A Study on Gel Fracturing Fluid for Coalbed Methane at Low Temperatures

Abstract

Active water and plant gum fracturing fluids are widely used for coalbed methane in China, however, the limitations of poor rheological property, high content of water insoluble substances, and high residual content need to be resolved. Considering the low temperature (20–40°C) and low permeability of the coalbed methane reservoir, gel fracturing fluid, which can solve the problems above, was studied in this article. The gel fracturing fluid is composed of nonionic polyacrylamide, cross-linker (ZrOCl₂), pH modifier, gel breaker containing (NH₄)₂S₂O₈, and activator. The optimized formula and performance evaluation of gel fracturing fluid were also investigated. The experimental results show that this gel fracturing fluid has the advantages of easy preparation, low cost, strong shearing resistance capacity, low filtration coefficient, rapid break, lack of residual after gel breaking, and ease of flow back. The performance of the gel fracturing fluid is superior to that of active water and vegetable gum, and it is very suitable for use as a fracturing treatment in coalbed methane at low temperatures.

Keywords:

• coalbed methane
• fracturing fluid
• low temperature
• performance evaluation
• zirconium gel