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

关键词:  大牛地  致密气田  超低浓度胍胶  强交联剂  高效助排剂  压裂破胶酶  地层伤害 

Key words:  Daniudi  tight gas field  ultra-low concentration gum  super cross-linker  high efficiency cleanup additive  hydraulic fracturing gel enzyme breaker  low damage

摘要:

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 ℃、170 s-1下剪切120 min后,黏度大于140 mPa·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22.4 mN/m,界面张力降至0.9 mN/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300 mg/L降至180 mg/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7.7×10⁴ m³/d和10.8×10⁴ m³/d,增产效果显著。 

Abstract:

The Daniudi gas field had the characteristics of low pressure, tight, poor physical property, water locking damage and sensibility etc., and only reformation measures of reservoir could obtain high productivity. On the basis of conventional 0.45% guar gum fracturing fluid system, a guar 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 0.45% to 0.30% by using the ultra-strong crosslinker SITAR-11, the viscosity of crosslinked jelly was more than 140 mPa·s under 90 ℃, 170 s-1 after shearing 120 min, and it still had fine prop-carrying ability under 38% high sand concentration. By using biochemical mixed efficient cleanup additive ZITHE-34, the surface tension of the gel breaking fluid reduced to 22.4 mN/m, and the interfacial tension reduced to 0.9 mN/m respectively. 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 operation was conducted to two horizontal wells in reservoirs of Shan 1 and He 1 in Daniudi gas field respectively, sand proportion and construction pressure all met the design requirements in the process of fracture, the flowback rates 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.