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Excess pore pressure behavior and evolution in deep coalbed methane reservoirs
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作者 Changqing Liu Zhaobiao Yang +3 位作者 Yong Qin Xia Yan Yunhai Wang Zhe Wang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第6期763-781,共19页
Deep coalbed methane(DCBM),an unconventional gas reservoir,has undergone significant advancements in recent years,sparking a growing interest in assessing pore pressure dynamics within these reservoirs.While some prod... Deep coalbed methane(DCBM),an unconventional gas reservoir,has undergone significant advancements in recent years,sparking a growing interest in assessing pore pressure dynamics within these reservoirs.While some production data analysis techniques have been adapted from conventional oil and gas wells,there remains a gap in the understanding of pore pressure generation and evolution,particularly in wells subjected to large-scale hydraulic fracturing.To address this gap,a novel technique called excess pore pressure analysis(EPPA)has been introduced to the coal seam gas industry for the first time to our knowledge,which employs dual-phase flow principles based on consolidation theory.This technique focuses on the generation and dissipation for excess pore-water pressure(EPWP)and excess pore-gas pressure(EPGP)in stimulated deep coal reservoirs.Equations have been developed respectively and numerical solutions have been provided using the finite element method(FEM).Application of this model to a representative field example reveals that excess pore pressure arises from rapid loading,with overburden weight transferred under undrained condition due to intense hydraulic fracturing,which significantly redistributes the weight-bearing role from the solid coal structure to the injected fluid and liberated gas within artificial pores over a brief timespan.Furthermore,field application indicates that the dissipation of EPWP and EPGP can be actually considered as the process of well production,where methane and water are extracted from deep coalbed methane wells,leading to consolidation for the artificial reservoirs.Moreover,history matching results demonstrate that the excess-pressure model established in this study provides a better explanation for the declining trends observed in both gas and water production curves,compared to conventional practices in coalbed methane reservoir engineering and petroleum engineering.This research not only enhances the understanding of DCBM reservoir behavior but also offers insights applicable to production analysis in other unconventional resources reliant on hydraulic fracturing. 展开更多
关键词 Deep coalbed methane CONSOLIDATION Excess pore-water pressure Excess pore-gas pressure Production data analysis
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Extreme massive hydraulic fracturing in deep coalbed methane horizontal wells:A case study of the Linxing Block,eastern Ordos Basin,NW China
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作者 YANG Fan LI Bin +3 位作者 WANG Kunjian WEN Heng YANG Ruiyue HUANG Zhongwei 《Petroleum Exploration and Development》 SCIE 2024年第2期440-452,共13页
Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the... Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the concept of large-scale stimulation by fracture network,balanced propagation and effective support of fracture network in fracturing design and developed the extreme massive hydraulic fracturing technique for deep coalbed methane(CBM)horizontal wells.This technique involves massive injection with high pumping rate+high-intensity proppant injection+perforation with equal apertures and limited flow+temporary plugging and diverting fractures+slick water with integrated variable viscosity+graded proppants with multiple sizes.The technique was applied in the pioneering test of a multi-stage fracturing horizontal well in deep CBM of Linxing Block,eastern margin of the Ordos Basin.The injection flow rate is 18 m^(3)/min,proppant intensity is 2.1 m^(3)/m,and fracturing fluid intensity is 16.5 m^(3)/m.After fracturing,a complex fracture network was formed,with an average fracture length of 205 m.The stimulated reservoir volume was 1987×10^(4)m^(3),and the peak gas production rate reached 6.0×10^(4)m^(3)/d,which achieved efficient development of deep CBM. 展开更多
关键词 deep coalbed methane extreme massive hydraulic fracturing fracture network graded proppants slick water with variable viscosity Ordos Basin
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The status and development strategy of coalbed methane industry in China 被引量:2
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作者 XU Fengyin HOU Wei +11 位作者 XIONG Xianyue XU Borui WU Peng WANG Hongya FENG Kun YUN Jian LI Shuguang ZHANG Lei YAN Xia FANG Huijun LU Qian MAO Delei 《Petroleum Exploration and Development》 SCIE 2023年第4期765-783,共19页
To achieve the goals of carbon peaking and carbon neutrality under the backgrounds of poor resource endowments, weak theoretical basis and other factors, the development of the coalbed methane industry of China faces ... To achieve the goals of carbon peaking and carbon neutrality under the backgrounds of poor resource endowments, weak theoretical basis and other factors, the development of the coalbed methane industry of China faces many bottlenecks and challenges. This paper systematically analyzes the coalbed methane resources, key technologies and progress, exploration effect and production performance in China and abroad. The main problems are summarized as low exploration degree, low technical adaptability, low return on investment and small development scale. This study suggests that the coalbed methane industry in China should follow the “two-step”(short-term and long-term) development strategy. The short-term action before 2030, can be divided into two stages:(1) From the present to 2025, to achieve new breakthroughs in theory and technology, and accomplish the target of annual production of 10 billion cubic meters;(2) From 2025 to 2030, to form the technologies suitable for most geological conditions, further expand the industry scale, and achieve an annual output of 30 billion cubic meters, improving the proportion of coalbed methane in the total natural gas production. The long-term action after 2030 is to gradually realize an annual production of 100 billion cubic meters. The strategic countermeasure to achieve the above goals is to adhere to “technology+management dual wheel drive”, realize the synchronous progress of technology and management, and promote the high-quality development of the coalbed methane industry. Technically, the efforts will focus on fine and effective development of coalbed methane in the medium to shallow layers of mature fields, effective development of coalbed methane in new fields, extensive and beneficial development of deep coalbed methane, three-dimensional comingled development of coalbed methane, applying new technologies such as coalbed methane displacement by carbon dioxide, microwave heating and stimulation technology, ultrasonic stimulation, high-temperature heat injection stimulation, rock breaking by high-energy laser. In terms of management, the efforts will focus on coordinative innovation of resource, technology, talent, policy and investment, with technological innovation as the core, to realize an all-round and integrated management and promote the development of coalbed methane industry at a high level. 展开更多
关键词 coalbed methane industry status strategic goal development countermeasures combined gas mining enhanced recovery in-situ conversion
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Fuzzy pattern recognition model of geological sweetspot for coalbed methane development
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作者 LIU Gaofeng LIU Huan +3 位作者 XIAN Baoan GAO Deli WANG Xiaoming ZHANG Zhen 《Petroleum Exploration and Development》 SCIE 2023年第4期924-933,共10页
From the perspective of geological zone selection for coalbed methane(CBM) development, the evaluation parameters(covering geological conditions and production conditions) of geological sweetspot for CBM development a... From the perspective of geological zone selection for coalbed methane(CBM) development, the evaluation parameters(covering geological conditions and production conditions) of geological sweetspot for CBM development are determined, and the evaluation index system of geological sweetspot for CBM development is established. On this basis, the fuzzy pattern recognition(FPR) model of geological sweetspot for CBM development is built. The model is applied to evaluate four units of No.3 Coal Seam in the Fanzhuang Block, southern Qinshui Basin, China. The evaluation results are consistent with the actual development effect and the existing research results, which verifies the rationality and reliability of the FPR model. The research shows that the proposed FPR model of geological sweetspot for CBM development does not involve parameter weighting which leads to uncertainties in the results of the conventional models such as analytic hierarchy process and multi-level fuzzy synthesis judgment, and features a simple computation without the construction of multi-level judgment matrix. The FPR model provides reliable results to support the efficient development of CBM. 展开更多
关键词 coalbed methane development geological sweetspot evaluation index system analytic hierarchy process multi-level fuzzy synthesis judgment fuzzy pattern recognition
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Integrity and Failure Analysis of Cement Sheath Subjected to Coalbed Methane Fracturing
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作者 Lingyun Zhao Heng Yang +3 位作者 Yuanlong Wei Yuhuan Bu Shaorui Jing Peiming Zhou 《Fluid Dynamics & Materials Processing》 EI 2023年第2期329-344,共16页
Perforation and fracturing are typically associated with the development of coalbed methane wells.As the cement sheath is prone to failure during this process,in this work,the effects of the casing pressure,elastic mo... Perforation and fracturing are typically associated with the development of coalbed methane wells.As the cement sheath is prone to failure during this process,in this work,the effects of the casing pressure,elastic modulus of the cement,elastic modulus of the formation,and casing eccentricity on the resulting stresses are analyzed in the frame of a finite element method.Subsequently,sensitivity response curves of the cement sheath stress are plotted by normalizing all factors.The results show that the maximum circumferential stress and Mises stress of the cement sheath increase with the casing internal pressure,elastic modulus of the cement and casing eccentricity.As the elastic modulus of the formation increases,the maximum circumferential stress of the cement sheath decreases,and its maximum Mises stress increases slightly.The cement sheath undergoes tensile failure during coalbed methane fracturing.The stress sensitivity of the cement sheath to the influential parameters is in the following order:casing internal pressure>elastic modulus of cement sheath>casing eccentricity>elastic modulus of formation. 展开更多
关键词 coalbed methane fracturing finite element method cement sheath integrity sensitivity analysis failure analysis
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Sorption of methane and CO_2 for enhanced coalbed methane recovery and carbon dioxide sequestration 被引量:13
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作者 Basanta Kumar Prusty 《Journal of Natural Gas Chemistry》 CAS CSCD 2008年第1期29-38,共10页
Sequestration of CO2 in deep and unmineable coal seams is one of the attractive alternatives to reduce its atmospheric concentration. Injection of CO2 in coal seams may help in enhancing the recovery of coalbed methan... Sequestration of CO2 in deep and unmineable coal seams is one of the attractive alternatives to reduce its atmospheric concentration. Injection of CO2 in coal seams may help in enhancing the recovery of coalbed methane. An experimental study has been carried out using coal samples from three different coal seams, to evaluate the enhanced gas recovery and sequestration potential of these coals. The coals were first saturated with methane and then by depressurization some of the adsorbed methane was desorbed. After partial desorption, CO2 was injected into the coals and subsequently they were depressurized again. Desorption of methane after the injections was studied, to investigate the ability of CO2 to displace and enhance the recovery of methane from the coals. The coals exhibited varying behavior of adsorption of CO2 and release of methane. For one coal, the release of methane was enhanced by injection of CO2, suggesting preferential adsorption of CO2 and desorption of methane. For the other two coals, CO2 injection did not produce incremental methane initially, as there was initial resistance to methane release. However with continued CO2 injection, most of the remaining methane was produced. The study suggested that preferential sorption behavior of coal and enhanced gas recovery pattern could not be generalized for all coals. 展开更多
关键词 COAL coalbed methane CO2 injection enhanced coalbed methane CO2 sequestration
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Characteristics of Coalbed Methane Resources of China
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作者 LIN Dayang YE Jianping +1 位作者 QIN Yong TANG Shuheng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2000年第3期706-710,共5页
The paper deals with the coalbed methane gas-bearing characteristics such as the gas content, theoretical gas saturation, gas concentration and abundance, as well as coal reservoir characteristics such as the adsorpti... The paper deals with the coalbed methane gas-bearing characteristics such as the gas content, theoretical gas saturation, gas concentration and abundance, as well as coal reservoir characteristics such as the adsorption, desorption and permeability of China's coal reservoirs. The paper also introduces the resources of coalbed methane with a gas content ≥ 4 m3/t and their distribution in China. 展开更多
关键词 coalbed methane gas-bearing parameters coal reservoir characteristics coalbed methane resources
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Coalbed methane genesis, occurrence and accumulation in China 被引量:31
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作者 Song Yan Liu Shaobo +3 位作者 Zhang Qun Tao Mingxin Zhao Mengjun Hong Feng 《Petroleum Science》 SCIE CAS CSCD 2012年第3期269-280,共12页
Coalbed methane (CBM) is an important type of unconventional gas. Commercial development of CBM in America has been very successful since the 1980s. The CBM industry in Australia and Canada has developed rapidly dur... Coalbed methane (CBM) is an important type of unconventional gas. Commercial development of CBM in America has been very successful since the 1980s. The CBM industry in Australia and Canada has developed rapidly during the last decade. Commercial development of CBM in China started in the 1990s, and has made great progress. The geological theory of CBM in China has achieved great advancement in genesis, occurrence and accumulation. On the aspect of CBM genesis, five CBM genetic types (primary biogenic gas, secondary biogenic gas, thermal degradation gas, pyrolysis gas and mixed gas) are identified by studying the geochemical characteristics of CBM, and a tracing indicator system is established. The discovery of secondary biogenic gas in medium-high rank coal reservoirs has widened the potential of CBM resources. On the aspect of CBM occurrence, the gas adsorption regulation under combined action of temperature and pressure is revealed by conducting adsorption experiments of different coal ranks under varying temperature and pressure conditions. Besides, by applying the adsorption potential theory in CBM research, the adsorption model under combined action of temperature and pressure is established. The new model can predict CBM resources accurately, and overcome the limitation of the traditional Langmuir model which uses just a single factor to describe the adsorption characteristics of deep buried coal. On the aspect of CBM accumulation, it is proposed that there are three evolutionary stages during CBM accumulation, including gas generation and adsorption, unsaturated gas adsorption, gas desorption-diffusion and preservation. Controlled by tectonic evolution, hydrodynamics and sealing conditions, CBM tends to be regionally enriched in synclines. Advances in geological theory of CBM in China can not only improve understanding of natural gas, but also provide new ideas for further exploration of CBM. 展开更多
关键词 China coalbed methane genetic type secondary biogenic gas adsorption model syncline enrichment
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A Comprehensive Model for Evaluating Coalbed Methane Reservoirs in China 被引量:19
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作者 YAO Yanbin LIU Dameng TANG Dazhen HUANG Wenhui TANG Shuheng CHE Yao 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2008年第6期1253-1270,共18页
Coalbed methane reservoir (CBMR) evaluation is important for choosing the prospective target area for coalbed methane exploration and production. This study aims at identifying the characteristic parameters and meth... Coalbed methane reservoir (CBMR) evaluation is important for choosing the prospective target area for coalbed methane exploration and production. This study aims at identifying the characteristic parameters and methods to evaluate CBMR. Based on the geological surveys, laboratory measurements and field works, a four-level analytic hierarchy process (AHP) model for CBMR evaluation is proposed. In this model, different weights are prioritized and assigned on the basis of three main criteria (including reservoir physical property, storage capacity and geological characteristics), 15 sub-criteria, and 18 technical alternatives; the later of which are discussed in detail. The model was applied to evaluate the CBMR of the Permo-Carboniferous coals in the Qinshui Basin, North China. This GIS-based fuzzy AHP comprehensive model can be used for the evaluation of CBMR of medium-high rank (mean maximum vitrinite reflectance 〉0.5 %) coal districts in China. 展开更多
关键词 coalbed methane reservoir reservoir evaluation reservoir characterization comprehensive model Fuzzy Hierarchy Process Approach (FAHP)
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The Classification and Model of Coalbed Methane Reservoirs 被引量:16
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作者 SUXianbo LINXiaoying +1 位作者 SONGYan ZHAOMengjun 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第3期662-666,共5页
Coalbed methane has been explored in many basins worldwide for 30 years, and has been developed commercially in some of the basins. Many researchers have described the characteristics of coalbed methane geology and te... Coalbed methane has been explored in many basins worldwide for 30 years, and has been developed commercially in some of the basins. Many researchers have described the characteristics of coalbed methane geology and technology systematically. According to these investigations, a coalbed methane reservoir can be defined: 'a coal seam that contains some coalbed methane and is isolated from other fluid units is called a coalbed methane reservoir'. On the basis of anatomization, analysis, and comparison of the typical coalbed methane reservoirs, coalbed methane reservoirs can be divided into two classes: the hydrodynamic sealing coalbed methane reservoirs and the self-sealing coalbed methane reservoirs. The former can be further divided into two sub-classes: the hydrodynamic capping coalbed methane reservoirs, which can be divided into five types and the hydrodynamic driving coalbed methane reservoirs, which can be divided into three types. The latter can be divided into three types. Currently, hydrodynamic sealing reservoirs are the main target for coalbed methane exploration and development; self-sealing reservoirs are unsuitable for coalbed methane exploration and development, but they are closely related with coal mine gas hazards. Finally, a model for hydrodynamic sealing coalbed methane reservoirs is established. 展开更多
关键词 coalbed methane reservoir CLASSIFICATION reservoir model HYDRODYNAMICS reservoir boundary
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Coalbed Methane-bearing Characteristics and Reservoir Physical Properties of Principal Target Areas in North China 被引量:15
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作者 TANGShuheng SUNShenglin +1 位作者 HAODuohu TANGDazhen 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第3期724-728,共5页
The coalbed methane (CBM) resources in North China amounts up to 60% of total resources in China. North China is the most important CBM accumulation area in China. The coal beds of the Upper Paleozoic Taiyuan and Shan... The coalbed methane (CBM) resources in North China amounts up to 60% of total resources in China. North China is the most important CBM accumulation area in China. The coal beds of the Upper Paleozoic Taiyuan and Shanxi formations have a stable distribution. The coal reservoir of target areas such as Jincheng, Yanquan-Shouyang, Hancheng, Liulin, etc. have good CBM-bearing characteristics, high permeability and appropriate reservoir pressure, and these areas are the preferred target areas of CBM developing in China. The coal reservoirs of Wupu, Sanjiaobei, Lu'an, Xinmi, Anyang-Hebi, Jiaozuo, Xinggong and Huainan also have as good CBM-bearing characteristics, but the physical properties of coal reservoirs vary observably. So, further work should be taken to search for districts with high pressure, high permeability and good CBM-bearing characteristics. Crustal stresses have severe influence on the permeability of coal reservoirs in North China. From west to east, the crustal stress gradient increases, while the coal reservoirs permeability decreases. 展开更多
关键词 coalbed methane (CBM) coal reservoir physical property crustal stress North China
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Coalbed methane adsorption and desorption characteristics related to coal particle size 被引量:7
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作者 冯艳艳 杨文 储伟 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第6期542-551,共10页
Effects of particle size on CH4 and CO2adsorption and desorption characteristics of coals are investigated at 308 K and pressures up to 5.0 MPa.The gas adsorption and desorption isotherms of coals with particle sizes ... Effects of particle size on CH4 and CO2adsorption and desorption characteristics of coals are investigated at 308 K and pressures up to 5.0 MPa.The gas adsorption and desorption isotherms of coals with particle sizes ranging from 250 μm to 840 μm are measured via the volumetric method,and the Langmuir model is used to analyse the experimental results.Coal particle size is found to have an obvious effect on the coal pore structure.With the decrease of coal particle size in the process of grinding,the pore accessibility of the coal,including the specific surface area and pore volume,increases.Hence,coal with smaller particle size has higher specific surface area and higher pore volume.The ability of adsorption was highly related to the pore structure of coal,and coal particle size has a significant influence on coal adsorption/desorption characteristics,including adsorption capacity and desorption hysteresis for CH4 and CO2,i.e.,coal with a smaller particle size achieves higher adsorption capacity,while the sample with a larger particle size has lower adsorption capacity.Further,coal with larger particle size is also found to have relatively large desorption hysteresis.In addition,dynamic adsorption performances of the samples are carried out at 298 K and at pressures of 0.1 MPa and 0.5 MPa,respectively,and the results indicate that with the increase of particle size,the difference between CO2 and CH4adsorption capacities of the samples decreases. 展开更多
关键词 particle size coalbed methane ADSORPTION DESORPTION
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Exploitation technology of pressure relief coalbed methane in vertical surface wells in the Huainan coal mining area 被引量:13
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作者 HAN Jia-zhang SANG Shu-xun +1 位作者 CHENG Zhi-zhong HUANG Hua-zhou 《Mining Science and Technology》 EI CAS 2009年第1期25-30,共6页
Exploitation technology of pressure relief coalbed methane in vertical surface wells is a new method for exploration of gas and coalbed methane exploitation in mining areas with high concentrations of gas, where tecto... Exploitation technology of pressure relief coalbed methane in vertical surface wells is a new method for exploration of gas and coalbed methane exploitation in mining areas with high concentrations of gas, where tectonic coal developed. Studies on vertical surface well technology in the Huainan Coal Mining area play a role in demonstration in the use of clean, new energy resources, preventing and reducing coal mine gas accidents and protecting the environment. Based on the practice of gas drainage engineering of pressure relief coalbed methane in vertical surface wells and combined with relative geological and exploration en- gineering theories, the design principles of design and structure of wells of pressure relief coalbed methane in vertical surface wells are studied. The effects of extraction and their causes are discussed and the impact of geological conditions on gas production of the vertical surface wells are analyzed. The results indicate that in mining areas with high concentrations of gas, where tectonic coal developed, a success rate of pressure relief coalbed methane in surface vertical well is high and single well production usually great. But deformation due to coal exploitation could damage boreholes and cause breaks in the connection between aquifers and bore-holes, which could induce a decrease, even a complete halt in gas production of a single well. The design of well site location and wellbore configuration are the key for technology. The development of the geological conditions for coalbed methane have a significant effect on gas production of coalbed methane wells. 展开更多
关键词 pressure relief coalbed methane EXPLOITATION vertical surface well Huainan coal mining area
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Experimental investigation of propagation mechanisms and fracture morphology for coalbed methane reservoirs 被引量:6
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作者 Chi Ai Xiao-Xuan Li +2 位作者 Jun Zhang Dan Jia Wen-Jing Tan 《Petroleum Science》 SCIE CAS CSCD 2018年第4期815-829,共15页
Fracture propagation mechanisms in coalbed methane(CBM) reservoirs are very complex due to the development of the internal cleat system. In this paper, the characteristics of initiation and propagation of hydraulic fr... Fracture propagation mechanisms in coalbed methane(CBM) reservoirs are very complex due to the development of the internal cleat system. In this paper, the characteristics of initiation and propagation of hydraulic fractures in coal specimens at different angles between the face cleat and the maximum horizontal principal stress were investigated with hydraulic fracturing tests. The results indicate that the interactions between the hydraulic fractures and the cleat system have a major effect on fracture networks. "Step-like’’ fractures were formed in most experiments due to the existence of discontinuous butt cleats. The hydraulic fractures were more likely to divert or propagate along the butt cleat with an increase in the angles and a decrease in the horizontal principal stress difference. An increase in the injection rate and a decrease in the fracturing fluid viscosity were more conducive to fracture networks. In addition, the influence on fracture propagation of the residual coal fines in the wellbore was also studied. The existence of coal fines was an obstacle in fracturing, and no effective connection can be formed between fractures. The experimental investigation revealed the fracture propagation mechanisms and can provide guidance for hydraulic fracturing design of CBM reservoirs. 展开更多
关键词 coalbed methane reservoir Butt cleat Propagation mechanisms Fracture morphology Step-like fractures
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New Progress on the Coal Fines Affecting the Development of Coalbed Methane 被引量:11
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作者 WEI Yingchun LI Chao +3 位作者 CAO Daiyong ZHANG Aoxiang WANG Anmin XIANG Xinxuan 《Acta Geologica Sinica(English Edition)》 CAS CSCD 2018年第5期2060-2062,共3页
Objective The production of coal fines is very common in the development of coalbed methane(CBM)in the eastern margin of the Ordos Basin,China.A large amount of produced coal fines seriously affect the productivity ... Objective The production of coal fines is very common in the development of coalbed methane(CBM)in the eastern margin of the Ordos Basin,China.A large amount of produced coal fines seriously affect the productivity of CBM wells(Wei Yingchun et al.,2013).Therefore,the production problems of CBM wells caused by coal fines have attracted extensive attention. 展开更多
关键词 New Progress on the Coal Fines Affecting the Development of coalbed methane GS CBM
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Drilling and completion technologies of coalbed methane exploitation: an overview 被引量:4
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作者 Tianshou Ma Jinhua Liu +1 位作者 Jianhong Fu Bisheng Wu 《International Journal of Coal Science & Technology》 EI CAS CSCD 2022年第5期1-31,共31页
Coalbed methane(CBM)drilling and completion technologies(DCTs)are signifcant basis for achieving efcient CBM exploration and exploitation.Characteristics of CBM reservoirs vary in diferent regions around the world,the... Coalbed methane(CBM)drilling and completion technologies(DCTs)are signifcant basis for achieving efcient CBM exploration and exploitation.Characteristics of CBM reservoirs vary in diferent regions around the world,thereby,it is crucial to develop,select and apply the optimum DCTs for each diferent CBM reservoir.This paper frstly reviews the development history of CBM DCTs throughout worldwide and clarifes its overall development tendency.Secondly,diferent well types and its characteristics of CBM exploitation are summarized,and main application scopes of these well types are also discussed.Then,the key technologies of CBM drilling(directional drilling tools,measurement while drilling,geo-steering drilling,magnetic guidance drilling,underbalanced drilling and drilling fuids),and the key technologies of CBM completion(open-hole,cavity and under-ream completion,cased-hole completion,screen pipe completion and horizontal well completion)are summarized and analyzed,it is found that safe,economic and efcient development of CBM is inseparable from the support of advanced technologies.Finally,based on the current status of CBM development,the achievements,existing challenges and future prospects are summarized and discussed from the perspective of CBM DCTs. 展开更多
关键词 coalbed methane CBM EXPLOITATION DRILLING COMPLETION Horizontal well L/U/V-shaped well Multilateral well
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The coalbed methane production potential method for optimization of wells location selection 被引量:11
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作者 Feng-Ke DOU Yong-Shang KANG +2 位作者 Shao-Feng QIN De-Lei MAO Jun HAN 《Journal of Coal Science & Engineering(China)》 2013年第2期210-218,共9页
A gas production potential method for optimization of gas wellsite locations selection is proposed in terms of the coalbed gas resources volume and the recoverability. The method uses the actual data about reservoirs ... A gas production potential method for optimization of gas wellsite locations selection is proposed in terms of the coalbed gas resources volume and the recoverability. The method uses the actual data about reservoirs in a coalbed gas field in central China to optimize wellsite locations in the studied area in combination with the dynamic data about actual production in the coalbed gas field, selects a favorable subarea for gas wells deployment. The method is established based on the basic properties of coal reservoirs, in combination with the coalbed thickness and the gas content to make an analysis of the gas storage potential of a coal reservoir, as well as resources volume and the permeability of a coal reservoir. This method can be popularized for optimization of wellsite locations in other methane gas development areas or blocks. 展开更多
关键词 coalbed methane gas potential gas production potential method optimization of wellsite locations
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An economic evaluation method of coalbed methane resources during the target selection phase of exploration 被引量:5
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作者 Dong-Kun Luo Liang-Yu Xia 《Petroleum Science》 SCIE CAS CSCD 2015年第4期705-711,共7页
Because forecasting a development program during the target selection phase of exploration for coalbed methane (CBM) is impossible, the conventional method that relies on a conceptual (or detailed) development pro... Because forecasting a development program during the target selection phase of exploration for coalbed methane (CBM) is impossible, the conventional method that relies on a conceptual (or detailed) development pro- gram cannot be used during the economic evaluation of CBM resources. Hence, this study focuses on establishing an economic evaluation model based on the characteristics of the target selection phase. The discounted cashflow method is applied to the construction of the model with the assumption that there is a uniform distribution of produc- tion wells. The computational error generated by the assumption is corrected by introducing a correction factor based on the production profile of single CBM wells. The case study demonstrates that the blocks lacking economic value can be screened out, and the most advantageous targets can be found by computing the resource values in the best- and worst-case scenarios. This technique can help to reduce wasted investments and improve the quality of decision-making in selecting targets for exploration. 展开更多
关键词 coalbed methane Exploration targetselection Economic evaluation Scenario analysis
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Optimum location of surface wells for remote pressure relief coalbed methane drainage in mining areas 被引量:9
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作者 HUANG, Huazhou SANG, Shuxun +3 位作者 FANG, Liangcai LI, Guojun XU, Hongjie REN, Bo 《Mining Science and Technology》 EI CAS 2010年第2期230-237,共8页
Based on engineering tests in the Huainan coal mining area,we studied alternative well location to improve the performance of surface wells for remote pressure relief of coalbed methane in mining areas.The key factors... Based on engineering tests in the Huainan coal mining area,we studied alternative well location to improve the performance of surface wells for remote pressure relief of coalbed methane in mining areas.The key factors,affecting location and well gas production were analyzed by simulation tests for similar material.The exploitation results indicate that wells located in various positions on panels could achieve relatively better gas production in regions with thin Cenozoic layers,low mining heights and slow rate of longwall advancement,but their periods of gas production lasted less than 230 days,as opposed to wells in regions with thick Cenozoic layers,greater mining heights and fast rates of longwall advancement.Wells near panel margins achieved relatively better gas production and lasted longer than centerline wells.The rules of development of mining fractures in strata over panels control gas production of surface wells.Mining fractures located in areas determined by lines of compaction and the effect of mining are well developed and can be maintained for long periods of time.Placing the well at the end of panels and on the updip return airway side of panels,determined by lines of compaction and the effect of mining,would result in surface wells for remote pressure relief CBM obtaining their longest gas production periods and highest cumulative gas production. 展开更多
关键词 pressure relief coalbed methane surface wells well location Huainan coal mining area
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Prediction of Flowing Bottomhole Pressures for Two-Phase Coalbed Methane Wells 被引量:5
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作者 LIU Xinfu 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2013年第5期1412-1420,共9页
A method is proposed to predict the flowing bottomhole pressures (FBHPs) for two-phase coalbed methane (CBM) wells. The mathematical models for both gas column pressure and two-phase fluid column pressure were dev... A method is proposed to predict the flowing bottomhole pressures (FBHPs) for two-phase coalbed methane (CBM) wells. The mathematical models for both gas column pressure and two-phase fluid column pressure were developed based on the well liquid flow equation. FBHPs during the production were predicted by considering the effect of entrained liquid on gravitational gradients. Comparison of calculated BHPs by Cullender-Smith and proposed method was also studied. The results show that the proposed algorithm gives the desired accuracy of calculating BHPs in the low- productivity and low-pressure CBM wells. FBHP is resulted from the combined action of wellhead pressure, gas column pressure and fluid column pressure. Variation of kinetic energy term, compressibility and friction factors with depth increments and liquid holdup with velocity should be considered to simulate the real BHPs adequately. BHP is a function of depth of each column segment. The small errors of less than 1.5% between the calculated and measured values are obtained with each segment within 25 m. Adjusting BHPs can effectively increase production pressure drop, which is beneficial to CBM desorption and enhances reservoir productivity. The increment of pressure drop from 5.37 MPa2 to 8.66 MPa2 leads to an increase of CBM production from 3270 m3/d to 6700 m3/d and is attributed to a decrease in BHP from 2.25 MPa to 1.33 MPa. 展开更多
关键词 coalbed methane productivity flowing bottomhole pressure gas column pressure two-phase fluid column pressure
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