基于地震速度预测南堡凹陷中深层地层压力

Prediction of overpressure distribution in mid-deep strata of Nanpu sag based on seismic velocity

南堡凹陷现有油井多位于中浅层,中深层岩性油气藏是研究区未来的勘探重点.基于高精度地震速度资料,综合应用速度对比法和Fillippone公式法,对南堡凹陷中深层进行地层压力预测.研究结果表明：①纵向上,南堡凹陷超压顶界面分布于3 000-3 500 m,超压普遍存在于东二段及其以下的中深层,并可大致划分为中部和深部2套超压系统;②区域上,随埋深增大,超压中心总体由凹陷中南部向中北部迁移,东营组超压中心主要位于中部林雀次凹及南部滩海区,沙河街组超压中心主要分布于中北部高尚堡-柳赞构造、老爷庙构造和南堡5号构造.速度对比法预测地层压力的精度较高,其成果对研究区的地层压力预测分析适用性更强.该成果有助于降低勘探成本和开发风险,并为下步中深层岩性油气藏的勘探提供参考.

Oil wells are mainly drilled in mid-deep strata in Nanpu sag. Deep strata is the exploration focus in future.Based on high-quality seismic velocity data,speed correlation method and Fillippone formula calculation method were applied synthetically to the prediction of pressure distribution in mid-deep strata of Nanpu sag. This study shows that:1in the vertical,the top interface of overpressure is between 3 000 and 3 500 meters in Nanpu sag. Overpressure is mainly located in the second member of Dongying Formation and the strata below,which can be roughly divided into middle overpressure system and deep overpressure system;2in the plane,overpressure center migrates from south-central part to north-central part of the sag with depth increasing. The overpressure center of the Dongying Formation mainly locates in central Linque sub-sag and south seabeach area. The overpressure center in the Shahejie Formation mainly distributes in north Gaoshangpu-Liuzan Structure,Laoyemiao and Nanpu Structure5. The results may not only reduce the cost of exploration and development risk,but also provide reference to the exploration of mid-deep lithologic oil-gas reservoir. In terms of pressure prediction method,speed correlation method has higher precision,which is suitable for pressure prediction in Nanpu sag.