水力压裂工艺中的分段破胶技术

STAGED GEL BREAKING TECHNOLOGY IN HYDRAULIC FRACTURING TREATMENT

针对水基冻胶压裂液常规破胶过程中破胶时间长、水化液粘度高、液体返排率低、对地层污染严重等问题,研究了储层温度、破胶时间、破胶剂浓度等对破胶效果的影响。室内研究表明,破胶剂浓度越大,破胶温度越高,破胶时间越长,则水化液粘度越小。在此基础上,根据不同施工阶段及液体经受的剪切时间和温度环境的不同,研制出适应于水基冻胶压裂液体系的分段破胶技术,使压裂液在施工过程中既能保持较高的携砂粘度,又能在压后快速破胶水化。应用该技术在现场进行了10井次压裂施工,压后平均关井时间为4h,返排周期为10.6d,平均返排率为89.7％,与常规破胶相比,压后关井时间缩短了8h,排液周期缩短了近10d,液体返排效率提高了38％。

Hydraulic Fracturing Treatment is one of the most effective stimulation for reservoir development. Because the postfrac-ture response will be influenced by hydrated fluid viscosity, solving the gel breaking problem of fracture fluid in fracture treatment is paramount important. This paper introduces the effect of reservoir temperature, breaking time, breaker concentration and others on gel breaking effectiveness. Experimental study has focused on decrease of breaking time and hydrated fluid viscosity, increase of clean up rate and minimization of reservoir damage. Results shows the more breaker concentration, the higher breaking temperature, and the longer breaking time, the lower hydrated fluid viscosity. This paper introduces a novel staged breaking technique, Field application result shews, comparative to conventional breaking technique the shut in time is decreased by 8h, clean up circle is decreased to 10. 6 d and clean up efficiency is increased by 38% .