低渗透油藏压敏效应与注水时机研究

为了研究低渗透油藏合理的超前注水时机,利用物理模拟实验研究压敏效应对低渗透油藏物性的影响,得到了低渗透油藏储层压力与渗透率呈指数变化的关系,进而运用油藏工程方法及理论推导得到了储层压力与产油量、产水量、注水量等生产指标的解析关系。依据油藏物质守恒原理,结合经济评价,提出了一种考虑压敏效应计算合理注水时机的方法,并编制了相应的软件。对江苏油田某区块进行了实际应用,得到了较好的效果。超前注水可以减少压敏效应对低渗透油藏开发的不利影响,合理的超前注水时机一般在1年以内,压力水平应该保持在1.05～1.2。

Discussion on pressure-sensitivity effect and water-flooding timing in low-permeability reservoir

The physical simulation experiments were made to research the reasonable water-flooding timing in the low-permeability reservoir. The influence of pressure-sensitivity effect on the physical property of the low-permeability reservoir was analyzed. The exponential relation of formation pressure with permeability of reservoir was induced. The analytic relationship between formation pressure and production parameters such as crude output, water production and water injection was obtained using reservoir engineering and rational deduction. An approach for calculating the reasonable water-flooding timing in consideration of the pressure-sensitivity effect was proposed on the basis of reservoir material balance principle and economic assessment. Relative software was compiled and applied to one block of Jiangsu Oilfield. The good effectiveness has been obtained. The result showed that the advanced water-flooding process could decrease the harmful impaction of pressure-sensitivity effect in the low-permeability reservoirs. The reasonable advanced water-flooding timing is always less than one year, and the pressure level should be maintained from 1.05 to 1.2.