DE-FE0005952

Goal
The goal of this project is to develop an advanced reservoir simulation and visualization tool for compositional flow and transport coupled with geomechanical deformation in porous media, with advanced mobility control methods such as foam, to better model and predict oil production during carbon dioxide (CO₂) flooding and improve predictions of oil production from residual oil zones.

Performer
The University of Texas at Austin, Austin, Texas 78713-7726

Background
CO₂ EOR has exhibited strong growth in the past 30 years and has expanded despite extreme crude oil price fluctuations. However, there are several issues challenging the oil recovery, economic efficiency, and applicability of the process.

Predictive simulation may be the only means to develop optimal strategies in the absence of complete characterization of the reservoir geology. It is critical to develop robust, scalable, and mechanistic numerical modeling tools because of the multiple scales of the various interacting processes in the reservoir, the basin scale of the reservoir, the need for long time predictions, and the potential for significant coupling between geomechanics and flow.

This project will develop an advanced CO₂ EOR simulator with visualization capability, coupled with an advanced phase behavior and foam mobility control module, coupled with geomechanical deformation in porous media, and an advanced grid for complex reservoirs. The project will also include support for the modeling of complex coupled processes of fluid flow and transport, geomechanical deformation, 3- phase flash, a mechanistic foam model, and a comprehensive relative permeability model that includes the effects of composition, interfacial tension, and hysteresis. The simulator will be used to accurately predict changes in the reservoir system during injection of viscous CO₂ and aid in the design and optimization of new generation CO₂ injection projects with permanent CO₂ storage in mind. The research will result in a computational framework and modules with advanced numerical algorithms and underlying technology for research in CO₂ applications, which will be validated against published results and benchmarked against other simulators. The project will support the education and training of an interdisciplinary work force.

Impact
Development of a new, computationally efficient, high-performance reservoir simulator with visualization capability for new generation CO₂ EOR and CO₂ storage will help maximize oil production after waterflooding and from residual oil zones. Success of this proposed project may help to build stakeholder confidence in the effectiveness of this advanced technology as well as develop optimal recovery strategies to produce a significant portion of the remaining domestic oil resources.

Accomplishments

• The simulation framework was assembled: the simulator under development will be an isothermal, three-dimensional, four phase, compositional, equation-of–state (EOS) simulator capable of simulating various recovery processes.
• A thermodynamically consistent relative permeability model based on Gibbs Free Energy was developed and a modified version of Jerauld’s three-phase hysteresis relative permeability model was implemented.
• An unstructured grid was formulated, implemented, and tested against commercial simulators. Several solvers have been identified to test for better computational efficiency and accuracy.
• A comprehensive literature survey on published foam models was completed

Current Status (December 2011)
After completing a comprehensive literature survey on published foam models, the team is now focusing on two recently developed foam-modeling approaches. The first is a foam model based on two simultaneous mechanisms affecting mobility of gas in the presence of foam, namely the reduction of the gas relative permeability because of the gas trapping, and the increase in the gas apparent viscosity due to the resistance of movement of lamellae. The second foam model follows the local-equilibrium approximation method to the population balance modeling where the foam texture is approximated by placing foam-generation and coalescence rates in equilibrium. This foam-texture approximation increases the applicability of population balance models in the full-field three-dimensional studies.

In addition to the model development using thermodynamically consistent relative permeability based on Gibbs Free Energy, a modified version of Jerauld’s three-phase hysteresis relative permeability model has been implemented into the new simulator and is currently being tested. This model is applicable to mixed-wet reservoirs and approaches the correct two- and three- phase flow when one phase appears or disappears due to mass transfer with other phase(s). The trapping behavior of oil and gas phases are capillary number dependent and scaled proportional to the capillary number of trapped phase, i.e. oil and/or gas. The curvatures of the gas and oil relative permeabilities are also scaled according to the capillary desaturation curve. Preliminary simulations have been performed to test Jerauld’s model, specifically hysteretic behavior, the impact on oil recovery and CO₂ breakthrough times for different mobility control methods such as Water Alternating Gas (WAG).

Project Start: February 1, 2011
Project End: September 30, 2013

DOE Contribution: $799,558
Performer Contribution: $199,884

Contact Information:
NETL – Sinisha (Jay) Jikich (sinisha.jikich@netl.doe.gov or 304-285-4320)
University of Texas at Austin – Mojdeh Delshad (delshad@mail.utexas.edu or 512-4711-3219)
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