Research On Modes Of Deposition In Sanan Development Area

Sanan development area has grown Sartu,Putaohua and Gaotaizi reservoirs, this group reservoir belongs to big scale fluvial-delta deposit in the north of Songliao Basin, the deposit thickness is about 500m, and mainly in sand-shale inter-bedding deposit. The deposit characteristics are: the number of layers is excessive; the thickness of single layer is thin; interlaminational,inlayer and areal heterogeneities are serious. Sanan reservoir was put into production in 1964, which is in water flooding and polymer flooding development, and has been in high water-cut late stage already. To further improve oil field development effects and enhance the ultimate recovery factor, taking researches on reservoirs deposition modes becomes very essential.On the basis of sedimentary petrography, this paper recovers Sanan development area's palaeogeomorphology by observing and depicting drilling cores, defines the source directions, and identifies Sa,Pu,Gao reservoirs sedimentary environments. According to log's theory, plotting the sedimentation units limitations and identifying the microfacies automatically are realized by interpreting logs synthetically under fractal theory,difference method and neural network. Applying refined reservoir depicting technology, this paper studies the utmost space distribution,geometric shape and connections of diversified sands by analyzing maps, and builds up each unit'sedimentation mode and refined geologic model. On this basis, this paper establishes the boundary of delta distributary plain facies and front facies, clarifies the lake strandline; defines the boundary of delta front facies and predelta, clarifies the pinchout line; and defines the boundary of inner-delta front facies and outer-delta front facies, the boundary of different sands in same subfacies, further enhances the accuracy of refined geologic model.Research on modes of deposition in Sanan development area, not only provides evidences for searching remaining oil abundance zones, optimizing wells location, predicting hydrocarbon productions and calculating reserves; but also provides reliable geologic model for reservoir numeric simulation research and optimizing development plans, and provides decision evidences for improving oilfield development effects and enhancing the ultimate recovery factor.