths is as follows: the total coalbed methane reserves at burial depths of 500 to 1500 m (coal seam top elevation +500 to -500 m) are 88.54×10 8 m 3 , of which the controlled geological reserves are 60.03×10 8 m 3 The predicted geological reserves are 27.16×10 8 m 3 The total geological reserves of coalbed methane at a depth of 1500 to 2000 m (-500 to -1000 m above sea level) are 4.80×10 8m 3 , of which the controlled geological reserves are 3.45×10 8 m 3 The predicted geological reserves are 1.35×10 8 m 3 .

[0091] 2. Regional structure, stratigraphy and hydrology

[0092] The regional tectonic position is located in the northern central part of the Xinjiang secondary tectonic unit North Tianshan Eugenetic Trough Fold Belt ( Figure 3 ).

[0093] The fold belt borders the Junggar Depression in the north and the Aqikuduk Fault in the south. It is distributed in a nearly east-west direction and is about 200 km wide from north to south. It has undergone the Variscan, Indosinian, Yanshan and Himalayan tectonic movements since the early Paleozoic, forming a series of faults, folds and intermountain depressions in the northwest, nearly east-west and northeast directions. The faults are mainly compressional, and the folds are all in the form of complex anticlines. The structural traces in the east are undulating.

[0094] The regional structure mainly includes two secondary structures in the North Tianshan fold belt, namely the third-level structural unit Urumqi piedmont sag and Bogda (Bogduo) anticline.

[0095] (1) The Urumqi piedmont sag is located at the northern foot of the Northern Tianshan Mountains and the southern edge of the Junggar Depression. It extends from Lake Aibi to Qitai in an east-west belt, with a width of about 50 km from north to south. It is a large Mesozoic-Cenozoic sag with the basement of the Hualixi fold developed.

[0096] The exposed strata include: Triassic, Jurassic, Cretaceous, Neogene and Quaternary. The depression settlement center shifted from east to west over time. The deepest part of the depression was in Changji and Miquan during the Triassic period, moved to Manas during the Jurassic period, and moved to Shawan and Anjihai during the Tertiary period. The sediment thickness reached 10,000 meters, and the stratum movement was mainly block segment uplift.

[0097] The Mesozoic and Cenozoic strata form three rows of parallel folds dominated by anticlines in front of the mountain, with south-dipping axial planes and boundary faults such as the Yaomoshan Fault and the deep fault on the southern edge of Junggar. The north wing of the fold is often accompanied by east-west compressional faults. Its structural traces are nearly east-west in the west and arc-shaped in the east due to the influence of the nappe.

[0098] (2) The Bogda (Bogduo) anticline is located in the mountain range east of Urumqi and west of Qijiaojing. It is 60-80 km wide from north to south and extends in an east-west direction.

[0099] The exposed strata in the area include the Middle and Upper Carboniferous, Permian, Triassic, Middle and Upper Jurassic, Lower Cretaceous, Neogene and Quaternary.

[0100] The structural morphology is mainly closed linear folds with an axial plane dipping to the south. The visible axis is 17 km long, with an axial direction of 60°-65° northeast and dipping to the southwest. The dip angle of the strata on the northern wing is generally 50°-60°, with local inversion; the dip angle of the southern wing is generally 50°, and the southwest part disappeared due to fault cutting.

[0101] Most faults are developed on the north and south wings of the anticline, and there are many high-angle thrust faults, which cause the area to be horst-like uplift. Its structural trend is wavy and extends in the east-west direction.

[0102] The Fukang mining area is located in the Urumqi piedmont depression, and the regional strata belong to the southern Junggar-Northern Tianshan regional division (I1 3 ), Gimsar Stratigraphic Community (I1 3-6 ), the region has exposed the Carboniferous and Permian of the Late Paleozoic, the Triassic, Jurassic, Cretaceous of the Mesozoic, and the Neogene and Quaternary of the Cenozoic. A brief table of regional stratigraphy is shown in Table 1 below, which is described from old to new as follows:

[0103] Table 1 Regional Stratigraphic Summary

[0104]

[0105] The area is located in the low mountain and hilly area at the northern foot of Bogda Mountain. The terrain is high in the south and low in the north, high in the east and low in the west. Mountain glaciers are developed above 3,600m above sea level at the northern foot of Bogda Mountain in Tianshan Mountain. There is a lot of precipitation, cold and humid climate, and snow all year round. The meltwater of ice and snow constitutes the main source of surface runoff in the area and is also an indirect source of groundwater.

[0106] Several rivers in the region, which are controlled by the Bogduo Mountain water system, cut through the mountains, cross the coal-bearing strata, and are roughly perpendicular to the mountains and strata, developing in a nearly north-south direction. From west to east, there are mainly Shizhuanggou, Quanshuigou, Baiyang River, Xigou and Huangshan River, all of which are developed on the northern slope of Bogduo Mountain. The water sources are meltwater, rainwater, flood water and spring water, which flow through the work area and replenish the underground aquifers in the area. The Quaternary neotectonic movement left two to five terraces on both sides of the river. Among all the water systems, the Baiyang River has the largest flow. According to the hydrological observation data of the Baiyang River Observation Station of the Changji Hydrology and Water Resources Survey Bureau of the Xinjiang Uygur Autonomous Region in 2004, the average flow in 2004 was 2.504m 3 / s, maximum flood flow 44m 3 / s, the maximum flow rate is 4.80m / s, the minimum flow rate is 0.21m / s, and the maximum peak flow rate in history is 150m 3 / s; Shizhuanggou is dry all year round and is a seasonal gully that can only form surface runoff during snowmelt and rainy seasons.

[0107] The above-mentioned surface water flows through this area. The coal-bearing rock system and the loose rock porous water-bearing rock system are recharged according to their respective permeability, forming the main recharge source of regional groundwater. The relatively sufficient recharge period is the snowmelt and rain flood period, and the recharge site is the surface runoff cutting part.

[0108] Due to the large slope of the regional terrain, the water-bearing space in the bedrock is not well developed, and rain and flood water often flow rapidly, resulting in limited recharge. The Quaternary loose rock gravel layer has relatively good permeability. The snowmelt and precipitation in the mountainous areas mostly gather in the valleys, replenishing the loose layer and enriching it with pore water. Because it is mostly distributed in valleys and river valleys, the recharge area is also limited due to the limited range.

[0109] The region has obvious continental arid to semi-arid climate characteristics, with strong evaporation and scarce precipitation. The annual evaporation is much greater than the precipitation in the same period. Relative to coal-bearing rock systems, it is generally difficult for atmospheric precipitation to fully wet the dry rock layers that are tens of meters thick. Even if there is a small amount of replenishment, it is mostly consumed by the strong evaporation after precipitation. Therefore, the atmospheric precipitation replenishment is extremely weak, and its direct infiltration replenishment is limited to river water and burned rock aquifers.

[0110] The regional groundwater level is obviously higher in the south and lower in the north, so the groundwater flows from south to north along the interlayers. Its discharge mode is point discharge from springs and spring groups. The vertical evaporation in the natural state mostly consumes the direct infiltration of atmospheric precipitation. For groundwater in coal-bearing rock systems, its discharge mode is mostly artificial pumping during mining.

[0111] (II) Application of patented technology in the research area

[0112] 1. Exploration well deployment in the study area

[0113] In 2024, it is planned to deploy a number of exploration wells in the Fukang mining area and its periphery, with overall deployment, taking into account both deep and shallow areas, and implementing them in batches to implement reserves and rapid production, and ensure that coalbed methane reserves and production will increase in 2024; 19 exploration wells will be deployed in four areas to explore the distribution and gas content of the medium-shallow to medium-deep coal seams in the south, and evaluate the development potential, laying the foundation for later large-scale development.

[0114] The regional structure is located in the middle section of the Urumqi piedmont depression on the southern edge of the Junggar Basin. Affected by the push of the Bogda anticline in the south, the depression is distributed in the region in the form of an arc-shaped narrow belt protruding northward. The fold morphology is mainly tight anticlines and synclines. The dip angles of the two wings of the fold are large. The fold axis is more than ten kilometers or even dozens of kilometers long, while the width of the fold axis is only 2 to 3 kilometers; the faults are mostly high-angle reverse faults and small-scale interlayer faults ( Figure 4 ). The upper strata are mainly the Badaowan coal-bearing strata, the lower strata are mainly the Xishanyao and Sangonghe formations, and the exploration direction is mainly to target the covering zone of deep reverse faults and also to explore the shallow layers.

[0115] According to the analysis and research of the previous coal exploration and coal-bed methane drilling data in the area, it is confirmed that there are two sets of fault combinations in the area. The upper part of the Fukang fault belongs to the hanging plate, and the lower part belongs to the foot plate. The hanging plate is relatively broken and the faults are well developed; the foot plate has a simple structure and is a relatively complete anticline. The coal seams are stably developed and have good prospects for coal-bed methane exploration ( Figure 5 ).

[0116] The results of the early exploration and trial production of coalbed methane in the area, as well as the research on the gas-controlling geological conditions and enrichment rules of coalbed methane, indicate that the target layers for coalbed methane exploration in this area include No. 39, 41, 42, 43, 44, and 45 coal seams, which are buried at a depth of 1500 to 3000 meters. The distribution in the whole area is stable, the thickness is large, and the gas content is high. Therefore, the above coal seams are selected as the main target layers for this coalbed methane exploration. From the exploration practice of the main coalbed methane production areas in China, vertical and directional wells are the main well types for exploration.

[0117] 2. Honeycomb coalbed methane development well pattern deployment

[0118] The honeycomb coalbed methane development well network is an innovative space utilization solution that adapts to the complexity of the underground geological structure and fault zones in the study area and avoids the layout restrictions of horizontal wells. By imitating the structure of the honeycomb, this well network design can maximize the coverage of coalbed methane resources while maintaining high mining efficiency and safety. This design not only improves the utilization rate of resources, but also may reduce development costs, providing new ideas and methods for the efficient development of coalbed methane. In the design of the honeycomb coalbed methane development well network, each wellbore is like a unit in a honeycomb, and they are distributed throughout the coalbed methane field according to certain rules and spacing. Such a layout can ensure that coalbed methane resources are fully and evenly mined in three-dimensional space, avoiding the mining blind spots that may appear in the traditional well network layout.

[0119] The specific deployment steps and technical means are as follows:

[0120] (1) Conduct geological exploration and analysis to determine the distribution, reservoir characteristics and geological conditions of coalbed methane. This step is the basis of the entire development process and requires the use of seismic exploration, drilling and coring and other technical means to obtain detailed geological information.

[0121] (2) Design a honeycomb well pattern layout based on the occurrence characteristics and geological conditions of coalbed methane. This usually includes determining the density of the well pattern, the well spacing, and the arrangement of the wells. The honeycomb pattern layout can ensure that each well can effectively contact the coalbed methane reservoir and increase the production of a single well.

[0122] (3) Accurately arrange the well locations. Use geographic information systems (GIS) and computer simulation technology to optimize the well locations to achieve the best mining results. At the same time, consider ground conditions and environmental protection requirements to ensure the rationality of the well location layout.

[0123] (4) Perform drilling operations. During the drilling process, directional and horizontal drilling techniques are used to ensure that the holes are drilled along the predetermined trajectory and angle to meet the layout requirements of the honeycomb well pattern. At the same time, advanced drilling fluids and drilling equipment are used to improve drilling efficiency and safety.

[0124] (5) Perform fracturing operations. Fracturing is a key technology to increase coalbed methane production. Fracturing fluid is injected into the well through a high-pressure pump to form cracks and increase the permeability of the coal seam.

[0125] (6) Conduct production testing and monitoring. Evaluate the development effect by testing the production and pressure of the wells, and adjust the production parameters based on the monitoring data. At the same time, establish a real-time monitoring system to track the production status of the coalbed methane wells over the long term to ensure safe production and efficient use of resources.

[0126] The honeycomb well pattern layout can effectively adapt to the geological conditions of complex fault zones, and improve the mining efficiency and resource recovery rate of coalbed methane through dense well pattern layout. In fault zones, the geological structure is complex, and conventional linear well patterns are difficult to effectively cover coalbed methane resources. The honeycomb well pattern can better control and develop coalbed methane resources through multi-point simultaneous operation.

[0127] Secondly, the honeycomb well pattern helps to reduce the cost of a single well and improve economic benefits. In complex fault zones, the construction difficulty and cost of a single well are high. The honeycomb well pattern can reduce the number of wells drilled and reduce drilling costs by optimizing the well location design, while increasing the output of a single well, thereby improving the overall economic benefits.

[0128] In addition, the honeycomb well pattern also focuses on the connectivity and synergy between wellbores. Through precise drilling and completion technologies, effective communication between wellbores can be achieved to form a complex and efficient fluid flow network. This not only helps the smooth production of coalbed methane, but also improves the recovery rate and reduces resource waste.

[0129] 3. Efficient drilling and fracturing technology

[0130] In the development of coalbed methane, efficient drilling and fracturing technology is the key. The selection and application of drilling technology directly affects the efficiency and cost of coalbed methane extraction. Honeycomb well pattern is mainly based on directional wells, which can improve the accuracy of drilling and increase the contact area with the coal seam, thereby improving the recovery rate of coalbed methane.

[0131] Hydraulic fracturing is a key step in coal seam gas development to release gas adsorbed in coal seams. Hydraulic fracturing injects high-pressure liquid into coal seams to create cracks in the coal seams, thereby increasing the permeability of the coal seams and releasing coal seam gas that was originally difficult to flow.

[0132] In addition to conventional horizontal well multi-stage fracturing, synchronous fracturing, repeated fracturing, microseismic monitoring and other technologies, the fracturing methods used in coalbed methane development in the study area have also expanded to include the following latest technologies:

[0133] (1) Intelligent fracturing technology: Combining big data analysis and artificial intelligence technology, a comprehensive analysis of coal seam geological conditions, historical fracturing data, etc. is performed to predict and optimize fracturing effects. Intelligent fracturing technology can more accurately design fracturing plans, reduce trial and error costs, and improve the efficiency and success rate of fracturing operations.

[0134] (2) Nanomaterial-enhanced fracturing technology: Add nanomaterials, such as nano-silicon and nano-aluminum, to the fracturing fluid to improve the physical and chemical properties of the fracturing fluid, increase the conductivity of the fractures and the permeability of coalbed methane. Nanomaterials can fill the tiny pores in the fractures and enhance the connectivity and stability of the fractures.

[0135] (3) Composite fracturing technology: Combining the advantages of multiple fracturing technologies to form a composite fracturing solution. For example, combining multi-stage fracturing of horizontal wells with volume fracturing technology, or combining water fracturing with waterless fracturing technology, to achieve more efficient coalbed methane extraction.

[0136] (4) Environmentally friendly fracturing technology: With the improvement of environmental awareness, environmentally friendly fracturing technology has gradually become a research hotspot. This includes using biodegradable fracturing fluid, reducing the use of chemical additives, optimizing wastewater treatment technology, etc., to reduce the impact of fracturing operations on the environment.

[0137] (5) Remote monitoring and automated fracturing technology: Using modern information technologies such as the Internet of Things and cloud computing to achieve remote monitoring and automated control of the fracturing operation site can not only improve operational efficiency, but also reduce personnel risks and ensure operational safety.

[0138] The selection and application of coalbed methane development technology should be comprehensively considered based on specific coalbed geological conditions, economic benefits, environmental impacts, etc. At the same time, with the continuous advancement and innovation of science and technology, coalbed methane development technology will continue to develop and improve.

[0139] 4. More stringent environmental protection

[0140] During the development of coalbed methane in the study area, more stringent environmental protection programs are implemented to ensure environmental sustainability and reduce negative impacts on the ecosystem. Some of the conventional methods adopted are: conducting a comprehensive environmental impact assessment before development to identify potential environmental risks and develop corresponding mitigation measures; ensuring the protection of groundwater and surface water during coalbed methane extraction, including monitoring water quality, preventing pollution and rational use of water resources; properly handling solid waste and wastewater generated during the mining process to avoid contamination of soil and water bodies; taking measures to reduce gas emissions such as methane and other volatile organic compounds in mining activities to reduce the impact on air quality; after mining, reclaiming the affected land to restore its original ecological functions and landscape; establishing a long-term environmental monitoring system, regularly reporting environmental conditions, and ensuring continued compliance with environmental protection standards; community participation and communication: working with local communities to ensure that they understand development activities and participate in the decision-making process when necessary to reduce social conflicts; strictly complying with national and local environmental protection laws and regulations to ensure that all development activities are legal and compliant.

[0141] By implementing these measures, the impact of coalbed methane development on the environment can be minimized, while promoting the harmonious coexistence of energy development and environmental protection. On this basis, the study area adopted technical measures to further refine or expand the above environmental protection scheme:

[0142] (1) Green mining technology: Actively adopt advanced green mining technologies, such as horizontal well drilling and fracturing fluid recovery and reuse, to reduce damage to the environment and waste of resources.

[0143] (2) Energy efficiency improvement: Optimize energy use during the mining process, such as using energy-efficient equipment, reducing electricity and fuel consumption, and lowering carbon emissions.

[0144] (3) Establishment of ecological buffer zones: Establish ecological buffer zones around mining areas in the form of natural vegetation or artificial wetlands as ecological barriers to reduce the impact of mining activities on surrounding ecosystems.

[0145] (4) Biodiversity conservation: During the planning and implementation of mining, special attention should be paid to the protection of local biodiversity, avoiding the destruction of important ecological habitats, and taking measures to promote the restoration of biodiversity.

[0146] (5) Emergency plan formulation: Develop detailed emergency plans for environmental pollution and ecological damage to ensure rapid response, effective control of the development of the situation and reduction of losses when sudden environmental incidents occur.

[0147] (6) Environmental education and training: Strengthen environmental education and training for mining personnel, improve their environmental awareness and operational skills, and ensure that they strictly abide by environmental regulations at work.

[0148] Through the implementation of these measures, the environment in coalbed methane development areas can be protected more comprehensively, and the coordination and unity of economic benefits, social benefits and environmental benefits can be achieved.

[0149] In summary, the present invention proposes a design method for the deployment of a honeycomb coalbed methane exploration and development well network, in order to achieve large-scale development and production of coalbed methane in the operating area with high quality, speed and low cost, and to maximize the utilization rate and recovery rate. With the continuous advancement of technology and the deepening of application practice, its role and effect will be further reflected and exerted.

[0150] With the continuous advancement of technology and the accumulation of experience, the honeycomb coalbed methane development well pattern is expected to be more widely used and promoted in the future. It will become one of the important technical means for the efficient development of coalbed methane and contribute to the sustainable development of the energy industry.

[0151] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the protection scope of the present invention in any form, and all technical solutions obtained by equivalent replacement and the like fall within the protection scope of the present invention. The parts not involved in the present invention are the same as the prior art or can be implemented by the prior art.

Claims

1. A honeycomb coalbed methane exploration and development well pattern deployment method, characterized in that: The following steps are involved: Step 1: Conduct geological exploration and analysis to determine the distribution, reservoir characteristics and geological conditions of coalbed methane; Step 2: Design a honeycomb well pattern layout based on the occurrence characteristics and geological conditions of coalbed methane, including determining the density of the well pattern, the well spacing, and the arrangement of the wells; Step 3: Accurately arrange the well locations: Use geographic information systems and computer simulation technology to optimize the well locations to achieve the best mining results; Step 4: Drilling: During the drilling process, directional and horizontal drilling techniques are used to ensure that the drilling is carried out according to the predetermined trajectory and angle to meet the layout requirements of the honeycomb well pattern; Step 5: Perform fracturing operations: inject fracturing fluid into the well through a high-pressure pump to form cracks and increase the permeability of the coal seam; Step 6: Conduct production testing and monitoring.

2. A honeycomb coalbed methane exploration and development well pattern deployment method according to claim 1, characterized in that: In step 1, detailed geological information is obtained by means of seismic exploration and coring.

3. A honeycomb coalbed methane exploration and development well pattern deployment method according to claim 1, characterized in that: In step 2, planning the honeycomb well location deployment to ensure the well pattern density and distribution uniformity includes: (1) Detailed analysis of the geological characteristics of the coalbed methane reservoir, including the thickness, permeability, gas content, and stress state of the coal seam; (2) Determine the well pattern density based on the development objectives of the coalbed methane reservoir and determine the optimal well spacing through simulation and optimization. (3) Select a honeycomb well site deployment mode: Use a hexagonal grid, with each well site located at the center of the hexagon, and the lines connecting adjacent well sites form a honeycomb structure.

4. A honeycomb coalbed methane exploration and development well pattern deployment method according to claim 1, characterized in that: In step 4, directional drilling is to drill along a predetermined trajectory by the drill bit to reach a specific position of the coal seam, and to ensure that the drill bit penetrates a predetermined area of ​​the coal seam by controlling the direction and angle of drilling to achieve precise penetration of the coal seam. Directional drilling uses a guidance system to monitor the drilling path in real time and adjust it according to geological data.

5. The method for deploying a honeycomb coalbed methane exploration and development well pattern according to claim 1, characterized in that: In step 4, horizontal drilling is used to expand the contact area of ​​drilling. After reaching the coal seam, the drilling path is changed to a horizontal direction and drilling is carried out along the layer of the coal seam. In addition, horizontal drilling uses a multi-section drilling tool assembly to maintain the stability and directionality of drilling.

6. The method for deploying a honeycomb coalbed methane exploration and development well pattern according to claim 1, characterized in that: In step 5, the fracturing operation includes: (1) Preparation and injection of fracturing fluid: Prepare fracturing fluid suitable for the characteristics of the coal seam, and inject the fracturing fluid into the well through a high-pressure pump. The liquid enters the coal seam under high pressure, causing cracks in the coal seam; (2) Fracture formation and expansion: After the fracturing fluid forms the initial fracture in the coal seam, as the fluid is continuously injected, the fracture will expand to the surrounding area, forming a complex fracture network. Then proppant is injected into the fracture to prevent the fracture from closing and keep the fracture open. (3) Fracture monitoring and optimization: Use microseismic monitoring or pressure monitoring to monitor the formation and expansion of fractures in real time, and adjust the fracturing parameters based on the monitoring results to optimize the morphology and distribution of the fracture network to improve the fluidity and recovery rate of coalbed methane; (4) Gas extraction and post-processing: After fracturing is completed, the coalbed methane begins to flow from the cracks and is extracted to the ground through the wellbore. The extracted coalbed methane is then dehydrated and desulfurized to meet the standards for transportation and use.

7. The method for deploying a honeycomb coalbed methane exploration and development well pattern according to claim 1, characterized in that: In step 6, the wellhead pressure, production, and gas composition parameters are monitored in real time, and the pressure, temperature, and permeability geological parameters of the coalbed methane reservoir are regularly evaluated. Through data monitoring and analysis, production parameters are adjusted in a timely manner.

8. The method for deploying a honeycomb coalbed methane exploration and development well pattern according to claim 1, characterized in that: During the development process, the use and disposal of fracturing fluids is controlled, and ground subsidence monitoring is implemented to reduce the impact on the environment.

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