Evaluation Of Waterflood Development Effect In Y9 Reservoir In JW Oil Block

The development practice shows that waterflooding can improve the ultimate recovery factor.Artificial water injection is an effective means to maintain formation energy,improve displacement efficiency and enhance ultimate oil recovery.Taking Y9 reservoir in JW oil area as an example,based on the fine division and correlation of Y9 reservoir strata in Yan’an Formation in JW oil area,this paper analyzes the basic geological conditions of the study area by systematically studying the distribution law of sand body,reservoir distribution characteristics and oil and gas enrichment law.On the basis of geological analysis,through comprehensive evaluation of reservoir sand body distribution and oil reservoir distribution characteristics,combined with water drive development characteristics of the study area,comprehensive analysis of the main influencing factors of waterflood development effect,to provide technical support for improving water drive utilization,realizing efficient development and program adjustment.The results show that the Y9 reservoir in JW oil field belongs to braided fluvial facies,mainly developed channel microfacies and floodplain microfacies,and the reservoir rock type is mainly gray-green medium-fine grained lithic feldspar sandstone,followed by quartz sandstone and a few feldspar lithic quartz sandstone,which is a typical structural-lithologic reservoir driven by elastic,dissolved gas and edge and bottom water.At present,it is in the development stage of medium and high water cut,with comprehensive water cut of 89.27%.The degree of water drive control,the degree of pressure maintenance,the corresponding rate of injection and production,and the water drive index are all low.The size and thickness of oil sands have great influence on water drive recovery.In order to better develop the oilfield,the current reasonable injection-production ratio should reach 1.2,and the injection-production ratio can be maintained at 1 when the local reservoir pressure recovers to 8.5Mpa.The ultimate technical recovery rate can reach 18.7%,and the recoverable reserves are 106.79×10~4t.