层状厚层油藏水驱效率预测模型

A prediction model of water flooding efficiency for layered thick reservoir

层状厚层油藏在纵向上通常表现出非均质性强、油层厚、储层物性差异大等特征。水驱开发厚层油藏会受到非均质性影响,从而造成含水上升快、采出程度低等问题,因此准确预测驱替效率是水驱开发厚层油藏的关键。考虑到层内流体窜流及储层非均质性等影响,引入拟相对渗透率函数,结合Welge-Craig水驱油理论,建立了厚层油藏驱替效率计算方法。矿场实例计算验证了本文模型的可靠性和实用性;通过敏感性分析认为,渗透率变异系数和流度比越大,原油驱替效率降低,造成水驱开发效果差。对于水驱开发层状厚层油藏,应加强储层纵向非均质性认识,完善注采井网,增大驱替效率,从而提高厚层油藏水驱采收率。

The thick oil reservoir usually featured with strong heterogeneity, thick oil layer and large difference in reservoir physical properties. Water flooding production of thick reservoir will be affected by heterogeneity, resulting in water cut rising rapidly and lowering oil recovery etc. So, prediction of water flooding efficiency is the key to develop the thick reservoir. Considering the fluid channeling and heterogeneity and introducing pseudo relative permeability function, and combined with Weldge-Craig water flooding theory, a method for calculating water flooding efficiency in thick oil reservoir was established. The reliability and practicability of the model were verified by the case calculation at site. Sensitivity analysis indicated that the larger the permeability variation coefficient and mobility ratio, the lower the crude oil displacement efficiency, which causes the poor development effect by water flooding. As for the water flooding development of layered thick reservoir, it is necessary to strengthen the understanding of reservoir heterogeneity vertically, perfect the injection and production well pattern, and increase the displacement efficiency, so as to improve water flooding recovery ratio of thick reservoir.