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
Commercial exploration and development of deep buried coalbed methane (CBM) in Daning-Jixian Block, eastern margin of Ordos Basin, have rapidly increased in recent decades. Gas content, saturation and well productivit...Commercial exploration and development of deep buried coalbed methane (CBM) in Daning-Jixian Block, eastern margin of Ordos Basin, have rapidly increased in recent decades. Gas content, saturation and well productivity show significant heterogeneity in this area. To better understand the geological controlling mechanism on gas distribution heterogeneity, the burial history, hydrocarbon generation history and tectonic evolution history were studied by numerical simulation and experimental simulation, which could provide guidance for further development of CBM in this area. The burial history of coal reservoir can be classified into six stages, i.e., shallowly buried stage, deeply burial stage, uplifting stage, short-term tectonic subsidence stage, large-scale uplifting stage, sustaining uplifting and structural inversion stage. The organic matter in coal reservoir experienced twice hydrocarbon generation. Primary and secondary hydrocarbon generation processes were formed by the Early and Middle Triassic plutonic metamorphism and Early Cretaceous regional magmatic thermal metamorphism, respectively. Five critical tectonic events of the Indosinian, Yanshanian and Himalayan orogenies affect different stages of the CBM reservoir accumulation process. The Indosinian orogeny mainly controls the primary CBM generation. The Yanshanian Orogeny dominates the second gas generation and migration processes. The Himalayan orogeny mainly affects the gas dissipation process and current CBM distribution heterogeneity.展开更多
基金Supported by the National Natural Science Foundation of China Project(52274014)Comprehensive Scientific Research Project of China National Offshore Oil Corporation(KJZH-2023-2303)。
文摘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.
基金This research was funded by the National Natural Science Foundation of China (Grant No. 41902178)National Science and Technology Major Project (Oil & Gas) (No. 2016ZX05065)+1 种基金Natural Science Foundation of Shanxi Province, China (No. 20210302123165)Open Fund of Beijing Key Laboratory of Unconventional Natural Gas Geological Evaluation and Development Engineering, China University of Geosciences (Beijing) (No. 2019BJ02001).
文摘Commercial exploration and development of deep buried coalbed methane (CBM) in Daning-Jixian Block, eastern margin of Ordos Basin, have rapidly increased in recent decades. Gas content, saturation and well productivity show significant heterogeneity in this area. To better understand the geological controlling mechanism on gas distribution heterogeneity, the burial history, hydrocarbon generation history and tectonic evolution history were studied by numerical simulation and experimental simulation, which could provide guidance for further development of CBM in this area. The burial history of coal reservoir can be classified into six stages, i.e., shallowly buried stage, deeply burial stage, uplifting stage, short-term tectonic subsidence stage, large-scale uplifting stage, sustaining uplifting and structural inversion stage. The organic matter in coal reservoir experienced twice hydrocarbon generation. Primary and secondary hydrocarbon generation processes were formed by the Early and Middle Triassic plutonic metamorphism and Early Cretaceous regional magmatic thermal metamorphism, respectively. Five critical tectonic events of the Indosinian, Yanshanian and Himalayan orogenies affect different stages of the CBM reservoir accumulation process. The Indosinian orogeny mainly controls the primary CBM generation. The Yanshanian Orogeny dominates the second gas generation and migration processes. The Himalayan orogeny mainly affects the gas dissipation process and current CBM distribution heterogeneity.