Wave-induced fluid pressure diffusion and anelasticity in partially saturated rocks: the influences of boundary conditions
Wave-induced fluid pressure diffusion and anelasticity in partially saturated rocks: the influences of boundary conditions
复制标题
部分饱和岩石中波浪引起的流体压力扩散和滞弹性：边界条件的影响
DOI：
10.5281/zenodo.4333180
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发表时间：
2020-12
期刊：
影响因子：
3.3
通讯作者：
Jianhua Geng
中科院分区：
文献类型：
--
作者：
Wang Yirong;Zhao Luanxiao;Cao Chenghao;Yao Qiuliang;Yang Zhifang;Cao Hong;Jianhua Geng
完全或部分饱和岩石中的开放或部分开放边界条件可能出现在许多现实地质场景中，了解波致流体压力扩散和滞弹性对许多地球科学和工程应用领域的影响是至关重要的。在毕奥孔隙弹性理论框架下，通过引入一个尺度因子来表征边界的张开程度，研究了边界条件对部分饱和岩石中地震波频散和衰减的影响。研究发现，存在两种类型的流体压力扩散同时发生：两种不混溶流体（如气体和盐水）之间的介观流体压力扩散和与外边界相关联的流体流动。边界条件显著地控制地震波的频散和衰减特征。细观渗流和外边界流的耦合作用加速了孔隙水压力的平衡过程，使特征频率比不排水情况高一个数量级。排水和部分排水条件也显着降低部分饱和岩石的速度，这可能甚至低于Gassmann的预测和干燥的岩石。通过与数值模拟结果对比，验证了理论模型的可靠性。我们证明，该模型能够更好地解释测井数据的速度-饱和度关系的部分饱和碳酸盐岩储层和实验数据的波频散的完全饱和砂岩，这两个都可能暴露于开放的边界条件。
Open or partially open boundary conditions in fully or partially saturated rocks possibly occur in many realistic geological scenarios, and it is critical to understand the influences of wave-induced fluid pressure diffusion and anelasticity for many fields of Earth science and engineering applications. Under the framework of Biots poroelasticity, by proposing a scale factor to represent the opening degree of the boundary, we have investigated the influences of boundary conditions on the seismic wave dispersion and attenuation in partially saturated rocks. It is found that there exist two types of fluid pressure diffusion taking place simultaneously: the mesoscopic fluid pressure diffusion between the two immiscible fluids (e.g. gas and brine) and the fluid flow associated with the outer boundary. The boundary conditions significantly control the seismic wave dispersion and attenuation signatures. The coupled fluid pressure diffusion of mesoscopic flow and outer boundary flow expedite the pore pressure equilibration processes and make the characteristic frequency one order of magnitude higher than the undrained scenario. The drained and partially drained condition also significantly decrease the velocity of partially saturated rocks, which can be even lower than that of Gassmanns prediction and dry rock. The reliability of the theoretical model is also validated by comparing it with numerical simulation for both drained and undrained conditions. We demonstrate that the proposed model is capable of better interpreting the logging data of velocity-saturation relationship for a partially saturated carbonate reservoir and experimental data of wave dispersion for a fully saturated sandstone, both of which are possibly exposed to the open boundary conditions.
DOI：
10.1002/jgrb.50090
发表时间：
2013-03
期刊：
Journal of Geophysical Research: Solid Earth
影响因子：
--
作者：
L. Adam;Thomas L. Otheim
通讯作者：
L. Adam;Thomas L. Otheim
影响因子：
2.8
作者：
J. Ba;J. Carcione;Weitao Sun
通讯作者：
J. Ba;J. Carcione;Weitao Sun