It is known that rock anisotropy can significantly influence the phase and energy velocities of an elastic wave,as well as its reflection/transmission(R/T)coefficients.As a result,it can distort the velocity analysis ...It is known that rock anisotropy can significantly influence the phase and energy velocities of an elastic wave,as well as its reflection/transmission(R/T)coefficients.As a result,it can distort the velocity analysis of seismic-reflection data.In this work we present a velocity analysis for seismic-reflection data based on the available anisotropic rock parameters.We analyzed the created errors on time-depth relation of the seismic-reflection data in neglecting rock anisotropy and/or neglecting the difference between energy velocity and phase velocity,including the case of wide-angle reflection.The calculated results show that the effect of rock anisotropy on time-depth relation of seismic-reflection data is dependent not only on the values of anisotropic parameters,but also on the space arrangement of both source and receiver-array.For all studied cases(weak,moderate or strong anisotropy),we found that the effect of rock anisotropy on time-depth relation could not be neglected.Nevertheless,for the case of weak anisotropy,the energy velocity may be replaceable by the phase velocity to obtain a very good approximation on time-depth relation.Consequently,the seismic-reflection data processing algorithm for numerical computations can be simplified.展开更多
We present a new solution for the elastic displacement and strain fields on or near Earth’s surface due to rectangular faults in an anisotropic half-space,expressed as a summation of(A)the solution in an infinite spa...We present a new solution for the elastic displacement and strain fields on or near Earth’s surface due to rectangular faults in an anisotropic half-space,expressed as a summation of(A)the solution in an infinite space which is singular,and(B)the complementary part which is regular and well-behaved.These two solutions are expressed in terms of the mathematically elegant and computationally powerful Stroh formalism and can be applied to the generally anisotropic rock half-space or a transversely isotropic rock mass with any oriented plane of isotropy.For any flat fault of polygonal shape,one needs only to carry out a simple line integral from 0 to 7 r in order to express the fault-induced response.Numerical examples are presented to demonstrate the significant effect of the rock anisotropy and layer orientation on the fault-induced displacement and strain fields in anisotropic rocks.Potential applications are wide ranging,from faults in sedimentary strata to strongly deformed metamorphic rocks with steeply dipping foliation.展开更多
A modified failure criterion is proposed to determine the strength of transversely isotropic rocks. Me-chanical properties of some metamorphic and sedimentary rocks including gneiss, slate, marble, schist, shale, sand...A modified failure criterion is proposed to determine the strength of transversely isotropic rocks. Me-chanical properties of some metamorphic and sedimentary rocks including gneiss, slate, marble, schist, shale, sandstone and limestone, which show transversely isotropic behavior, were taken into consider-ation. Afterward, introduced triaxial rock strength criterion was modified for transversely isotropic rocks. Through modification process an index was obtained that can be considered as a strength reduction parameter due to rock strength anisotropy. Comparison of the parameter with previous anisotropy in-dexes in literature showed reasonable results for the studied rock samples. The modified criterion was compared to modified Hoek-Brown and Ramamurthy criteria for different transversely isotropic rocks. It can be concluded that the modified failure criterion proposed in this study can be used for predicting the strength of transversely isotropic rocks.展开更多
基金supported by the National Natural Science Foundation of China(40974078)the US Department of Energy(DE-FC2608NT0 005643)+1 种基金the Natural Science Foundation of Shaanxi Province,China (2007D15)North Dakota Industrial Commission with five industrial companies:Encore Acquisition,Hess,Marathon Oil,St.Mary Land & Exploration,and Whiting Petroleum(NDIC-G015-031)
文摘It is known that rock anisotropy can significantly influence the phase and energy velocities of an elastic wave,as well as its reflection/transmission(R/T)coefficients.As a result,it can distort the velocity analysis of seismic-reflection data.In this work we present a velocity analysis for seismic-reflection data based on the available anisotropic rock parameters.We analyzed the created errors on time-depth relation of the seismic-reflection data in neglecting rock anisotropy and/or neglecting the difference between energy velocity and phase velocity,including the case of wide-angle reflection.The calculated results show that the effect of rock anisotropy on time-depth relation of seismic-reflection data is dependent not only on the values of anisotropic parameters,but also on the space arrangement of both source and receiver-array.For all studied cases(weak,moderate or strong anisotropy),we found that the effect of rock anisotropy on time-depth relation could not be neglected.Nevertheless,for the case of weak anisotropy,the energy velocity may be replaceable by the phase velocity to obtain a very good approximation on time-depth relation.Consequently,the seismic-reflection data processing algorithm for numerical computations can be simplified.
基金the China Scholarship Council(CSC) for supporting her visit at the University of Akron
文摘We present a new solution for the elastic displacement and strain fields on or near Earth’s surface due to rectangular faults in an anisotropic half-space,expressed as a summation of(A)the solution in an infinite space which is singular,and(B)the complementary part which is regular and well-behaved.These two solutions are expressed in terms of the mathematically elegant and computationally powerful Stroh formalism and can be applied to the generally anisotropic rock half-space or a transversely isotropic rock mass with any oriented plane of isotropy.For any flat fault of polygonal shape,one needs only to carry out a simple line integral from 0 to 7 r in order to express the fault-induced response.Numerical examples are presented to demonstrate the significant effect of the rock anisotropy and layer orientation on the fault-induced displacement and strain fields in anisotropic rocks.Potential applications are wide ranging,from faults in sedimentary strata to strongly deformed metamorphic rocks with steeply dipping foliation.
文摘A modified failure criterion is proposed to determine the strength of transversely isotropic rocks. Me-chanical properties of some metamorphic and sedimentary rocks including gneiss, slate, marble, schist, shale, sandstone and limestone, which show transversely isotropic behavior, were taken into consider-ation. Afterward, introduced triaxial rock strength criterion was modified for transversely isotropic rocks. Through modification process an index was obtained that can be considered as a strength reduction parameter due to rock strength anisotropy. Comparison of the parameter with previous anisotropy in-dexes in literature showed reasonable results for the studied rock samples. The modified criterion was compared to modified Hoek-Brown and Ramamurthy criteria for different transversely isotropic rocks. It can be concluded that the modified failure criterion proposed in this study can be used for predicting the strength of transversely isotropic rocks.
