Experimental Study of Methane Hydrate Formation in Water-Continuous Flow Loop

As the offshore oil and gas fields are maturing, the water production rate from the reservoir is increasing progressively year by year. The methane hydrate formation in water-continuous systems has become a significant flow assurance issue for offshore oil and gas production. In this study, a group of methane hydrate formation experiments are designed to study characteristics of hydrate formation in the water-continuous flow loop, which were performed under void fractions from 2.6 to 5.0%, flow velocities from 1.24 to 1.57 m/s, subcooling temperatures from 4.5 to 7.2 degrees C, and hydrate particle concentration from 0 to 0.14 kg/kg. The methane hydrate formation process is considered as a mass transfer process, and the multiple influencing factors on the hydrate formation are analyzed experimentally, such as flow velocity, subcooling temperature, and hydrate particle concentration. Results show that higher flow velocity induces higher hydrate formation rate. Higher hydrate particle concentration results in lower hydrate formation rate. Thus, an integrated mass transfer coefficient is proposed, including the effect of the hydrate particle concentration and the flow velocity. In this work, the effect of subcoolings on the integrated mass transfer coefficient is found to be negligible. A corresponding mass transfer-limited hydrate formation model is proposed to predict methane hydrate formation in the water-continuous system, which is a function of the proposed integrated mass transfer coefficient, flow velocity, hydrate particle concentration, subcooling, and gas-liquid interfacial area. After comparing with experimental data, the proposed hydrate formation model shows its good agreement with experimental data.