低温煤层气清洁压裂液破胶性能评价及现场应用

Gel Breaking Performance Evaluation and Field Application of Clean Fracturing Fluid for Development of Low Temperature Coal Bed Gas

清洁压裂液不仅具有较强的携砂能力,同时具有较强的造缝能力(滤失系数小),且摩阻低等优点。然而浅层煤层气温度较低(25?35℃)。煤层气储层内缺乏能使清洁压裂液破胶的液态烃或游离状态的自由水,这使得清洁的压裂液不易破裂,在压裂过程中会造成严重的储层破坏。主要针对低温煤层气清洁压裂液体系破胶剂及破胶性能进行了探讨,开发出适用于低温煤层气清洁压裂液体系的破胶剂,该破胶剂可以在25℃低温下彻底破胶清洁压裂液,同时对压裂液造成的破坏程度进行评估。压裂液破坏率仅为11%。清洁压裂液系统已在山西省沁水盆地应用。

Clean fracturing fluid has many advantages, such as strong sand carrying capacity, strong ability to width generation, low friction and so on. However, the temperature of coal bed gas in shallow part is low（25~35℃）. And there are no liquid hydrocarbons or a large amount of free water in the reservoir, so gel breaking of the fracturing fluid is difficult, which can result in serious reservoir damage during fracturing. In this paper, many gel breakers for cleaning fracturing fluid were introduced. And performances of these gel breakers were evaluated under the condition of low temperature. On the base of the research, the suitable gel breaker for clean fracturing fluid was recommended for coal bed gas in shallow part. The breaker can break clean fracturing fluid gel completely under the low temperature（25℃）.At the same time, the degree of damage caused by fracturing fluid was evaluated. The damage rate of fracturing fluid was only 11%.The system of cleaning fracturing fluid has been applied in Qinshui basin of Shanxi province. The field application experiment has achieved good results.