SCCO: Thermodiffusion for the Oil and Gas Industry

Abstract

The accurate knowledge of pre-exploitation fluid compositional profile is one of the necessary pre-requisites for a successful field plan development of a petroleum reservoir by the oil and gas industry. Thermodiffusion, leading to a partial diffusive separation of species in a mixture subject to thermal gradient, is thought to play an important role in oil and gas reservoir due to the geothermal gradient. Although major improvements in measuring, simulating and modelling thermodiffusion coefficients have been achieved in the last decades, the improvements are mostly limited to binary liquid mixtures at atmospheric pressure. Thus, the need for accurate data, that would prove invaluable as benchmark reference data for validating models and simulations, was one of the main drivers behind the project “Soret Coefficient measurements of Crude Oil” (SCCO) which used a microgravity set-up implemented in the SJ-10 satellite. This unique project, resulting from a partnership between European Space Agency and China’s National Space Science Center enhanced by collaboration among academics from France, Spain, United Kingdom, China and industrialists from France and China, aimed to measure the thermodiffusion coefficients of multicomponent oil and gas mixtures under high pressures. Within this framework, some results on thermodiffusion of one ternary oil mixture and one quaternary gas condensate have been obtained in microgravity and have been qualitatively confirmed by molecular simulations. More precisely, these microgravity results have confirmed on multicomponent mixtures that thermodiffusion leads to a relative migration of the lightest hydrocarbon to the hot region. These results support the idea that, in oil and gas reservoirs, thermodiffusion is not negligible being able to counteract the influence of gravity-driven segregation on the vertical distribution of species.