超稠油复合降粘剂SDG-3的研究和应用

Study on preparation and application of composite viscosity reducer SDG-3 aimed at ultra-heavy oil

摘要:

针对塔河油田超稠油开采难度大、常规油溶性和水溶性降黏剂存在较大局限性的问题，采用脂肪醇聚氧乙烯醚、NaOH、氯乙酸、醇类和混合芳烃为原料，制备了一种高效复合降黏剂SDG-3。考察了其分散原油重组分能力、界面活性、乳化性能、降黏性能、耐温耐盐性和破乳性能。结果表明：SDG-3能分散超稠油中重组分，质量分数1%的SDG-3在不含水条件下使原油黏度从181 000 mPa•s降低至81 989mPa•s，降低了54.7% ； 使地层水（矿化度2.2×105mg/L）-超稠油(1.81×105mPa•s)界面张力由27mN/m降低至0.32mN/m，对超稠油乳化效果优于常规水溶性降黏剂，形成的O/W乳状液平均粒径为2.5μm，对委内瑞拉、中海油、塔河超稠油降黏率均达到99%以上，优于常规油溶性降黏剂降黏率的72.6%，耐盐度达2.2×105mg/L，耐高温达140℃，与油田破乳剂配伍性好。在塔河油田进行现场实验期间，日平均节约稀油率66.6 %，平均提高稠油采收率为14.4 %。

Abstract:

In view of the problem of mining ultra-heavy oil is very difficult in Tahe oilfield, and traditional chemical methods for reducing viscosity of heavy petroleum fluids include oil-soluble and water-soluble viscosity reducers have their own limitations. In this work, a new effective composite viscosity reducer SDG-3 was developed, its performance of ability of dispersing heavy components, interfacial activity, emulsifying properties, viscosity reducing, salt and heat resistance, demulsification, et al, were evaluated. Experimental test show that, without the presence of water, the viscosity reducer SDG-3 with amounts of 1wt.% can provide a degree of viscosity reduction (DVR%) of 50% for the ultra-heavy oils tested, possessing the ability of dispersing heavy components in crude oil. A much lower oil-water interfacial tension (IFT) of 0.32 mN/m can be achieved when SDG-3 is added into water with a high salinity of 2.2×105 mg\L and heavy oil with viscosity of 1.81×105 mPa•s than the IFT of 27 mN/m without SDG-3. Emulsification capability of SDG-3 for ultra-heavy oil looks better than water-soluble viscosity reducer, the average droplet size of the oil in water (O/W) emulsion was 2.5μm. We can achieve more a degree of viscosity reduction (DVR) of 99% for Venezuela, CNOOC and Tahe (China) heavy oils when the emulsification occurs, which was better than traditional oil-soluble viscosity reducer whose DVR is 72.6%. SDG-3 has capacity of temperature-resistant 140 ◦C and salt-tolerant 2.2×105mg/L, respectively, having no influence on post-processing. Field tests of the new composite viscosity reducer are carried out in the Tahe oilfiled of Xinjiang province in China. The field tests show that 66.6 % less light oil is needed to dilute the heavy oil to the desired viscosity when the new viscosity reducer is used. On average, a 14.4% increase in the heavy-oil production rate can be obtained.