致密气藏用乳液清洁压裂液的研究与应用

Research and application of emulsion clean fracturing fluid for tight gas reservoir

针对致密气藏常用胍胶压裂液摩阻高、残渣含量多、对地层损害率大,而大部分聚合物类稠化剂溶解时间较长,无法满足在线混配对稠化剂溶解时间的要求,研发出一种乳液型清洁压裂液体系.该压裂液由乳液稠化剂组成,是一种以改性聚丙烯酰胺与多组分有机溶剂复合而成的材料,是一种可在线成胶的稠化剂.实验表明,该乳液稠化剂在水中溶解速度快,满足在线配液的需要,且具有一定的抗温抗剪切能力.利用2.0%乳液稠化剂配制清洁压裂液,该压裂液在60℃下具有良好的携砂性、降阻性、易返排及配伍性能,并且压裂液破胶彻底、无残渣、伤害小.乳液清洁压裂液成功应用于宜川3口致密气井,最高砂比为25%,平均砂比为18%,返排液黏度小于5 mPa·s,获得了良好改造效果.

The guar gum fracturing fluid used for tight gas reservoirs has high friction,high residue content,and great damage to the formation,and many polymer thickeners have a long dissolution time,which cannot meet the online mixing and dissolution time demand.To solve these problems,an emulsion-type clean fracturing fluid system was developed.The fracturing fluid is composed of an emulsion thickener,which is composed of a modified polyacrylamide and a multi-component organic solvent,can be gelatinized online.Experiments show that the emulsion thickener dissolves quickly in water,meets the needs of online dispensing,and has temperature and shear resistance.The mass fraction of 2.0%emulsion thickener was used to prepare a clean fracturing fluid,which has good sand-carrying,drag reduction,high flow back rate and compatibility properties at 60℃,meanwhile,the fracturing fluid is completely broken without residue.The clean fracturing fluid was succssfully applied in three tight gas wells in Yichuan,with a maximum sand ratio of 25%and an average sand ratio of 18%.The viscosity of the returning fluid was less than 5 mPa·s.The reservoir has achieved a good transformation effect.