A New Approach to Evaluate KHI Performance

The Karan field is Saudi Aramco’s first offshore non-associated gas, which started production in mid-2011. The gas is sour (2% H2S and 8% CO2) and lean with no hydrocarbon condensate. The gas is predicted to produce 2 bbl/mmscf of condensed water with 750 ppm of organic acids. Condensation of water creates a high risk for both corrosion and gas hydrates during winter. As such, there is a great challenge to find a suitable and compatible Kinetic Hydrate Inhibitor (KHI) in the presence of a Corrosion Inhibitor (CI) for a predominantly Hydrate Structure I system. Saudi Aramco approached Hydrafact Ltd (a Heriot-Watt University spin-out company), which offered a new technique for evaluating KHI performance and has considerable knowledge of KHI inhibition mechanisms. This paper describes the work that has been done to independently evaluate KHI performance for the Karan field. The work involves evaluation of various mixture KHI and CI at different concentrations for the Karan system, using crystal growth
inhibition (CGI) and traditional induction time methods with test protocols for the latter specified by Saudi Aramco. In addition, the effect of corrosion inhibitor on KHI performance was also analysed. The performance of two different KHIs was also compared. The work done has increased Saudi Aramco confidence and understanding of hydrate inhibition using KHI.