Isolation and Performance Test of Green Low Dosage Hydrate Inhibitors from Local Materials for Improving Flow Assurance in Oil and Gas Industry

Abstract

The formation of gas hydrates in oil and gas industry can be minimized or prevented by the use of inhibitors. This paper reports on hemicellulose and modified lignin as low dosage gas hydrate inhibitors (LDGHIs). LDGHIs were isolated from sugarcane bagasse (SCB), plant gum exudates (PGE) of Acacia trees, and coconut coir, and further characterized by Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) spectrometer, porosimeter and thermogravimetric analyzer (TGA). The PGE and SCB yielded 77.75% and 12.38% of hemicellulose, respectively, while coconut coir yielded 35.59% of lignin which was modified to sodium lignosulfonate (SLS) to improve its solubility in water. The inhibition performance of the isolated hemicellulose and modified lignin on gas hydrate was evaluated in terms of percentages of water converted into gas hydrate. In the absence of inhibitors, a large percentage of water (75.20%) was converted to gas hydrates while in the presence of the hemicellulose, the minimum amount of water converted into gas hydrates was 43.37%. The inhibition ability of hemicellulose from PGE and SCB increased with an increase in concentration. The statistical test indicated no significant difference between the percentage of water that formed gas hydrates in the presence of hemicellulose from PGE and SCB (n =4, p = 0.06 at CI = 95%). On the other hand, SLS promoted gas hydrates growth. In the presence of SLS, all liquid in the reactor was converted to gas hydrates. Thus, SLS may be used as a promoter for gas hydrates in natural gas storage and carbon dioxide sequestration while hemicellulose from both PGE and SCB as low dosage hydrate inhibitors.