低渗致密气藏压裂过程中伤害实验研究

Experimental study on fracturing damage in low permeability tight gas reservoir

水力压裂是川西低渗致密气藏勘探评价及开发建产的关键技术,但压裂过程中由于液相的浸入、压裂液破胶不彻底、压裂液残渣的滞留、压裂液老化等因素,大大降低了压裂增产效果。针对压裂过程中的各种伤害,通过实验进行了评价。研究结果表明,水锁与压裂液滤失是造成储层伤害的2个主要因素。水锁增加了启动压差,使得压后返排困难,破胶液在地层中长时间逗留,加大了压裂液对地层的伤害。压裂液滤失形成的滤饼大大降低了储层的渗透率,一般可达50%以上。研究结果表明,压裂施工中可以通过减少压裂液中的固相颗粒与加快返排速度等措施来减少对地层的伤害。

Hydraulic Fracturing is a key exploitation technology in west Sichuan low permeability tight gas reservoir,but in the fracturing process, the fracturing effect is greatly reduced because of many factors, such as ,fracturing fluid immersion ,gel in fracturing fluid being not completely broken,and so on. In this paper,fracturing damage is evaluated by experiment. It is believed that water lock and fluid filtration are two main factors. Water lock increases initiating pressure and causes problems in the after circulation, so the gel breaker will stay a longer time in the stratarn, which increases fracturing fluid damage to the strata. According to the article, fracturing damage can be reduced by cut down the solid-phase particles in the fracturing fluid and accelerate flowback ratio.