利用错格虚谱法模拟礁、滩相储层地震波场

Application of staggerred pseudospectrum method in simulating seismic wave field of reef beach facies reservoirs

文中基于中国西部F地区的声波测井资料设计了四层礁、滩相地质模型,并用气、水分别替换礁、滩内部的流体,利用错格虚谱法模拟礁、滩相储层地震波场,避免了常规虚谱法在选用粗网格模拟小尺寸礁、滩时出现的不收敛现象,提高了计算效率。结果表明:①无论是含气还是含水,礁、滩相的边界与尺寸都能清晰分辨,但与礁、滩同时含气的模型相比,在滩含水、礁含气的模型中,礁边界成像较为清晰,滩边界较模糊;②若仅从完全弹性波动传播理论出发,从地表观测记录可以准确检测到深度大于3000m的小尺寸礁、滩结构,并且在已知围岩速度与孔隙度分布的前提下,可从地震剖面中直接识别礁、滩中的气、水分布。然而,在实际工作中,礁、滩的识别受到多种因素制约,尤其是地震波的衰减和频散,所以对于含流体的地层,其在地震频段的速度建模将是目前必须解决的一个难题。

Based on sonic log data in F area of western China, four-layer reef beach facies geological model was designed in this paper, air and water were used to replace the fluid inside the reef and beach, and the staggerred pseudospectrum method was used to simulate seismic wave field of the reef beach facies reservoirs, as a result the non-convergence was avoided when routine pseudospectrum method was used to simulate the small size reef and beach, and the calculation efficiency was raised. The studies achieved the following results: (1): whether reef and beach contain gas or water, their sizes and boundary can be clearly imaged, when comparing with the gas-bearing reef and beach model, for the model in which the reef bearing water and the beach bearing gas, reef’s boundary can be clearly imaged while the beach’s boundary was imaged fuzzily. (2): if totally based on full elastic wave propagation theory, small reef beach structure which is 3000 meter below the surface can be accurately detected from surface seismic data, if the surround rock’s velocity and porosity are known, the gas and water distribution can be directly detected from surface seismic data, but in real world the detecting of reef and beach are affected by many factors, especially the seismic wave attenuation and frequency dispersion, therefore for strata which contain fluid, the velocity modeling within the seismic frequency band will be the problem which must be overcame at the moment.