Simulation Based Technique of Methanol and Calcium Chloride Hydrate Inhibitors Injection for Hydrate Formation Prevention

The effective prevention of hydrate formation and ensuring safe and efficient production of deepwater oil and gas resources are technical challenges in the petroleum industry. Combination of thermodynamic inhibitors has been proposed to improve the inhibition of hydrate formation and has received significant research attention. However, much has not been done to investigate the synergistic effect of hydrates inhibitors. In this work, the effectiveness of methanol and combination with calcium chloride (CaCl₂) on hydrate formation were analyzed. A simulation based method was applied to each volume section of the Pipeline/Riser system and a phase behavior and fluid property program was used to generate input file required by the simulation model. Sensitivity analysis was done for different percentage of inhibitor moles required to suppress hydrate formation for methanol injection and the co-injection of methanol with CaCl₂. The result shows that the fluid temperature was above the hydrate formation temperature up to a length of about 9660.54m along the pipeline/riser system and hydrate volume fraction which grows to a maximum value of 0.0000554089 at 12952.7m for the uninhibited system. For the injection of 10mol%, 20mol%, 30mol%, 40mol%, and 50mol% methanol, the hydrate volume fraction grows to a maximum value of 0.0000589137, 0.0000664168, 0.0000422186, 0.0000145381, and 0.000000440159 at 12952.7m, 12952.7m, 13448.5m, 13715.1m, and 13893.4m respectively. Methanol concentration of 60mol% was the optimum concentration required for hydrate prevention. For the co-injection of methanol and CaCl₂, 40mol% methanol and 20mol% CaCl₂ was required for hydrate prevention. The co-injection of methanol and CaCl₂ results in the reduction of the quantity of methanol required for hydrate prevention by 20%. The co-injection of alcohol and electrolytes should be deployed to reduce the significant quantities of alcohol required for hydrate suppression.