辫状河三角洲前缘水下分流河道精细刻画方法:以南堡凹陷M油田东一段为例

Fine description method of the underwater distributary channel in a braided river delta front:A case study of the first Member of the Dongying Formation in the M Oilfield,Nanpu Depression

河道单成因砂体划分精度直接影响剩余油刻画精度,进而决定了开发治理和调整的效果。以南堡凹陷M油田辫状河三角洲前缘沉积储层为例,优选地震属性刻画单一朵体边界,在辫状河三角洲前缘地质知识库约束下追踪河道主流线,采用拟声波反演技术刻画河道边界,结合动态资料验证,进行了水下分流河道的精细刻画。研究表明:M油田同期多朵体发育,单个朵体发育2~8支河道,水下分流河道宽度在80~240 m之间,最宽可达440 m,单成因砂体厚度为2.6~5.8 m,河道的宽厚比为25∶1~78∶1,动态验证资料及钻井结果的对比表明河道刻画预测精度吻合率达90%。通过河道精细刻画,提高了砂体展布方向的预测精度和剩余油刻画的精度,为后期开发治理提供了地质依据。这种对砂体边界进行逐级刻画的储层综合预测方法在复杂断块泛连通辫状河三角洲前缘储层的水下分流河道刻画方面具有一定的参考价值。

The division accuracy of a single-genesis sand body in a river channel determines the evaluation resolution of residual oil content and limits the efficiency of oil production.The following methods were used to describe the underwater distributary channel of the M oilfield in the Nanpu Depression.First,the seismic attribute was optimized to identify the boundary of a single channel-lobe complex.Then,the channel main stream line was traced with the constraint of the geological knowledge base of the braided river delta front,and the channel boundary was delineated using acoustic inversion technology.Finally,the results of channel characterization were verified with dynamic data.The research shows that the M Oilfield has multiple channel-lobe complexes developed in the same period.Even a single channel-lobe complex contains 2-8 channels.The width of the underwater distributary channel ranges from 80-240 m,with a maximum width of 440 m.The thickness of asingle channel sand body is 2.6-5.8 m,and the width-thickness ratio of the channel ranges from 25∶1 to 78∶1.The dynamic verification data and drilling results show that the prediction accuracy of channel distribution is 90%.The high prediction accuracy of the channel sand body distribution can promote the evaluation resolution of residual oil content,and provide constructive guidance for later development and management.The method has a certain reference value in the underwater distributary channel characterization of the braided river delta front reservoir in the complicated fault block.