黏弹性裂缝诱导各向异性介质地震波场传播特征——以束鹿凹陷沙河街组三段下亚段泥灰岩储层为例

广泛发育裂缝的泥灰岩储层具有复杂的黏弹性和各向异性性质,使得地震波在其中的传播机理尚不完全清楚,这成为制约该类储层油气勘探取得进一步突破的重要因素。综合考虑裂缝储层的各向异性与黏弹性性质,利用Kelvin-Voigt黏弹性模型、线性滑动裂缝模型与Hudson模型,构建了黏弹性各向异性裂缝性储层等效介质模型;采用旋转交错网格有限差分算法近似计算空间导数,同时采用复频移递归积分非分裂PML边界条件来吸收边界反射,进而对所建立的等效介质模型的地震波场进行数值模拟。研究结果显示地震波传播特征受基质Q值、裂缝充填流体、裂缝体密度及裂缝倾角与方位角等参数的影响。

Seismic wave field propagation characteristics of viscoelastic fracture-induced anisotropic medium:a case study of calcilutite reservoirs in the lower part of Member 3 of Shahejie Formation,Shulu sag

Calcilutite reservoirs with wide development of fissures have complex viscoelastic and anisotropic properties, leading to a vague understanding of seismic wave propagation mechanism, which has become an important factor to restrict further breakthroughs in hydrocarbon exploration in this type of reservoir. In comprehensive consideration of viscoelastic and anisotropic properties of fissure reservoirs, an equivalent medium model was established for viscoelastic-anisotropic fissure reservoirs using Kelvin-Voigt viscoelastic model, linear sliding fissure model and Hudson model. The rotated staggered grid finite-difference algorithm was adopted for approximate calculation of spatial derivative. Meanwhile, the complex frequency shift recursive integral NPML boundary condition was utilized to absorb boundary reflection, so as to perform numerical simulation on seismic wave of equivalent medium model. Research results demonstrate that the seismic wave propagation characteristics are influenced by matrix Q value, filling fluids, volume density, dip angle and azimuth of fissures and other parameters.