An Experimental Study of Potassium Formate as a Potential Gas Hydrate Inhibitor in a Vertical Pipe
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Blocking of petroleum producing pipelines with clathrate hydrates of natural gases is a large issue in the industry. It causes loss of income in addition with health, safety and environmental concerns. This master thesis considers inhibition and dissociation of clathrate hydrates of natural gases with the thermodynamic inhibitor potassium formate. Potassium formate is a salt frequently used during drilling operations, but the writer has not found information about the usage of the salt as a thermodynamic inhibitor in petroleum production. Its application as a thermodynamic inhibitor is of large interest due to its properties, especially for shut-in wells as the salt is considered very heavy and has a large solubility in water. The distribution of the salts sodium chloride (NaCl) and potassium formate (HCOOK) in a two-meter vertical pipe was investigated to simulate a shut-in well or riser. The salt solutions were added to the top of the distilled water filled pipe. Pycnometers were used to measure the brine densities at different heights in the pipe. Higher densities corresponded with more salt. The hypothesis about the heavy HCOOK salt accumulating at the bottom of the pipe was not confirmed, when it was found that both salts became almost homogeneously dispersed in the pipe after short time for all brine concentrations investigated. It means that the salt would inhibit the whole water phase and not only the lower or upper part, as the conventional hydrate inhibitors in the petroleum industry are known to do. Potassium formate s quick distribution to a homogeneous mix could improve flow assurance in production wells. It is an advantage for producing wells to have a homogeneous salt distribution, because the whole water phase gets protected against hydrates. But it is a disadvantage for hydrate dissociation in the bottom a pipe if the inhibitor should be used to penetrate the water phase and accumulate at the bottom to dissociate hydrates.