转向剂对岩石破裂压力及裂缝扩展效果影响试验
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摘要
转向剂的质量分数和施工排量是油气井压裂设计和施工的重要参数。通过物模试验分析上浮与下沉转向剂单独及共同作用下,转向剂质量分数、施工排量对人工岩心破裂压力及裂缝扩展效果的影响。结果表明:岩心在清水压裂条件下,破裂压力略大于围压且二者呈近似一次函数关系;岩心在不同排量的上浮或下沉转向剂单独作用下,在最佳质量分数范围内,破裂压力随质量分数增大明显提高,较同条件清水压裂增幅为17.30%～93.46%;相同条件下,采用大排量压裂可得到更高的破裂压力;下沉转向剂作用下,岩心的破裂压力受转向剂质量分数和施工排量的影响更加明显;上浮与下沉转向剂共同作用,可更加有效地改善裂缝尖端封堵效果,破裂压力可达单独作用最佳质量分数时的1.88～3.32倍;转向剂压裂较清水压裂而言,更易形成复杂裂缝,从而改善压裂效果。
The mass fraction and construction displacement of the diverting agents are vital parameters in the fracturing design and construction in oil wells. In this study, the influence of mass fraction and displacement of diverting agents on the fracture pressure and crack propagation of artificial cores is analyzed by simulation tests. The experiment is performed under two kinds of situations, i.e. the separate and combined action of the floating and sinking diverting agents. The results show that under the condition of water fracture, the fracture pressure of artificial cores are slightly larger than the confining pressure, and there is an approximately linear function between them. Under the separate actions of the floating or sinking diverting agent with different displacements, in the range of best mass fraction, the fracture pressure of artificial cores increases obviously with the growing of the mass fraction, and increases by 17.30%-93.46% higher than that of the water fracturing under same conditions. Under the same conditions, the higher fracture pressure can be obtained by using larger displacements. Under the action of sinking diverting agent, the fracture pressure is more easily affected by the mass fraction and displacements. Under the combined action of the floating and sinking diverting agents, the blocking effect can be significantly improved, which can make the fracture pressure 1.88-3.32 times than that under separate conditions with best mass fraction. Comparing with the water fracturing, the diverting agent fracturing is more beneficial to form complex cracks, which helps to improve the fracturing effect.
The mass fraction and construction displacement of the diverting agents are vital parameters in the fracturing design and construction in oil wells. In this study, the influence of mass fraction and displacement of diverting agents on the fracture pressure and crack propagation of artificial cores is analyzed by simulation tests. The experiment is performed under two kinds of situations, i.e. the separate and combined action of the floating and sinking diverting agents. The results show that under the condition of water fracture, the fracture pressure of artificial cores are slightly larger than the confining pressure, and there is an approximately linear function between them. Under the separate actions of the floating or sinking diverting agent with different displacements, in the range of best mass fraction, the fracture pressure of artificial cores increases obviously with the growing of the mass fraction, and increases by 17.30%-93.46% higher than that of the water fracturing under same conditions. Under the same conditions, the higher fracture pressure can be obtained by using larger displacements. Under the action of sinking diverting agent, the fracture pressure is more easily affected by the mass fraction and displacements. Under the combined action of the floating and sinking diverting agents, the blocking effect can be significantly improved, which can make the fracture pressure 1.88-3.32 times than that under separate conditions with best mass fraction. Comparing with the water fracturing, the diverting agent fracturing is more beneficial to form complex cracks, which helps to improve the fracturing effect.
引文
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[8] 马收,唐汝众,宋长久.人工转向剂控制缝高试验研究及现场应用[J].石油地质与工程,2006,20(6):70-74.MA Shou,TANG Ruzhong,SONG Changjiu.The paleochannel characteristics and formation condition in the Zhonggual area of Junggar basin[J].Petroleum Geology and Engineering,2006,20(6):70-74.
[9] 李年银,赵立强,刘平礼,等.裂缝高度延伸机制及控缝高酸压技术研究[J].特种油气藏,2006,13(2):61-63,108.LI Nianyin,ZHAO Liqiang,LIU Pingli,et al.Fracture height extension mechanism and fracture height control acid-fracturing technology[J].Special Oil and Gas Reservoirs,2006,13(2):61-63,108.
[10] CLEARY M P.Analysis of mechanisms and procedures for producing favorable shapes of hydraulic fractures[R].SPE 9260,1980.
[11] MORITA N,WHITFILL D L,WAHL H A.Stress-intensity factor and fracture cross-sectional shape predictions from a three-dimensional model for hydraulically induced fractures[J].Journal of Petroleum Technology,1988:1329-1342.
[12] 马红卫,刘玉章,李宜坤,等.柔性转向剂在多孔介质中的运移规律研究[J].油田化学,2007,29(4):80-99.MA Hongwei,LIU Yuzhang,LI Yikun,et al.Research on flexible migration in porous media[J].Oil Drilling & Production Technology,2007,29(4):80-99.
[13] HODGES J E,Jr PAOLI B F.Modern techniques and thorough evaluation yield more consistent stimulation results in frontier formation[R].SPE 10892,1982.
[14] SMITH J E.High sand concentration fracturing treatments[J].World Oil,1990:91-102.
[15] de PATER C J,CLEARY M P,QUINNT S,et al.Experimental verification of dimensional analysis for hydraulic fracturing [J].SPE Production & Operations,1994(11):230-238.
[16] 柳贡慧,庞飞,陈治喜.水力压裂模拟试验中的相似准则[J].石油大学学报(自然科学版),2000,24(5):45-48.LIU Gonghui,PANG Fei,CHEN Zhixi.Development of scaling laws for hydraulic fracture simulation tests[J].Journal of the University of Petroleum,China(Edition of Natural Science),2000,24(5):45-48.
[2] 任文明.转向剂对水力裂缝垂向扩展的影响研究[D].青岛:中国石油大学(华东),2007.REN Wenming.The influential study of diverting agent to hydraulic fracture vertical propagation[D].Qingdao:China University of Petroleum(East China),2007.
[3] 俞然刚,任文明.转向剂形成水力压裂人工隔层的机制分析[J].钻井液与完井液,2007,24(6):66-68,92-93.YU Rangang,REN Wenming.Mechanism analysis of hydraulic fracturing artificial barrier formed with diverting agents[J].Drilling Fluid & Completion Fluid,2007,24(6):66-68,92-93.
[4] 谢桂学.周边脱砂压裂技术研究[D].成都:西南石油学院,2001.XIE Guixue.Periphery screen out fracturing technique[D].Chengdu:Southwest Petroleum Institute,2001.
[5] 魏斌,陈平,张冕,等.变排量压裂技术及其现场应用[J].石油钻采工艺,2000,22(6):70-71,80.WEI Bin,CHEN Ping,ZHANG Mian,et al.Fracturing technology with alteration discharge capacity and its field application[J].Oil drilling & Production Technology,2000,22(6):70-71,80.
[6] 郭大立,赵金洲,曾晓慧,等.控制裂缝高度压裂工艺技术试验研究及现场应用[J].石油学报,2002,23(3):91-94.GUO Dali,ZHAO Jinzhou,ZENG Xiaohui,et al.Experimental research and application of fracture-controlled fracturing technology[J].Acta Petrolei Sinica,2002,23(3):91-94.
[7] 李哲,杨兆中,李小刚.水力压裂模型的改进及其算法更新研究(上)[J].天然气工业,2005,25(1):88-92,214.LI Zhe,YANG Zhaozhong,LI Xiaogang.Improved model for hydraulic fracturing and its algorithm renewal study(1)[J].Natural Gas Industry,2005,25(1):88-92,214.
[8] 马收,唐汝众,宋长久.人工转向剂控制缝高试验研究及现场应用[J].石油地质与工程,2006,20(6):70-74.MA Shou,TANG Ruzhong,SONG Changjiu.The paleochannel characteristics and formation condition in the Zhonggual area of Junggar basin[J].Petroleum Geology and Engineering,2006,20(6):70-74.
[9] 李年银,赵立强,刘平礼,等.裂缝高度延伸机制及控缝高酸压技术研究[J].特种油气藏,2006,13(2):61-63,108.LI Nianyin,ZHAO Liqiang,LIU Pingli,et al.Fracture height extension mechanism and fracture height control acid-fracturing technology[J].Special Oil and Gas Reservoirs,2006,13(2):61-63,108.
[10] CLEARY M P.Analysis of mechanisms and procedures for producing favorable shapes of hydraulic fractures[R].SPE 9260,1980.
[11] MORITA N,WHITFILL D L,WAHL H A.Stress-intensity factor and fracture cross-sectional shape predictions from a three-dimensional model for hydraulically induced fractures[J].Journal of Petroleum Technology,1988:1329-1342.
[12] 马红卫,刘玉章,李宜坤,等.柔性转向剂在多孔介质中的运移规律研究[J].油田化学,2007,29(4):80-99.MA Hongwei,LIU Yuzhang,LI Yikun,et al.Research on flexible migration in porous media[J].Oil Drilling & Production Technology,2007,29(4):80-99.
[13] HODGES J E,Jr PAOLI B F.Modern techniques and thorough evaluation yield more consistent stimulation results in frontier formation[R].SPE 10892,1982.
[14] SMITH J E.High sand concentration fracturing treatments[J].World Oil,1990:91-102.
[15] de PATER C J,CLEARY M P,QUINNT S,et al.Experimental verification of dimensional analysis for hydraulic fracturing [J].SPE Production & Operations,1994(11):230-238.
[16] 柳贡慧,庞飞,陈治喜.水力压裂模拟试验中的相似准则[J].石油大学学报(自然科学版),2000,24(5):45-48.LIU Gonghui,PANG Fei,CHEN Zhixi.Development of scaling laws for hydraulic fracture simulation tests[J].Journal of the University of Petroleum,China(Edition of Natural Science),2000,24(5):45-48.