Sedimentology And Reservoir Modeling In BanO-BanⅢ Oil Group Of The Madong Oilfield

Madong Oilfield, located in the south wing of Dagang Burial Hill which is in the north of Huanghua Sag and the downthrown side of Gangdong Fault, has a perfect dip reversal anticline cut by faults.The sandstones in the First Member of the Shahejie Formation are the main oil reservoir sediment, which holds beach and bar facies. Affected by the understanding of underground, it's recently at low speed and inefficient development stage. The basic research of the reservoir is weak, and the exploration and development of petroleum urgently needs new breakthrough.Guided by high-resolution sequence stratigraphy and sedimentology, and through the identification and classification of different hierarchical base-level cycles, the regional sequence stratigraphic frameworks are established, and moreover, the spatial distribution of sand body and the characteristics of sedimentary microfacies can be discussed, and the evolutionary process as well as the sedimentary model can also be confirmed. On this basis, building up the 3-D reservoir model of the study area and fitting the original geological reserves, which provides ensurence for the development adjustment of the remaining oil.Based on the analysis of the data of core, well logging and drilling of 36 wells in Madong oilfield, and combined with the change of palaeostructure and palaeoclimate, the study on high-resolution sequence stratigraphy in the Ban0-Banâ…¢Oil Group of the Madong Oilfield is conducted. The Ban0-Banâ…¢Oil Group is divided into 1 long-term base-level cycles (LSC1) and 5 medium-term base-level cycles (MSC1-MSC5) according to the base-level cycle theory and accommodation changes. The first three middle-term base-level cycles are located in the descent stage of the long-term base-level cycle, and are correspondeding with the BO oil group and the upper part of the BI oil group. The fourth and fifth middle-term base-level cycles are located in the upward stage of the long-term base-level cycle, and are corresponding with the lower part of the Bâ… oil group, Bâ…¡and B oil group. The short-term base- level cycles in the study area can be further classified into two types, which are upward thinning non-symmetry cycle sequence and symmetry cycle sequence. Finally, the sequence stratigraphic framework of B0-Bâ…¢oil group is established.The beach bar systems are recognized on the basis of the detailed observation and description of core, and combined with the well logging, areal geology and all kinds of analyzed assay datum. The beach and bar are the main microfacies of this area. The sedimentary facies of sand body and microfacies are definite, and the plans of the sand and microfacies of every small layer are drawn. Finally, the model diagram of beach and bar facies in this area is established.Adopting multi-information cooperation and stochastic modeling method, the 3-D reservoir models are built up. Based on the distribution of the depositional microfacies and the sequential indicator simulation, the depositional microfacies model is built up. Utilizing the facies-controlled and sequential Gauss simulation method, the attribute parameter model is built up. At last, the original geological reserve is calculated. With comparing fit reserve with original geological reserve, the error is 2%, so the model is credible.