页岩储层超临界二氧化碳压裂裂缝形态研究
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摘要
目前超临界CO2压裂技术尚不成熟,裂缝形成与扩展机理尚不明确。为深入认识超临界CO2压裂裂缝延伸规律及空间形态,基于位移间断边界元方法,通过引入Pen-Robinson方程来实现超临界CO2压裂过程的模拟。结合室内物理模拟实验,初步探讨了页岩储层水力压裂与超临界CO2压裂裂缝扩展形态的差异。研究结果表明,由于超临界CO2的扩散性及良好的渗透能力,通过增加围岩孔隙压力,从而减少了地应力对裂缝扩展的约束,使裂缝起裂压力低于水力压裂。超临界CO2压裂时产生的体积应变增量与压后裂缝破坏程度比水力压裂更高,使得在裂缝形态复杂程度高于水基压裂液。同时,超临界CO2压裂裂缝断面复杂、不平整,裂缝表面粗糙度比水力压裂更大。
The supercritical CO_2 fracturing technology is yet to be improved,and the mechanisms of fracture generation and propagation are still not clear at present. In order to get an in-depth understanding of hydraulic fracture propagation behaviors and geometry under supercritical CO_2 fracturing,we introduced the Pen-Robinson equation to simulate the process of supercritical CO_2 fracturing,based on the displacement discontinuity boundary element method. Combined with lab physical simulation experiments,the differences of hydraulic fracture propagation behaviors and geometry between conventional fracturing with water-based fluid and fracturing with supercritical CO_2 in the shale reservoir were discussed.The results show that the pressurization in the pores of surrounding rocks will function to reduce the constraint of in-situ stress on fracture propagation,thanks to the diffusivity and good permeability of supercritical CO_2,and in turn the initiation pressure for fractures is lower than that of conventional fracturing. The incremental volumetric strain generated during and the failure of fractures after supercritical CO_2 fracturing are higher than those under conventional fracturing,thus the fracture geometry under supercritical CO_2 fracturing is more complex than that under fracturing with water-based fluid;meanwhile,the fracture plane under supercritical CO_2 fracturing is more complex and uneven,and has higher tortuosity than that under conventional fracturing with water-based fluid.
The supercritical CO_2 fracturing technology is yet to be improved,and the mechanisms of fracture generation and propagation are still not clear at present. In order to get an in-depth understanding of hydraulic fracture propagation behaviors and geometry under supercritical CO_2 fracturing,we introduced the Pen-Robinson equation to simulate the process of supercritical CO_2 fracturing,based on the displacement discontinuity boundary element method. Combined with lab physical simulation experiments,the differences of hydraulic fracture propagation behaviors and geometry between conventional fracturing with water-based fluid and fracturing with supercritical CO_2 in the shale reservoir were discussed.The results show that the pressurization in the pores of surrounding rocks will function to reduce the constraint of in-situ stress on fracture propagation,thanks to the diffusivity and good permeability of supercritical CO_2,and in turn the initiation pressure for fractures is lower than that of conventional fracturing. The incremental volumetric strain generated during and the failure of fractures after supercritical CO_2 fracturing are higher than those under conventional fracturing,thus the fracture geometry under supercritical CO_2 fracturing is more complex than that under fracturing with water-based fluid;meanwhile,the fracture plane under supercritical CO_2 fracturing is more complex and uneven,and has higher tortuosity than that under conventional fracturing with water-based fluid.
引文
[1] Beckwith R. Hydraulic fracturing:The fuss,the facts,the future[J].Journal of Petroleum Technology,2010,62:34-40.
[2] Peng P,Ling K,He J,et al. Shale gas reservoir treatment by a CO2-based technology[J]. Journal of Natural Gas Science&Engineering,2015,26:1595-1606.
[3]王志刚.涪陵焦石坝地区页岩气水平井压裂改造实践与认识[J].石油与天然气地质,2014,35(3):425-430.Wang Zhigang. Practice and cognition of shale gas horizontal well fracturing stimulation in Jiaoshiba of Fuling area[J]. Oil and Gas Geology,2014,35(3):425-430.
[4] Liu L,Zhu W,Wei C,et al. Microcrack-based geomechanical modeling of rock-gas interaction during supercritical CO2fracturing[J].Journal of Petroleum Science and Engineering,2018,164:91-102.
[5] Scanlon B R,Reedy R C,Nicot J P. Comparison of water use for hydraulic fracturing for unconventional oil and gas versus conventional oil[J]. Environmental Science&Technology,2014,48(20):12386-12393.
[6] Wang H,Li G,Shen Z. A feasibility analysis on shale gas exploitation with supercritical carbon dioxide[J]. Energy Sources,Part A:Recovery,Utilization,and Environmental Effects,2012,34(15):1426-1435.
[7] Jackson R E,Gorody A W,Mayer B,et al. Groundwater protection and unconventional gas extraction:The critical need for field-based hydrogeological research[J]. Ground Water,2013,51(4):488-510.
[8] Jung J W,Espinoza D N,Santamarina J C. Properties and phenomena relevant to CH4-CO2replacement in hydrate-bearing sediments[J].Journal of Geophysical Research Atmospheres,2010,115:155-162.
[9] Heller R,Zoback M. Adsorption of methane and CO2on gas shale and puremineral samples[J]. Journal of Unconventional Oil&Gas Resources,2014,8:14-24.
[10] Dehghanpour H,Zubair H A,Chhabra A,et al. Liquid intake of organic shales[J]. Energy Fuels,2012,26:5750-5758.
[11] Friehauf K E,Sharma M M. Fluid selection for energized hydraulic fractures[R]. SPE Annual Technical Conference and Exhibition,2019.
[12] Gupta A P,Gupta A,Langlinais J. Feasibility of supercritical CO2as a drilling fluid for deep underbalanced drilling operation[R]. SPE Annual Technical Conferenceand Exhibition,2005.
[13] Kizaki A,Tanaka H,Ohashi K,et al. Hydraulic fracturing in Inadagranite and Ogino tuff with supercritical CO2[C]∥ISRM regional symposium—7thAsian rock mechanics symposium. International Society for Rock Mechanics,2012.
[14] Chen Y,Nagaya Y,Ishida T. Observations of fractures induced by hydraulic fracturing in anisotropic granite[J]. Rock Mechanics and Rock Engineering,2015,48:1455-1461.
[15] Inui S,Ishida T,Nagaya Y,et al. AE monitoring of hydraulic fracturing experiment in granite blocks using supercritical CO2,water and viscous oil[C]∥48th US rock mechanics/geomechanics symposium.American RockMechanics Association,2014.
[16] Zou Yushi,Li Ning,Ma Xinfang,et al. Experimental study on the growth behavior of supercritical CO2-induced fractures in a layered tight sandstone formation[J]. Journal of Natural Gas Science and Engineering,2018,49:145-156.
[17] Zhou X,Burbey T J. Fluid effect on hydraulic fracture propagation behavior:A comparison between water and supercritical CO2-like fluid[J]. Geofluids,2014,14(2):174-188.
[18] Zhang X,Lu Y,Tang J,et al. Experimental study on fracture initiation and propagation in shale using supercritical carbon dioxide fracturing[J]. Fuel,2016,190(15):370-378.
[19] Wang J,Elsworth D,Wu Y,et al. The influence of fracturing fluids on fracturing processes:A comparison between water,oil and SCCO2[J]. Rock Mechanics and Rock Engineering,2018,51(1):299-313.
[20] Wu K,Olson J E. A simplified three-dimensional displacement discontinuity method for multiple fracture simulations[J]. International Journal of Fracture,2015,193(2):191-204.
[21]刘国威,李庆斌,左正.相场断裂模型分步算法在ABAQUS中的实现[J].岩石力学与工程学报,2016,35(5):1019-1030.Liu Guowei,Li Qingbin,Zuo Zheng. Implementation of a staggered algorithm for a phase field mpdel in ABAQUS[J]. Chinese Journal of Rock Mechanics and Engineering,2016,35(5):1019-1030.
[22] Xu G,Wong S W. Interaction of multiple non-planar hydraulic fractures in horizontal wells[C]. International Petroleum Technology Conference,2013.
[23] Zou Y S,Ma X F,Zhang S C,et al. Numerical investigation into the influence of bedding plane on hydraulic fracture network propagation in shale formations[J]. Rock Mechanics and Rock Engineering,2016,49(9):3597–3614.
[24] Ma X,Zhou T,Zou Y S. Experimental and numerical study of hydraulic fracture geometry in shale formations with complex geologic conditions[J]. Journal of Structural Geology,2017,98:53-66.
[25]周彤,张士诚,邹雨时,等.四川盆地东北缘强应力大倾角页岩储层水力压裂裂缝形态[J].新疆石油地质,2016,37(3):336-341.Zhou Tong,Zhang Shicheng,Zou Yushi,et al. Hydraulic fracture geometry of shale gas reservoirs with strong tectonic stress and large dip angle in northeastern margin of Sichuan Basin[J]. Xinjiang Petroleum Geolgoy,2016,37(3):336-341.
[26]王飞.位移不连续法及其在岩体工程中的应用[D].上海交通大学,2010.Wang Fei. Displacment discontinuity method and its application on rock engineering[D]. Shanghai Jiao Tong University,2010.
[27]王在明.超临界二氧化碳钻井液特性研究[D].中国石油大学,2008.Wang Zaiming. Study on characteristics of supercritical carbon dioxide drilling fluid[D]. China University of Petroleum,2008.
[28]里德R C,普劳斯尼茨J M.气体和液体性质[M].李芝芬,杨怡生,译.北京:石油工业出版社,1994.Reid R C,Prausnitz J M. Theproperties of gases and liquids[M]. Li Zhifeng,Yang Yisheng,translated. Beijing:Petroleum Industry Press,1994.
[2] Peng P,Ling K,He J,et al. Shale gas reservoir treatment by a CO2-based technology[J]. Journal of Natural Gas Science&Engineering,2015,26:1595-1606.
[3]王志刚.涪陵焦石坝地区页岩气水平井压裂改造实践与认识[J].石油与天然气地质,2014,35(3):425-430.Wang Zhigang. Practice and cognition of shale gas horizontal well fracturing stimulation in Jiaoshiba of Fuling area[J]. Oil and Gas Geology,2014,35(3):425-430.
[4] Liu L,Zhu W,Wei C,et al. Microcrack-based geomechanical modeling of rock-gas interaction during supercritical CO2fracturing[J].Journal of Petroleum Science and Engineering,2018,164:91-102.
[5] Scanlon B R,Reedy R C,Nicot J P. Comparison of water use for hydraulic fracturing for unconventional oil and gas versus conventional oil[J]. Environmental Science&Technology,2014,48(20):12386-12393.
[6] Wang H,Li G,Shen Z. A feasibility analysis on shale gas exploitation with supercritical carbon dioxide[J]. Energy Sources,Part A:Recovery,Utilization,and Environmental Effects,2012,34(15):1426-1435.
[7] Jackson R E,Gorody A W,Mayer B,et al. Groundwater protection and unconventional gas extraction:The critical need for field-based hydrogeological research[J]. Ground Water,2013,51(4):488-510.
[8] Jung J W,Espinoza D N,Santamarina J C. Properties and phenomena relevant to CH4-CO2replacement in hydrate-bearing sediments[J].Journal of Geophysical Research Atmospheres,2010,115:155-162.
[9] Heller R,Zoback M. Adsorption of methane and CO2on gas shale and puremineral samples[J]. Journal of Unconventional Oil&Gas Resources,2014,8:14-24.
[10] Dehghanpour H,Zubair H A,Chhabra A,et al. Liquid intake of organic shales[J]. Energy Fuels,2012,26:5750-5758.
[11] Friehauf K E,Sharma M M. Fluid selection for energized hydraulic fractures[R]. SPE Annual Technical Conference and Exhibition,2019.
[12] Gupta A P,Gupta A,Langlinais J. Feasibility of supercritical CO2as a drilling fluid for deep underbalanced drilling operation[R]. SPE Annual Technical Conferenceand Exhibition,2005.
[13] Kizaki A,Tanaka H,Ohashi K,et al. Hydraulic fracturing in Inadagranite and Ogino tuff with supercritical CO2[C]∥ISRM regional symposium—7thAsian rock mechanics symposium. International Society for Rock Mechanics,2012.
[14] Chen Y,Nagaya Y,Ishida T. Observations of fractures induced by hydraulic fracturing in anisotropic granite[J]. Rock Mechanics and Rock Engineering,2015,48:1455-1461.
[15] Inui S,Ishida T,Nagaya Y,et al. AE monitoring of hydraulic fracturing experiment in granite blocks using supercritical CO2,water and viscous oil[C]∥48th US rock mechanics/geomechanics symposium.American RockMechanics Association,2014.
[16] Zou Yushi,Li Ning,Ma Xinfang,et al. Experimental study on the growth behavior of supercritical CO2-induced fractures in a layered tight sandstone formation[J]. Journal of Natural Gas Science and Engineering,2018,49:145-156.
[17] Zhou X,Burbey T J. Fluid effect on hydraulic fracture propagation behavior:A comparison between water and supercritical CO2-like fluid[J]. Geofluids,2014,14(2):174-188.
[18] Zhang X,Lu Y,Tang J,et al. Experimental study on fracture initiation and propagation in shale using supercritical carbon dioxide fracturing[J]. Fuel,2016,190(15):370-378.
[19] Wang J,Elsworth D,Wu Y,et al. The influence of fracturing fluids on fracturing processes:A comparison between water,oil and SCCO2[J]. Rock Mechanics and Rock Engineering,2018,51(1):299-313.
[20] Wu K,Olson J E. A simplified three-dimensional displacement discontinuity method for multiple fracture simulations[J]. International Journal of Fracture,2015,193(2):191-204.
[21]刘国威,李庆斌,左正.相场断裂模型分步算法在ABAQUS中的实现[J].岩石力学与工程学报,2016,35(5):1019-1030.Liu Guowei,Li Qingbin,Zuo Zheng. Implementation of a staggered algorithm for a phase field mpdel in ABAQUS[J]. Chinese Journal of Rock Mechanics and Engineering,2016,35(5):1019-1030.
[22] Xu G,Wong S W. Interaction of multiple non-planar hydraulic fractures in horizontal wells[C]. International Petroleum Technology Conference,2013.
[23] Zou Y S,Ma X F,Zhang S C,et al. Numerical investigation into the influence of bedding plane on hydraulic fracture network propagation in shale formations[J]. Rock Mechanics and Rock Engineering,2016,49(9):3597–3614.
[24] Ma X,Zhou T,Zou Y S. Experimental and numerical study of hydraulic fracture geometry in shale formations with complex geologic conditions[J]. Journal of Structural Geology,2017,98:53-66.
[25]周彤,张士诚,邹雨时,等.四川盆地东北缘强应力大倾角页岩储层水力压裂裂缝形态[J].新疆石油地质,2016,37(3):336-341.Zhou Tong,Zhang Shicheng,Zou Yushi,et al. Hydraulic fracture geometry of shale gas reservoirs with strong tectonic stress and large dip angle in northeastern margin of Sichuan Basin[J]. Xinjiang Petroleum Geolgoy,2016,37(3):336-341.
[26]王飞.位移不连续法及其在岩体工程中的应用[D].上海交通大学,2010.Wang Fei. Displacment discontinuity method and its application on rock engineering[D]. Shanghai Jiao Tong University,2010.
[27]王在明.超临界二氧化碳钻井液特性研究[D].中国石油大学,2008.Wang Zaiming. Study on characteristics of supercritical carbon dioxide drilling fluid[D]. China University of Petroleum,2008.
[28]里德R C,普劳斯尼茨J M.气体和液体性质[M].李芝芬,杨怡生,译.北京:石油工业出版社,1994.Reid R C,Prausnitz J M. Theproperties of gases and liquids[M]. Li Zhifeng,Yang Yisheng,translated. Beijing:Petroleum Industry Press,1994.