Successful Applications of Borate Crosslinked Fracturing Fluids at High Temperature

Abstract

Abstract In the past when hydraulically fracturing a reservoir with a bottomhole temperature greater than 300°F (149°C), the only choice for a fracturing fluid was the transition metal crosslinked CMHPG (carboxymethyhydroxypropyl guar) system. While being labeled as a somewhat "clean" fracturing fluid system, these zirconium crosslinked systems required large volumes of gel stabilizers for long term fluid stability. Shear stability of these fluids was also not as good as the borate crosslinked guar or HPG (hydroxypropyl guar) systems used at lower temperatures. To improve the shear stability of fracturing fluids above 300°F while lowering the overall system cost to the operators, development of a borate crosslinked HPG based fracturing fluid system for use above 300°F was initiated. This paper describes the development of a high temperature (>300°F) borate crosslinked HPG fracturing fluid system and its field applications. In the process of developing this system, a different type of gel stabilizer that is more effective than common gel stabilizers such as sodium thiosulfate and less toxic than methanol was developed and applied in this system.