东海盆地西湖凹陷W气田平湖组煤系潮控砂体储层地震预测

东海西湖凹陷油气资源丰富，具有较好的勘探开发潜力，其中平湖组作为重要的含油气层系，已成为近期勘探开发的焦点。平湖组普遍发育薄煤层，导致含油气砂体的地震响应存在多解性，严重制约着开发生产。为了识别薄煤层影响下的含油气砂岩，开展了储层地震预测研究工作。首先，通过岩芯、测井和分析化验资料解析了潮控沉积环境特征；然后，利用岩石物理分析技术归纳总结了在薄煤层影响下含水砂岩、含气砂层的叠前道集响应规律；最后，利用地球物理属性完成了潮控砂体储层预测，并结合沉积特征实现研究区有利目标优选。研究表明：平湖组以潮控三角洲-潮汐沉积环境为主，其中，水下分流河道、河口坝和潮汐砂坝等沉积微相是优势储集体；砂体储层受到薄煤层影响呈现近道为波峰、远道为波谷的Ⅱ -p类AVO特征；利用叠前道集响应规律指导叠前纵波速度/横波速度（Vp/Vs）反演，完成潮控储层定量预测；综合古地貌和沉积微相认识，实现了研究区潮控环境下潜力精细描述，明确③号砂体属于一类有利目标，可作为潜力目标。本研究方法有效提高了研究区储层预测工作的精确度，为该区块下一步深层煤系潮控砂体的井位部署提供了技术支撑。

Seismic prediction of tide-controlled sand reservoir in Pinghu Formation coal seam,W Gas Field,Xihu Sag,East China Sea Basin

The Xihu Sag in the East China Sea is rich in oil and gas resources and has good exploration and development potential. Pinghu Formation, as an important oil-bearing horizon, has become the focus of exploration and development in the near future. Thin coal seams are widely developed in Pinghu Formation, which leads to multiple solutions of seismic amplitude, phase, and frequency of oil-bearing sand bodies, which seriously restricts the development and production. To identify oil-bearing sandstone under the influence of thin coal seams, reservoir earthquake prediction was carried out. First, the characteristics of tide-controlled sedimentary environment were analyzed in detail through core, well logging, and analytical laboratory data. Then, using rock physical analysis technology, the characteristics of pre-stack collection response of water-bearing sandstone and gas-bearing sand under the influence of thin coal seams were summarized. Finally, the geophysical properties were used to predict the reservoir of tide-controlled sand body, and the favorable target selection in the study area was realized in combination with the sedimentary characteristics. Results show that the Pinghu Formation mainly developed tide-controlled delta-tidal sedimentary environment, in which underwater distributary channel, estuary bar, and tidal sand bar were the dominant sedimentary microfacies. Under the influence of thin coal seam, the sand-body reservoir shows AVO type-Ⅱ response characteristics with wave crest in the short path and trough in the far path. Using prestack gathers response law to guide the P/S velocity ratio inversion, control reservoir quantitative prediction was completed. Based on the understanding of paleo-geomorphology and sedimentary microfacies, the potential of the tidal control environment in the study area could be accurately described, and No.3 sand body is a favorable and potential target. This method improved effectively the accuracy of reservoir prediction in the study area, and provided a technical support for the well location deployment of the deep coal measure tidal control sand body in the block.