绒囊暂堵转向压裂裂缝转向能力及其力学机理分析
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摘要
现场已用绒囊转向剂实施造缝转向,其转向力学机理尚未研究。室内利用7枚?25 mm致密砂岩天然岩心人工造缝模拟压裂后初始裂缝,选择其中3枚注入绒囊转向剂实施封堵,利用三轴试验机测量7枚岩心径向应力-应变曲线,计算绒囊转向剂封堵后岩心水平应力差值5.33MPa,相对未封堵岩心水平应力差值8.57 MPa下降37.81%。绒囊转向剂封堵后岩心脆性系数0.45降至0.16,下降64.44%。实验表明,利用绒囊转向剂封堵裂缝可提高岩石整体强度,降低岩石水平应力差,为重复压裂后新缝转向提供力学环境。室内以300 mm×300 mm×300 mm大尺寸岩心模拟地层,在真三轴压裂模拟系统中利用胍胶压裂形成初始裂缝后,注入绒囊转向剂实施暂堵,再注入胍胶模拟二次压裂。测试二次压裂破裂压力相对初次压裂升高约10 MPa,剖开岩心定性观察暂堵后二次压裂岩心中新缝与初始裂缝方向差异明显,未封堵岩心中新缝与初始裂缝方向重合。研究认为,绒囊转向剂通过提高含裂缝岩石破裂压力,降低地层水平应力差值,增大新缝起裂角度,促使裂缝转向。
Fuzzy-ball diverting agent has been applied on site for fracture initiation and diverting, but its mechanical mechanisms of diverting have not been studied yet. In this paper, 7 natural cores(?25 mm) of tight sandstone were adopted in laboratory to simulate the postfrac initial fractures by using artificial fractures. And fuzzy-ball diverting agent was injected into 3 cores to plug the fractures. The radial stress-strain curves of 7 cores were measured by means of the triaxial testing machine. The horizontal stress differential of the cores after they were plugged with fuzzy-ball diverting agent was calculated, and it is 5.33 MPa, which is 37.81% lower than that of the plugged cores, i.e., 8.57 MPa. And the brittleness coefficient of the cores plugged with fuzzy-ball diverting agent drops by 64.44% from 0.45 to 0.16. It is indicated that to adopt fuzzy-ball diverting agent for plugging fractures can increase the overall strength of rock and decrease the horizontal stress differential of rock, so as to provide the mechanical setting for the diverting of new fractures after refracturing. In laboratory, large-size cores of 300 mm×300 mm×300 mm were used to simulate the strata. In the true triaxial fracturing simulation system, the initial fractures were created by using guar, fuzzy-ball diverting agent was injected for temporary plugging and then guar was injected again to simulate the secondary fracturing. The fracturing pressure of secondary fracturing was tested and it is about 10 MPa higher than that of primary fracturing. Finally, the cores were split for qualitative observation. It is shown that the orientation of new fractures created by secondary fracturing after temporary plugging is obviously different from that of initial fractures while the orientation of new fractures in unplugged cores is coincident with that of initial fractures. In conclusion, fuzzy-ball diverting agent can increase the fracturing pressure of rocks with fractures, decrease the in-situ horizontal stress differential and increase the fracture initiation angle of new fractures so as to promote the diverting of fractures.
Fuzzy-ball diverting agent has been applied on site for fracture initiation and diverting, but its mechanical mechanisms of diverting have not been studied yet. In this paper, 7 natural cores(?25 mm) of tight sandstone were adopted in laboratory to simulate the postfrac initial fractures by using artificial fractures. And fuzzy-ball diverting agent was injected into 3 cores to plug the fractures. The radial stress-strain curves of 7 cores were measured by means of the triaxial testing machine. The horizontal stress differential of the cores after they were plugged with fuzzy-ball diverting agent was calculated, and it is 5.33 MPa, which is 37.81% lower than that of the plugged cores, i.e., 8.57 MPa. And the brittleness coefficient of the cores plugged with fuzzy-ball diverting agent drops by 64.44% from 0.45 to 0.16. It is indicated that to adopt fuzzy-ball diverting agent for plugging fractures can increase the overall strength of rock and decrease the horizontal stress differential of rock, so as to provide the mechanical setting for the diverting of new fractures after refracturing. In laboratory, large-size cores of 300 mm×300 mm×300 mm were used to simulate the strata. In the true triaxial fracturing simulation system, the initial fractures were created by using guar, fuzzy-ball diverting agent was injected for temporary plugging and then guar was injected again to simulate the secondary fracturing. The fracturing pressure of secondary fracturing was tested and it is about 10 MPa higher than that of primary fracturing. Finally, the cores were split for qualitative observation. It is shown that the orientation of new fractures created by secondary fracturing after temporary plugging is obviously different from that of initial fractures while the orientation of new fractures in unplugged cores is coincident with that of initial fractures. In conclusion, fuzzy-ball diverting agent can increase the fracturing pressure of rocks with fractures, decrease the in-situ horizontal stress differential and increase the fracture initiation angle of new fractures so as to promote the diverting of fractures.
引文
[1]SIEBRITS E,ELBEL J I.Refracture reorientation enhances gas production in Barnett Shale tight gas wells[R].SPE 63030,2000:1-3.
[2]WRIGHT C A,CONANT R A,STEWART D W,BYERLY P M.Reorientation of propped refracture treatments[R].SPE 28078,1994:94-101.
[3]郑力会,魏攀峰,张峥,聂帅帅,楼宣庆,崔可心,付毓伟.联探并采:非常规油气资源勘探开发持续发展自我救赎之路[J].天然气工业,2017,37(5):126-127.ZHENG Lihui,WEI Panfeng,ZHANG Zheng,NIEShuaishuai,LOU Xuanqing,CUI Kexin,FU Yuwei.Joint exploration and development:A self-salvation road to sustainable development of unconventional oil and gas resources[J].Natural Gas Industry,2017,37(5):126-127.
[4]郑力会,翁定为.绒囊暂堵液原缝无损重复压裂技术[J].钻井液与完井液,2015,32(3):76-78.ZHENG Lihui,WENG Dingwei.Study on repeating fracturing while causing no damage to original fractures[J].Drilling Fluid&Completion Fluid,2015,32(3):76-78.
[5]郑力会,崔金榜,聂帅帅,刘斌,付毓伟,李宗源.郑X井重复压裂非产水煤层绒囊流体暂堵转向试验[J].钻井液与完井液,2016,33(5):103-108.ZHENG Lihui,CUI Jinbang,NIE Shuaishuai,LIU Bin,FU Yuwei,LI Zongyuan.Temporary plugging diverting test with fuzzy ball fluids in non-water producing coal beds in re-fracturing Well Zheng X[J].Drilling Fluid&Completion Fluid,2016,33(5):103-108.
[6]聂帅帅,郑力会,陈必武,侯涛,彭睿,付毓伟.郑3X煤层气井绒囊流体重复压裂控水增产试验[J].石油钻采工艺,2017,39(3):362-369.NIE Shuaishuai,ZHENG Lihui,CHEN Biwu,HOU Tao,PENG Rui,FU Yuwei.An experiment on refracturing with fuzzy-ball fluid for water control and stimulation of CBM Well Zheng 3X[J].Oil Drilling&Prodution Technology,2017,39(3):362-369.
[7]王永昌,姜必武,马延风,郭健康,王连军.安塞油田低渗透砂岩油藏重复压裂技术研究[J].石油钻采工艺,2005,27(5):78-80.WANG Yongchang,JIANG Biwu,MA Yanfeng,GUOJiankang,WANG Lianjun.Study of repeated fracturing technology in low-permeable sand oil reservoir in Ansai oil field[J].Oil Drilling&Production Technology,2005,27(5):78-80.
[8]SOLARES J R,AL-HARBI M,AL-SAGER AM,AMOROCHO R,RAMANATHAN V.Successful application of innovative fiberdiverting technology achieved effective diversion in acidstimulation treatments in Saudi Arabian deep gas producers[C].SPE Asia Pacific Oil and Gas Conference and Exhibition,Perth,Australia,20-22 October 2008.
[9]王盛鹏,唐邦忠,崔周旗,赵安军,吴刚,卢昊.一种新型油溶性暂堵剂及应用[J].钻井液与完井液,2015,32(1):87-89.WANG Shengpeng,TANG Bangzhong,CUI Zhouqi,ZHAO Anjun,WU Gang,LU Hao.A new oil soluble temporary plugging agent and its application[J].Drilling Fluid&Completion Fluid,2015,32(1):87-89.
[10]李玮,纪照生.暂堵转向压裂机理有限元分析[J].断块油气田,2016,23(4):514-517.LI Wei,JI Zhaosheng.Finite element analysis of temporary plugging and fracturing mechanism[J].Fault-block Oil&Gas Field,2016,23(4):514-517.
[11]WRIGHT C A.Reorientation of propped re-fracture treatments in the Lost Hills Field[R].SPE 27896,1994.
[12]张广清,陈勉,赵艳波.新井定向射孔转向压裂裂缝起裂与延伸机理研究[J].石油学报,2008,29(1):116-119.ZHANG Guangqing,CHEN Mian,ZHAO Yanbo.Study on initiation and propagation mechanism of fractures in oriented perforation of new wells[J].Acta Petrolei Sinica,2008,29(1):116-119.
[13]DETOURNAY E,BOONE T J.Discussion on pore pressure influence on tensile fracture propagation in sedimentary rock[J].Rock Mech,Sci&Geomech,1991,30(3):322.
[14]胡永全,彭惠群.堵老裂缝压新裂缝重复压裂技术[J].西南石油大学学报(自然科学版),2000,22(3):61-64.HU Yongquan,PENG Huiqun.Hydraulic re-fracturing technique for forming new fractures while blocking old fractures[J].Journal of Southwest Petroleum University(Edition of Natural Science),2000,22(3):61-64.
[15]夏宏泉,杨双定,弓浩浩,王成龙.岩石脆性实验及压裂缝高度与宽度测井预测[J].西南石油大学学报(自然科学版),2013,35(4):81-89.XIA Hongquan,YANG Shuangding,GONG Haohao,WANG Chenglong.Research on rock brittleness experiment and logging prediction of hydraulic fracture height&width[J].Journal of Southwest Petroleum University(Edition of Natural Science),2013,35(4):81-89.
[16]郑力会,陈必武,张峥,汤继丹,孙昊.煤层气绒囊钻井流体的防塌机理[J].天然气工业,2016,36(2):72-77.ZHENG Lihui,CHEN Biwu,ZHANG Zheng,TANGJidan,SUN Hao.Anti-collapse mechanism of the CBMfuzzy-ball drilling fluid[J].Natural Gas Industry,2016,36(2):72-77.
[17]郭宝利,袁孟雷,孟尚志,王风宇,郭卫.一种新型堵漏模拟装置[J].钻井液与完井液,2003,20(3):47-51.GUO Baoli,YUAN Menglei,MENG Shangzhi,WANGFengyu,GUO Wei.A novel lost circulation simulator[J].Drilling Fluid&Completion Fluid,2003,20(3):47-51.
[18]吴勇,陈凤,承宁.利用人工暂堵转向提高重复压裂效果[J].钻采工艺,2008,31(4):59-61.WU Yong,CHEN Feng,CHENG Ning.Enhancing refracturing effect with artificial temporary plugging technology[J].Drilling&Production Technology,2008,31(4):59-61.
[19]周法元,蒲万芬,刘春志,赵冀,刘涛.转向重复压裂暂堵剂ZFJ的研制[J].钻采工艺,2010,33(5):111-113.ZHOU Fayuan,PU Wanfen,LIU Chunzhi,ZHAOJi,LIU Tao.Development of steering refracturing temporary blocking agent ZFJ[J].Drilling&Production Technology,2010,33(5):111-113.
[20]王道成,张燕,邓素芬,向超,王川,龙顺敏,张亚东,刘爽.转向酸的实验室评价及现场应用[J].石油与天然气化工,2013,42(3):265-269.WANG Daocheng,ZHANG Yan,DENG Sufen,XIANGChao,WANG Chuan,LONG Shunmin,ZHANGYadong,LIU Shuang.Laboratory evaluation and field application of self-diversion acid[J].Chemical Engineering of Oil and Gas,2013,42(3):265-269.
[21]付美龙,陈畅,胡泽文.转向重复压裂高效暂堵剂性能评价[J].西安石油大学学报(自然科学版),2016,31(5):43-47.FU Meilong,CHEN Chang,HU Zewen.Performance evaluation of high efficiency temporary plugging agent for steering refracturing[J].Journal of Xi’an Shiyou University(Natural Science Edition),2016,31(5):43-47.
[22]陈勉,庞飞,金衍.大尺寸真三轴水力压裂模拟与分析[J].岩石力学与工程学报,2000,19(增刊1):868-872.CHEN Mian,PANG Fei,JIN Yan.Experiments and analysis on hydraulic fracturing by a lare-size triaxial simulator[J].Chinese Journal of Rock Mechanics and Engineering,2000,19(S1):868-872.
[23]RICKMAN R,MULLEN M J,PETRE J E,GRIESER WV,KUNDERT D.A practical use of shale petrophysics for stimulation design optimization:all shale plays are not clones of the barnett shale[C].SPE Technical Conference and Exhibition.Society of Petroleum Engineers,Colorado,USA,21-24 September 2008.
[2]WRIGHT C A,CONANT R A,STEWART D W,BYERLY P M.Reorientation of propped refracture treatments[R].SPE 28078,1994:94-101.
[3]郑力会,魏攀峰,张峥,聂帅帅,楼宣庆,崔可心,付毓伟.联探并采:非常规油气资源勘探开发持续发展自我救赎之路[J].天然气工业,2017,37(5):126-127.ZHENG Lihui,WEI Panfeng,ZHANG Zheng,NIEShuaishuai,LOU Xuanqing,CUI Kexin,FU Yuwei.Joint exploration and development:A self-salvation road to sustainable development of unconventional oil and gas resources[J].Natural Gas Industry,2017,37(5):126-127.
[4]郑力会,翁定为.绒囊暂堵液原缝无损重复压裂技术[J].钻井液与完井液,2015,32(3):76-78.ZHENG Lihui,WENG Dingwei.Study on repeating fracturing while causing no damage to original fractures[J].Drilling Fluid&Completion Fluid,2015,32(3):76-78.
[5]郑力会,崔金榜,聂帅帅,刘斌,付毓伟,李宗源.郑X井重复压裂非产水煤层绒囊流体暂堵转向试验[J].钻井液与完井液,2016,33(5):103-108.ZHENG Lihui,CUI Jinbang,NIE Shuaishuai,LIU Bin,FU Yuwei,LI Zongyuan.Temporary plugging diverting test with fuzzy ball fluids in non-water producing coal beds in re-fracturing Well Zheng X[J].Drilling Fluid&Completion Fluid,2016,33(5):103-108.
[6]聂帅帅,郑力会,陈必武,侯涛,彭睿,付毓伟.郑3X煤层气井绒囊流体重复压裂控水增产试验[J].石油钻采工艺,2017,39(3):362-369.NIE Shuaishuai,ZHENG Lihui,CHEN Biwu,HOU Tao,PENG Rui,FU Yuwei.An experiment on refracturing with fuzzy-ball fluid for water control and stimulation of CBM Well Zheng 3X[J].Oil Drilling&Prodution Technology,2017,39(3):362-369.
[7]王永昌,姜必武,马延风,郭健康,王连军.安塞油田低渗透砂岩油藏重复压裂技术研究[J].石油钻采工艺,2005,27(5):78-80.WANG Yongchang,JIANG Biwu,MA Yanfeng,GUOJiankang,WANG Lianjun.Study of repeated fracturing technology in low-permeable sand oil reservoir in Ansai oil field[J].Oil Drilling&Production Technology,2005,27(5):78-80.
[8]SOLARES J R,AL-HARBI M,AL-SAGER AM,AMOROCHO R,RAMANATHAN V.Successful application of innovative fiberdiverting technology achieved effective diversion in acidstimulation treatments in Saudi Arabian deep gas producers[C].SPE Asia Pacific Oil and Gas Conference and Exhibition,Perth,Australia,20-22 October 2008.
[9]王盛鹏,唐邦忠,崔周旗,赵安军,吴刚,卢昊.一种新型油溶性暂堵剂及应用[J].钻井液与完井液,2015,32(1):87-89.WANG Shengpeng,TANG Bangzhong,CUI Zhouqi,ZHAO Anjun,WU Gang,LU Hao.A new oil soluble temporary plugging agent and its application[J].Drilling Fluid&Completion Fluid,2015,32(1):87-89.
[10]李玮,纪照生.暂堵转向压裂机理有限元分析[J].断块油气田,2016,23(4):514-517.LI Wei,JI Zhaosheng.Finite element analysis of temporary plugging and fracturing mechanism[J].Fault-block Oil&Gas Field,2016,23(4):514-517.
[11]WRIGHT C A.Reorientation of propped re-fracture treatments in the Lost Hills Field[R].SPE 27896,1994.
[12]张广清,陈勉,赵艳波.新井定向射孔转向压裂裂缝起裂与延伸机理研究[J].石油学报,2008,29(1):116-119.ZHANG Guangqing,CHEN Mian,ZHAO Yanbo.Study on initiation and propagation mechanism of fractures in oriented perforation of new wells[J].Acta Petrolei Sinica,2008,29(1):116-119.
[13]DETOURNAY E,BOONE T J.Discussion on pore pressure influence on tensile fracture propagation in sedimentary rock[J].Rock Mech,Sci&Geomech,1991,30(3):322.
[14]胡永全,彭惠群.堵老裂缝压新裂缝重复压裂技术[J].西南石油大学学报(自然科学版),2000,22(3):61-64.HU Yongquan,PENG Huiqun.Hydraulic re-fracturing technique for forming new fractures while blocking old fractures[J].Journal of Southwest Petroleum University(Edition of Natural Science),2000,22(3):61-64.
[15]夏宏泉,杨双定,弓浩浩,王成龙.岩石脆性实验及压裂缝高度与宽度测井预测[J].西南石油大学学报(自然科学版),2013,35(4):81-89.XIA Hongquan,YANG Shuangding,GONG Haohao,WANG Chenglong.Research on rock brittleness experiment and logging prediction of hydraulic fracture height&width[J].Journal of Southwest Petroleum University(Edition of Natural Science),2013,35(4):81-89.
[16]郑力会,陈必武,张峥,汤继丹,孙昊.煤层气绒囊钻井流体的防塌机理[J].天然气工业,2016,36(2):72-77.ZHENG Lihui,CHEN Biwu,ZHANG Zheng,TANGJidan,SUN Hao.Anti-collapse mechanism of the CBMfuzzy-ball drilling fluid[J].Natural Gas Industry,2016,36(2):72-77.
[17]郭宝利,袁孟雷,孟尚志,王风宇,郭卫.一种新型堵漏模拟装置[J].钻井液与完井液,2003,20(3):47-51.GUO Baoli,YUAN Menglei,MENG Shangzhi,WANGFengyu,GUO Wei.A novel lost circulation simulator[J].Drilling Fluid&Completion Fluid,2003,20(3):47-51.
[18]吴勇,陈凤,承宁.利用人工暂堵转向提高重复压裂效果[J].钻采工艺,2008,31(4):59-61.WU Yong,CHEN Feng,CHENG Ning.Enhancing refracturing effect with artificial temporary plugging technology[J].Drilling&Production Technology,2008,31(4):59-61.
[19]周法元,蒲万芬,刘春志,赵冀,刘涛.转向重复压裂暂堵剂ZFJ的研制[J].钻采工艺,2010,33(5):111-113.ZHOU Fayuan,PU Wanfen,LIU Chunzhi,ZHAOJi,LIU Tao.Development of steering refracturing temporary blocking agent ZFJ[J].Drilling&Production Technology,2010,33(5):111-113.
[20]王道成,张燕,邓素芬,向超,王川,龙顺敏,张亚东,刘爽.转向酸的实验室评价及现场应用[J].石油与天然气化工,2013,42(3):265-269.WANG Daocheng,ZHANG Yan,DENG Sufen,XIANGChao,WANG Chuan,LONG Shunmin,ZHANGYadong,LIU Shuang.Laboratory evaluation and field application of self-diversion acid[J].Chemical Engineering of Oil and Gas,2013,42(3):265-269.
[21]付美龙,陈畅,胡泽文.转向重复压裂高效暂堵剂性能评价[J].西安石油大学学报(自然科学版),2016,31(5):43-47.FU Meilong,CHEN Chang,HU Zewen.Performance evaluation of high efficiency temporary plugging agent for steering refracturing[J].Journal of Xi’an Shiyou University(Natural Science Edition),2016,31(5):43-47.
[22]陈勉,庞飞,金衍.大尺寸真三轴水力压裂模拟与分析[J].岩石力学与工程学报,2000,19(增刊1):868-872.CHEN Mian,PANG Fei,JIN Yan.Experiments and analysis on hydraulic fracturing by a lare-size triaxial simulator[J].Chinese Journal of Rock Mechanics and Engineering,2000,19(S1):868-872.
[23]RICKMAN R,MULLEN M J,PETRE J E,GRIESER WV,KUNDERT D.A practical use of shale petrophysics for stimulation design optimization:all shale plays are not clones of the barnett shale[C].SPE Technical Conference and Exhibition.Society of Petroleum Engineers,Colorado,USA,21-24 September 2008.