Sedimentary Characteristics And Prediction Of Favorable Area Of Putaohua Oil Layer In Toutai Oil Field

The Putaohua oil layer developed by Toutai Oil field is in Yongle oilfield. It is tectonically located in the southeast of Sanzhao depression of central depression belt in Songliao Basin,including the Yongle syncline and the slope between Yongle syncline and Putaohua anticline in the west. The target layer,which is delta internal and external front sediments,is a low permeable fractured and thin and poor reservoir.The non-produng reserves of Putaohua oil layer,distributed mainly around Yuan-13 block,is in the southeast part of Yongle oilfield. They are all difficulty producing oil layer characterized by ” three-low” oil layer,which include low reserve richness,low permeability and low single well productivity.In recent years,the proportion of low efficient wells in extended area increased.In order to develop the non-producing reserves effectively,thus meeting the need of productivity construction in new blocks.Therefore, we carried out research on sand body characteristics of Putaohua oil layer in Toutai oil field and predicted favorable area.Using geology,sequence stratigraghy,sedimentology and petroleum geology,this paper systematically studied sedimentary facies of this area.By selecting typical wells as mark wells,the Putaohua oil layer in studying area is divided into 5 small layers and further into 9 sedimentary units. After establishing skeleton section,we conducted correlation of formations of the whole 896 wells.Then,the logging facies models are established,and the microfacies map for the 9 sedimentary units of this area is finished and is described in detail.On the basis,by drawing isograms map of sandbody thickness,counting thickness and drilling ratio of sand body of each unit and analyzing the plane and vertical distribution characteristics,the distribution,horizon and evolution of sandbody of different microfacies sandbodies is summarized.The core observation shows that the fracture mainly belongs to internal fracture and structural fracture,and the position and oil-bearing occurrence is analyzed. With the result of hydrofracturing,pressure testing,tracer test and test data,the influence fracture has on permeability and fracture direction is summarized.In the non-producing area,we take the method of re-understanding sedimentary regularity and drilling test wells to predict and optimize favorable area. As to the uncertainty of sand-body distribution,we take the drilling model of rolling outer-spread to trace the sand body and the drilling ratio of channel sand body increased.And the development well pattern,pattern shape and development scheme for different sand body are optimized.