Multiphase
Simulations of Alternative Production Scenarios in Fractured Reservoirs
Wang, Huabing1, Craig Forster2,
Yao Fu2, Chung-Kan Huang2, Yi-Kun Yang2,
Milind Deo2 (1) University of Utah, Salt Lake City, UT (2)
University of Utah,
A fully-implicit, three-dimensional,
three-phase, discrete fault/fracture, black-oil
simulator provides new insight regarding oil production from fractured
reservoirs. Results obtained with a controlled volume finite element (CVFE)
method compare favorably to those obtained using both single- and dual-porosity
finite difference methods (e.g., ECLIPSE). A regularized network of 30
orthogonal faults within a 1000 by 1000 by 200 feet, impermeable, model domain
is used to test simulator performance. In this simple reservoir, cumulative oil
recoveries over 900 days of primary and water-flood production are similar for
CVFE, single-porosity and dual-porosity approaches. CVFE simulations of a
complex discrete feature network illustrate the consequences of uncertainty in
knowing fracture/fault properties (e.g., porosity, permeability, thickness, dip
orientation, connectivity and flow transmissibility. For example, spatial
variability in permeability values within the fault planes yields enhanced oil
production due to the high-permeability pathways developed within the faults.
Two different, equally plausible, intra-fault permeability structures yield
simulated cumulative production 25% and 14% greater than that obtained for the
uniform permeability case. CVFE simulations of production from reservoirs
containing both faults/fractures and significant formation permeability (e.g.,
clastic reservoirs) reveal the combined effects of formation permeability
heterogeneity, fracture/fault network geometries and spatial variability in
fault/fracture properties – captured in a multiphase context – that cannot be
evaluated with conventional simulators. The inherent variability in
fault/fracture properties, combined with uncertainty in knowing the detailed
geometric connections between different regions of the discrete feature
network, impacts the pattern of sweep in ways that are best understood using a
multiphase simulator.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California