裂缝性储层射孔井起裂压力影响因素分析
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摘要
水力压裂是目前最为常用、有效的储层增产措施.为了更好地进行压裂优化设计,提高储层改造效果,需要开展水力压裂裂缝起裂和扩展机理研究.裂缝性储层发育大量天然裂缝,具有强均质性,导致该类储层水力裂缝起裂与延伸规律复杂,具有强不确定性.因此,该文针对裂缝性地层起裂机制,基于张性起裂准则,考虑天然裂缝数量、产状及射孔工程参数,建立裂缝性储层起裂压力预测模型.分析结果表明:天然裂缝面存在,易导致水力裂缝沿裂缝面起裂,从而降低起裂压力.尤其随裂缝数量增加,起裂压力下降趋势更为明显.同时,起裂压力分布受工程参数控制,在高方位角和低井斜角条件下,起裂压力较大.研究成果对裂缝性储层压裂作业具有一定理论指导意义.
Hydraulic fracturing is the most common and effective stimulation treatment. To better the fracturing design and improve the stimulation treatment,the mechanism of fracture initiation and propagation was investigated. In fracture formation,lots of natural fractures exist,having strong anisotropy and causing extreme complication and uncertainty of fracture initiation and propagation. Therefore,the mechanism of fracture initiation was stressed with the tensile criterion to establish the initiation pressure model in view of the natural fracture number,the occurrence and the intersection between perforation and fracture.The results indicate that,the natural fracture tends to cause initiation along the fracture plane and decrease the initiation pressure. In particular,with an increasing number of fracture planes,this decline will be more significant. Besides,the distribution of initiation pressure is related to several engineering parameters.For a high perforation azimuth and a low wellbore deviation,the initiation pressure will be relatively larger.The findings can offer reference for hydraulic fracturing in application.
Hydraulic fracturing is the most common and effective stimulation treatment. To better the fracturing design and improve the stimulation treatment,the mechanism of fracture initiation and propagation was investigated. In fracture formation,lots of natural fractures exist,having strong anisotropy and causing extreme complication and uncertainty of fracture initiation and propagation. Therefore,the mechanism of fracture initiation was stressed with the tensile criterion to establish the initiation pressure model in view of the natural fracture number,the occurrence and the intersection between perforation and fracture.The results indicate that,the natural fracture tends to cause initiation along the fracture plane and decrease the initiation pressure. In particular,with an increasing number of fracture planes,this decline will be more significant. Besides,the distribution of initiation pressure is related to several engineering parameters.For a high perforation azimuth and a low wellbore deviation,the initiation pressure will be relatively larger.The findings can offer reference for hydraulic fracturing in application.
引文
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[10]虞建业,沈飞,顾庆宏,等.水平井射孔参数对压裂起裂压力的影响[J].油气地质与采收率,2011,18(1):105-107.(YU Jianye,SHEN Fei,GU Qinghong,et al.Influence of perforation parameters on hydraulic fracturing of fracture pressure in horizontal well[J].Petroleum G eology and Recovery Efficiency,2011,18(1):105-107.(in Chinese))
[2]金衍,陈勉,张旭东,等.天然裂缝地层斜井水力裂缝起裂压力模型研究[J].石油学报,2006,27(5):124-126.(JIN Yan,CHEN Mian,ZHANG Xudong,et al.Hydraulic fracturing initiation pressure models for directional wells in naturally fractured formation[J].Acta Petrolei Sinica,2006,27(5):124-126.(in Chinese))
[3]朱海燕,邓金根,刘书杰,等.定向射孔水力压裂起裂压力的预测模型[J].石油学报,2013,34(3):556-562.(ZHU Haiyan,DENG Jingen,LIU Shujie,et al.A prediction model for the hydraulic fracture initiation pressure in oriented perforation[J].Acta Petrolei Sinica,2013,34(3):556-562.(in Chinese))
[4]郭建春,邓燕,赵金洲.射孔完井方式下大位移井压裂裂缝起裂压力研究[J].天然气工业,2006,26(6):105-107.(GUO Jianchun,DENG Yan,ZHAO Jinzhou.Study on breakdown pressure of hydraulic fracturing for extended reach wells with perforation completion[J].Natural G as Industry,2006,26(6):105-107.(in Chinese))
[5]冯彦军,康红普.水力压裂起裂与扩展分析[J].岩石力学与工程学报,2013,32(S2):3169-3179.(FENG Yanjun,KANG Hongpu.Hydraulic fracturing initiation and propagation[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(S2):3169-3179.(in Chinese))
[6]赵金洲,任岚,胡永全,等.裂缝性地层水力裂缝张性起裂压力分析[J].岩石力学与工程学报,2013,31(S1):2855-2862.(ZHAO Jinzhou,REN Lan,HU Yongquan,et al.Hydraulic fracture tensile initiation pressure analysis for fractured formations[J].Chinese Journal of Rock Mechanics and Engineering,2013,31(S1):2855-2862.(in Chinese))
[7]吕志凯,何顺利,罗富平,等.射孔水平井分段压裂起裂压力理论研究[J].石油钻探技术,2011,39(4):72-76.(LUZhikai,HE Shunli,LUO Fuping,et al.Study on hydraulic fracture initiation pressure of staged fracturing in perforated horizontal wells[J].Petroleum Drilling Techniques,2011,39(4):72-76.(in Chinese))
[8]EATON B A.Fracture gradient prediction and its application in oilfield operation[J].Journal of Petroleum Technology,1969,21(10):1353-1360.
[9]郭天魁,张士诚,刘卫来,等.页岩储层射孔水平井分段压裂的起裂压力[J].天然气工业,2013,33(12):87-93.(GUO Tiankui,ZHANG Shicheng,LIU Weilai,et al.Initiation pressure of multi-stage fracking for perforated horizontal wells of shale gas reservoirs[J].Natural G as Industry,2013,33(12):87-93.(in Chinese))
[10]虞建业,沈飞,顾庆宏,等.水平井射孔参数对压裂起裂压力的影响[J].油气地质与采收率,2011,18(1):105-107.(YU Jianye,SHEN Fei,GU Qinghong,et al.Influence of perforation parameters on hydraulic fracturing of fracture pressure in horizontal well[J].Petroleum G eology and Recovery Efficiency,2011,18(1):105-107.(in Chinese))