The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In typical wellbore operations, various treatment fluids may be pumped into the well and eventually into the formation to restore or enhance the productivity of the well. For example, a reactive or non-reactive “fracturing fluid” or a “frac fluid” may be pumped into the wellbore to initiate and propagate fractures in the formation thus providing flow channels to facilitate movement of the hydrocarbons to the wellbore so that the hydrocarbons may be pumped from the well. In such fracturing operations, the fracturing fluid is hydraulically injected into a wellbore penetrating the subterranean formation and is forced against the formation strata by pressure. The formation strata are forced to crack and fracture, and a proppant is placed in the fracture by movement of a viscous-fluid containing proppant into the crack in the rock. The resulting fracture, with proppant in place, provides improved flow of the recoverable fluid (i.e., oil, gas or water) into the wellbore. In another example, a reactive stimulation fluid or “acid” may be injected into the formation. Acidizing treatment of the formation results in dissolving materials in the pore spaces of the formation to enhance production flow. It is common in all these types of operations to add further chemical components to treat the formation. In the case of proppant, scale inhibitors, filter cake remover, surfactant, gas hydrate inhibitors and other chemicals may be used.
Viscosifying agent based on polymer gels have been widely used for fracturing operations. However, none of said methods allows guar or guar derivative-based frac fluids when foamed or energized with CO2 to be used at elevated temperatures due to the low pH caused by CO2. The applicants found that some salt can be used with guar or guar derivatives to be usable at elevated temperatures.