Performance evaluation of fracturing fluids in the presence of NaCl, CaCl2 and KCl as hydrate inhibitors for extremely low temperature stimulation applications

Naturally occurring gas hydrates are established as an abundant reserve of natural gas. Production initiatives raised challenges such as low production rate, freezing problems, water, and sand production along with geomechanical concerns. Recent studies suggest that fracturing the sediment can significantly improve the conductivity and productivity of such reserves. This study is an initiative to verify the suitability of conventionally used polymer (guar) for fracturing at extremely low temperatures along with the integration of widely available gas hydrate inhibitors for efficient stimulation. Established inhibitors such as NaCl, CaCl2 and KCl were introduced to linear and crosslinked gels to study their compatibility with the reference guar-based gels. The inhibitor integrated linear gel samples demonstrated similar performance trends to that of the reference gel establishing their compatibility with the polymer, whereas the inhibitor integrated crosslinked samples displayed deswelling nature. The low concentration inhibitor integrated linear gel samples performed superior to the reference gel whereas the high concentration sample inhibited the swelling performance of the polymer. Both the reference and inhibitor integrated linear gel samples gradually disintegrated after 48 h leaving behind soft cloudy residue, whereas the inhibitor integrated crosslinked samples rapidly released water and contracted into a solid residue which can cause serious flow related disruptions during operations and apparently damage the conductivity of the sediment for long term. This study delivers crucial understanding on how various salts interact with guar polymers at low temperatures and whether their presence can be a boon or bane during the design of a fracturing fluid.