页岩气井压裂返排液损害实验评价及机理研究
|
摘要
页岩气井通过大规模水力压裂形成复杂缝网,泵入的压裂液会与页岩相互作用,一方面通过自吸进入储层深部无法返排,另一方面压裂液会与页岩相互作用致页岩和液体特性都发生不同程度的变化,产生胶体残渣,造成页岩微粒运移。页岩储层普遍具有孔隙度和渗透率极低、天然微裂缝发育等特点,压裂液滞留于地层以及破碎支撑剂、胶体残渣和裂缝面破碎页岩微粒是否会对储层造成损害,文章从常规驱替损害害评价和自吸损害评价着手研究了页岩气井压裂损害机理。研究结果表明,页岩自吸致裂缝起裂扩展的积极作用和压裂液滞留于储层堵塞孔隙吼道的消极作用是同时存在的,裂缝发育程度的不同二者各自所起的主导作用是有差异的,对于微裂缝发育的储层,在导致水相圈闭损害的同时也可能诱发基质微裂缝的起裂扩展。返排液固相微粒对页岩储层的损害随岩样/裂缝尺度而呈现差异性,对于渗透率较高的裂缝流动通道,以固相堵塞和液相圈闭为主,且损害后渗透率难以有效恢复。研究结果对于针对页岩气井储层特征优化、页岩气井的关井时间和制定返排制度起到很好的指导作用。
In shale gas development,fluid flowback after fracturing is highly regarded,it is a key part of later production.The flowback at Changning block mainly adopts experience method or the flowback data of adjacent wells,without theoretical understanding. At present,the study on flowback fuild is mainly focusing on the environmental protection and disposal of the return fluid,the changes of ion content in the flowback fluid are rarely paid attention to. In order to explore the ion source of flowback fluid,to further understand shale and the interaction mechanism of fracturing fluid,the ion source and ion content change of fluid flowback have been studied,the results show that,(1)the change of ion content after the interaction between shale and fracturing fluid is mainly due to the dissolution or cation exchange of shale itself,partly from proppant and clay minerals,(2) the contents of Na+,K+,Ca2 +,and Mg2 +in the flowback fluid are increased with the increase of the flowback time,and the change of ion content becomes stable after 4 ～ 10 days,(3)the change of ion content can reflect the interaction between the fracturing fluid and the shale and the proppant,and provide the theoretical basis for the optimization of well soaking time.
In shale gas development,fluid flowback after fracturing is highly regarded,it is a key part of later production.The flowback at Changning block mainly adopts experience method or the flowback data of adjacent wells,without theoretical understanding. At present,the study on flowback fuild is mainly focusing on the environmental protection and disposal of the return fluid,the changes of ion content in the flowback fluid are rarely paid attention to. In order to explore the ion source of flowback fluid,to further understand shale and the interaction mechanism of fracturing fluid,the ion source and ion content change of fluid flowback have been studied,the results show that,(1)the change of ion content after the interaction between shale and fracturing fluid is mainly due to the dissolution or cation exchange of shale itself,partly from proppant and clay minerals,(2) the contents of Na+,K+,Ca2 +,and Mg2 +in the flowback fluid are increased with the increase of the flowback time,and the change of ion content becomes stable after 4 ～ 10 days,(3)the change of ion content can reflect the interaction between the fracturing fluid and the shale and the proppant,and provide the theoretical basis for the optimization of well soaking time.
引文
[1]Dehghanpour H,Zubair H A,Chhabra A&Ullah A.Liquid intakeof organic shales[J].Energy&Fuels,2012,26(9):5750-5758.
[2]Dehghanpour H,Lan Q,Saeed Y,Fei H&Qi Z.Spontaneous imbibition of brine and oil in gas shales:Effect of water adsorptionand resulting microfractures[J].Energy&Fuels,2013,27(6):3039-3049.
[3]Makhanov K,Dehghanpour H,Kuru E.An Experimental Study of Spontaneous Imbibition in Horn River Shales[C]//https://doi.org/10.2118/162650-MS,SPE Canadian Unconventional Resources Conference,2012,30 October-1 November,Calgary,Alberta,Canada.
[4]Ghanbari E,Abbasi M,Dehghanpour H,Bearinger D.Flowback Volumetric and Chemical Analysis for Evaluating Load Recovery and Its Impact on Early-Time Production[C]//https://doi.org/10.2118/167165-MS,paper SPE-167165 presented at Unconventional Resource Conference,2013,Calgary,Canada,5-7 November.
[5]Sharma M&Agrawal S.Impact of Liquid Loading in Hydraulic Fractures on Well Productivity[C]//https://doi.org/10.2118/1113-0162-JPT.In 2013 SPE Hydraulic Fracturing Technology Conference.
[6]Dutta R,Lee C H,Odumabo S,Ye P,Walker S,Karpyn Z&Ayala L.Quantification of Fracturing Fluid Migration due to Spontaneous Imbibition in Fractured Tight Formations[C]//https://doi.org/10.2118/154939-MS,2012,In SPE Americas Unconventional Resources Conference.
[7]韩慧芬,贺秋云,王良.长宁区块页岩气井排液技术现状及攻关方向探讨[J].钻采工艺,2017,40(4):69-71.
[2]Dehghanpour H,Lan Q,Saeed Y,Fei H&Qi Z.Spontaneous imbibition of brine and oil in gas shales:Effect of water adsorptionand resulting microfractures[J].Energy&Fuels,2013,27(6):3039-3049.
[3]Makhanov K,Dehghanpour H,Kuru E.An Experimental Study of Spontaneous Imbibition in Horn River Shales[C]//https://doi.org/10.2118/162650-MS,SPE Canadian Unconventional Resources Conference,2012,30 October-1 November,Calgary,Alberta,Canada.
[4]Ghanbari E,Abbasi M,Dehghanpour H,Bearinger D.Flowback Volumetric and Chemical Analysis for Evaluating Load Recovery and Its Impact on Early-Time Production[C]//https://doi.org/10.2118/167165-MS,paper SPE-167165 presented at Unconventional Resource Conference,2013,Calgary,Canada,5-7 November.
[5]Sharma M&Agrawal S.Impact of Liquid Loading in Hydraulic Fractures on Well Productivity[C]//https://doi.org/10.2118/1113-0162-JPT.In 2013 SPE Hydraulic Fracturing Technology Conference.
[6]Dutta R,Lee C H,Odumabo S,Ye P,Walker S,Karpyn Z&Ayala L.Quantification of Fracturing Fluid Migration due to Spontaneous Imbibition in Fractured Tight Formations[C]//https://doi.org/10.2118/154939-MS,2012,In SPE Americas Unconventional Resources Conference.
[7]韩慧芬,贺秋云,王良.长宁区块页岩气井排液技术现状及攻关方向探讨[J].钻采工艺,2017,40(4):69-71.