oa Sequence Stratigraphy and Sedimentary Environment of the Upper Part of Main Pay Member in Rumaila Oil Field

The Main Pay Member in Rumaila oil field has had a very high recovery of OOIP by now. The key study has been focused on the distribution of remaining oil. However, due to the incision of fluvial channel to each other, it is very difficult to reveal the nature of small-scale sequence stratigraphy and sedimentary evolution. This study developed a detailed sequence stratigraphic and sedimentary framework based on integration of the regional geological background, the core description data, the modal data, the palynology and biostratigraphy data and the wire log data. The estuary stratigraphic and facies model fit perfectly with core and log data in the upper part of Main Pay Member. It can explain the reason why sand bodies and shale in AB and C units are continuous in a large scale respectively and the genesis of the unconformity surface between AB and C. The model also explained the evolution process of ancient estuary including the process of delta vanishing, estuary emerging, developing, and vanishing. It is hoped that, the model can help to study the residual oil in the Main Pay Member and to identify the ancient estuary.