煤储层双相EDA介质的地震波场模拟

Seismic wave simulation of biphase EDA medium in coal-bed media

基于二维—二分量弹性波方程交错网格高阶有限差分法数值模拟,对各向同性介质模型、高裂隙密度含干裂隙和饱和水裂隙煤层各向异性介质和双相介质的二维层状模型进行了弹性波场数值模拟.结果表明:双相EDA介质中存在第二类纵波(慢纵波).各向异性理论和双相介质理论比单相理论要好,单相理论存在衰减问题.各向异性和双相理论在含气情况下比较近似,流相为水的双相理论更加复杂,流相为水的双相理论的地震属性值较小且规律不明显.目前认为双相介质模型和各向异性更符合实际情况,可以用其研究煤层气的富集区.

Based on 2-D, 2-C elastic wave-equation staggering grid high-order finite-difference numeric simulation, The numeric simulation of elastic wave field is carried out for the model of isotropy and anisotropy and biphase theory with watePsaturated and dry medium 2-D layered model with fracture-bearing coal seam with high fractured density. The results show that the biphase EDA medium exists second＇ mode of P-wave （ slow P wave）. In comparison with anisotropie theory and the biphase theory, the single phase elastic theory underestimates the attenuation of seismic waves. In a case of dry medium, the anisotropic theory and the biphase theory is similar. The biphase theory with the fluid is more complex, the seismic attribution data of which is smaller and the data regularity of which is not obvious. Currently, it is considered that the biphase theory and the anisotropie theory is more consistent with the practical situation, which can be used to study the rich Region of coalbed methane.