西湖凹陷B构造水下分流河道预测技术及应用

Technology for Prediction of Underwater Distributary Channel Reservoir and Application in B Structure,Xihu Sag

西湖凹陷B构造的砂岩储层具有低孔渗特征,且属浅水沉积环境,水下分流河道发育,砂体横向变化快。为准确刻画砂体的横向变化,且在低孔渗储层中找到物性相对好且含油气的有利储层,研究了叠前反演技术在水下分流河道储层预测中的应用。通过岩石物理分析,找到了能够识别砂体和有利储层的参数和参数组合;通过低孔渗砂岩储层地震反射特征的研究,证实了利用叠前反演预测物性好且含气有利储层的可行性;研究了叠前反演在工区的技术流程和关键环节,利用反演结果刻画了B构造S1层水下分流河道分布范围,预测了有利储层,指导评价井位的部署。经钻探验证,预测结果得到了证实。

The sandstone reservoirs in B Structure are characterized by low porosity and low permeability, deposited under shallow water depositional system, with underwater distributary channels well developed, and the sand bodies change quickly in lateral di- rection. For delineating the lateral change of sand bodies correctly and finding the favorable reservoirs with good physical properties and high hydrocarbon saturation from low porosity and low permeability reservoirs, pre-stack inversion technology for prediction of underwater distributary channel reservoir has been used. Based on petrophysic analysis, the elastic parameters and their combination that can be used to identify sand bodies and favorable reservoir are established. It has been confirmed through analysis of seismic characteristics of low porosity and low permeability sandstone reservoirs that it is feasible to identify favorable reservoir using pre- stack inversion. Then the process and key techniques for pre-stack inversion are optimized for the study area. The pre-stack inversion results have been used to delineate the geometry and distribution range of underwater distfibutary channels in S1 layer in Structure B, and also used to predict favorable reservoirs and guide the drilling location design of an appraisal well in B Structure. It has been confirmed by the actual drilling results that this reservoir predication technique is effective.