Eventos Anais de eventos
ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
Study of Gas Hydrate Formation and Deposition Mechanisms in Hydrocarbon Systems
Submission Author:
Erlend Oddvin Straume , PR
Co-Authors:
Celina Kakitani, Rigoberto Morales, Amadeu Sum
Presenter: Erlend Oddvin Straume
doi://10.26678/ABCM.ENCIT2016.CIT2016-0255
Abstract
“Hydrate Management” strategies in oil and gas production differ from standard “Hydrate Avoidance” design in the fact that, instead of focusing on preventing hydrate formation, these strategies focus on ensuring flow and avoiding blockage formation in multiphase flow conditions where hydrates are stable. In order to safely implement hydrate management strategies, it is required to study and understand mechanisms and behaviors connected to hydrate formation in different multiphase systems involving gas, oil and water. To further obtain insight into the different processes leading to hydrate deposition and blockage formation, a number of tests using a visual rocking cell have been performed in a gas-limited scenario with water, gas and liquid hydrocarbon mixtures. Various stages of hydrate formation were measured and observed under continuous mixing, as a factor of a number of variables (temperature, pressure, presence of thermodynamic inhibitors and anti-agglomerants). Phenomena such as deposition, sloughing, agglomeration and bedding were identified. In this work, a lower tendency to deposit on mineral oil wetted surfaces was observed, as compared to surfaces exposed to condensate or the gas phase. Nevertheless, hydrate deposition was also observed in the oil system, mainly at surfaces only exposed to the gas phase. A porosity analysis was performed for each experiment. Hydrate deposits with high porosity formed under high subcooling conditions, resulting in sloughing of the hydrate deposit due to the wetting and weight of the deposit. Another observed phenomenon was the phase separation during constant flow of the oil and water phases due to the incipient hydrate formation. This work presents some relationships between the phenomena observed (such as deposition, sloughing, agglomeration, bedding) and parameters, such as subcooling, porosity and type of liquid hydrocarbon in the system.
Keywords
Hydrates, Flow assurance, multiphase flow
