低渗透油藏超前注水理论及其应用

低渗透油藏最显著的特征是存在启动压力梯度和介质变形现象,这使其在开发过程中渗流阻力增大、单井产量降低,递减速度加快,稳产难度加大,并降低最终采收率。对低渗储层启动压力梯度和介质变形进行了物理模拟实验,定量描述了两者的非线性变化规律,分析了介质变形对储层物性参数的影响。通过室内实验、渗流理论、数值模拟以及矿场试验研究,建立了低渗透油藏非线性渗流数学模型,提出了在超前注水期运用保持合理地层压力水平、注水压力、注水强度和注水时机的开发技术,在长庆等低渗透油田现场应用后取得较好的开发效果,提高单井产量15%~20%。

Advance water-flooding theory for low-permeability reservoirs and its application

The low-permeability reservoir is noticeably characterized with threshold pressure gradient and medium deformation, which makes high filtration resistance, low oll productivity, quickly decline of oil production and low oil recovery during reservoir development. The changing rules of threshold pressure and medium deformation were described quantitatively on the basis of physical simulation experiment. The effects of media deformation on formation parameters were analyzed. A model for non-linear seepage of lowpermeability reservoir was built on the basis of laboratory experiment, filtration theory, numerical simulation and pilot testing. The study result shows that reasonable pressure level, injection pressure, injection intensity, and injection time in the stage of advance water-flooding should be determined. The theory of advance water-flooding was applied in Changqing Oilfield, and the production rate of oil was raised by 15% to 20%.