煤储层速敏伤害机理及防速敏试验研究

Study on velocity sensitivity damage mechanism and its proof test of coal reservoir

为了探索煤储层速敏伤害的控制方法,采用质量分数1.5%KCl溶液为基液,在其中加入不同浓度的阴离子型表面活性剂AS和非离子型表面活性剂NS,配置出35种溶液,对河东煤田柳林地区沙曲矿的焦煤进行煤粉沉降试验、直剪试验,最终优选出用于防速敏的最佳表面活性剂体系为质量分数0.05%AN复配溶液(AS和NS的比例为9∶1),由此构成了表面活性剂压裂液(1.5%KCl+0.05%AN)。研究结果表明:表面活性剂压裂液能润湿煤粉,增大煤粉颗粒间的黏聚力,导致水力压裂产生的煤粉经润湿后迅速沉降、固定,从而减少悬浮煤粉的数量,进而减少孔喉或裂缝狭窄处受到堵塞的机会,实现对煤储层速敏伤害的有效控制。

In order to discover a velocity sensitivity damage control method of the coal reservoir,1.5% KCl solution was applied as a base fluid,different density anion type surfactant AS and nonionic type surfactant NS were added in the KCl solution and thus 35 types solution were prepared. Those 35 solutions were applied to the fine coal settling experiment and direct shear experiment of the coking coal in Shaqu Mine of Liulin Area of Hedong Coalfield. Finally,an optimum surfactant system for the velocity sensitivity proof was optimized as 0.05%AN complex solution（ the ratio of AS and NS was 9 ∶ 1） and therefore a surfactant fracturing fluid（ 1.5% KCl ＋ 0. 05% AN） was made. The study results showed that the surfactant fracturing fluid could moisture the fine coal,could improve the cohesion between the particles of the fine coal and could make the fine coal from the hydraulic fracturing rapidly setting and fixing after the watering. Thus the quantity of the suspended fine coal was reduced,the jamming opportunity occurred at the borehole throat and the narrow point of the cracks could be reduced and could realize the effective control of the velocity sensitivity damage to the coal reservoir.