自然伽马反演在双家坝构造飞仙关组鲕滩储层预测中的应用

以往川东地区飞仙关组鲕滩储层预测,主要采用常规剖面寻找"亮点"反射,或作速度反演寻找低速异常体,取得了一定的效果。但是随着勘探的深入,认识到"亮点"反射或低速异常体不一定真正是鲕滩储层的地震响应。当飞一—飞三段内发育有膏盐层或较厚的泥灰岩段时,也会形成"亮点"反射或低速异常体,如果只靠常规剖面或速度反演,就可能造成误解。针对这种情况,采用伽马反演,来排除因泥质含量增加形成的低速异常现象,再结合速度反演,较准确地预测出了双家坝地区飞仙关组鲕滩的发育情况,落实了其分布范围,为下一步勘探提供了可靠的资料。

Application of natural gamma inversion in the prediction for the oolitic beach reservoir in Feixianguan Formation in Shuanjiaba Structure

The prediction for oolitic reservoirs of Feixianguan Formation was used to looking for bright spots on conventional sections or for low velocity anomalies on velocity data set in east Sichuan. However, bright spots and low velocity anomalies is not always the seismic responses from oolitic reservoirs. If there are gypsum or thick marlite intervals, bright spots and low velocity anomalies may appear. To cope with this problem, we used gamma inversion to rule out the low velocity anomalies that caused by increment of shale content, and then predicted the distribution of oolitic beach of Feixianguan Formation in Shuangjiaba area in combination with velocity inversion. Desire results have been yielded.