Reservoirs Prediction Of Dongying Formation Of Eastern Step-faulted Slope In Chengdao Oilfield

The study area is on eastern, step-faulted slope of Chengdao oilfield, which is characterized by deep buried, thin beds with fast lateral variations, and poor seismic data with low resolution,which hampered the design of development plan. Reservoir seismic responses were analyzed using seismic forward modeling firstly. Multiple seismic attributes and quantitative prediction techniques combining with sedimentary facies were used subsequently and successfully predicted key oil-bearing layers(Ed8⁷⁺⁸、Ed9³⁺⁴). Key conclusions made in this paper as following:（1） Dongying Formation can be divided into 10 sand beds, and the 8^th, as well as the 9^th, is key oil-bearing bed,which were deposited in underwater-fan environment with lacustrine backgrounds, developed underwater distributary channels and inter-channel deposits.（2） Seismic forward simulation proved that the oil-bearring reservoirs of the 8^th, as well as the 9^th formation can be identified, which can be used guide reservoir prediction. Real sections are affected by noise, so seismic resolution is of lower quality than simulation results. That is to say, reflection characteristics of them are different to some extent. According to real reservoirs characters As a result, Seismic forward simulation can be used moderately.（3） Seismic attributes analysis showed that the RMS and max amplitude can reflect reservoir development. Using present wells and seismic data, Model inversion can effectively predict reservoirs with high resolution, which need to give 30% the control percent of geological model.（4） The result of reservoir prediction showed that Ed93+4and Ed87+8reservoir develops along channel-valley near step-faulted slope and its distribution are controlled by paleotopography. The distribution of Ed93+4reservoirs gradually widens form SW to NE, stretching up to 5km length along channel direction.The max thickness of Ed93+4is about 40-50 m between CB326^CB32A-4, and its thickness decreases quickly vertical channel direction. The distribution of Ed87+8reservoirs is smaller than that of Ed93+4,and affected by many small underwater turbidite fans. Among them the smallest fan is located in CB325 WELL and the biggest in CB32 well with 30 m the max thickness near CB32A-4well.（5） The study results are used in five blocks with Ed reservoirs in Chengdao oilfield, getting good reservoir prediction results, with high percentage of real reservoirs and predicted reservoirs.