气顶边水油藏均衡驱替井网构建及配注研究

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

  • 摘要: 针对气顶边水油藏天然能量开发中后期地层能量不足导致的递减加快、气窜加剧、举升困难等问题,通过高部位采气井转注气、低部位污水回注井边外注水、油环内部油井转注水实现了能量补充立体井网的构建。机理上,油井转注扩大水驱波及系数,动用井间滞留剩余油并降低含水率;气顶注气与边外注水的协同作用可维持油气界面与油水界面的动态平衡,提升气驱与水驱的驱动倍数,进而提高原油采收率。流线模型研究表明,该立体井网能够较好地针对气顶边水油藏特征实现多向均衡驱替。在此基础上,联立气驱−水驱特征曲线建立了注气与注水的均衡驱替配注公式,结合油藏数值模拟最终确定了配注参数。现场试验中,试验井组有效起到了降低气油比、降低含水率、提高产液量、提高产油量的目标。以均衡驱替为目标的立体井网部署与不同驱替介质配注量计算方法,为同类型油藏的注采优化提供了借鉴。

     

    Abstract: 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.

     

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