Research On Remaining Oil Distribution Of The Middle Es3 Member In Block Fan 29 Of Daluhu Oilfield

The 4 sand group of the 3 member of the Shahejie Formation,the main oil-bearing layer of Fan 29 block in the Dalihu Oilfield,is a typical lithologic-structural low permeability reservoir.With the progress of exploration and development,some problems like bad water injection effect,fast rising of water saturation in wells and complex distribution of residual oil and other issues have been occurred,because of the complexity of geological conditions and the strong heterogeneity of the reservoirs.These problems have affected the further exploration and development in this area.Based on the comprehensive utilization of data of core,well logging,testing and production,those problems mentioned above were studied.Firstly,the 4 sand group of the 3member of the Shahejie Formation was divided into 16 single sand layers from 4 layers through the stratigraphic division and correlation.Then,the sedimentary facies in this area were divided into the microfacies main body of channel,inter channel,leaf body,lateral margin of the middle fan,fan margin and lacustrine mud.Finally,the reservoir heterogeneity was studied from the three parts of in-layer,inter-layer and plane.Based on the above geological study,the reservoir three-dimensional geological models were established and combined with the numerical simulation method to quantitatively predict the distribution of remaining oil.The accuracy of the probability distribution of the geological model and the accuracy of the production history fitting of the numerical simulation are both high,indicating that the results have a certain degree of credibility.The results show that in the four layers of 4 sand group of the 3 member of the Shahejie Formation,the 4~3 layer is still the main target of development because of its largest remaining oil reserves.And the 4~2 layer have very significant remaining oil reserves due to the minimum degree of recovery.For the 4~5 layer,the distribution of remaining oil is relatively concentrated,but the total amount is smaller than the 4~3 and 4~2layers.The remaining oil reserves are the least for 4~4 layer.The remaining oil is mainly distributed at the top of the reservoirs and the block if interlayer in layers.But in the lateral,the remaining oil is mainly distributed in zones near the fault line,of sandstone thinning out and in imperfection of well network.Based on the analysis of control factors of the remaining oil distribution in the study area,it was found that the remaining oil distribution is mainly controlled by the sedimentary microfacies,reservoir heterogeneity,micro-structure,fractures,perfecting degree of well network,the correspondence of injection and production,and perforation location.The vertical remaining oil distribution is mainly controlled by differences of physical property between different layers,granular rhythm of sand,reservoir properties,and the correspondence of injection and production.And the lateral remaining oil distribution is controlled by the sedimentary microfacies,reservoir properties,the direction of fractures,perfecting degree of well network,and the correspondence of injection and production.