Characterizing Enhanced Oil Recovery from Lattice Boltzmann Simulations
on Artificially Generated Porous Media Samples
Abstract
An understanding of fluid flow and transport in porous media is crucial
in the development of better oil and gas recovery processes. With the
emergence of parallel computing, today this is achieved more efficiently
through direct numerical simulations of microscopic flow and transport.
In order for this to be done, porous media models have to be created and
multi-phase flow must be simulated. The Lattice Boltzmann Method (LBM)
is a flexible computational tool that allows one to simulate fluid flow
in complex heterogeneous media. It treats flow as the collective
dynamics of pseudo particles and obtains a macroscopic equivalent to the
Navier Stokes equations by approximating collision and propagation. For
this research, the Rothman and Keller Lattice Boltzmann Method (LBM) was
used to simulate two-phase fluid flow in two-dimensional porous media
structures. This color gradient method can simulate different
wettability and large viscosity ratios with ease and accuracy using a
vectorized 2-Dimensional LBM code. Nine different artificial
two-dimensional porous media across three porosity values (60%, 65%,
and 70%) were created. This was done to understand the influence of
pore structure and arrangement on fluid flow for porous medias with the
same porosity value. A total of 81 simulations were conducted in which a
βredβ fluid was injected in a porous medium that was initially
saturated with a βblueβ fluid of a different viscosity. Different
wetting angles and viscosity ratios were used for the simulation to
understand their influence on the flow morphology. The result showed
that the viscous fingers for the wetting fluid (π = 0β¦) were somewhat
broader and more rounded relative to the fingers of the non-wetting
fluid (π = 180β¦). It also showed that the recovery factor benefits from
higher porosity values. Observing the flow patterns from the simulations
showed that the flow morphology of porous medias with the same porosity
are similar irrespective of the pore arrangement and structure. The
results from this experiment show that with increased viscosity ratio,
the recovery ratio is higher, which means more production.