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注水开发几乎不能从碳酸盐岩油藏中采出原油,因为碳酸盐岩油藏通常是油湿性和裂缝性的。将稀释的表面活性剂溶液注入裂缝中能够降低油水界面张力(IFT),改变岩石与中间体/水湿性物质的润湿性从而提高原油产量。一个三维、两相、多组分、有限差分和全隐式数值模拟模型已开发出来,此模型综合了吸附作用、相态特性、润湿性、相关毛细管压力/相对渗透率变量。此模拟软件的可靠性已经通过对比岩心级模拟结果与实验室中得到的实验结果得以证实。从界面张力降低、润湿性改变和渗透率差异等方面来研究表面活性剂辅助重力泄油对这些过程参数的敏感性。在早期阶段通过改变润湿性来驱动原油生产,但在后期重力是主要驱动力。使润湿性向着水湿状态改变的表面活性剂能使高界面张力系统具有较高的采收率。对于低界面张力系统,不能改变润湿性的表面活性剂能使油田具有较高采收率。润湿性的大幅度改变可以提高原油采收率。对于低界面张力系统采收率随渗透率的降低而显著降低,而对于高界面张力系统影响很小。
Waterflooding can barely recover crude oil from carbonate reservoirs because carbonate reservoirs are generally oil-wet and fractured. Injecting a dilute surfactant solution into the fracture reduces the oil-water interfacial tension (IFT) and changes the wettability of the rock with the intermediate / water-wetted material to increase the crude oil production. A three-dimensional, two-phase, multi-component, finite difference and all implicit numerical simulation model has been developed that incorporates adsorption, phase behavior, wettability, and related capillary pressure / relative permeability variables. The reliability of this simulation software has been verified by comparing the results of core-level simulations with those obtained in the laboratory. The sensitivity of surfactant-assisted gravity drainage to these process parameters was studied in terms of reduced interfacial tension, changes in wettability, and differences in permeability. Crude oil production is driven by changing wettability in the early stages, but gravity is the main driver later on. Surfactants that change wettability toward a wet state of the water provide a high recovery of high interfacial tension systems. For low interfacial tension systems, surfactants that do not alter their wettability provide oilfields with enhanced oil recovery. Significant changes in wettability can improve oil recovery. For low interfacial tension system, the recovery rate decreases remarkably with the decrease of permeability, while it has little effect on high interfacial tension system.