超低浓度胍胶压裂液体系在大牛地致密气田的现场试验

Field trials of ultra-low concentration guar gum fracturing fluid system in Daniudi tight gas reservoir

大牛地气田具有低压致密、储层物性差、易水锁伤害及敏感性等特征,不经过储层改造措施无法获得高产能。在常规0.45%(w)胍胶压裂液体系的基础上,通过对交联剂、助排剂和破胶剂进行优化调整,研发出一种超低浓度胍胶压裂液体系。结果表明,使用强交联剂SITAR-11,可将羟丙基胍胶的质量分数由常规的0.45%降低至0.30%,交联后的冻胶在90℃、170s^(-1)下剪切120min后,黏度大于140mPa·s,在38%的高砂比时,仍具有优良的携砂能力。使用生化复配型高效助排剂ZITHE-34,破胶液表面张力降至22.4mN/m,界面张力降至0.9mN/m。使用压裂破胶酶FANFA-06和APS耦合式破胶技术,残渣量由常规体系破胶后的300mg/L降至180mg/L,降低了对地层的伤害。在大牛地气田山1和盒1储层进行了2口水平井的压裂施工,压裂过程中加砂比和施工压力均满足设计要求,压后返排率为28.2%和30.1%,无阻流量为7.7×10~4 m^3/d和10.8×10~4 m^3/d,增产效果显著。

The Daniudi gas field had the characteristics of low pressure , tight , poor physicalproperty, water locking damage and sensibility etc . , and only reformation measures of reservoir could obtain high productivity . On the basis of conventional 0. 4 5 % guar gum fracturing fluid system , aguar gum fracturing fluid system with ultra-low concentration was developed through the adjustment and optimization of the cross-linking agent , cleanup additive and gel breaker . The result showed that the concentration of hydroxypropyl guar gum could decrease from 0. 4 5 % to 0. 30% by using the ultra-strong crosslinker SITAR-11 , the viscosity of crosslinked jelly was more than 140 mPa ？ s under 90 C , 170 s_1 after shearing 120 min , and tt still had fine prop-carrying ability under 3 8 % high sand concentration. By using biochemical mixed efticient cleanup additive ZITHE-34 , the surface tension of the gel breaking lluid reduced to 22. 4 mN/m , and the interfacial tension reduced to 0. 9 mN/mrespectively. By using fracturing gel breaking enzymes FANFA-06 and APS coupling gel breaking technology, the residue value reduced from 300 mg/L （after gel breaking by conventional system） to 180 mg/L, which greatly reduced the formation damage. The fracturing operationtwo horizontal wells in reservoirs of Shan 1 and He 1 in Daniudi gas Held respectively, sand proportion and construction pressure all met the design requirements m the process of fracture, the flowbackrates after fracturing were 28. 2 % and 30. 1 % , the open-flow capacities were 7. 7 × 104 m3 /d and 10. 8 ×104 m3/d , and the yield-increasing effect was remarkable.