振幅随方位角变化裂缝检测技术及其应用

AVA fracture detection and its application in JM area.

川西坳陷深层须家河组埋藏深,岩石超致密,具有很强的非均质性和各向异性。近年的勘探实践表明,裂缝是否发育对该地区深层超致密储层的孔隙度和渗透性的改善具有重大作用,是天然气能否富集、产出和高产的主控因素。目前,国外在利用P波振幅检测定向垂直裂缝方面取得了成功的经验,其本质是利用P波振幅随方位角变化(AVA)估算裂缝的方位和密度。为此,针对川西深层须家河组裂缝型气藏,利用宽方位采集的三维地震资料,研制并建立了一套预测裂缝方向和裂缝发育强度的P波方位各向异性裂缝检测技术,并且在JM地区三维地震勘探中进行了初步的应用研究,取得了较好的效果。

The reservoir of Xujiahe Formation in west Sichuan depression is deep buried, super-tight, less changeable in lithological parameters, and strongly in-homogeneous and anisotropic. Practice has proved that fracture helps enhance the porosity and permeability of the deep tight reservoirs, thus controls the concentration and production of natural gas. P-wave amplitude has been successfully applied to detect vertically oriented fractures by foreign colleagues. Essentially, this technique makes use of the fact that P-wave amplitude changes periodically with the orientation and density of the fractures. Taking the characteristics of the fractured reservoir of Xujiahe Formation into account, the author developed a suite of P-wave azimuthally anisotriopic fracture detection methods (AVA) to detect fracture azimuth and fracture density on wide azimuth 3D seismic data. The AVA technology has been successfully used in the 3D seismic exploration in JM area