稠油化学堵调降黏复合驱油体系构建及驱油机理分析

Establishment of combined viscosity reduction flooding system for chemical water shutoff and profile control in heavy oil reservoirs and analysis of its mechanism

稠油油藏经过多轮次蒸汽吞吐后,井间存在热连通和高耗热通道,热效率低,开发效果差。化学堵调降黏复合驱作为一种绿色低碳的有效开采接替技术,研究其复合驱油机理对于指导油田现场项目实施具有重要意义。针对试验区油藏特征,筛选化学剂,构建化学堵调降黏复合驱油体系,通过室内实验研究稠油化学堵调降黏复合驱油体系的驱油机理,结果表明高黏度堵调剂降低油水流度比,提高小孔径孔隙剩余油的动用程度,有效抑制黏性指进,起到改善流度、调整流场的作用;降黏剂吸附在原油表面,改善油相流动能力,提高驱油效率,同时乳液液滴卡堵相应尺寸喉道,提高窜流通道的渗流阻力,扩大波及范围,起到乳化降黏、乳液调剖作用;堵调剂降黏剂协同增效,堵调剂提高了降黏剂的乳化能力,促进降黏剂进入低渗透区,提高整体动用,堵调剂动用边部剩余油、降黏剂动用残余油,显著降低剩余油饱和度。

After multi-cycle cyclic steam stimulation(CSS),heat interconnections and high heat-consuming channels form between oil wells in heavy oil reservoirs,which results in low thermal efficiency and poor development effect.Since the combined viscosity reduction flooding for chemical water shutoff and profile control is considered as a green and low-car⁃bon replaced method for effective recovery,studying its mechanisms is crucial to guiding on-site projects.Considering the characteristics of the experimental oil reservoir,this paper selects chemical agents to build the combined viscosity reduc⁃tion flooding system for chemical water shutoff and profile control,and studies the oil displacement mechanism of the sys⁃tem by laboratory experiments.The results show that water shutoff and profile control agents with high viscosity can reduce the oil-water mobility ratio,enhance the production of residual oil in small pores,effectively inhibit viscous fingering,im⁃prove the mobility,and adjust the flow field.Absorbed on the surface of crude oil,viscosity reducers can improve the oil phase flow ability and enhance the oil flooding efficiency.Meanwhile,by blocking throats of corresponding size,emulsion droplets help increase the flow resistance of the channeling-path and expand the swept ranges,which can realize viscosity reduction and profile control.There is synergistic effect between water shutoff and profile control agents and viscosity reduc⁃ers.Water shutoff and profile control agents improve the emulsifying capacity of viscosity reducers and facilitate them to en⁃ter the low-permeability area,which improve the production overall reservoirs.Since the remaining oil at the edges and the residual oil could be produced by using water shutoff and profile control agents and viscosity reducers respectively,the re⁃maining oil saturation is significantly reduced.