摘要
针对目前低渗、碱敏、深层、高温等在压裂中所存在的问题，研发出一个耐高温共聚物压裂液体系。采用共聚物FTS-17作为稠化剂，引入具有延缓释放功能的复合型交联剂（含有多种金属离子以及可以和它们形成配位络合物的有机化合物，可以在弱酸性条件下与压裂液进行交联），通过实验确定了原胶液与交联剂质量比和复合交联剂中锆盐含量的最佳适用范围，考察了耐140℃高温的压裂液流变、滤失及破胶性能，并进行了现场实验与应用。耐140℃高温的压裂液配方为：0.6% FTS-17稠化剂 +0.3% FTZP-6助排剂+0.3% FTFM起泡剂+0.2% FTFP-6防膨剂+0.6% FTJL-3交联剂+0.02% FTPJ-8破胶剂，在恒温140℃、剪切速率170 s-1条件下，连续剪切120 min以上，压裂液的黏度大于120 mPa·s，这表明该压裂液体系具有良好的耐温和抗剪切性能。此外，压裂液破胶的残渣量仅为50 mg/L，破胶液的黏度仅为1.6 mPa·s，破胶液的表面张力为23.56 mN/m，与煤油的界面张力为2.46 mN/m，这表明该压裂液不仅具有良好的降滤失性，而且残渣量低，对地层的伤害小。共聚物压裂液体系已在青海、长庆等油田进行了现场试验，现场最高施工压力80 MPa，压裂后返排率达75%。
Abstract
aiming at problems of low permeability, alkali-sensitive, deep zone, high temperature and so on, a fracturing fluid system of high temperature resistance copolymer was developed by using copolymer as thickener and introducing a compound cross-linking agent capable of retarded release, which contained metal ions as well as organic compound that can form co-ordination complex with the former. Thereby cross linking reaction between the fracturing fluid and the compound cross-linking agent under acidic condition. The mass ratio of base fluid to cross linking agent and the optimal applicable range of zirconium salt content in the compound cross linking agent were determined. The rheological property, filtration property and gel breaking property of the fracturing fluid were examined at 140℃ and the field test was performed. The formula of the fracturing fluid with temperature resistance of 140℃ was as follows: 0.6% FTS-17 thickener +0.3% FTZP-6 cleanup additive +0.3% FTFM foaming agent +0.2% FTFP-6 anti-swelling agent +0.6% FTJL-3 cross linking agent +0.02% FTPJ-8 gel breaker. Under conditions of constant temperature of 140℃ and shear rate of 170 s-1, the viscosity of the fracturing fluid was over 120 mPa?s after continuous shearing for 120 min, showing good properties of temperature resistance and shearing resistance. After gel breaking, the residue of fracturing fluid was only 50?mg/L. The viscosity of gel breaking fluid was only 1.6 mPa?s, the surface tension of gel breaking fluid is 23.56 mN/m, and the interfacial tension between the gel breaking fluid and kerosene was 2.46?mN/m, which showed that the fracturing fluid had good property of reducing filtration, fewer residues, and was less harmful to formation. This copolymer fracturing fluid system had been tested in Qinghai and Changqing oilfields; the highest field operation pressure was 80?MPa; the flowback rate was up to 75%.
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