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研究了相对渗透率曲线、分流方程和Buckly-Leverett(贝克利-列维特)方程等在传统水驱提高采收率理论中的作用,从贝克利-列维特方程及物质平衡关系出发,从理论上推导出了水驱油效率及采收率计算公式。结合中国东部高含水/特高含水油田提高水驱采收率的实践,从理论上进一步分析了最终水驱油效率不是一个定值。研究表明:在油田开发过程中,随着水驱时间的延长,油田开发深度的不断加大,储层孔隙结构、孔渗参数和流体参数不仅随着油藏温度和压力变化,而且随着流体的不断采出,流体性质,尤其是粘度发生了较大的变化。通过初步理论分析,提出在油田开发过程中相对渗透率曲线是不连续的,相对渗透曲线上的2个端点值Kro和Krw在水驱油田开发中是变化的,残余油饱和度不是一个定值,且极限为零。由导出公式分析认为,不论采用何种驱替介质来驱扫储层中的原油,均可起到既提高驱油效率又扩大波及体积的双重作用。该理论的提出揭示了高含水油田进一步大幅度提高采收率的机理所在。研究认为,新理论是对传统水驱理论的挑战,还需要在理论上和试验研究中进一步证实。
The effects of relative permeability curves, shunt equations and Buckly-Leverett equation on the traditional waterflooding enhanced oil recovery are studied. Based on the Beckley-Levitt equation and the material balance, The formulas of water flooding efficiency and oil recovery are deduced. Combining the practice of improving waterflood recovery in high water / ultra-high water-cut oilfields in eastern China, it is theoretically further analyzed that the final waterflooding efficiency is not a definite value. The results show that the depth of oilfield development increases with the increase of water flooding time, and the pore structure, pore permeability parameters and fluid parameters of reservoirs not only change with the reservoir temperature and pressure, The continuous mining, the fluid properties, especially the viscosity has undergone major changes. Based on the preliminary theoretical analysis, it is suggested that the relative permeability curve is discontinuous during the oilfield development. The two endpoints Kro and Krw on the relative permeability curve change in the development of waterflooding oilfield, and the residual oil saturation is not a fixed value , And the limit is zero. According to the derivation formula analysis, no matter what kind of displacement medium is used to sweep the crude oil in the reservoir, it can both play the dual role of improving the displacement efficiency and expanding the volume. The proposal of this theory reveals the mechanism of further substantial oil recovery in high-water-cut oilfields. The research holds that the new theory is a challenge to the traditional water-flooding theory and needs further confirmation in theory and experiment.