Study on Well Pattern Construction and Injection Distribution of Balanced Displacement in Gas Cap Edge Water Reservoir

In response to the problems of accelerated decline, intensified gas cut and difficult lifting caused by insufficient formation energy in the middle and later stages of natural energy development in gas top edge water reservoirs, a three-dimensional well network for energy replenishment is constructed through gas injection from high-position gas production Wells, external water injection from low-position wastewater reinjection Wells, and water injection from oil Wells within the oil ring. Mechanistically, oil well transfer increases the sweep coefficient of water flooding, utilizes the remaining oil between Wells and reduces the water content. The synergistic effect of gas top injection and peripheral water injection can maintain the dynamic balance of the oil-gas interface and the oil-water interface, increase the driving factor of gas flooding and water flooding, and thereby enhance the crude oil recovery rate. The research results of the streamline model show that this three-dimensional well pattern can better achieve multi-directional balanced displacement in accordance with the characteristics of gas top edge water reservoirs. Furthermore, by linking the characteristic curves of gas flooding and water flooding, a balanced displacement and replacement injection formula for gas injection and water injection was established. Combined with reservoir numerical simulation, the injection indicators were finally determined. The test well group effectively achieved the goals of reducing the gas-oil ratio, lowering the water content, increasing the liquid production and oil production. The deployment of three-dimensional well patterns aiming at balanced displacement and the calculation methods of different displacement medium injection volumes provide a reference for the injection and production optimization of the same type of oil reservoirs.