Study On Improving Water Injection Development Effect And Countermeasure In Block Y59

The evaluation method of waterflooding development effect is the core content of oilfield dynamic analysis.Through analysis,we can find out and grasp the changing characteristics and rules of reservoir parameters in oilfield development,and timely adjust the parts that do not conform to the development rules and affect the final development effect,so as to achieve higher ultimate recovery.For oilfields in the middle and low water cut development stage,the main methods to improve the water injection development effect are reservoir transformation,well pattern adjustment technology,optimization of water injection quality and so on.For the poor development effect of water flooding in low-porosity and low-permeability fault-block reservoirs in Y59 well area during the middle-low water cut stage,the current development effect of water flooding,the characteristics of water flooding effectiveness and the main factors affecting the development effect in the study area are analyzed and studied by using reservoir engineering method.The results show that the reservoir in Y59 well area belongs to low porosity and permeability reservoir with strong sensitivity and heterogeneity.At present,the recovery rate is 7.9%,and the productivity effect is poor.Through the analysis of water flooding index,it is found that the control degree of water flooding reserves is 42.1%,the production degree of water flooding reserves is 31.5%,the predicted water flooding recovery rate is 24.8%,the energy retention level is 86.5%,and the current water flooding development effect in Y59well area is poor.The main characteristics of water injection effectiveness in wellbore area are general effective wells and weak effective wells.Among 73 wells,27 wells are general effective,accounting for 37%of the total number of wells,and 24 wells are weak effective.Comprehensive analysis of the main factors affecting water flooding development effect in Y59 well area is as follows:low porosity and permeability reservoir,poor reservoir physical properties;poor continuity of reservoir sand body;strong heterogeneity of reservoir;strong reservoir sensitivity;low injection-production well number ratio of 0.25,low injection-production well number;low injection volume of water injection wells,serious formation energy deficit;low corresponding injection-production ratio;The interval between injection wells and production wells is too large.In view of the present situation of water injection development in Y59 well area,the five indexes of formation pressure,water injection pressure,water injection volume,injection-production ratio and well pattern density are mainly adjusted.The formation pressure in well area should be maintained at about 20 MPa,the maximum injection pressure in water injection well is13.8-19.6MPa,and the reasonable well pattern density is 23.86 wells/km~2.Finally,17wells are determined to adjust the injection-production relationship;10 wells are involved in the injection-production pattern adjustment;at the same time,the feasibility study of nitrogen/water alternating flooding is suggested to improve the recovery degree and ultimate recovery factor of the wellbore area.For low permeability reservoirs in medium and water cut development stage,the purpose of improving water flooding effect and enhancing oil recovery is achieved by means of hole filling and water plugging,and the theory of water flooding development in low permeability oilfields is further enriched.This paper has a good reference value and guiding role in improving the development effect of water flooding in low permeability oilfields in medium and low water cut stages.