封闭油藏注水开发阶段注采比计算新方法

New Calculation Methods of Injection-production Ratio for Water-injecting Development Stage in Closed Reservoirs

目前的阶段注采比计算方法只考虑了地层压力或含水率等单个因素的影响,而实际开发中,注采比的大小受油藏压力、含水率、累积水油比等多因素的影响。针对这一问题,利用累积注水量与累积产油量的半对数关系式,结合封闭油藏物质平衡方程,推导了阶段注采比与累积产油量、地层压力和含水率的关系式。再利用累积产油量与含水饱和度的关系式、两种不同相对渗透率与含水饱和度的关系式,推导了两种阶段注采比的计算关系式。最后,实例计算结果表明:研究的计算方法可用于封闭油藏注水开发的阶段注采比计算与预测。

At present, the calculation methods of stage injection-production ratio only considered a single factor, such as formation pressure or water cut; however, the stage injection-production ratio is controlled by many factors, such as formation pressure, water cut and cumulative water-oil production ratio in real development. To solve the problem, we derived the relationship formulation of stage injection-production ratio with cumulative oil production, formation pressure and water cut using the semi-logarithmical curve of cumulative water injection with cumulative oil production, combining the material balance equation of closed reservoir. Then two calculation formulations of stage injection-production ratio were further derived using the relationship formulation of cumulative oil production with water saturation and the two relationship formulations of relative permeability with water saturation. At the end, calculations of stage injection-production ratio using the above two calculation formulations for an example closed reservoir with water-injection development history showed that the new calculation methods are applicable and useful.