基于相渗时变的海上稠油油藏提液机理研究

Research on mechanisms of enhanced liquid for offshore heavy oil reservoirs based on deformation phase permeability curve

渤海稠油油田油井提液后出现含水稳定甚至下降、可采储量增加及采收率提高等现象,这与常规渗流理论不完全相符,导致采用常规相对渗透率曲线进行历史拟合困难。针对这一问题,利用网络模型开展了微观提液机理分析研究,得到一条反映驱替压力梯度变化情况下的相对渗透率变形相渗曲线(相渗时变),以此提高历史拟合和指标预测的精度。微观网络模拟证实,提高驱替压力梯度后扩大了可动用孔喉的级别以及波及范围,同时增加了活塞式驱替发生的几率,从而提高了驱油效率,现场应用效果表明利用变形相渗可较准确地拟合提液后生产动态,指导开发指标预测。

The Bohai heavy oilfield production shows a stable or even decreased water cut,increased recoverable reserves and improved oil recovery ratio after enhanced liquid.This phenomenon is not completely consistent with the existing mechanics of fluids in porous media,and results in poor history matching in numerical model.To address this issue,a network model was used to analyze the microscopic enhanced fluid mechanism and obtain a relative permeability curve(deformation phase permeability curve),reflecting the variation of the displacement pressure gradient to improve the accuracy of history matching and index prediction.Microscopic network simulation confirms that increasing the displacement pressure gradient expands the level and sweep range of available pore throats,while increasing the probability of piston displacement,thus improving the oil displacement efficiency.Field application shows that the use of “transformation relative permeability curve” can more accurately fit the production dynamics after enhanced liquid and guide the prediction for development index.