注水开发是目前油田最主要的开发方式之一,受地层、流体、井网等条件的影响,注入水在地下驱替不均衡.油田进入高、特高含水开发阶段,剩余油分布越来越复杂,传统的开发调整措施面临较大的困难.生产实践表明,注入水在地下驱替的均衡程度与油藏开发效果密切相关,为此提出均衡驱替的概念用以指导油田开发调整方案设计,但目前主要是基于经验的定性认识,缺少定量的、理论上的论证.因此,基于油藏工程和渗流力学理论,首先推导注水开发过程中各注采方向累积注水量与累积产油量的关系式,来描述各注采方向的驱替动态;然后推导各注采方向的驱替动态和油田开发净现值的关系式,并对其进行分析;最后推导均衡驱替注采井距及注采压差优化设计公式.
Water flooding is one of the most important ways to develop oilfields currently. Influenced by reservoirs,fluid,well pattern and other conditions,water displacement in different directions are obviously different from each other. Whenwater flooding reservoir entered to high and extra-high water cut stage,the remaining oil distribution becomes more andmore complex,and traditional development adjustment methods may not be applicable. Practices of oilfield development in?dicate that the production performance is closely related to the equalization degree of displacement by injected water. Theequilibrium displacement concept was proposed and used to guide the design of production plan. However,the relationshipbetween the displacement equalization degree and the development performance was mainly studied on the basis of qualita?tive analysis but lacking of quantitative and theoretical analysis. Based on reservoir engineering and seepage flow mechan?ics theory,the relationship between the cumulative water injection and cumulative oil production in various injection-pro?duction directions during the water flooding was derived to describe the displacement dynamics. Then the relationship be?tween the net present value and the displacement dynamics was derived and analyzed. Moreover,formulas for well spacingand optimization design of injection-production pressure difference was given to achieve equilibrium development.