Omar Javier Varela Londoño's thesis
by
Omar Javier Varela Londoño, MSE
University of Texas at Austin, 1999
Supervisor: Larry W. Lake
Lately the oil industry has given great importance to reservoir management, and reservoir uncertainty analysis
in reservoir simulation studies is a key in achieving better results. Different approaches such as scaling,
experimental design, response surface and Monte Carlo simulation have been used to deal with this uncertainty;
however, they have never been combined to the best of our knowledge to generate a new procedure that would be
more efficient for these problems. The main objective of this research is to develop a novel approach to
investigate and quantify the uncertainty in reservoir simulation studies. The approach must be able to exploit
and optimize information. The emphasis will be in the uncertainties that arise from the reservoir description.
Initially, the mathematical formulation was derived for a specific process (primary depletion), the scaling of
the governing equations, by inspectional analysis, generated a minimal set of dimensionless groups that is able
to describe the given process. The resulting groups were validated and also used in one-way sensitivity analysis
to quantify their importance on oil recovery. Heterogeneity, generated by permeability and porosity distributions,
was also analyzed. Then, based on this analysis and typical operational considerations, the number of groups was
reduced. Experimental design techniques were used to generate data to apply surface response methodology.
Finally, Monte Carlo simulation, with special sampling, was applied to the polynomials generated through
surface response technique and the results were compared.
Results show that the approach developed reduces significantly the parameters in the process without loosing
accuracy; therefore, the amount of reservoir simulation work is also reduced. For the process analyzed, there
are to two key parameters: absolute permeability and horizontal anisotropy. Heterogeneity is not a controlling
factor in the oil recovery.
Back to theses index
