煤层气井压裂液体系优化——以彬长矿区大佛寺井田为例

OPTIMIZATION OF FRACTURING LIQUID SYSTEM OF CBM:A CASE STUDY ON DAFOSI WELL FIELD,BINCHANG DISTRICT

以彬长矿区大佛寺井田4#煤储层为研究对象,通过对煤储层物性、水敏性、地表水水质及配伍性、防膨剂的防膨性与伤害性等进行系统分析,掌握煤储层的水敏、储层伤害原因及规律,筛选出合理的活性水压裂液体系,为彬长矿区及类似地区的地面煤层气开发提供一定的借鉴和参考作用。研究结果表明,大佛寺4#煤中易水化膨胀的黏土矿物含量较少,煤心渗透率与压裂用水矿化度呈正相关关系,表现出较强水敏特征。进一步优化压裂液配方发现:大佛寺井田地表水与煤储层水具有良好的配伍性,适合作为压裂用水;1. 5%KCl溶液对储层伤害较低且经济性较好,可作为压裂液防膨剂。结合前人研究结果,最终确定大佛寺井田煤层气井压裂液配方为:大佛寺地表水+1. 5%KCl防膨剂+0. 3%DB-80助排剂。

This paper,based on a case study on N0. 4 coal seam of Dafosi well field,Binchang district,analyzes its reservoir physical properties,water sensibility,surface water quality and compatibility,anti-swelling agent＇s features and harmfulness,and selects appropriate active hydraulic fracturing liquid system,aiming at providing references for Binchang district or similar regions to develop ground CBM. Results show that the N0. 4 coal seam bears less quantity of expansive clay minerals,and coal permeability is positive to fracturing water mineralization,with a strong water sensibility. Optimization of fracturing liquid formula indicates a good compatibility of ground water and coal reservoir water,good to be used as fracturing water. 1. 5% KCl solution,less harmful to reservoir and less costly,may be used as anti-swelling agent. This final fracturing liquid formula is written as ground water ＋ 1. 5% KCl anti-swelling agent ＋0. 3% DB-80 cleanup additive.