Impacts of anisotropy on the dynamic and static elastic characteristics of shales under stress effects
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摘要: 静态弹性力学参数是页岩油开采及注水压裂工程的关键参数, 应力效应下各向异性对页岩动静态弹性特征具有重要的影响, 开展储层动静态弹性特征的主控因素与控制机理研究是页岩油气开采及注水压裂工程中一项亟须解决的关键科学问题。通过不同加压方式下页岩的三轴压缩力学与声学联测实验, 研究各向异性对页岩纵、横波速度及宏观力学性质的影响, 探究页岩动静态弹性特征的响应规律。结果表明:①随压力的增加, 页岩动、静态杨氏模量增大, 且增大速率由快到慢趋于稳定值; ②层理角度一定时, 动态杨氏模量大于静态杨氏模量, 二者呈正相关, 动、静态泊松比关系较差; ③岩石动、静态刚度系数均随围压增大而增大, 与纵波相关的动态刚度系数C11、C33比与横波相关的动态刚度系数C44、C66变化更明显; ④页岩动、静态各向异性均随围压的增大而增大。研究结果可以揭示页岩动、静态弹性特征响应机理, 并能够为页岩油气储层开采与水力压裂改造提供关键力学参数。Abstract: The static elastic parameters are crucial for shale oil and gas production and fracturing through water injection. Under stress effects, anisotropy exerts significant impacts on the dynamic and static elastic characteristics of shales. Investigating the dominant factors and mechanisms controlling reservoirs' dynamic and static elastic characteristics is a burning key scientific problem in shale oil and gas production and fracturing through water injection. Based on triaxial compression tests combining mechanics and acoustics for shales under different pressurization methods, this study delved into the impacts of anisotropy on the compressional/shear wave (P-and S-wave) velocities and macromechanical properties of shales, and the response patterns of dynamic and static elastic characteristics of shales. The results are as follows: (1) With an increase in the pressure, the dynamic and static Young's moduli of shales increase at a gradually decelerating rate, finally tending to be stable; (2) At certain bedding angles, the dynamic and static Young's moduli are positively correlated, with the former higher than the latter, whereas the dynamic and static Poisson's ratios manifest a subtle correlation; (3) The dynamic and static stiffness coefficients of shales increase with the confining pressure. The P-wave-related dynamic stiffness coefficients C11 and C33 display more significant changes than the S-wave-related dynamic stiffness coefficients C44 and C66; (4) The dynamic and static anisotropies of shales also increase with the confining pressure. The results of this study reveal the response mechanisms of the dynamic and static elastic characteristics of shales while providing crucial mechanical parameters for the exploitation and hydraulic fracturing of shale oil and gas reservoirs, thus demonstrating significant scientific research value.
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Key words:
- shale /
- anisotropy /
- elastic property /
- static modulus /
- formation pressure
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[1] Wang Y, Zhao L X, Han D H, et al.Anisotropic dynamic and static mechanical properties of organic-rich shale:The influence of stress[J].Geophysics, 2021, 86(2):C51-C63.
[2] Gong F, Di B R, Zeng L B, et al.Static and dynamic linear compressibility of dry artificial and natural shales under confining pressure[J].Journal of Petroleum Science and Engineering, 2020, 192:107242.
[3] Bustin A M M, Bustin R M.Importance of rock properties on the producibility of gas shales[J].International Journal of Coal Geo-logy, 2012, 103:132-147.
[4] Sone H, Zoback M D.Mechanical properties of shale-gas reservoir rocks:Part 1:Static and dynamic elastic properties and anisotropy[J].Geophysics, 2013, 78(5):D381-D392.
[5] Barree R D, Cox S A, Miskimins J L, et al.Economic optimization of horizontal-well completions in unconventional reservoirs[J].SPE Production & Operations, 2015, 30(4):293-311.
[6] Jin Y, Chen K P, Chen M.Analytical solution and mechanisms of fluid production from hydraulically fractured wells with finite fracture conductivity[J].Journal of Engineering Mathematics, 2015, 92(1):103-122.
[7] Zhang F S, Damjanac B, Maxwell S.Investigating hydraulic fracturing complexity in naturally fractured rock masses using fully coupled multiscale numerical modeling[J].Rock Mechanics and Rock Engineering, 2019, 52(12):5137-5160.
[8] Holt R M, Fjær E, Stenebråten J F, et al.Brittleness of shales:Relevance to borehole collapse and hydraulic fracturing[J].Journal of Petroleum Science and Engineering, 2015, 131:200-209.
[9] Vahid S, Ahmad G.Hydraulic fracture initiation from a wellbore in transversely isotropic rock[C]//45thUS Rock Mechanics/Geomechanics Symposium, OnePetro, 2011.
[10] Bian H Y, Wang F, Zhang C G, et al.A new model between dynamic and static elastic parameters of shale based on experimental studies[J].Arabian Journal of Geosciences, 2019, 12(19):609.
[11] Canady W.A method for full-range Young’s modulus correction[C]// SPE.The Woodlands, Texas, USA, 2011.
[12] Dong Y, Lu N, McCartney J S.Scaling shear modulus from small to finite strain for unsaturated soils[J].Journal of Geotechnical and Geoenvironmental Engineering, 2018, 144(2):04017110.
[13] Hornby B E, Schwartz L M, Hudson J A.Anisotropic effective-medium modeling of the elastic properties of shales[J].Geophysics, 1994, 59(10):1570-1583.
[14] Kaarsberg E A.Introductory studies of natural and artificial argillaceous aggregates by sound-propagation and X-ray diffraction methods[J].The Journal of Geology, 1959, 67(4):447-472.
[15] Zhao L X, Qin X, Zhang J Q, et al.An effective reservoir parameter for seismic characterization of organic shale reservoir[J].Surveys in Geophysics, 2018, 39(3):509-541.
[16] Johnston D H.Physical properties of shale at temperature and pressure[J].Geophysics, 1987, 52(10):1391-1401.
[17] Miller D, Plumb R, Boitnott G.Compressive strength and elastic properties of a transversely isotropic calcareous mudstone[J].Geophysical Prospecting, 2013, 61(2):315-328.
[18] Liu Q, Liang B, Sun W J, et al.Experimental study on the difference of shale mechanical properties[J].Advances in Civil Engineering, 2021, (1):1-14.
[19] Li C B, Zou B B, Zhou H W, et al.Experimental investigation on failure behaviors and mechanism of an anisotropic shale in direct tension[J].Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 2021, 7(4):98.
[20] Davarpanah S M, Ván P, Vásárhelyi B.Investigation of the relationship between dynamic and static deformation moduli of rocks[J].Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 2020, 6(1):29.
[21] 边会媛, 王飞, 张永浩, 等.储层条件下致密砂岩动静态弹性力学参数实验研究[J].岩石力学与工程学报, 2015, 34(S1):3045-3054.
Bian H Y, Wang F, Zhang Y H, et al.Experimental study of dynamic and static elastic parameters of tight sandstones under reservoir conditions[J].Chinese Journal of Rock Mechanics and Engineering, 2015, 34(S1):3045-3054.
[22] 王飞, 边会媛, 张永浩, 等.不同温压下页岩动态与静态弹性模量转换研究[J].石油与天然气地质, 2018, 39(5):1048-1055.
Wang F, Bian H Y, Zhang Y H, et al.Experimental study on dynamic and static elastic modulus conversion forshale under different temperatures and pressures[J].Oil & Geology, 2018, 39(5):1048-1055.
[23] 赵贤正, 周立宏, 蒲秀刚, 等.湖相页岩滞留烃形成条件与富集模式--以渤海湾盆地黄骅坳陷古近系为例[J].石油勘探与开发, 2020, 47(5):856-869.
Zhao X Z, Zhou L H, Pu X G, et al.Formation conditions and enrichment model of retained petroleum in lacustrine shale:A case study of the Paleogene in Huanghua depression, Bohai Bay Basin, China[J].Petroleum Exploration & Development, 2020, 47(5):856-869.
[24] 马霄一, 李呈呈, 白俊, 等.基于超声测试的页岩岩石物理特征分析[J].石油地球物理勘探, 2021, 56(4):801-808, 673.
Ma X Y, Li C C, Bai J, et al.Analysis of physical characteristics of shale rock based on ultrasonic testing[J].Oil Geophysical Prospecting, 2021, 56(4):801-808, 673.
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