Performance evaluation of methane hydrate inhibitor (NaCl) integrated polymer gels for extremely low temperature hydraulic fracturing applications

Gas hydrates (GH) are an abundantly available natural resource that has trapped huge amounts of methane gas through millions of years where its quantity is estimated to be twice that of all other types of hydrocarbon sources put together. The efforts to produce from these reserves resulted in inferior yield compared to conventional counterparts due to the limited conductivity of the sediment and freezing problems. Sourcing fracturing technology to GH reserves is estimated to increase the yield during the initial periods of production, according to recent studies. This novel work focuses on testing traditional polymers fluids for low temperature scenarios and evaluate their compatibility with established GH inhibitors such as sodium chloride (NaCl). Dissolved Na+ and Cl ions slows down the hydrogen bonding with water molecules crucial for hydrate formation. Experiments have been conducted to analyze the stability of guar and xanthan gum-based linear and cross-linked gels for temperatures similar to GH reservoir conditions. The compatibility of NaCl as an inhibitor was also tested to determine the suitability of sea water for such operations to improve performance from offshore reserves. The inhibitor integrated linear gel samples followed similar viscosity and viscoelastic trends to that of the reference endorsing the inhibitor's compatibility with the polymers at low temperatures. The xanthan gum integrated guarbased linear gel samples indicated synergistic performance enhancement by showing viscosity performance increment at a rate of 34.2% (low conc.) to 96.6% (medium conc.) and viscoelastic performance enhancement at a rate of 70.6% (low conc.) to 250% (medium conc.) compared to reference guar-based gel. The NaCl integrated crosslinked samples proved its incompatibility by demonstrating rapid deswelling nature by liberating water according to its increase in concentration, along with leaving stable residue that can seriously damage the sediment's conductivity long term, whereas the linear gel samples gradually degraded after 48 h where the xanthan gum integrated samples showed better resistance to degradation compared to their guar-based counterparts. This work has produced excellent observations that can be benefitted for future endeavors in improving production from GH reserves.