塔河油田南部缝孔型碳酸盐岩储层叠前地震预测

Pre-stack seismic prediction of fractured-vuggy carbonate reservoirs in the south of Tahe oilfield

塔河油田南部中、下奥陶统碳酸盐岩储层以裂缝型储层为主,经溶蚀形成缝孔型有效储集体。裂缝的展布受断裂控制,油层厚度小,水体活跃。储层具有大小规模不同、空间分布形态不规则、充填性质各异的缝孔组合特征。针对这类缝孔型储层,提出了叠前地震各向异性分析和叠前弹性参数反演预测方法。实际地震资料的应用表明,前者能有效预测裂缝发育强度及方位,结合井资料后者能有效预测缝孔带发育级别及含流体指示,两项预测结果与已知的缝洞储层及钻探结果基本吻合。两项叠前地震预测技术均揭示了塔河南部视层状区域呈块体状及条带状展布的几个有利缝孔储集发育带,从而提高了预测小尺度缝孔型碳酸盐岩储层空间展布规律的能力。

The carbonate reservoirs of the Middle and Lower Ordovician in southern Tahe oilfield are mainly of fractured-vuggy type featured in effective fractures and vugs formed by dissolution. The distribution of fractures in these reservoirs is controlled by faults, the oil layers are thin, and water bodies are active. The fracture-vug combinations are of different scales, irregular spatial distributions, and various filling properties. In view of the characteristics of the fractured-vuggy carbonate reservoirs in the study area, two techniques are presented, namely the pre-stack anisotropy analysis technology for detecting the intensity and azimuth of fractures and the pre-stack elastic parameter inversion method for predicting, in combination with log data, the growth of the fractured-vuggy zones and fluid-bearing indicators. The application of the techniques in southern Tahe oilfield reveals that the prediction results are basically consistent with data gathered from the known fractured-vuggy reservoirs and drilling data. The application of these two techniques has improved the prediction of spatial distribution of smallscale fractured-vuggy reservoirs and also shows that there are several favorable fractured-vuggy zones distributed in the southern Tahe oilfield.