摘要
针对陕北低渗透油田地质特征和温度（80℃），按配方3% 20碳磺酸盐类阴离子表面活性剂（D3F-AS05，自制）+6% KCl+0.6% KOH+0.2% EDTA得到阴离子型表面活性剂压裂液。研究了该压裂液的流变性、黏弹性、抗剪切性、悬砂性和气体破胶性能。结果表明，剪切速率为170 s-1时，80℃下压裂液黏度为90~100 mPa·s，随剪切时间增加，压裂液黏度基本不变，流变性良好。压裂液的储能模量和耗能模量比值为39.2，远高于瓜胶压裂液的储能模量和耗能模量的比值（2），表现出较好的低黏高弹特性。剪切速率从170 s-1变为0、200、500 s-1后再恢复至170 s-1，压裂液黏度随之变化后再恢复至90~100 mPa·s，抗剪切性较好。二氧化碳气体注入压力由0增至4 MPa，压裂液黏度由65 mPa·s迅速降至2 mPa·s；天然气注入压力由0增至12 MPa，压裂液黏度降低一半；氮气不改变压裂液黏度。温度变化分别为40℃、60℃、80℃、100℃，该阴离子型表面活性剂压裂液黏度先增加后降低，在80℃时达到最大，平均为94 mPa·s左右；单粒径陶粒支撑剂在其中的平均沉降速率逐渐增大。相同温度下（不超过100℃），单粒径陶粒在瓜胶中的平均沉降速率明显大于在阴离子压裂液中的值，而10%砂比陶粒在阴离子压裂液中的平均沉降速率最小。
Abstract
According to the geological characteristics and temperature (80℃) conditions of low permeability oil field in northern Shaanxi, homemade 20 carbon atoms sulfonate anionic surfactant (D3F-AS05) was used in performing hydraulic fracturing. Anion fracturing fluid was composed of 3% D3F-AS05, 6% KCl, 0.6% KOH and 0.2% EDTA. The performance of anion fracturing fluid was studied, such as rheological property, viscoelastic, shear resistance, suspended sand performance, and gas gel breaking performance. The results showed that the anion fracturing fluid had good rheological properties at 80℃. The viscosity of fluid remained at 90~100 mPa·s at a shearing rate of 170 s-1. The viscosity of fluid was essentially constant with the increase of shearing time. The ratio of storage modulus to loss modulus was 39.2, but that of guar gum fracturing fluid was only 2. The viscosity of anion fracturing fluid was low and elasticity was good. After a series of shearing rate changes (170, 0, 200, 500, 170 s-1), the viscosity of anion fracturing fluid changed and returned to the original state (90~100 mPa·s) finally. The injection pressure of carbon dioxide gas increased from 0 to 4 MPa, the viscosity of fracturing fluid rapidly dropped from 65 to 2 mPa·s. The injection pressure of natural gas increased from 0 to 12 MPa, the viscosity of fracturing fluid reduced by half. Nitrogen did not change the viscosity of fracturing fluid. As the temperature increased from 40 ℃ to 100 ℃（40，60，80，100 ℃）, the viscosity of anionic surfactant fracturing fluid increased first and then decreased. At 80℃, the viscosity of fracturing fluid reached a maximum (about 94 mPa·s in average). The average settlement rate of single particle proppant in this fracturing fluid gradually increased with increasing temperature. At the same temperature (less than 100℃), the average settlement rate of single particle size ceramic in guar gum fracturing fluid was significantly greater than that in anion fracturing fluid. The average settlement rate of ceramic with 10% sand ratio was minimum in anion fracturing fluid.
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