Study on delamination exploitation limit of high water cut injection well in late period

Abstract

During the later phase of reservoir development, the efficiency of water injection in wells declines, necessitating careful consideration of water injection methods and parameters. This study focuses on the Daqing Lamadian oilfield and investigates the strategy for dividing the stratified water injection layer section. The research takes into account several characterisation characteristics related to the physical attributes of the formation. Additionally, it establishes the methodology for calculating the boundaries of fluid volume in stratified water injection, taking into account various factors such as well distances, layer thicknesses, oil saturation, and others. The findings indicate that the extent of recovery diminishes as the coefficient of variation of seepage resistance within the water injection layer section increases. The most effective approach for segmenting the layers is by utilizing the coefficient of variation of seepage resistance. This method allows for the determination of the boundaries of the injection volume for various layers. The injection water volumes for different layer groups in the Lamadian oilfield are as follows: 1000 m3/d for S I, 9100 m3/d for S II, 4600 m3/d for S III, 1100 m3/d for P I, 4100 m3/d for P II, 2500 m3/d for G I, and 100 m3/d for G II. The results offer technical validation for the selection of injection parameters for well groups during the later stages of high water cut.