东海西湖凹陷平湖组富煤环境相控储层预测技术

A New Phase-controlled Reservoir Prediction Technique for Coal-rich Environment in the Pinghu Formation of the Xihu Sag,the East China Sea

储层预测的常规方法是地震确定性反演和叠后地质统计学反演,但这些方法难以解决复杂地质背景中薄储层的预测。西湖凹陷平湖组埋深大,沉积环境复杂,储层相变快且普遍发育薄煤层,其储层预测一直是勘探开发的重点和难点。采用分步反演方法,在地质模式的指导下,基于本区岩石物理特征,优先利用叠后地质统计学反演方法预测煤层,再将煤层作为已知的岩相信息,建立三维岩相比例体,用于约束叠前地质统计学反演方法,进而达到提高分辨率、精细雕刻富煤环境中薄储层的目的。该技术有效解决了东海煤系地层储层预测可靠性差的难题,保障了开发井的顺利实施,将平湖组储层预测精度提高了15%,深化了沉积储层认识,具有较大的推广应用价值。

Although deterministic inversion and post-stack geostatistical inversion have been widely used in reservoir prediction,they are not very effective in predicting thin reservoirs in complex geological background.In the Xihu Sag,difficulties in exploration and development have been caused by four problems,i.e.,large burial depth,complex sedimentary environment,rapid reservoir phase transition and thin coal seams.Based on regional geological modelling and rock physical characteristics,the post-stack geostatistical method is likely better in coal seam prediction.The coal seam is taken as a known geological parameter to constrain the pre-stack geostatistical inversion.Consequently,seismic resolution is enhanced and fine thin reservoirs are delineated.This technique could solve the current poor reservoir prediction in the East China Sea,and facilitates well development.More importantly,the accuracy of reservoir prediction is improved by 15%,and the understanding in the reservoir sedimentation is enhanced,which makes this technique more applicable in other places.