摘要
在压裂施工过程中,包裹惰性囊衣的胶囊破胶剂处于几十兆帕的高压液体内,传统观念认为胶囊破胶剂施工结束后通过裂缝闭合挤压释放达到延缓破胶的作用,其忽略了压裂过程中液柱压力、泵注压力和地层压力等的影响。为揭示井筒压力对胶囊破胶剂释放时机的影响,研究了压力和加压时间对过硫酸钾胶囊破胶剂释放率的影响,对比了胶囊破胶剂加压前后的囊衣包裹情况,考察了胶囊释放对压裂液黏度的影响。结果表明,胶囊破胶剂在压力作用下囊衣逐渐破碎、剥落,胶囊破胶剂释放率随压力和加压时间的增加而增大,在压力为35 MPa、加压时间为40 min时的释放率为62%;在温度低于50℃时,胶囊破胶剂释放在短时间内对压裂液黏度影响较小,高温下胶囊破胶剂的提前释放将使得压裂液黏度快速降低直至破胶,影响压裂液携砂效果。
During the fracturing process, encapsulated gel breaker with an inert capsule was placed inside a high pressure liquid with several tens megapascal. The release of capsule after the break of rubber was closed through the crack closure in traditional conception, and the effect of liquid column pressure, pump pressure and formation pressure was neglected in fracturing process. In order to reveal the effect of wellbore pressure on the release time of encapsulated gel breaker, the influence of pressure and pressure time on release rate of potassium persulfate encapsulated gel breaker was studied, the situation of clothing package of encapsulated gel breaker before and after compression was compared, the influence of capsule release on the viscosity of fracturing fluid was investigated. The results showed that the capsule package of gel breaker gradually brake and peeled under pressure, the release rate of encapsulated gel breaker increased with increasing pressure and pressure time. The release rate was 62% when the pressure was 35 MPa and the time was 40 min. When the temperature belowed 50℃, the release of encapsulated gel breaker in a short period of time had little effect on the viscosity of fracturing fluid, while that at high temperature would make the viscosity of fracturing fluid decreased rapidly until gel breaking, which effected the sand-carrying of fracturing fluid.
出处
《油田化学》
CAS
CSCD
北大核心
2016年第4期619-622,共4页
Oilfield Chemistry
基金
国家科技重大专项课题"低渗
特低渗透油气田经济开发关键技术"(项目编号2011ZX05013-003)
关键词
胶囊破胶剂
过硫酸钾
高压
释放率
压裂液
encapsulated gel breaker
potassium persulfate
high pressure
release rate
fracturing fluid
