渤海P油田L60油组超短期基准面旋回及对储层的控制

Ultra-short-term Base Level Cycle and Its Control on the Reservoir in Oil Series L60 in Oilfield P, Bohai

渤海P油田1区馆陶组L60油组为多期叠置的辫状河砂体。此文应用高分辨率层序地层学理论,将研究层段超短期基准面旋回划分为低可容纳空间下的向上变深非对称型旋回和高可容纳空间下的向上变深非对称型旋回;对研究层段河道砂体期次进行了划分与对比,并依据A/S值的变化,将研究区的河道砂体划分为叠切型、叠加型和单一型三种堆叠样式。在此基础上,对超短期基准面旋回控制下的各期次沉积微相特征进行了细致刻画,探讨了不同期次超短期基准面旋回下的隔夹层分布和发育规律。砂体水淹特征证实,超短期基准面上升早期,泥质隔夹层分布局限,渗流遮挡作用较弱,剩余油多连片分布在动用程度较低的砂体上部;随着超短期基准面逐渐上升,局部的泥质隔夹层逐步变厚,至超短期基准面上升晚期时,发育更为广泛,可进行横向对比,并有较强的渗流遮挡作用,剩余油分段式分布在砂体内。

Oil series L60 in Guantao Formation in Block 1 of Oilfield P,Bohai consists of multi-stage stacking braided river sandstones.Based on the theory of high resolution sequence stratigraphy,the authors divided the ultra-short-term base level cycles into two unsymmetrical cycles i.e.upward-deepening in low accommodation and upward-deepening in high accommodation.According to the classification and correlation of sandstone bodies in the study interval,together with the change of A/S,the channel sand bodies are divided into three types:cutting type,stacking type and single type.On this basis,the characteristics of sedimentary micro-facies under ultra-short-term base level cycles are carefully described,and the distribution and development rules of interbedded layers under different ultra-short-term base level cycles in different periods are discussed.The flooded characteristics of the sand reservoir demonstrate that in the early ascent period of ultra-short-term base level,the argillaceous interlayers distributed locally,the blocking effect of percolation was weak and the remaining oil distributed in the upper part of the sand bodies.With the gradual increase of the ultra-short-term base level,however,the argillaceous interlayers were thickened locally.To the late period,the argillaceous interlayers distributed extensively and can be laterally correlated,the blocking effect of percolation was relatively strong and the remaining oil distributed in the sand bodies in the form of segment.