低渗油田N_(2)驱气窜特征及泡沫防窜实验研究

Experimental Study on Gas Channeling Characteristics and Foam Channeling Prevention in N_(2) Displacement of Low Permeability Oilfields

针对B油田氮气驱气窜问题,通过室内物理模拟实验分析了长岩心N_(2)驱替过程的生产特征和气窜规律,由于B油田具有高温高盐低渗的特点,采用瓦林搅拌法筛选出合适的泡沫防窜体系,并通过物理模拟实验研究了体系的防窜效果和注入时机。实验结果表明,以采出程度和累积气油比作为指标可将气驱过程划分为三个阶段:无气采油阶段、油气同产阶段、气窜阶段。适合目标油田的泡沫防窜体系是:0.6%ZHDQ-5起泡剂+0.1%WP-1稳泡剂溶液。该体系封堵率可达到90%,推荐在累积气油比达到20 cm^(3)/cm^(3)注入泡沫防窜体系,可在前期气驱的基础上提高采收率17%。

Aiming at the problem of gas channeling in nitrogen flooding of B oilfield,the production characteristics and gas channeling law of N_(2) flooding are analyzed through laboratory physical simulation experiments of long cores.As B oilfield has the characteristics of high temperature,high salt and low permeability,the suitable foam channeling prevention system was optimized by Waring blender stirring method,and the channeling prevention effect and injection timing of the system were studied through physical simulation experiments.The experimental results show that the gas flooding process can be divided into three stages by taking recovery degree and cumulative gas-oil ratio as indicators:oil production without gas stage,oil-gas production stage and gas channeling stage.The composition of the foam channeling prevention system suitable for the target oilfield is the solution of 0.6% ZHDQ-5 foaming agent+0.1%WP-1 foam stabilizer.The plugging ratio of the system can reach 90%.It is recommended to inject the foam channeling prevention system when the cumulative gas-oil ratio reaches 20 cm^(3)/cm^(3),which can improve the oil recovery by 17%on the basis of previous gas flooding.