The impact of CO2 sequestration on the host formation is an issue occurring over geologic time. Laboratory tests can provide important results to investigate this matter but have limitations due to a relatively short ...The impact of CO2 sequestration on the host formation is an issue occurring over geologic time. Laboratory tests can provide important results to investigate this matter but have limitations due to a relatively short timeline. Based on literature review and core sample observation, naturally occurred geological phenomena, stylolites are studied in this paper for understanding CO2 sequestration in deep carbonate formations. Stylolites are distinctive and pervasive structures in carbonates that are related to water-assisted pressure solution. Pressure solution involving stylolitization is thought to be the main mechanism of compaction and cementation for many carbonates. In parallel, CO2 sequestration in carbonate formation involves extensive chemical reactions among water, CO2 and rock matrix, favoring chemical compaction as a consequence. An analogue between stylolites and CO2 sequestration induced formation heterogeneity exists in the sense of chemical compaction, as both pressure solution in stylolites and CO2 enriched solution in CO2 sequestration in carbonate formations may all introduce abnormal porous regions. The shear and/or tension fractures associated with stylolites zones may develop vertically or sub-vertically; all these give us alert for long-term safety of CO2 sequestration. Thus a study of stylolites will help to understand the CO2 sequestration in deep carbonate formation in the long run.展开更多
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
基金funded by US Department of Energy through contracts of DE-FC26- 05NT42592 (CO2 sequestration) and DE-FC26- 08NT0005643 (Bakken Geomechanics)by North Dakota Industry Commission together with five industrial sponsors (Denbury Resources Inc., Hess Corporation, Marathon Oil Company, St. Mary Land & Exploration Company, and Whiting Petroleum Corporation) under contract NDIC-G015-031by North Dakota Department of Commerce through UND’s Petroleum Research, Education and Entrepreneurship Center of Excellence (PREEC)
文摘The impact of CO2 sequestration on the host formation is an issue occurring over geologic time. Laboratory tests can provide important results to investigate this matter but have limitations due to a relatively short timeline. Based on literature review and core sample observation, naturally occurred geological phenomena, stylolites are studied in this paper for understanding CO2 sequestration in deep carbonate formations. Stylolites are distinctive and pervasive structures in carbonates that are related to water-assisted pressure solution. Pressure solution involving stylolitization is thought to be the main mechanism of compaction and cementation for many carbonates. In parallel, CO2 sequestration in carbonate formation involves extensive chemical reactions among water, CO2 and rock matrix, favoring chemical compaction as a consequence. An analogue between stylolites and CO2 sequestration induced formation heterogeneity exists in the sense of chemical compaction, as both pressure solution in stylolites and CO2 enriched solution in CO2 sequestration in carbonate formations may all introduce abnormal porous regions. The shear and/or tension fractures associated with stylolites zones may develop vertically or sub-vertically; all these give us alert for long-term safety of CO2 sequestration. Thus a study of stylolites will help to understand the CO2 sequestration in deep carbonate formation in the long run.
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.
