渤海C油田馆陶组辫状河沉积模式及控制因素

Sedimentary Model and Control Factors of Braided River in Guantao Formation of Oilfield C in Bohai sea

渤海C油田馆陶组发育辫状河沉积,已钻井揭示开发潜力巨大。为了认识馆陶组砂体叠置规律与沉积演化模式,查明宏观沉积控制因素,本文利用岩芯、测井、钻井、现代调研资料等开展沉积特征、砂体分布规律与沉积控制因素研究。研究表明:馆陶组发育心滩、辫状河道、泛滥平原微相,其中心滩与辫状河道砂体呈单独型、接触型、切叠型和多期叠置型接触;砂体的分布样式受基准面旋回控制,中期基准面上升半旋回的中-下部易形成大面积连片分布砂体,在纵向上呈拼合板状,而中期基准面旋回的下降半旋常形成独立式分布的砂体;单一期次心滩宽度为62~467 m,长度为269~1896 m,单河道宽度为20~151 m,古物源、古构造背景、古气候演变共同控制了辫状河的演化,并建立了在不同古环境背景下的两种辫状河沉积模式。本文研究成果对储层地质建模和提高开发井砂体钻遇率具有重要意义。

In Guantao Formation of Oilfield C in Bohai sea is developed braided river sedimentation and drilling has revealed its potential oil-gas resources.In order to understand the stacking pattern and sedimentary evolution model of sand bodies in the Guantao Formation,and identify macroscopic sedimentary control factors,this article uses data of logging,drilling,and modern research to study sedimentary characteristics,sand body distribution patterns,and sedimentary control factors.In the Guantao Formation are developed sedimentary microfacies,such as central bank,braided channel,and flood plain sedimentation.In the central bank and braided channel microfacies occur separate sand body,contact,shear,and multi-stage superimposed sand bodies.The distribution pattern of sand bodies is controlled by cycle of reference planes.In middle period of the cycle tend to develop large areal contiguous sand bodies at middle to lower parts of the upward half cycle and longitudinally the sand bodies occur in assembled plates.However,in the downward half cycle is often formed independent sand bodies.The single-staged central bank sedimentation is approximately 62~467 m wide,269~1896 m long.A single channel is approximately 20~151 m wide.The evolution of the braided river is jointly controlled by the ancient source,paleotectonic background,and paleoclimate evolution.According to different paleoenvironmental backgrounds are built two sedimentary models of the braided river.Results of this article are of great significance for geological modeling of reservoir and improving the hit rate of sand bodies in development wells.