塔中地区碳酸盐岩缝洞型储层叠前流体识别

塔中地区奥陶系碳酸盐岩的储集空间是由裂缝和次生溶蚀孔洞组成的,其地震响应为"串珠状"反射。由于受到地表沙丘覆盖和埋藏深度较大的影响,导致地震资料信噪比较低、储层成像精度差。同时该储层油水关系复杂,利用叠后地震方法进行油气检测时,无法有效识别储层中的油水特征。以上难题严重制约了塔中地区碳酸盐岩勘探开发的进程。针对上述问题,基于塔中地区高密度地震资料开展了研究,由于高密度数据信噪比、储层成像精度相对较高,因此有利于进行缝洞体储层叠前烃类检测方法研究。首先,利用岩石物理建模得到了准确度较高的纵、横波速度;其次,对油气、水井进行AVO正演,正演结果表明不同类型井的AVO响应特征是有差异的,可以用AVO属性分析技术对碳酸岩储层流体识别;最后,利用叠前同时反演技术对研究区储层进行定量的流体预测,预测结果与该区试油成果对比分析,流体预测精度达到83. 3%,该方法为研究区内提升钻井成功率,降低油气勘探风险提供了有效的技术支持。

Pre-stack fluid identification for fractured-vuggy carbonate reservoir in Tazhong area

The reservoir space of the Ordovician carbonates in Tazhong area,Tarim Basin,is mainly composed of fractures and secondary dissolved pores and cavities,and its seismic responses are bead-like reflections.The fact that the reservoir is covered by surface dunes and buried in depth leads to a relatively low signal-to-noise ratio of seismic data and the poor imaging precision for the reservoir.The oil-water contact is complex in the reservoir,making it hard to effectively identify its features by using post-stack hydrocarbon detection method.These problems have seriously restricted the progress of exploration and development of carbonate reservoirs in this area.In order to address these problems,we conducted research based on high-density seismic data in Tazhong area.As the high-density seismic data have higher signal-to-noise ratio and reservoir imaging precision,they are beneficial to study pre-stack hydrocarbon detection method for fractured-vuggy reservoirs.Firstly,more accurate P and S wave velocity can be worked out by Rock Physics Model.Secondly,AVO forward modeling of oil/gas and water wells is conducted,showing discrepant responses from different wells as a result.Therefore,the AVO attributive analysis technique can be used to identify liquids in carbonate reservoirs.Finally,pre-stack simultaneous inversion technique is used to quantitatively identify fluid types in reservoirs in the research area; The predictions are in turn compared with the results of formation testing,revealing an accuracy of liquid predictionsof 83.3%,which manifests that this method provides effective technical support for improving the success rate of drilling and reducing risks of hydrocarbon exploration.