最新刊期
卷 16 ， 期 5 ， 2026
- 摘要：China’s coalbed methane (CBM) research focuses on the development of deep CBM. However, medium-shallow CBM resources are abundant and highly proven. Currently, the main challenge is the difficulty in effectively utilizing a large amount of adsorbed gas. If the remaining adsorbed gas can be effectively utilized, the production scale of medium-shallow CBM could achieve a significant breakthrough. To clarify the development direction of surface well development technology for enhancing recovery in medium-shallow CBM, this study conducts an in-depth discussion based on a chain mass-transfer model of “in-situ desorption-matrix diffusion-cleat seepage-fracture conductivity” and reviews the definition and connotation of recovery efficiency in medium-shallow CBM. Among these processes, matrix diffusion, as the key link connecting microscopic desorption and macroscopic seepage, is identified as the core factor restricting the overall recovery efficiency. Furthermore, the influencing factors are systematically classified into two categories: (1) the main seepage controlling factors affecting pressure drop sweep efficiency, such as fracture conductivity, well pattern layout, and pressure drop rate; (2) the main diffusion controlling factors affecting desorption efficiency, including matrix block size, gas diffusion coefficient, water saturation, and temperature and pressure conditions. On this basis, this study systematically reviews the mainstream technologies for enhancing recovery, such as well pattern optimization, gas injection displacement (CO2 flooding, N2 flooding), negative pressure extraction, desorption agent injection, physical field energy enhancement (acoustic wave, microwave, electric field), microbial stimulation, and hydraulic slotting. Their applicable conditions, field application effects, and failure mechanisms are also analyzed. It is found that although these technologies can increase production under certain conditions, they generally have the common limitations of difficult matrix entry, easy energy dissipation, and limited stimulation effect. In other words, external energy cannot effectively act inside the matrix, the pressure drop sweep range is limited, the desorption efficiency improvement is insufficient, and the stimulation effect rapidly decreases over time, making sustainable development difficult to achieve. For medium-shallow CBM development, the mobilization rate of recoverable reserves (i.e., the kinetic process) is more practically significant than the absolute amount of recoverable reserves (i.e., the thermodynamic state). Rapid and efficient mobilization of adsorbed gas within the matrix is the key to increasing production and enhancing recovery efficiency. Therefore, surface well development technologies for enhancing recovery should focus on three directions: increasing mass-transfer driving force in the matrix, reducing matrix block size, and enhancing the gas-phase flow capacity within the matrix. Among these, reducing matrix block size is currently the most readily achievable breakthrough direction. Increasing the matrix mass-transfer driving force has limited effectiveness, while enhancing the gas phase flow capacity within the matrix requires long-term research and development to achieve a breakthrough.关键词：medium-shallow coalbed methane (CBM);surface well development;enhancing recovery;main controlling factors;Technical limitations;development direction172|772|0更新时间：2026-08-06
- 摘要：In view of the difficulties in the geological engineering “sweet spot” of coal-rock gas development in Jiaxian block of Ordos Basin, such as unclear fine evaluation, difficult fine control of drilling trajectory of long horizontal section horizontal well, small space for liquid control, efficiency improvement and cost reduction in large-scale fracturing transformation, and inaccurate control of efficient and economical drainage, the development concept of geological engineering integration has been developed. Through the application practice of development pilot test, the key technology of integrated and efficient development of coal-rock gas with “sweet spot” evaluation, optimal and fast drilling, fracturing transformation and efficient drainage is formed. Based on the integrated “sweet spot” evaluation technology, a three-factor and 12-item evaluation index system of geological engineering economy in the developed “sweet spot” is established. Based on the mud logging data while drilling, the identification standard of black gold target is established to support the development of selected areas and the deployment and implementation of horizontal wells. By optimizing the wellbore structure, optimizing the high-efficiency speed-up tools, and adopting the integrated guidance technology of seismic geology and engineering, the optimal and fast drilling of large well cluster horizontal wells in factory is realized, and the drilling rate of coal rock is guaranteed to be more than 98%. The integrated fracturing technology system of geological engineering with “high displacement + moderate scale + complex fracture network + multi-scale support” as the core is formed, and the ultra-low pre-liquid controlled hydraulic fracturing technology and few cluster long fracture fracturing technology are explored, which further improves the pertinence and economy of coal rock gas fracturing transformation. A full-cycle integrated drainage technology system of “initial oil control pressure self-flowing, medium-term auxiliary bubble drainage + gas lift, and later artificial lifting” has been formed to improve the drainage and gas recovery efficiency of coal-rock gas wells. Practice shows that the integrated and efficient development technology of coal, rock and gas has realized the deep integration of geological engineering, formed the closed-loop optimization of the whole development cycle, reduced the development cost and realized the scale benefit development of coal, rock and gas while ensuring the drilling effect and production effect of single well.关键词：Ordos Basin;Coal-rock gas;geology-engineering integration;“sweet spot” evaluation;Optimized drilling;volume fracturing;Drainage schedule93|12|0更新时间：2026-08-06
Specialist Forum
- 摘要：The cross-scale characteristics of pore systems in deep coal reservoirs directly affect the occurrence state and seepage capacity of coalbed methane (CBM), and have an important influence on the adsorption-desorption processes of deep CBM. To better evaluate the gas content of deep CBM, this study took the No.8 high-rank coal seam as the study object in the southeastern Ordos Basin. Multiple experimental methods, including high-pressure mercury intrusion, liquid nitrogen (N₂) adsorption, carbon dioxide (CO2) adsorption, and scanning electron microscopy (SEM), were adopted to characterize the pore structure of deep high-rank coal reservoirs at multiple scales. The results revealed that the pores in deep high-rank coal reservoirs were predominantly organic matter pores and microfractures. Nanoscale and micron-scale pores were circular or elliptical, while microfractures were long band-shaped. Some pores and fractures were filled with clay minerals and pyrite. Micropores, mesopores, and macropores were continuously developed in deep high-rank coal reservoirs, with pore sizes exhibiting multimodal distribution characteristics. Among them, the micropore segment curve showed a stepped peak, and micropores ranging from 0.4 nm to 0.7 nm occupied an absolutely dominant proportion. The dominant pore size of mesopores (2-50 nm) was 3-5 nm. Macropores with pore sizes larger than 50 nm and microfractures were relatively poorly developed, yet they contributed the most to reservoir permeability and served as the primary storage space for free gas. Deep CBM had multiphase occurrence characteristics, mainly occurring as adsorbed gas and free gas. The measured total gas content of the No. 8 coal seam in the study area ranged from 28.39 m³/t to 35.85 m³/t. The Langmuir volume varied between 26.09 m³/t and 29.52 m³/t, and the gas saturation reached 116%-150%, indicating an overall oversaturated state. Overall, micropores accounted for more than 99% of the specific surface area of the No. 8 coal seam. The gas content of deep high-rank coal was dominated by adsorbed gas, and adsorption capacity remained the primary controlling factor for gas content evaluation. Deep coal reservoirs contained some macropores and microfractures that provided storage space for free gas. Deep CBM was generally in an oversaturated state, with widespread free gas and high gas saturation.关键词：southeastern Ordos Basin;deep coalbed methane (CBM);pore structure;occurrence state;No. 8 coal seam25|38|0更新时间：2026-08-06
- 摘要：The traditional desorption method for determining coalbed methane (CBM) gas content suffers from high costs, long cycles, and limited regional coverage, making it unsuitable for rapid economic recoverability assessments, cost reduction, and efficiency improvement. To address this, a CBM gas content prediction method based on an improved Stacking ensemble algorithm was proposed. This method optimizes the hyperparameters of five heterogeneous base models—support vector machine (SVM), random forest (RF), XGBoost, LightGBM, and multi-layer perceptron (MLP)—through grid search. It constructed a new meta-training set by innovatively weighting and averaging the raw training-set features and prediction results from each base model, which was then input into a linear regression meta-model for secondary learning. This achieved dual integration of raw features and base-model prediction information. The model was applied to CBM blocks in the southern Qinshui Basin. The results demonstrated that the improved Stacking ensemble model achieved a coefficient of determination of 0.94 on the test set, representing improvements of 10.64% and 6.38% over the optimal single base model and standard Stacking model, respectively. Compared with the standard Stacking model, the mean absolute error, root mean square error, and mean squared error are reduced by 14.3%, 25.2%, and 43.7%, respectively. SHAP (SHapley Additive exPlanations, a method for interpreting machine learning model predictions) interpretability analysis indicated that coal seam slant depth, spontaneous potential, and natural gamma ray are the primary features influencing gas content prediction. Field application demonstrated good agreement between predicted and measured values for eight wells, with a mean absolute error below 0.84 m³/t and a mean relative error controlled within 6%. This model significantly enhances the accuracy and reliability of CBM gas content prediction, providing a new technical approach for CBM resource area selection and efficient development.关键词：coalbed methane (CBM);gas content;machine learning;Stacking ensemble model;interpretability analysis56|25|0更新时间：2026-08-06
- 摘要：The development of coalbed methane (CBM) from low-rank coal in the Fukang block, Xinjiang, has entered a bottleneck stage. A large amount of adsorbed methane in the microscopic pores of low-rank coal has low desorption efficiency, and the adsorption and desorption mechanisms remain unclear, resulting in low initial production rates, short durations of stable production, and poor development performance in newly commissioned CBM wells. To address the challenges of low CBM recovery rates and the difficulty in effectively mobilizing adsorbed methane, low-rank coal from the Fukang block, Xinjiang, was selected as the study subject. The coal’s pore size distribution, molecular formula (C100H108O16N3), and molecular structure were characterized using elemental analysis, N2 adsorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and 13C-nuclear magnetic resonance (13C-NMR), and a slit-type pore model was constructed. Adsorption behavior under varying slit widths, pressures, and temperatures was simulated using the grand canonical Monte Carlo (GCMC) method, and the non-isothermal Langmuir adsorption isotherm for low-rank coal in the Fukang block was fitted. Subsequently, under the conditions of 10.0 MPa and 308 K, molecular dynamics simulations of isothermal depressurization desorption processes were conducted for slit coal-methane adsorption configurations with different apertures. The results showed that: (1) The dominant molecular architecture of Fukang low-rank coal was a chain-like structure composed of benzene and naphthalene rings connected by aliphatic carbon chains, and contained functional groups such as carboxyl, hydroxyl, and pyrrole groups. (2) At pore aperture below 2 nm, strong nano-confinement effect deepened the adsorption potential well, leading to a single-peak methane density distribution, with micropore filling as the primary methane storage mechanism. When the aperture was above 2 nm, the density distribution transitioned to a double-peak pattern accompanied by a non-adsorption zone, indicating a shift toward surface-dominated adsorption. (3) Under high-pressure conditions, elevated temperature reduced adsorption potential energy and provided kinetic energy for methane desorption, and this effect was more pronounced in slit pores with apertures above 2 nm. Adsorbed methane still existed in the center of the slit, and the adsorption was jointly dominated by micropore filling and surface adsorption. (4) In the slit with an aperture of 1 nm, high desorption energy barriers and low diffusion coefficients (7.5×10-10 m2/s) led to significant desorption hysteresis. In the slit with an aperture of 3 nm, the desorption energy barrier was low, the diffusion coefficient was relatively high (64.7×10-10 m2/s), and no obvious desorption hysteresis occurred. In conclusion, reducing the adsorption/desorption energy barrier in low-rank coal micropores is crucial to enhancing methane desorption efficiency and diffusion capacity. Through the coordinated regulation of depressurization, pore expansion, and temperature increase, the combined fracturing technology of pre-injected CO2 and self-heating fracturing fluids, together with well-pattern thermal fluid displacement, represents an important technical direction for improving recovery rates of low-rank CBM reservoirs in the Fukang, Xinjiang.关键词：Fukang, Xinjiang;low-rank coal;coalbed methane (CBM);adsorption and desorption;molecular simulation;micropore filling12|3|0更新时间：2026-08-06
- 摘要：To clarify the multi-scale pore-fracture structural characteristics and main controlling factors of coal-rock reservoirs in the Shenmu-Jiaxian block on the eastern margin of the Ordos Basin, multiple experiments were conducted, including CT (computed tomography) scanning, scanning electron microscopy, high-pressure mercury injection, low-temperature nitrogen adsorption, and low-temperature carbon dioxide adsorption. A multi-scale full-pore-size distribution chart of coal rocks in the study area was established using the stitching method of all pore diameters, and the reasons for the differences in gas content and pore development between the Shenmu and Jiaxian blocks were explored. The results showed that (1) In terms of multi-scale pore-fracture characteristics, the study area as a whole developed cleavage fractures and millimeter-scale fractures parallel or vertical to bedding. The average total fissure ratio of the Shenmu and Jiaxian blocks were 7.01% and 6.06%, respectively. The average total fissure ratio in the Shenmu block was slightly higher, yet over 90% of the fractures were filled with high-density minerals. The storage space types of coal seams in the Shenmu block were mainly tissue pores, with rare gas pores and intercrystalline pores of clay minerals, and pore diameters ranging from several micrometers to tens of micrometers. The storage space types of coal seams in the Jiaxian block were mainly tissue pores and gas pores, with visible intercrystalline fractures of clay minerals in some areas. Pore diameters ranged from several nanometers to tens of micrometers, and microscale fractures developed. (2) In terms of full-pore-size distribution characteristics, the proportion of micropores in both blocks was above 99%, indicating that coal rock in the study area had a strong adsorption capacity. The coal seam reservoir space in the Shenmu block was mainly composed of macropores, with an average proportion of 74.72% for macropores, 23.28% for micropores, and an average specific surface area of 41.24 m2/g for micropores. The coal seam storage space in the Jiaxian block was mainly composed of macropores and micropores, with macropores accounting for an average of 64.00%, micropores accounting for an average of 34.85%, and micropores having an average specific surface area of 102.73 m2/g. The adsorption capacity of the Jiaxian block was better than that of the Shenmu block. (3) In terms of factors affecting gas occurrence patterns, the differences in maceral content and ash content between the two blocks resulted in different types of pore and fracture development. Specifically, coal rocks in the Jiaxian block had a higher degree of thermal evolution, higher vitrinite content, more developed pores, and a larger specific surface area of micropores with pore widths below 2 nm, indicating stronger adsorption and hydrocarbon generation capability. Both the roof and floor were composed of low-permeability lithologies with high compressive strength and high elastic deformation capabilities, providing favorable sealing conditions that are conducive to the preservation of coalbed methane (CBM) reservoirs. The research provides a theoretical basis for efficient exploration and development of deep CBM in the study area.关键词：Ordos Basin;Shenmu-Jiaxian block;deep coalbed methane (CBM);pore-fracture structure;full-pore-size characterization56|18|0更新时间：2026-08-06
- 摘要：Oil and gas exploration in the Zhu I Depression of the Pearl River Mouth Basin indicates promising prospects for deep oil and gas resources of the Paleogene in the Lufeng Sag, yet the accumulation conditions and enrichment patterns on the western gentle slope of the Lufeng 13 east subsag remain unclear. To address this issue, well logs, seismic data, and laboratory analyses were integrated with basin modeling to systematically examine the oil and gas accumulation conditions in this area. It clarified the accumulation conditions, revealed the accumulation processes, and established accumulation models for the study area. Results showed two oil and gas charging phases in the western gentle slope zone of the Lufeng 13 east subsag: low-maturity oil charging occurred from the mid-Hanjiang to the mid-Yuehai deposition (12.3-7.5 Ma) and oil and gas charging of higher-maturity crude oil mixed with some natural gas occurred from the late Yuehai deposition to the present (5.7-0 Ma). The Wenchang Formation developed low-porosity, low-permeability and medium-porosity, medium-permeability reservoirs, while the Enping Formation developed medium-porosity, medium- to low-permeability reservoirs, both offering favorable storage conditions. Two sets of regional mudstone caprocks developed in the Wenchang Formation provided effective sealing capacity for oil and gas. In contrast, the Enping Formation contained multiple sets of local caprocks with relatively weak sealing capacities. During the first phase of large-scale oil and gas charging, crude oil migrated laterally through Wenchang sandstones to accumulate near the Huilu low uplift. It also migrated vertically along the NW-trending early-inactive faults and continuously active faults into the Enping reservoirs. The second large-scale oil and gas charging phase followed the same migration pathways as those in the first phase. Based on the oil and gas accumulation patterns identified in the study area, two accumulation models were proposed: a lateral migration and accumulation model characterized by adjacent source rocks and lateral reservoirs, and a vertical fault-conduit migration and accumulation model characterized by lower source rocks and upper reservoirs. The Wenchang reservoirs near the Huilu low uplift were identified as a favorable area.关键词：Pearl River Mouth Basin;Zhu Ⅰ Depression;Lufeng Sag;gentle slope belt;oil and gas accumulation conditions;oil and gas accumulation process25|11|0更新时间：2026-08-06
- 摘要：China is rich in deep and ultra-deep natural gas resources. The cumulative proven geological reserves approach 5×1012 m3, and the cumulative production exceeds 5 000 ×108 m3, making these resources a critical strategic domain for ensuring national energy security. However, deep and ultra-deep gas reservoirs are all water-bearing and generally developed with sparse well patterns. Under the condition of sparse well pattern development, it is difficult to accurately depict the leading edge of water invasion, and conventional dynamic monitoring methods fail to effectively monitor interwell regions, which has become a key factor restricting the efficient development of deep/ultra-deep water-bearing gas reservoirs. This study leveraged the advantages of the wide field electromagnetic method (WFEM) to distinguish gas-bearing, gas-water transition, and water-bearing zones through differences in inversion resistivity. Taking well group 1 of the Longwangmiao Formation gas reservoir, Moxi area, Sichuan Basin as the research subject, a 3D WFEM detection of 2 km2 was conducted. The geoelectric characteristics at the depths of 5 000 m underground were obtained, a set of fluid identification methods integrating seismic and electromagnetic data was formed, and a geoelectric model was constructed. The WFEM was used for the first time to identify the leading edge of water invasion in deep edge-water gas reservoirs. The results showed that: based on the linear regression relationship between well-logging resistivity and the WFEM inverted resistivity, it was determined that the WFEM inverted resistivity in the water-bearing zones of well group 1 was less than 227 Ω·m, the wide field electromagnetic inversion resistivity in the gas-water transition zones ranged from 227 Ω·m to 383 Ω·m, and the wide field electromagnetic inversion resistivity in the pure gas-baering zones was greater than 383 Ω·m. The edge water advanced relatively uniformly from Well 1 into the interior of the gas reservoir without obvious water invasion channels. The leading edge of the water invasion showed uneven water invasion characteristics, with an overall water invasion rate of approximately 50 m/a. The well group should adopt a water control strategy combining drainage and control. The daily drainage capacity of Well 1 was 300-400 m3/d, and the daily gas production capacity of the internal wells should be reduced from the current 200×104 m3/d to below 150×104 m3/d. This achievement has broad application prospects in the description of gas-water distribution in deep/ultra-deep gas reservoirs, the characterization of the leading edge of water invasion, and precise water control. This technology opens up a new avenue for the efficient development of deep edge-water gas reservoirs.关键词：Longwangmiao Formation Moxi;wide field electromagnetic method;deep edge-water gas reservoir;resistivity;water invasion front;water control strategy97|98|0更新时间：2026-08-06
Oil and Gas Exploration
- 摘要：Since breakthroughs were made in China’s coalbed methane (CBM) production in 2005, its industrialization and commercialization have not met expectations due to unstable production and poor economic benefits. CBM, shale gas, and tight sandstone gas are major unconventional natural gas resources worldwide. Their integrated development and commingled production approach that prioritizes coal seams while also exploring tight sandstone gas and shale gas can effectively improve the degree of reserve utilization, ensure stable production, and reduce CBM production costs. Based on the lithology, gas-bearing properties, and development potential of coal-measure source rocks and reservoirs in the southern Sichuan Basin, this study established a comprehensive evaluation model and proposed a lithology (lithofacies)-gas-bearing combination-productive layer combination model for the “three classes and five types” of coal-measure gas reservoirs. On this basis, it identified that the “mudstone/shale roof interbedded with coal seam” type was the dominant symbiotic combination for development. Development concepts and technologies for coal-measure gas in multiple thin coal seams were analyzed. According to the fluid-flow mechanism within coal-measure gas reservoirs, a flow model was proposed. Class Ⅰ and Class Ⅱcombinations were selected as the main sections for fracturing stimulation, and a set of key technologies suitable for the stimulation of low-permeability composite reservoirs (e.g., coal seam, mud shale) was established. The geological background of gas accumulation, reservoir characteristics, and the gas-bearing properties of the roof and floor strata were systematically studied for Well Chuanlincan 1. Guided by the oil and gas migration pathway theory and drawing on the shale gas stimulation methods, a set of reservoir enhancement measures for “mudstone + coal reservoir” was formulated, and the gas production target was achieved. This is a landmark project for the comprehensive evaluation of the development potential of hydrocarbon gases in the Upper Permian Longtan Formation coal measures. This technology provides a valuable reference and has application value for promoting the development of similar coal-measure gas reservoirs in southwestern China.关键词：Sichuan Basin;coal-measure gas reservoir;favorable area selection;comprehensive evaluation model;Well Chuanlincan 1;development model15|14|0更新时间：2026-08-06
- 摘要：Accurate acquisition of bottom-hole flowing pressure in coalbed methane (CBM) wells is of great significance for optimizing drainage and production processes and improving CBM recovery. However, existing methods for calculating bottom-hole flowing pressure generally have problems such as high economic cost, poor data timeliness, limited applicability, or insufficient accuracy. In particular, deep CBM wells usually employ gas-lift drainage and production, and the dynamic liquid level data is difficult to obtain, which renders traditional wellbore flow models inapplicable and seriously constrains dynamic monitoring and production optimization of these wells. To solve this problem, a new method for calculating bottom-hole flowing pressure in deep CBM wells was proposed, aiming to quickly and accurately calculate bottom-hole flowing pressure using wellhead casing pressure data in the absence of dynamic liquid level data by establishing a more accurate wellbore flow model. In this method, a nonlinear formula for characterizing the dynamic liquid level position was innovatively proposed, and the vertical wellbore was divided from top to bottom into a pure gas column section and a gas-water two-phase liquid column section based on the dynamic liquid level position, thereby establishing a refined wellbore flow model. The pressure of the pure gas column section was calculated using the average temperature and deviation coefficient method, and the pressure of the gas-water two-phase liquid column section was calculated using the Hasan-Kabir analytical method. A comprehensive and efficient numerical iteration method was established to solve the closed strongly nonlinear equation system composed of the nonlinear formula for dynamic liquid level position, the pressure calculation formula for the pure gas column section, and the pressure calculation formula for the gas-water two-phase liquid column section, ultimately obtaining the bottom-hole flowing pressure of deep CBM wells. Finally, taking deep CBM Well A in the Daning-Jixian block of the Ordos Basin as an example, field application testing of the algorithm was conducted. The results indicated that this algorithm significantly improved the accuracy of field flowing-pressure calculation and demonstrated high computational efficiency. In addition, this method showed favorable applicability in production dynamic data analysis, providing efficient and reliable technical support for dynamic monitoring of unconventional gas reservoirs.关键词：Ordos Basin;deep coalbed methane (CBM);wellbore flow model;bottom-hole flowing pressure;two-phase flow;dynamic liquid level;nonlinearity29|19|0更新时间：2026-08-06
- 摘要：Deep coal seams are characterized by geological conditions of high in-situ stress, high reservoir temperature, low permeability, and complex tectonic features, resulting in significant differences in gas occurrence states and migration mechanisms compared with shallow coal seams. Conventional commercial numerical simulators are generally based on simplified dual-porosity models, making it difficult to accurately describe the complex stress sensitivity and multiphase flow dynamics of deep coal seams during production and drainage. This leads to considerable discrepancies between simulation results and actual production data. To address this issue, this study established an efficient numerical simulation method suitable for deep coalbed methane (CBM) characteristics, aiming to accurately characterize single-well gas production, water production, bottom-hole flowing pressure, and produced gas composition. Based on the geological and engineering characteristics of deep coal seams, a fully coupled numerical model was developed considering a quasi-triple-porosity medium (matrix pores, microfractures, and large fractures), competitive adsorption/desorption of multicomponent gases (CH4, CO2, etc.), multiscale diffusion, gas-water two-phase seepage, and coal matrix shrinkage/deformation effects. A typical deep CBM Well JS6-7P01 in the Daning-Jixian block of the Ordos Basin was selected as a case study for history matching and analysis. In terms of computational performance, comparisons under different computational conditions showed that, compared to conventional decoupled or simplified simulation methods, the proposed method increased the computation time by only 0.1-0.2 hours, and the number of Newton iterations and linear iterations by only 10.5% under 4-core and 8-core CPU parallel computing conditions. Regarding matching accuracy and geological understanding, the model performed history matching of gas production, water production, bottom-hole flowing pressure, and produced CO2 molar fraction variations for Well JS6-7P01, achieving a comprehensive history fitting rate of 92%. Based on the numerical simulation results, the contribution proportions of free gas and adsorbed gas during production were further quantitatively calibrated, clarifying the sources of productivity contribution in deep CBM reservoirs. Different stages of fluid flow were finely divided. Finally, the seepage characteristics of deep CBM under multi-field coupling effects were characterized based on the evolution patterns of six fields, including pressure field, saturation field, desorption degree field, permeability field, CO2 adsorption mass density field, and CH4 adsorption mass density field. This method overcomes the limitations of conventional numerical simulation methods and provides a preliminary exploration and an effective tool for the prediction and decision-making of deep CBM development.关键词：Ordos Basin;deep coalbed methane (CBM);multi-field coupling;numerical simulation;computational efficiency;history matching10|4|0更新时间：2026-08-06
- 摘要：To reveal the influence of water content on CO2 injection-enhanced coalbed methane recovery (CO2-ECBM) (CO2 displacement of CH4) in deep coal seams, this study used Fukang deep coal as the research object. Experiments such as 13C nuclear magnetic resonance spectroscopy (13C-NMR) and X-ray photoelectron spectroscopy (XPS) were conducted. A coal matrix model was constructed using molecular simulation software, and the microscopic mechanism of water’s effect on the CO2-ECBM process in deep coal seams was studied using molecular simulation methods. The results showed that after coal matrix adsorbed gas, it underwent significant expansion, and the pore volume significantly decreased. When saturated with adsorbed CH4, the coal matrix porosity decreased by 72.2% compared to the initial value. When the molar ratio of CO2 to CH4 (
Oil and Gas Development
- 摘要：Hydraulic jet pumping is a widely used drainage and production technique in the artificial lift stage of deep coalbed methane (CBM) wells. In the early stage of deep CBM development in the Daning-Jixian block, there was generally a lack of systematic and in-depth understanding of the relationship between key parameters such as the nozzle/throat area ratio of the hydraulic jet pump and gas well production, as well as the drainage and production conditions of gas wells, which led to insufficient specificity and effectiveness in parameter regulation. Based on the drainage and production characteristics of the concentric double-tubing hydraulic jet pumps and the production conditions of deep CBM wells in the Daning-Jixian block, this study conducted research on working condition analysis, parameter optimization, and design verification calculation methods/flows for hydraulic jet pumps in deep CBM wells. Using the developed calculation software for hydraulic jet pumps, case calculations and analyses were carried out on the hydraulic jet pump drainage and production wells in the Daning-Jixian block. The research results showed that: (1) When the friction coefficient proposed by Gosline and O’Brien was adopted, the error between the theoretical pressure ratio and the actual pressure ratio was minimal, which was more in line with the actual working conditions of hydraulic jet pumps in deep CBM wells. (2) In the Daning-Jixian block, the hydraulic jet pump drainage and production in deep CBM wells generally had problems such as low flow ratio, low pump efficiency, scaling and blockage in the tubing and jet pump, and erosion-induced diameter enlargement of the jet pump under some operating conditions. (3) By optimizing nozzle/throat combinations with high area ratios and reducing the power fluid flow rate, the drainage and production pressure ratio of hydraulic jet pumps in deep CBM wells was effectively increased, and the pump efficiency and liquid production were also increased. It is recommended that when building the ground facilities for hydraulic jet pumps in deep CBM wells, the gas and liquid metering pipelines for single wells should be optimized to facilitate accurate measurement of the daily gas and liquid production at the production site. This is conducive to improving the accuracy of the working condition analysis of hydraulic jet pumps in single wells, and has guiding significance for improving the drainage and production continuity of hydraulic jet pumps in deep CBM wells and reducing maintenance and well repair costs.关键词：deep coalbed methane (CBM);hydraulic jet pump;parameter optimization;working condition analysis;Ordos Basin;Daning-Jixian block31|18|0更新时间：2026-08-06
- 摘要：To tackle the difficulties in real-time evaluation of coalbed methane (CBM) reservoir fracturing performance and the insufficient consideration of multi-scale fracture network closure in conventional inversion models, this study identified the hierarchical closure processes of cleats, natural fractures, and hydraulic fractures using the inflection points from the shut-in pressure decline curves. Taking multi-stage fracture closure as the core mechanism, the study integrated coupled material balance principles with pressure transient analysis methods. Inversion formulas for fracture surface area, half-length, and complexity index were derived. And a shut-in pressure decline inversion model for coal rock reservoirs was established. Using the granulated coal reservoir in Fukang, Xinjiang, as a validation case, the fracture half-length inverted by the model was 45.4% lower than the microseismic monitoring result, as the model only captured the wet stimulated reservoir volume (SRV) with sustained conductivity and excluded fractures without effective flow contribution, making the results more consistent with engineering reality. The model was further applied to medium-shallow high-rank coal in the Qinshui Basin and deep coal rock in the Ordos Basin. Results revealed significant differences in fracturing performances among the three coal types. For shallow granulated coal, the surface area proportions of main fractures and secondary fractures were 9.18% and 52.17%, respectively. The fracture network was short and complex, with a complexity index of 10.03. For medium-shallow high-rank coal, the main fracture accounted for 14.29%, and secondary fractures accounted for 77.5%. The fracture network extended relatively far along main fractures, with a complexity index of 6.05. For deep coal reservoirs, main and secondary fractures accounted for 22.08% and 77.92%, respectively. No connected cleat system was observed and the network had a complexity index of 3.67. Comparative analysis showed that coal integrity and in-situ stress conditions jointly controlled fracture network development patterns. Granulated coal restricted main fracture extension due to coal structure disruption and heavy fluid loss. Primary-structure coal and deep coals exhibited lower leakoff, allowing stable extension of main fractures. However, high vertical stress in deep coals inhibited fracture branching and limited network complexity. The proposed model overcomes the limitations of conventional approaches by accurately identifying multi-stage fracture closure characteristics, distinguishing fracture development differences caused by coal structures, and improving the technical framework of shut-in pressure decline inversion for evaluating CBM fracturing performance. It provides theoretical support for the optimization and effectiveness evaluation of fracturing designs in CBM reservoirs.关键词：low-rank coal;high-rank coal;deep coal rock;hydraulic fracturing;fracturing parameter inversion;multi-stage fracture closure11|4|0更新时间：2026-08-06
- 摘要：To address the unclear spatial differentiation characteristics of scaling types and the lack of targeted acidizing solutions, this study integrated mineralogical analysis, hydrogeochemical methods, and scale dissolution experiments to elucidate the east-west differentiation patterns of downhole tubing scaling mechanisms within the Yanchuannan coalbed methane (CBM) field. Differentiated descaling technical pathways were formed. Mineralogical characterization revealed that the scaling materials in the western Wanbaoshan structural belt were predominantly calcite, representing typical carbonate scale, whereas those in the eastern Tanping structural belt were a complex mixture of calcite, siderite, pyrite, and clay minerals. Geochemical analysis indicated that a weakly acidic environment with a high-Ca2+/Mg2+ ratio in the west drove rapid carbonate scaling, whereas a weakly alkaline, high-sulfate environment in the east governed mineral composite deposition dominated by iron minerals. Scale dissolution experiments showed that hydrochloric acid (HCl) with a mass fraction of 6% was highly effective against carbonate scale (78.8%-93.0% dissolution rate), whereas a sulfamic acid composite system (descaling agent-to-water volume ratio of 1∶10) had lower corrosivity and achieved a scale dissolution rate of 76.3%-81.9%. Based on these results, a flexible zoning strategy was proposed. Sulfamic acid is recommended as a primary choice for periodic field-wide maintenance. HCl with mass fraction of 6% and corrosion inhibitors can be used for enhanced cleaning at specific stages for severe carbonate scale accumulation in the western region. For eastern composite scales with significant silicate components and insufficient maintenance effects, targeted hydrofluoric acid (HF) treatment may be adopted under strict safety protection. This research forms a precise descaling method of “scale identification—mechanism analysis—acid fluid selection,” providing a theoretical basis and practical guidance for scaling prevention and control in CBM wells under similar geological conditions.关键词：Yanchuannan coalbed methane (CBM) field;downhole tubing;scaling causes;descaling agent;differentiated descaling48|25|0更新时间：2026-08-06
Engineering Techniques
- 摘要：With the increasing uncertainty in the global energy market and the implementation of the “Digital & Intelligence PetroChina” strategy, traditional economic evaluation faces challenges such as strong dependence on experience, significant data silo effects, and insufficient dynamic response capabilities. To address these challenges, this paper constructed a digital-intelligent closed-loop management system for economic evaluation covering the entire chain of data, model, decision-making, and supervision. Nine professional decision-making models were proposed, including neural network-based economic recoverability prediction, three-level reserve marginal benefit evaluation, and single-well production optimization. A dual-loop management architecture of “project-level micro loop” and “enterprise-level macro loop” was designed. A standardized database covering five categories of indicators, including basic data, development data, and cost data, common parameters, and investment data, was established. Data authenticity and the scientific soundness of decision-making were ensured through dynamic review, intelligent warning, and retrospective analysis. Practical applications showed that this system significantly improved economic evaluation accuracy and strongly supported quality and efficiency improvement in oil fields. In terms of economic evaluation of oil and gas resources, the evaluation results effectively guided the optimization of exploration directions. Through analogy analysis of blocks P, T, U, and V of oilfield S, blocks P and T were selected for priority implementation, achieving good economic benefits. In terms of optimizing investment in production capacity construction during the development phase, block X of unit N achieved an investment surplus of 10%, and the internal rate of return increased from 8.3% to 9.6% through scheme optimization. In terms of measure-based efficiency improvement, 166 ineffective measure wells were identified and rejected through pre-evaluation in 2024, successfully avoiding risks of 33 million yuan. Overall, the constructed digital-intelligent closed-loop management system effectively solves the limitations of traditional economic evaluation and realizes a transformation from discrete construction project analysis to full-process intelligent decision-making. This system not only provides a scalable digital-intelligent transformation path for oil and gas field enterprises, but its “full-lifecycle dynamic optimization” concept also has guiding significance for the intelligent development of the energy industry.关键词：oil and gas field;economic evaluation;digital intelligence;data;model83|212|0更新时间：2026-08-06
- 摘要：Due to high geothermal temperature (152 ℃), high formation pressure, and pronounced stress-shadowing effects, the development of deep tight oil reservoirs in the Dongying Sag (burial depth: 3 700-4 300 m) faces typical challenges such as short fracture half-lengths (<80 m), rapid production decline (decline rate >40% within three months), and significant productivity variations resulting from suboptimal alignment between geological and engineering parameters. This study proposed an enhanced energized fracturing technique of “supercritical CO2 pre-pad injection and precise activation of imbibition fluid”, designed to address the core issues of difficult energy replenishment, restricted fracture propagation, and low mobilization efficiency of matrix crude oil in deep reservoirs. Through phase-state control of supercritical CO2 (temperature: 35 ℃, pressure: 15 MPa, density: 0.8 g/cm³), this technology leveraged its high diffusivity (0.12 cm²/s) and its phase-transition expansion potential for pre-pad energized fracturing and fracture creation. Combined with an optimized anionic petroleum sulfonate imbibition fluid system which reduced interfacial tension to 0.15 mN/m and optimized the contact angle to 65°, it effectively lowered capillary resistance, improved reservoir wettability, and enabled precise activation of matrix crude oil. To tackle the multi-parameter optimization challenge, a numerical simulation database containing 960 schemes was constructed based on an orthogonal experimental design (L64(45)), covering six key geological parameters and five engineering parameters targeted for optimization. Furthermore, a coupled optimization model integrating a back-propagation (BP) neural network and a genetic algorithm (GA) was developed. Taking cumulative oil production as the objective function, global optimization was conducted for CO2 injection volume, imbibition fluid injection volume and injection rate, soaking time, and daily fluid production. Model validation results indicated that the BP neural network achieved a relative prediction error of less than 2.5%. The hidden layer contained 13 nodes for new wells (MSE = 0.003 7) and 8 nodes for old wells (MSE = 0.004 3). The GA converged within 75 generations (crossover probability, Pc=0.4 and mutation probability, Pm=0.2), demonstrating both high accuracy and efficiency. Field applications showed remarkable results. The improved process increased the average fracture half-length from 78 m to 161 m, representing a 106.4% enhancement. The 90-day production decline rate of a typical well Y22 was reduced by 13.3%. After parameter optimization, the productivity of new and old wells increased by 16.8% and 11.2%, respectively. This study establishes a decision-making process integrating numerical simulation, parameter learning, and dynamic optimization. It effectively addresses the challenge of vertical fracture propagation in box-shaped reservoirs and provides a valuable paradigm for the efficient development of unconventional oil and gas resources.关键词：energized fracturing;deep tight oil reservoir;supercritical CO2;BP neural network;genetic algorithm;parameter optimization20|15|0更新时间：2026-08-06
Digital and Intelligent Energy
-
Development path and strategic exploration of China’s natural gas economy under “dual carbon” goals AI导读
摘要：Against the backdrop of ongoing efforts toward carbon peaking and carbon neutrality goals and the strengthening of energy security constraints, it is essential to clearly define the role of natural gas in China’s energy structure transformation. Exploring practical pathways for the high-quality development of the natural gas sector has become particularly important. By integrating literature review, statistical comparison, industrial chain analysis, and supply-demand balance scenario calculation, this study constructs an analytical framework focusing on natural gas demand growth, supply security, infrastructure construction, market mechanism reform, and key application scenarios. It systematically examines the realistic foundation, major shortcomings, and strategic directions for China’s natural gas economic development under the “dual carbon” goals, and proposes relevant policy and measure recommendations. The research finds that China’s natural gas market still holds growth potential. In 2025, apparent consumption exceeded 4 265.5×108 m3, domestic production steadily increased, pipeline gas and liquefied natural gas (LNG) imports continued to diversify, and application scenarios such as gas-fired power generation, industrial substitution, urban gas, transportation, and marine fuel still have development potential. However, the industry has transitioned from simple scale expansion to a new phase emphasizing safety, economic efficiency, and low-carbon synergy, facing constraints including slowing consumption growth, volatile import prices, insufficient industrial chain coordination, shortcomings in infrastructure construction, and imperfect market-oriented mechanisms. Scenario calculation indicates that China’s natural gas demand peak is significantly influenced by the pace of energy substitution, gas-fired power peak regulation, the economic viability of industrial gas use, and the development speed of non-fossil fuels. Under the baseline scenario, it is expected to enter a peak plateau around 2035-2040. Natural gas serves as a low-carbon transitional energy source, a resource for energy security adjustment, and a flexible support resource for the new power system in China’s energy transition. Going forward, China should adhere to principles of safety priority, low-carbon synergy, and economic feasibility. By enhancing domestic gas supply and diversified imports, strengthening coordination and mutual promotion across the industrial chain, advancing infrastructure construction and technological innovation, and improving market mechanisms, a natural gas economic development path aligned with the “dual carbon” goals will be formed.关键词：natural gas;carbon peaking;“dual carbon” goals;industrial chain;supply-demand demand46|17|0更新时间：2026-08-06
Comprehensive Research
- Postal code：210019
- Tel：025-66201780 Email：66scjs@vip.sina.com
- Technical support is provided by Beijing Founder electronics co., LTD 苏ICP备2025204824号-1
苏公网安备32010502011276号 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
- Total Visits：116448 Visits Today：520
0