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碳酸盐岩洞缝型油气藏是我国乃至世界的重要油气藏类型之一,属典型的复杂非均匀介质。其中,岩溶洞穴型油气藏是最容易发现的。为了解决这类储层的勘探开发及预测问题,需要从理论上对它们的地震波场进行研究。我们利用随机介质模型和非均匀介质弹性波动方程计算了不同高度和宽度的充满流体藏层的合成地震剖面。结果表明当绕射波偏移为珠子状的同相轴时即使远小于四分之一波长的溶洞在常规带宽的地震剖面上也是可分辨的,绕射波是溶洞高度和宽读的函数。我们引人一个宽度-振幅因子。可以用这个宽度-振幅因子从对无限宽溶洞计算的绕射波计算有限宽度的溶洞的绕射振幅。
Carbonate cave fractured reservoirs are one of the most important types of reservoirs in China and the world, and are typical heterogeneous heterogeneous media. Among them, karst cave reservoirs are the most easily found. In order to solve the exploration, development and prediction of such reservoirs, it is necessary to theoretically study their seismic wavefields. We calculate synthetic seismic sections filled with fluid reservoirs of different heights and widths using random medium models and inhomogeneous medium elastic wave equations. The results show that even a much smaller than one quarter wavelength karst cave is resolvable on a conventional bandwidth seismic profile when the diffraction wave is shifted to a bead-shaped axis and the diffraction wave is a function of karst height and width. We introduce a width-amplitude factor. This width-amplitude factor can be used to calculate the diffraction amplitude of a finite width of karst caves from a diffraction wave calculated for an infinite width of karst cave.