Summary
This paper compares three techniques for coupling multiphase porous flow and
geomechanics. Sample simulations are presented to highlight the similarities
and differences in the techniques. One technique uses an explicit algorithm to
couple porous flow and displacements in which flow calculations are performed
every timestep and displacements are calculated only during selected timesteps.
A second technique uses an iteratively coupled algorithm in which flow
calculations and displacement calculations are performed sequentially for the
nonlinear iterations during each timestep. The third technique uses a
fully coupled approach in which the program’s linear solver must solve
simultaneously for fluid flow variables and displacement variables. The
techniques for coupling porous flow with displacements are described and
comparison problems are presented for single-phase and three-phase flow
problems involving poroelastic deformations. All problems in this paper
are described in detail, so the results presented here may be used for
comparison with other geomechanical/porous-flow simulators.
Introduction
Many applications in the petroleum industry require both an understanding of
the porous flow of reservoir fluids and an understanding of reservoir stresses
and displacements. Examples of such processes include subsidence, compaction
drive, wellbore stability, sand production, cavity generation, high-pressure
breakdown, well surging, thermal fracturing, fault activation, and reservoir
failure involving pore collapse or solids disposal. It would be useful to
compare porous flow/geomechanics techniques for all of these processes, because
some of these processes involve a stronger coupling between porous flow and
geomechanics than others. However, this paper looks at a subset of these
processes and compares three coupling techniques for problems involving
subsidence and compaction drive. All of the sample problems presented in this
paper assume that the reservoir absolute permeabilities are constant during a
run. Displacements influence fluid flow through the calculation of pore
volumes, and fluid pressures enter the displacement calculations through the
poroelastic constitutive equations.
Several authors have presented formulations for modeling poroelastic,
multiphase flow. Settari and Walters (1999) discuss the different methods that
have been used to combine poroelastic calculations with porous flow
calculations. They categorize these different methods of coupling poroelastic
calculations with porous flow calculations as decoupled (Minkoff et al. 1999a),
explicitly coupled, iteratively coupled, and fully coupled. The techniques
discussed in this paper are explicitly coupled, iteratively coupled, and fully
coupled.
© 2006. Society of Petroleum Engineers
View full textPDF
(
608 KB
)
History
- Original manuscript received:
3 February 2003
- Revised manuscript received:
25 November 2005
- Manuscript approved:
29 November 2005
- Version of record:
20 March 2006
View Cart
