琼东南盆地深水区松南低凸起基岩潜山地球物理特征及评价研究

Study and application of geophysical characteristics and evaluation technique of basement buried-hills of Songnan low uplift in deep water area of Qiongdongnan basin

基岩潜山油气藏具有背斜构造、整装油气田的特点,具有巨大的勘探潜力。琼东南盆地深水区钻探W8-1井实钻气层为88.4 m,探井揭开深水区基岩潜山勘探的序幕。琼东南盆地深水区基岩潜山具有埋深浅、风化程度高的特点,潜山埋深约为1000 m,风化壳孔隙度达到23%。上覆泥岩厚度薄与高孔风化壳的储盖组合导致基岩潜山顶界面反射为非波峰反射特征,需要针对性开展潜山界面识别以及潜山内幕储集性评价。从琼东南盆地基岩潜山岩石物理规律出发,探索潜山风化壳岩石物理敏感参数,建立不同风化程度地震响应特征模板,应用叠前反演、AVO分析等多属性综合预测潜山顶界面,运用DBSCAN波形聚类技术扫描潜山内幕与已钻井类似波形特征区域、变方位角裂缝扫描预测潜山内幕储集性。经多属性联合预测多个潜在有利目标,钻探W8-3井获得高产气流,证实该技术方法的有效性。

Basement buried-hills reservoir has the characteristics of anticline structure and monoblock oilfield/gasfield,which has great exploration potential integral fracturing-oilfield/gasfield monoblock oilfield/gasfield.W8-1 well has drilled 88.4m gas reservoir in deep water area of Qiongdongnan Basin,which open a new era of exploration for basement buried-hills in deep water area.The buried hill in the deep water area of Qiongdongnan basin is characterized by shallow buried depth and high weathering degree,with 1000 m buried depth and 23%porosity.The special combination of reservoir and cap rock results with the reflection of the interface between the cap rock and buried-hills is not strong peaks(the wavelet is positive).It is necessary to carry out buried-hills top identification and internal reservoir evaluation.In this paper,based on the rock physics of buried-hills,petrophysical sensitive parameters are explored and typical seismic response characters are modeled for different weathering degrees.Seismic muti-attribute of pre-stack inversion and AVO analysis are used to predict the interface of buried-hills tops.Waveform clustering technology is used to find the areas similar to drilled wells,and variable azimuth crack scans is used to predict the inside storage of buried hills.Multiple favorable target areas for natural gas exploration are predicted.The effectiveness has been proved by high gas flows in y8-3 area.