The Q Oilfield in the Bohai Sea is characterized by typical fluvial sedimentation,with bottom water reservoirs accounting for about 40%of the oilfield's reserves.Currently,the comprehensive water cut is 94%,indicating that it is in the stage of extra-high water cut.During the development process,the oilfield faces challenges such as complex reservoir structures,poor water injection effects,and significant difficulties in tapping potential.Therefore,it is urgent to conduct research on fine water injection and adjustment tapping technology for bottom water reservoirs during the extra-high water cut period.For the interlayer-developed bottom water reservoir represented by Zone A,based on a detailed dissection of the reservoir structure and utilizing a combination of reservoir engineering and numerical simulation methods,staged water injection within the layer was implemented to vertical water injection wells relying on the interlayer,effectively addressing the issue of effective water injection in bottom water reservoirs.For the rigid bottom water reservoir without interlayers represented by Zone B,a high-precision reservoir numerical model was used to study the variation of sweep volume during water drive,resulting in the formation of a sweep coefficient chart between horizontal wells and the proposal of layout boundary parameters for horizontal wells.After applying the research results to the bottom water reservoirs of the Q Oilfield in the Bohai Sea,continuous stable production was achieved for six years.The natural decline rate in Zone A decreased from 35%to 18%,and the recovery rate of the main sand body in Zone B increased by 5 percentage points,significantly improving the development effect and providing a reference for the development of similar bottom water reservoirs in the stage of extra high water cut.
bottom water reservoirextra high water cut periodfine water injectionadjusting and tapping potentialsweep efficiency
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