Full text loading...
-
Analytical Modelling of Low-salinity Waterflooding with Fines Migration
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, ECMOR XV - 15th European Conference on the Mathematics of Oil Recovery, Aug 2016, cp-494-00029
- ISBN: 978-94-6282-193-4
Abstract
Low-salinity waterflood is presently one of the most cost-effective EOR methods. The governing system of equations for oil and water flow with changing water salinity is derived. So-called mechanistic model is developed. This model accounts for two EOR factors: a) fines migration, which is induced by salinity variation and reduces the relative permeability of water, and b) wettability alteration, which affects the relative permeability and capillary pressure. The “lump-salt” description is used, i.e. the ionic water composition is represented by the total ionic concentration. The basic equations are simplified for three basic asymptotic cases: 1) large length scales, 2) low-velocities, 3) high-velocities. An exact analytical solution is derived for 1d displacement large-scale-approximation problem of oil using high-salinity water followed by the injection of low-salinity-slug and high-salinity water chase drive. The solution is obtained by so-called splitting method, where the Lagrangian coordinate is used as a free variable instead of time. The effects of wettability alteration and fines migration on oil recovery as two distinct physical mechanisms are analyses using the analytical model. The significant EOR-effects of both mechanisms are observed for the typical oil-reservoir conditions.