半渗透隔板底水油藏油井临界产量计算方法研究

Research on Well Critical Production Evaluation Methods in Bottom Water Reservoir with Semi-permeable Baffle

底水油藏油井临界产量是开采油藏时的重要研究内容,现有的临界产量计算公式均未考虑半渗透隔板对临界产量的影响,因此,为了更准确地对该类油藏的临界产量进行预测,综合考虑隔板渗透性和隔板厚度对油井临界产量的影响,并运用等值渗流阻力、镜像反映法分别推导出带半渗透隔板底水油藏直井和水平井的临界产量公式,通过实例分析发现,用直井开发此类油藏时,当油层厚度小于40 m时,隔板主要起抑制水锥的作用;当油层厚度大于40 m时,隔板会削弱底水的驱动能量。对于水平井,用常规的水平井临界产量公式评价半渗透隔板底水油藏的水平井临界时,会低估油井的临界产量。这对类似底水油藏的开发具有一定的指导意义。

Critical production is an important research in bottom water reservoir development. Existing critical production formulas were not to consider the impact of a semi-permeable baffle. In order to forecast critical produc- tion more accurately for this type of reservoir, vertical and horizontal wells critical production in bottom water reser- voir are deduced by using equivalent filtrational resistance, potential superposition principle and mirror image meth- od considering both impact of baffle permeability and baffle height. The example analyses show that when using ver- tical wells to develop such reservoir, if the reservoir thickness is less than 40 m, baffle mainly affects inhibition of water cone ; if reservoir thickness is greater than 40 m, baffle will decrease bottom water drive energy. Critical pro- duction will be underestimated by using conventional critical production formula to evaluate critical production of horizontal well in bottom water reservoir with semi-permeable baffle. It has some significance for similar exploitation of bottom water reservoir.