Kinetics features of natural gas hydrates crystallisation and dissociation in water/crude oil and water/asphaltene-resin-paraffin deposit emulsions

摘要

The crystallisation and dissociation of natural gas hydrates synthesised in paraffin oil emulsions of the Irelyakh deposit (Eastern Siberia) and in emulsions of asphaltene-resin-paraffin deposits (ARPDs) originated from this oil have been studied with application of high-pressure differential scanning calorimetry (HP DSC). Crystallisation of hydrate-containing phase in the water-in-ARPD (W/ARPD) emulsions with formation of natural gas hydrates enriched with methane and ethane has been defined to proceed much slower than the rate of formation and composition of hydrates formed in water-in-oil (W/O) emulsions. The hydrates grow better in emulsified water droplets than in bulk water, while the hydrate content decreases with increase of water cut in W/O emulsion, and a slower rate of hydrate formation in the W/ARPD emulsion, as compared with W/O emulsion, leads to a greater conversion of water droplets into hydrate phase. It has been shown that more stable hydrates are formed in W/ARPD. [Received: September 9, 2017; Accepted: February 13, 2018]