高埋深储层泥岩弹塑性力学特征试验研究
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摘要
泥岩作为油气储层常见复杂介质,高埋深环境下的力学特性与浅部岩石呈现明显不同。本文以油气藏工程高埋深储层泥岩为研究对象,在物理特性分析的基础上,探讨了其弹塑性力学特性。首先开展了不同围压作用下的三轴常规压缩实验;泥岩均具有较大塑性压缩和延性扩容变形,强度硬化特征显著,破坏呈现延性屈服平台;且峰值强度随围压增加而增大。其次探讨了屈服破坏、塑性硬化和体积扩容等特性;泥岩破坏符合非线性屈服准则,硬化特性可用幂函数予以描述,且体积呈现典型的压缩向扩容转化。基于上述分析,最后采用非关联流动法则,在热动力学框架下构建了弹塑性本构模型,进而模拟研究了深层泥岩的弹塑性力学特性,模拟与试验结果具有良好的一致性,印证了弹塑性力学分析的准确性。相关成果可为深部泥岩储层油气藏工程理论研究和稳定分析提供可靠的依据。
As a common complex media in oil and gas reservoirs,the mechanical properties of mudstone in high depth environment are obviously different from those of shallow rocks.Based on the analysis of physical characteristics,the elastoplastic mechanical properties of mudstone with high buried depth in oil and gas reservoir engineering were studied.Firstly,triaxial conventional tests were conducted to characterize the mechanical behavior of mudstone under different confining pressures.The mudstone exhibited significant plastic compression and ductility dilation strain.Meanwhile,it also showed obvious strength hardening behavior and the failure exhibited ductile yielding platform.The peak strength increased with an increase in confining pressure.Secondly,the characteristics of yield failure,plastic hardening and volume dilation were discussed to study the elastoplastic mechanical properties of mudstone.The failure surface of mudstone performed a nonlinear yield behavior and the hardening characteristics could be described by power function.And the volume presented typical compression dilatancy transformation.Finally,an elastoplastic constitutive model was proposed with the use of non-associated flow rule under the framework of thermodynamics.The simulation was in good agreement with the experimental results,which confirmed the accuracy of the elastoplastic mechanical analysis.These results can provide reliable basis for engineering research and stability analysis of deep mudstone reservoir.
As a common complex media in oil and gas reservoirs,the mechanical properties of mudstone in high depth environment are obviously different from those of shallow rocks.Based on the analysis of physical characteristics,the elastoplastic mechanical properties of mudstone with high buried depth in oil and gas reservoir engineering were studied.Firstly,triaxial conventional tests were conducted to characterize the mechanical behavior of mudstone under different confining pressures.The mudstone exhibited significant plastic compression and ductility dilation strain.Meanwhile,it also showed obvious strength hardening behavior and the failure exhibited ductile yielding platform.The peak strength increased with an increase in confining pressure.Secondly,the characteristics of yield failure,plastic hardening and volume dilation were discussed to study the elastoplastic mechanical properties of mudstone.The failure surface of mudstone performed a nonlinear yield behavior and the hardening characteristics could be described by power function.And the volume presented typical compression dilatancy transformation.Finally,an elastoplastic constitutive model was proposed with the use of non-associated flow rule under the framework of thermodynamics.The simulation was in good agreement with the experimental results,which confirmed the accuracy of the elastoplastic mechanical analysis.These results can provide reliable basis for engineering research and stability analysis of deep mudstone reservoir.
引文
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[22]周辉,张凯,冯夏庭,等.脆性大理岩弹塑性耦合力学模型研究[J].岩石力学与工程学报,2010,29(12):2398-2409.
[23]舒才,施峰,胡国忠,等.基于广义Hoek-Brown屈服准则的非线性弹塑性岩石(体)本构模型及其数值实现[J].岩石力学与工程学报,2016,35(增1):2627-2634.
[24]周维垣,孙卫军.岩石的临界状态非关联弹塑性本构模型[J].岩石力学与工程学报,1990,9(1):1-10.
[25]孟召平,李明生,陆鹏庆,等.深部温度、压力条件及其对砂岩力学性质的影响[J].岩石力学与工程学报,2006,25(6):1177-1181.
[26]郤保平,赵阳升,赵金昌,等.层状盐岩温度应力耦合作用蠕变特性研究[J].岩石力学与工程学报,2008,27(1):90-96.
[27]胡云华.高应力下花岗岩力学特性试验及本构模型研究[D].武汉:中国科学院武汉岩土力学研究所,2008.
[2]Corkuma A G,Martinb C D.The mechanical behaviour of weak mudstone(Opalinus Clay)at low stresses[J].International Journal of Rock Mechanics and Mining Sciences,2007,44(2):196-209.
[3]茅献彪,张连英,刘瑞雪.高温状态下泥岩单轴蠕变特性及损伤本构关系研究[J].岩土工程学报,2013,35(增2):30-37.
[4]Monfared M,Sulem J,Delage P,et al.A laboratory investigation on thermal properties of the opalinus claystone[J].Rock Mechanics and Rock Engineering,2011,44:735-747.
[5]张连英,张树娟,茅献彪,等.考虑温度效应的泥岩损伤特性试验研究[J].采矿与安全工程学报,2012,29(6):852-858.
[6]张豫川,潘增志,王祖耀,等.砂岩与砂质泥岩渗透性能试验研究[J].地下空间与工程学报,2017,13(2):301-306.
[7]岳齐贤,赵建立,沈水龙.泥岩地区沉井施工对土体及高铁桥基影响研究[J].地下空间与工程学报,2014,10(4):878-883.
[8]王军保,刘新荣,王铁行.灰质泥岩蠕变特性试验研究[J].地下空间与工程学报,2014,10(4):770-775.
[9]徐可可.温度对深部泥岩物理力学特性影响试验研究[D].淮南:安徽理工大学,2016.
[10]陈亮,刘建锋,王春萍,等.北山深部花岗岩弹塑性损伤模型研究[J].岩石力学与工程学报,2013,32(2):289-298.
[11]祝效华,刘伟吉.热孔弹塑性完全耦合作用下的井底岩石应力分布[J].中国石油大学学报(自然科学版),2016,40(5):72-78.
[12]王仁,殷有泉.工程岩石类介质的弹塑性本构关系[J].力学学报,1981(4):317-325.
[13]周辉,杨凡杰,张传庆,等.考虑围压效应的大理岩弹塑性耦合力学模型研究[J].岩石力学与工程学报,2012,31(12):2389-2399.
[14]Zhang Y,Shao J F,Xu W Y,et al.Experimental and numerical investigations on strength and deformation behavior of cataclastic sandstone[J].Rock Mechanics and Rock Engineering,2015,48(5):1083-1096.
[15]Wang J Y,Zhang Y,Jin P J,et al.Elastoplastic modeling of mechanical behavior of weak rock at different time scales[J].Journal of Central South University,2017,24(3):699-707.
[16]Dafalias Y F.Elasto-plastic coupling within a thermodynamic strain space formulation of plasticity[J].International Journal of Nonlinear Mechanics,1977,12(5):327-337.
[17]张凯,周辉,冯夏庭,等.大理岩弹塑性耦合特性试验研究[J].岩土力学,2010,31(8):2425-2434.
[18]江权,冯夏庭,陈国庆.考虑高地应力下围岩劣化的硬岩本构模型研究[J].岩石力学与工程学报,2008,27(1):144-152.
[19]卢允德,葛修润,蒋宇,等.大理岩常规三轴压缩全过程试验和本构方程的研究[J].岩石力学与工程学报,2004,23(15):2489-2493.
[20]赵星光,蔡明,蔡美峰.岩石剪胀角模型与验证[J].岩石力学与工程学报,2010,29(5):970-981.
[21]Alejano L R,Alonso E.Considerations of the dilatancy angle in rocks and rock masses[J].International Journal of Rock Mechanics and Mining Sciences,2005,42(4):481-507.
[22]周辉,张凯,冯夏庭,等.脆性大理岩弹塑性耦合力学模型研究[J].岩石力学与工程学报,2010,29(12):2398-2409.
[23]舒才,施峰,胡国忠,等.基于广义Hoek-Brown屈服准则的非线性弹塑性岩石(体)本构模型及其数值实现[J].岩石力学与工程学报,2016,35(增1):2627-2634.
[24]周维垣,孙卫军.岩石的临界状态非关联弹塑性本构模型[J].岩石力学与工程学报,1990,9(1):1-10.
[25]孟召平,李明生,陆鹏庆,等.深部温度、压力条件及其对砂岩力学性质的影响[J].岩石力学与工程学报,2006,25(6):1177-1181.
[26]郤保平,赵阳升,赵金昌,等.层状盐岩温度应力耦合作用蠕变特性研究[J].岩石力学与工程学报,2008,27(1):90-96.
[27]胡云华.高应力下花岗岩力学特性试验及本构模型研究[D].武汉:中国科学院武汉岩土力学研究所,2008.