岩石水压致裂影响参数的仿真
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摘要
针对影响水压致裂实验中起裂和失稳压力变化的诸多因素,通过RFPA2D-Flow数值仿真实验,建立了水压致裂模型,研究了孔隙水压力系数、围压比及非均匀性等因素对水压致裂的影响.研究结果表明,试件孔隙水压力系数及围压比的变化对水压致裂起裂压力和失稳压力影响明显;随着孔隙水压力系数的增大,岩石试件的起裂压力和失稳压力都随之减小,最大降幅可达37%;而围压比从1.0增加到1.5过程中,起裂压力和失稳压力降低了大约16%.分析结果对水压致裂施工设计及研究具有一定的参考价值.
Allowing for factors affecting initial fracture pressure and breakdown pressure in hydraulic fracturing test,a hydraulic fracturing model was built by RFPA2DFlow numerical simulation.The effect of pore water pressure coefficient,confining pressure ratio and heterogeneity on hydraulic fracturing was studied.The results showed that the changes of pore water pressure coefficient and confining pressure ratio have a remarkable effect on the initial fracture pressure and breakdown pressure during hydraulic fracturing process.The initial fracture pressure and breakdown pressure decrease with rising pore water pressure coefficient,and the largest drop could reach 37%.The initial fracture pressure and breakdown pressure decrease about 16% for the confining pressure ratio from 1.0 to 1.5.The investigation can provide meaningful guides for the design of hydraulic fracture engineering in practice.
Allowing for factors affecting initial fracture pressure and breakdown pressure in hydraulic fracturing test,a hydraulic fracturing model was built by RFPA2DFlow numerical simulation.The effect of pore water pressure coefficient,confining pressure ratio and heterogeneity on hydraulic fracturing was studied.The results showed that the changes of pore water pressure coefficient and confining pressure ratio have a remarkable effect on the initial fracture pressure and breakdown pressure during hydraulic fracturing process.The initial fracture pressure and breakdown pressure decrease with rising pore water pressure coefficient,and the largest drop could reach 37%.The initial fracture pressure and breakdown pressure decrease about 16% for the confining pressure ratio from 1.0 to 1.5.The investigation can provide meaningful guides for the design of hydraulic fracture engineering in practice.
引文
[1]Yang T H,Tham L G,Tang C A.Influence of heterogeneityof mechanical properties on hydraulic fracturing in permeablerocks[J].Rock Mechanics and Rock Engineering,2004,37(4):251-275.
[2]高龙生,刘建中,张雪.高压差应力下的水力压裂试验[J].中国地震,1989,5(3):1-7.(Gao Long-sheng,Liu Jian-zhong,Zhang Xue.Hydro-fracturing experiment under high differential stress[J].Earthquake Research in China,1989,5(3):1-7.)
[3]吴景浓.室内岩石水压致裂三轴试验研究[J].岩土工程学报,1986,8(4):61-69.(Wu Jing-nong.Research on laboratory triaxial test for rockhydro-fracture[J].Chinese Journal of GeotechnicalEngineering,1986,8(4):61-69.)
[4]刘建军,冯夏庭,裴桂红.水力压裂三维数学模型研究[J].岩石力学与工程学报,2003,22(12):2042-2046.(Liu Jian-jun,Feng Xia-ting,Pei Gu-i hong.Study onmathematical model of three dimensional hydraulic fracturing[J].Chinese Journal of Geotechnical Engineering,2003,22(12):2042-2046.)
[5]詹美礼,岑建.岩体水力劈裂机制圆筒模型试验及解析理论研究[J].岩石力学与工程学报,2007,26(6):1173-1181.(Zhan Me-i li,Cen Jian.Experimental and analytical study onhydraulic fracturing of cylinder sample[J].ChineseJournal ofRock Mechanics and Engineering,2007,26(6),1173-1181.)
[6]Song I,Haimson B C.Effect of pressurization rate and initialpore pressure on the magnitude of hydrofracturing breakdownpressure in table rock sandstone[J].Rock Mechanics in theNational Interest,2001,7:235-242.
[7]Noghabai K.Discrete versus smeared versus element-embedded crack models on ring problem[J].Journal ofEngineering Mechanics,2000,4:307-314.
[8]Bruno M S,NakagawaF M.Pore pressure influenceon tensilefracture propagation in sedimentary rock[J].InternationalJournal of Rock Mechanics and Mining Sciences,1991,28(4):261-273.
[9]Charlez P A.Rock mechanics[M].Paris:TechnicalPublisher,1991.
[2]高龙生,刘建中,张雪.高压差应力下的水力压裂试验[J].中国地震,1989,5(3):1-7.(Gao Long-sheng,Liu Jian-zhong,Zhang Xue.Hydro-fracturing experiment under high differential stress[J].Earthquake Research in China,1989,5(3):1-7.)
[3]吴景浓.室内岩石水压致裂三轴试验研究[J].岩土工程学报,1986,8(4):61-69.(Wu Jing-nong.Research on laboratory triaxial test for rockhydro-fracture[J].Chinese Journal of GeotechnicalEngineering,1986,8(4):61-69.)
[4]刘建军,冯夏庭,裴桂红.水力压裂三维数学模型研究[J].岩石力学与工程学报,2003,22(12):2042-2046.(Liu Jian-jun,Feng Xia-ting,Pei Gu-i hong.Study onmathematical model of three dimensional hydraulic fracturing[J].Chinese Journal of Geotechnical Engineering,2003,22(12):2042-2046.)
[5]詹美礼,岑建.岩体水力劈裂机制圆筒模型试验及解析理论研究[J].岩石力学与工程学报,2007,26(6):1173-1181.(Zhan Me-i li,Cen Jian.Experimental and analytical study onhydraulic fracturing of cylinder sample[J].ChineseJournal ofRock Mechanics and Engineering,2007,26(6),1173-1181.)
[6]Song I,Haimson B C.Effect of pressurization rate and initialpore pressure on the magnitude of hydrofracturing breakdownpressure in table rock sandstone[J].Rock Mechanics in theNational Interest,2001,7:235-242.
[7]Noghabai K.Discrete versus smeared versus element-embedded crack models on ring problem[J].Journal ofEngineering Mechanics,2000,4:307-314.
[8]Bruno M S,NakagawaF M.Pore pressure influenceon tensilefracture propagation in sedimentary rock[J].InternationalJournal of Rock Mechanics and Mining Sciences,1991,28(4):261-273.
[9]Charlez P A.Rock mechanics[M].Paris:TechnicalPublisher,1991.
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