Research On Remaining Oil Distribution And Production Stabilization Strategy Of Block Wei-5,Gaoyou Sag

There exist some problems in the development of block wei-5 in Gaoyou sag,such as low production rate,low degree of reserve recovery,unsatisfied utilization degree,fast water rising and high production decline.In order to solve problems above,quantitative remaining oil distribution was analyzed by using reservoir numerical simulation and reservoir engineering method on the basis of geological characteristics.Using observed geological data to start geology recognition,and made a fine description of micro-structure,sedimentary micro facies and heterogeneity features of block wei-5,then a 3D geological model was built.Quantified classification for water flooded layer was studied by using logging technology and quantitative remaining oil distribution was analyzed by using reservoir numerical simulation and reservoir engineering method.Technical policy and limit for subdivision,vector pattern optimization and potential analysis of W/O transition zone were completed.Finally a series technology of stabilized production for heavy oil reservoir in block wei-5 was built up.Remarkable effect was obtained in adjustment of block wei-5 in Gaoyou sag.Main achievements were below:(1)New conclusions were obtained by further geological research:(1)formation of the low place in block wei-5 was flatten out,the contour line was extrapolated and the oil area was getting larger;(2)differences between sedimentary environment of the three sandstones were bigger and respectively were delta front,shore and shallow lake facies and mere from E1f11 to E1f13.The main factor to influence reservoir was deposition condition and inhomogeneity between layers inside and planes was intense.(3)there exists regionality barrier between three sandstones which was thick,distributional stability and primarily mudstone,and the thickness was between 0.6-3.2m.(2)A 3D geological model was built by using Petrel software on the basis of sedimentary facies and seismical data etc.(3)Qualitative discrimination model of water flooded layer was formed by analyzing Physical properties of rock after water flooding and logging curve feature,and quantitative evaluation was formed by rebuilding saturation model.(4)Technical limit for subdivision and vector pattern optimization were studied by using reservoir simulation and optimum partition method based on entropy.(5)Selection and optimization of W/O transition zone were established by theoretical model.Potential tapping was carried out in the W/O transition zone which has a producing reserve of 0.74 million ton.(6)The achievements of this study have effectively affected the production maintaining adjustment,15 DEVs have been completed while 8 WIWs,and about 37.3 thousand of oil production has been improved,more than two hundred thousand tons of recoverable reserve which takes 4.2% of the OOIP has been found.