Study On The Potential Tapping Measures Of Water Cut Period At An12 Block Of Liaohe Oilfield

Liaohe oilfield has been developed for more than 40 years.In order to achieve the goal of high yield and stable production,Liaohe oilfield has completed five large-scale comprehensive adjustments,the better adjustment results have been achieved,which increased the recovery rate of the entire oil field.However,after the oil field entering the stage of high-water-cut development,if we only developed and adjusted the individual layers or single wells,it would be unable to obtain a good adjustment effect.In response to this situation,it is necessary to make large-scale adjustments to the well networks developed for water injection,increase the degree of remaining oil utilization in the reservoirs,and improve the overall development effect of oilfield.In this paper,aiming at An12 block in Liaohe Oilfield,we studied the current development status of the existing layer systems,combining with the numerical simulation method,the fundamental principles of the water drive layer reorganization including the rank difference of reservoir permeability,the thickness of the combined layer system,and the rank difference of stratigraphic coefficient were obtained.The principles above can be summarized as follow: the rank difference of permeability was less than 4,the optimal effective thickness after combination was about 10 meters,and best value of the rank difference of stratigraphic coefficient was about 3.Based on the above indicators,after considering the actual well pattern and development status of An12 block,two sets of strata were determined: An I 6-9~An II 1-3,An II 4-6~An II 19-22.Afterwards,according to the reorganization and adjustment scheme of strata and the basic principles of the adjustment for oilfield well network,four specific options of well pattern optimization were identified.Afterwards,numerical simulation method was used to analyze the enhanced oil recovery,the workload of adjustment measures and the economic indicators of reconstruction plans,then the optimal well distribution plan was obtained: No.8 injection and production wells of one encryption were used as water injection wells and new drilling production oil wells,which formed a five-spot well pattern with an area of 212 m,and this method was used to exploit the layer system of An I 6 ~ An II 3.No.1 injection and production wells of secondary encryption were used as water injection wells and new drilling production oil wells,which formed a five-spot well pattern with an area of 212 m,this method was used to exploit An II 4 layer system.The plan three divided two sets of strata and used two sets of five-spot well pattern with an area of 212 m,adopting this plan,we newly drilled 54 wells and the cumulative oil production in ten years was 635 thousand tons,the stage recovery rate was 6.04%,which was 4.37% higher than the original scheme.When the crude oil price is 70 dallars/barrel(3149 yuan/ton),the after-tax financial return rate of internal will be 20.2%,the investment recovery period will be 3.9 years,and the economic benefit forecast has the best effect,both of the development effect and economic benefit reach a higher level.