Aron Behr

Effects of Fines Migration on Low-Salinity Waterflooding: Analytical Modelling

We discuss the governing system for oil–water flow with varying water composition. The model accounts for wettability alteration, which affects the relative permeability, and for salinity-variation-induced fines migration, which reduces the relative permeability of water. The overall ionic strength represents the aqueous phase composition in the model. One-dimensional displacement of oil by high-salinity water followed by low-salinity-slug injection and high-salinity water chase drive allows for exact analytical solution. The solution is derived using the splitting method. The analytical model obtained analyses the effects of wettability alteration and fines migration on oil recovery as two distinct physical mechanisms. For typical reservoir conditions, the significant effects of both mechanisms are observed.

Low-Salinity Fines-Assisted Waterflooding: Multiscale Analytical and Numerical Modelling

The aim of this work is the development of mathematical models for oil–water flow with varying injected water compositions in oil reservoirs. The model accounts for two main mechanisms of low salinity waterflooding (LSW): Wettability alteration and salinity-variation-induced fines migration. Analytical and numerical models are developed and applied to low salinity fines-assisted core flood tests. In large reservoir scale, the general system of equations permits for an analytical solution. The solution is obtained by recently developed splitting technique, where the stream function is used as a variable instead of time. Large-scale approximation assumes that six dimensionless groups for dissipative and non-equilibrium effects are negligibly small. Numerical results are obtained for the general system, which accounts for dissipative and non-equilibrium effects. The effects of fines migration and wettability variation on oil recovery are discovered as two separate mechanisms in LSW. The significant EOR-effects of both mechanisms are observed under the typical oil reservoir conditions.

Coreflood planning criteria for relative permeability computation by Welge-JBN method

Relative permeability computation is extensively applied in petroleum engineering through the Welge-JBN’s method in unsteady-state corefloods. The purpose of this work is to determine admissible coreflood parameters that could limit the application of the Welge-JBN method. These parameters are presented through theoretical and operational criteria. The theoretical criteria include capillary number and capillary–viscous ratio. The operational criteria consist of measurement precision for pressure, volume sampling for either of phases, water cut measurement precision, and number of samples taken during one pore volume injected. The minimum core length and fluid displacement velocity for specific rock and fluid properties could be determined through these criteria. A laboratory coreflood example was performed using the proposed parameters.

Analytical Modelling of Low-salinity Waterflooding with Fines Migration

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.