摘要
早期纤维素压裂液存在配液难、耐温差、破胶不彻底、对地层伤害大等问题。本文介绍的速溶无残渣纤维素压裂液基液由0.4%羟乙基羧甲基纤维素FAG-500、0.2%增黏剂FAZ-1、0.5%调节剂FAJ-305组成。分析了该压裂液的抗盐性、耐温耐剪切性、携砂性、破胶性、动态滤失及伤害性。结果表明，在中等矿化度（242~2444 mg/L）条件下，基液黏度约为67.5 mPa·s，在pH 4.5~5.0下，在基液中加入交联剂FAC-201形成冻胶。在120℃、170 s-1条件下，压裂液冻胶剪切70 min后的黏度约为150 mPa·s，可满足低于130℃储层压裂需求。加入0.002%破胶剂过硫酸铵后，冻胶在100℃、170 s-1条件下剪切1.5 h后的黏度约为200 mPa·s，破胶剂不影响施工时体系的流变性能。破胶后无残渣，破胶液表面张力为24.44 mN/m，界面张力3.20 mN/m。在90℃下，0.3% FAG-500压裂液冻胶的储能模量G′和耗能模量G″分别为7.2 Pa和1.6 Pa。砂比为40%的交联冻胶携砂液在90℃水浴加热6 h后，无沉砂现象，携砂性能良好。压裂液对岩心的渗透率损害率为24.75%。该纤维素压裂液具有速溶易配制、酸性交联、无需防膨剂等特点。在长庆油田两口致密油井和两口致密气井进行了现场应用，施工成功率大于95%，施工有效率100%。
Abstract
In the early, cellulose fracturing fluid had problems in fluid mixing, temperature resistance, gelout and severe formation damage. In this paper, an instant dissolving cellulose fracturing fluid with no residue was composed with 0.4% hydroxyethyl carboxymethyl cellulose FAG-500, 0.2% viscosity increaser FAZ-1 and 0.5% regulator FAJ-305. The viscosity characteristics of fracturing fluid solution, such as the resistance to salt, high temperature and shearing, proppant carrying ability, breaking property, dynamic filtration and halmful performance were analyzed. The results showed that the viscosity of base fluid was about 67.5 mPa·s under the condition of medium salinity (242—2444 mg/L). The gel was formed by adding crosslinking agent FAC-201 under 4.5—5.0 pH value. The viscosity of gel was about 150 mPa·s after shearing 70 min under 120℃, 170 s-1, which satisfied the requirements of formation fracturing under 130℃. The viscosity of gel was about 200 mPa·s after shearing 90 min under 100℃, 170 s-1 when 0.002% gel breaker ammonium persulfate was added. The gel breaker did not affect the rheological properties of construction system. There was no residue after breaking process, and the surface tension of gel breaking liquid was 24.44 mN/m, the interfacial tension was 3.20 mN/m. The energy storage modulus G′ and the energy consumption modulus G" of 0.3% fracturing fluid gel was 7.2 Pa and 1.6 Pa at 90℃ respectively. The carrier performance of cross-linked gel carrier fluid in sand ratio 40% was well with no grit after 6 h bath heating. The damage rate of core permeability was 24.75%. The cellulose fracturing fluid had some characteristics, including instant dissolving, acid cross-linked, without expansion agent, and so on. The cellulose fracturing fluid was applied in two tight oil wells and two tight gas wells of Changqing oilfiled. The rate of well-construction was more than 95% and the rate of effective construction was 100%.
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