Summary
Compositional reservoir simulators that are based on equation-of-state (EOS)
formulations typically do not handle the modeling of aqueous phase behavior,
and those that are designed for modeling chemical processes typically assume
simplified hydrocarbon phase behavior. There is a need to have a single
reservoir simulator capable of combining both approaches to benefit from the
advantages of both aqueous and hydrocarbons models. Developing and implementing
fully implicit procedures for modeling both hydrocarbon and aqueous phase
behavior simultaneously is a complex process. An approach to integrate a
surfactant phase behavior model into an existing fully implicit, parallel, EOS
compositional simulator is presented in this paper. Physical property models
describing the flow and transport of surfactant and polymer species have been
implemented. These properties include surfactant phase behavior, interfacial
tension, capillary desaturation, viscosity, adsorption, and relative
permeability as a function of trapping number. Polymer properties include
viscosity, permeability reduction, inaccessible pore volume, and adsorption.
The simulation results were validated by comparison with the explicit
chemical-flooding simulator UTCHEM and are shown in this paper. Test runs were
performed with high-resolution models in a parallel environment, with results
indicating a good scalability of the simulator.
Introduction
Increased oil production using improved oil recovery processes requires
numerical modeling of such processes to minimize the risk involved in
development decisions. The oil industry is requiring much more detailed
analyses with a greater demand for reservoir simulation with geological,
physical, and chemical models of much more detail than the past. Reservoir
simulation has become an increasingly widespread and important tool for
analyzing and optimizing oil recovery projects.
Numerical simulation of large petroleum reservoirs with complex recovery
processes is computationally challenging because of the problem size and
detailed property calculations involved. This problem is compounded by the
finer resolution needed to model such processes accurately. Traditionally, such
simulations have been performed on workstations or high-end desktop computers.
These computers restrict the problem size because of their address- able memory
limit, and simulation studies of the entire project life become time-consuming.
Parallel reservoir simulation, especially on low-cost, high-performance
computing clusters, has alleviated these issues to a certain extent. Recent
publications describe the development of such approaches and emphasize the
necessity and advantages of using parallel processing. 1--4
Compositional reservoir simulators that are based on EOS formulations do not
handle the modeling of aqueous phase behavior and those that are designed for
chemical-flood modeling typically assume simplified hydrocarbon phase behavior.
There is need to have a single reservoir simulator capable of combining both
approaches to benefit from the advantages of both models. The overall objective
of this research is to develop such technology using a computational framework
that also allows parallel processing. The initial stage of development involved
the formulation of a fully implicit, parallel, EOS compositional simulator. 5
The description of the framework approach used for modular code development and
the application to gas injection is in Wang et al. 6
In this paper, we focus on the implementation of the chemical module to the
existing EOS simulator, its validation, and its application to large-scale
chemical-flooding simulations. The formulation of the compositional model is
briefly described. The assumptions for the chemical model and its formulation
are described next. We use Hand's rule 7 to describe surfactant/oil/brine Type
II(--) phase behavior. The trapping number model for relative permeability is
implemented to capture the changes in residual saturations caused by the
lowered interfacial tension. The validation of the implementation against the
explicit chemical flooding simulator UTCHEM is shown. Application to
large-scale problems and tests showing the parallel performance of the
simulator are described. The approach we used to couple the models is easy to
implement, computationally efficient, and extendable to many other interesting
reservoir problems involving aqueous chemistry. With the capability of parallel
processing, the general purpose adaptive simulator (GPAS) can now be used to
simulate chemical flooding on a larger scale than before.
© 2005. Society of Petroleum Engineers
View full textPDF
(
1,963 KB
)
History
- Original manuscript received:
12 January 2004
- Revised manuscript received:
7 February 2005
- Manuscript approved:
22 February 2005
- Version of record:
15 June 2005
View Cart
