低界面张力小分子驱油剂提高低渗透油藏采收率技术

Improving Oil Recovery in Low Permeability Reservoir by Low Interfacial Tension Small Molecule Oil Displacement Agent

孟文玉 唐善法 王思瑶 董沅武 王 睿 高 洁 陈泽群

MENGWenyu TANG Shanfa WANG Siyao DONGYuanwu WANG Rui GAO Jie CHEN Zequn

对低渗透油藏注入性差、洗油效率低，水驱无法有效提高采收率等问题，提出了一种低界面张力小分子 驱油剂（LST溶液）提高低渗透油藏采收率新技术，评价了该驱油剂的界面活性、增黏性、乳化性、润湿性及其油 藏环境适应性和驱油效果。结果表明，该驱油剂具有良好的界面活性和增黏性。在6788.23mg/L的矿化水中， 质量分数为0.4%时的LST溶液的油水界面张力为0.012mN/m，且黏度与油藏原油黏度（3.4mPa·s）相近。LST 溶液具有较好的油水乳化能力，可改善油藏水润湿性。在47.2℃、油水比为1∶1的条件下，LST乳状液的稳定时 间为120min。岩心经LST溶液处理后，水相接触角由57.0°降至12.5°，油相接触角由24.3°增至38.6°。LST溶液 具有良好的静态抗吸附性能，经岩心3次吸附后，LST残液与原油间的界面张力仍能达到10-2mN/m数量级，黏度 达2.895 mPa·s，乳状液静置10、120min的析水率分别为38.6%、73.4%。LST溶液的耐盐性能较好。在矿化度为 16 570 mg/L的环境下，其油水界面张力低于7×10-2mN/m、黏度为3.06mPa·s。LST溶液的驱油效果较好，可有 效封堵高渗透孔道，启动低渗透孔道残余油。注入0.4PV0.4%LST溶液可使均质岩心（0.05μm2）的水驱驱油 效率提高11.21百分点，非均质岩心（级差3～10）水驱后的综合采收率提高6.55百分点～19.41百分点。LST 溶液可以实现低剂量或低成本有效提高水驱采收率，在低渗透非均质油藏化学驱提高采收率方面具有较好的 应用前景。

Aiming at the problems of poor injection，low oil washing efficiency and inability of water flooding to improve oil recovery in low permeability reservoirs，a new technology of low interfacial tension small molecule oil displacement agent（LST solution） to improve oil recovery in low permeability reservoirs was proposed. The interfacial activity，viscosity increase， emulsification，wettability，reservoir environment adaptability and oil displacement effect of LST solution were evaluated. The results showed that the displacement agent had good interfacial activity and viscidity. In the mineralized water with salinity of 6788.23 mg/L，the interfacial tension of 0.4% LST solution was 0.012 mN/m，meanwhile the viscosity was similar to that of reservoir crude oil（3.4 mPa·s）. LST solution had good oil-water emulsification ability and could improve reservoir water wettability. The stabilization time of LST emulsion was 120 min at 47.2 ℃ and 1∶1 ratio of oil to water. After the core was treated with LST solution，the water-phase antenna decreased from 57.0° to 12.5°，while the oil-phase antenna increased from 24.3° to 38.6°. LST solution had good static anti-adsorption properties. After three times of core adsorption，the interfacial tension between LST residue and crude oil could still reach the order of 10-2 mN/m，and then the viscosity could reach 2.895 mPa·s. The water eluting rate of the emulsion after standing for 10 min and 120 min was 38.6% and 73.4%，respectively. The salt resistance of LST solution was good. When the salinity was 16 570 mg/L，the oil-water interfacial tension was lower than 7×10-2 mN/m and the viscosity was 3.06 mPa·s. LST solution had a good displacement effect，which could effectively plug the high permeability pore and start the residual oil in low permeability pore. Injecting 0.4 PV 0.4% LST solution could increase the water flooding efficiency of homogeneous core（0.05 μm2）by 11.21 percentage points，while the integrated recovery efficiency of heterogeneous core（3— 10 difference）by 6.55—19.41 percentage points. LST solution could effectively improve water drive recovery at low dosage or low cost，which had a good application prospect in enhancing oil recovery by chemical drive in low permeability heterogeneous reservoirs.

10.19346/j.cnki.1000-4092.2023.04.019