焦石坝地区页岩各向异性及其影响的分析研究
|
摘要
黑色富含有机质页岩由于沉积方式的特殊性,一般具有较强的各向异性。但现有大部分研究是基于各向同性理论开展页岩储层预测工作,这与页岩的实际地质特点不符。文中联合利用实验室岩石力学测试数据以及各向异性参数经验公式计算焦石坝地区页岩的各向异性参数,并进一步探讨了各向异性对页岩岩石速度、储层AVO响应特征以及岩石力学参数计算的影响。结果表明,各向异性对页岩速度、脆性指数预测结果影响较大,在地层倾角较大时进行速度分析及页岩可压性预测时应考虑各向异性参数的影响;同时,AVO正演结果表明地震反射入射角小于40°时,各向异性算法与各向同性算法计算的页岩AVO响应差异较小,利用各向同性叠前反演方法进行页岩储层预测具有可行性。
Because of the particular depositional mode,black organic matter-rich shales are generally characterized by strong velocity anisotropy; however,most researches on shale are on the basis of isotropic theory,which obviously ignores the geological characteristics of shale.In this paper,anisotropic parameters of shale are calculated by combining rock mechanical measurements in the laboratory with the empirical methods from the literature.On the one hand,the parameters are used to investigate their effects on the calculation of velocity versus bedding direction and rock mechanical parameters,and the result shows that the anisotropic characteristics of shale cannot be neglected when the dip angle of the strata is large.On the other hand,little difference between AVO responses of anisotropic and isotropic methods when the incidence angle is less than 40° indicates the feasibility of isotropic pre-stack seismic inversion in predicting shale " sweet spot".
Because of the particular depositional mode,black organic matter-rich shales are generally characterized by strong velocity anisotropy; however,most researches on shale are on the basis of isotropic theory,which obviously ignores the geological characteristics of shale.In this paper,anisotropic parameters of shale are calculated by combining rock mechanical measurements in the laboratory with the empirical methods from the literature.On the one hand,the parameters are used to investigate their effects on the calculation of velocity versus bedding direction and rock mechanical parameters,and the result shows that the anisotropic characteristics of shale cannot be neglected when the dip angle of the strata is large.On the other hand,little difference between AVO responses of anisotropic and isotropic methods when the incidence angle is less than 40° indicates the feasibility of isotropic pre-stack seismic inversion in predicting shale " sweet spot".
引文
[1]郭旭升,李宇平,刘若冰,等.四川盆地焦石坝地区龙马溪组页岩微观孔隙结构特征及其控制因素[J].天然气工业,2014,34(6):9-16.Guo X S,Li Y P,Liu R B,et al.Characteristics and controlling factors of micro-pore structures of Longmaxi Shale Play in the Jiaoshiba area,Sichuan Basin[J]. Natural Gas Industry,2014,34(6):9-16.
[2] Vernik L,Liu X. Velocity anisotropy in shales:A petrophyscial study[J].Geophysics,1997,62(2):521-532.
[3] Vernik L,Milovac J.Rock physics of organic shales[J].The Leading Edge,2011,Special Section:Shales:318-323.
[4] Sayer C.The effect of kerogen on the elastic anisotropy of organicrich shales[J].Geophysics,2013,78(2):65-74.
[5] Sayers C. Seismic anisotropy of shales[J]. Geophysical Prospecting,2005,63:667-676.
[6]郭彤楼,刘若冰.复杂构造区高演化程度海相页岩气勘探突破的启示——以四川盆地东部盆缘JY1井为例[J].天然气地球科学,2013,24(4):643-650.Guo T L,Liu R B. Implications from marine shale gas exploration breakthrough in complicated structural area at high thermal stage:Taking Longmaxi Formation in well JY1 as an example[J].Natural Gas Geoscience,2013,24(4):613-650.
[7] Thomsen L. Weak elastic anisotropy[J]. Geophysics,1986,51(10):1954-66.
[8]唐杰.各向异性岩石的静态模量与动态模量实验研究[J].岩石力学与工程学报,2014,33(s1):3185-3191.Tang J.Experimental study of static and dynamic moduli for anisotropic rock[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(s1):3785-3191.
[9] Luan X Y,Di B R,Wei J X,et al.Laboratory measurements of brittleness anisotropy in synthetic shale with different cementation[C]//Expanded Abstracts of the 84thAnnual SEG Meeting,Society of Exploration Geophysicists,2014:26-31.
[10] Ryan-Grigor S.Empirical relationships between transverse isotropy parameters and VP/VS:Implications for AVO[J]. Geophysics,1997,62(5):1359-1364.
[11] Li Y Y.An empirical method for estimation of anisotropic parameters in clastic rocks[J].The Leading Edge,2006,25:706-711.
[12] Hiroki S.Mechanical properties of shale gas reservoir rocks and its relation to the insi-tu stress variation observed in shale gas reservoir[D].Stanford University,2012:38-44.
[13] Sayers C. The effect of anisotropy on the Young's moduli and Poisson's ratios of shales[J]. Geophysical Prospecting,2013,61:416-426.
[14] Deng J X,Shen H,Xu Z H,et al.Dynamic elastic properties of the Wufeng-Longmaxi formation shale in the southeast margin of the Sichuan Basin[J].Journal Geophysics Engineering,2014,11:1-11.
[15]陈颙,黄庭芳.岩石物理学[M].北京:北京大学出版社,2001:35-38.Chen Y,Huang T F. Rock Phycis[M]. Beijing:Peking University Press,2001:35-38.
[16]陈祖庆.海相页岩TOC地震定量预测技术及应用——以四川盆地焦石坝地区为例[J].天然气工业,2014,34(6):24-29.Chen Z Q. Quantitative seismic prediction technique of marine shale TOC and its application:A case from the Longmaxi Shale Play in the Jiaoshiba area,SichuanBasin[J].Natural Gas Industry,2014,34(6):24-29.
[17] Sena A,Castillo G,Chesser K.Seismic reservoir characterization in resource shale plays:Stress analysis and sweet spot discrimination[J].The Leading Edge,2011,Special Section:Practical Applications of Anisotropy:758-764.
[18] Wright J.The effects of transverse isotropy on reflection amplitude versus offset[J].Geophsics,1987,52(4):564-567.
[19] Thomsen L.Weak anisotropic reflections,Offset Dependent Reflectivity:Theory and Practice of AVO analysis[C]//Expanded Abstracts of the 73rdAnnual SEG Meeting,Society of Exploration Geophysicists,2013.
[20] Ruger A.Reflection coefficients and azimuthal AVO Analysis in anisotropic media[C]//SEG Geophysical Monograph Series Number10,Society Exploration Geophysicists,2002.
[21] Rickman R,Mullen M,Petre E.A practical use of shale petrophysics for stimulation design optimization:All shale plays are not clones of the Barnett Shale[C]//Denver:SPE Annual Technical Conference and Exhibition,2008.
[22] Thomsen L.On the use of isotropic parametersλ,E,ν,K to understand anisotropic shale behavior[C]//Expanded Abstracts of the83rdAnnual SEG Meeting,Society of Exploration Geophysicists,2013:320-324.
[2] Vernik L,Liu X. Velocity anisotropy in shales:A petrophyscial study[J].Geophysics,1997,62(2):521-532.
[3] Vernik L,Milovac J.Rock physics of organic shales[J].The Leading Edge,2011,Special Section:Shales:318-323.
[4] Sayer C.The effect of kerogen on the elastic anisotropy of organicrich shales[J].Geophysics,2013,78(2):65-74.
[5] Sayers C. Seismic anisotropy of shales[J]. Geophysical Prospecting,2005,63:667-676.
[6]郭彤楼,刘若冰.复杂构造区高演化程度海相页岩气勘探突破的启示——以四川盆地东部盆缘JY1井为例[J].天然气地球科学,2013,24(4):643-650.Guo T L,Liu R B. Implications from marine shale gas exploration breakthrough in complicated structural area at high thermal stage:Taking Longmaxi Formation in well JY1 as an example[J].Natural Gas Geoscience,2013,24(4):613-650.
[7] Thomsen L. Weak elastic anisotropy[J]. Geophysics,1986,51(10):1954-66.
[8]唐杰.各向异性岩石的静态模量与动态模量实验研究[J].岩石力学与工程学报,2014,33(s1):3185-3191.Tang J.Experimental study of static and dynamic moduli for anisotropic rock[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(s1):3785-3191.
[9] Luan X Y,Di B R,Wei J X,et al.Laboratory measurements of brittleness anisotropy in synthetic shale with different cementation[C]//Expanded Abstracts of the 84thAnnual SEG Meeting,Society of Exploration Geophysicists,2014:26-31.
[10] Ryan-Grigor S.Empirical relationships between transverse isotropy parameters and VP/VS:Implications for AVO[J]. Geophysics,1997,62(5):1359-1364.
[11] Li Y Y.An empirical method for estimation of anisotropic parameters in clastic rocks[J].The Leading Edge,2006,25:706-711.
[12] Hiroki S.Mechanical properties of shale gas reservoir rocks and its relation to the insi-tu stress variation observed in shale gas reservoir[D].Stanford University,2012:38-44.
[13] Sayers C. The effect of anisotropy on the Young's moduli and Poisson's ratios of shales[J]. Geophysical Prospecting,2013,61:416-426.
[14] Deng J X,Shen H,Xu Z H,et al.Dynamic elastic properties of the Wufeng-Longmaxi formation shale in the southeast margin of the Sichuan Basin[J].Journal Geophysics Engineering,2014,11:1-11.
[15]陈颙,黄庭芳.岩石物理学[M].北京:北京大学出版社,2001:35-38.Chen Y,Huang T F. Rock Phycis[M]. Beijing:Peking University Press,2001:35-38.
[16]陈祖庆.海相页岩TOC地震定量预测技术及应用——以四川盆地焦石坝地区为例[J].天然气工业,2014,34(6):24-29.Chen Z Q. Quantitative seismic prediction technique of marine shale TOC and its application:A case from the Longmaxi Shale Play in the Jiaoshiba area,SichuanBasin[J].Natural Gas Industry,2014,34(6):24-29.
[17] Sena A,Castillo G,Chesser K.Seismic reservoir characterization in resource shale plays:Stress analysis and sweet spot discrimination[J].The Leading Edge,2011,Special Section:Practical Applications of Anisotropy:758-764.
[18] Wright J.The effects of transverse isotropy on reflection amplitude versus offset[J].Geophsics,1987,52(4):564-567.
[19] Thomsen L.Weak anisotropic reflections,Offset Dependent Reflectivity:Theory and Practice of AVO analysis[C]//Expanded Abstracts of the 73rdAnnual SEG Meeting,Society of Exploration Geophysicists,2013.
[20] Ruger A.Reflection coefficients and azimuthal AVO Analysis in anisotropic media[C]//SEG Geophysical Monograph Series Number10,Society Exploration Geophysicists,2002.
[21] Rickman R,Mullen M,Petre E.A practical use of shale petrophysics for stimulation design optimization:All shale plays are not clones of the Barnett Shale[C]//Denver:SPE Annual Technical Conference and Exhibition,2008.
[22] Thomsen L.On the use of isotropic parametersλ,E,ν,K to understand anisotropic shale behavior[C]//Expanded Abstracts of the83rdAnnual SEG Meeting,Society of Exploration Geophysicists,2013:320-324.