Oil & Natural Gas Projects
Exploration and Production Technologies
Heavy and Thermal Oil Recovery Production Mechanisms
This project was selected in response to DOE's Oil Exploration and Production
solicitation DE-PS26-01NT41048 (focus area: Heavy Oil and Thermal Recovery).
The goal was to improve understanding of heavy oil reservoirs and to develop
innovative technologies to produce heavy oil.
The emphasis of this work was to investigate the mechanisms and factors that
control the recovery of heavy oil under primary and enhanced modes of operation.
The ultimate objective was to provide the technical underpinnings needed to
improve reservoir recovery efficiencies.
All work was completed at Stanford University. Industry participants over the
life of the project were Aera Energy LLC (Bakersfield, CA), ChevronTexaco Technology
Co. (San Ramon, CA), ConocoPhillips (Houston, TX), ExxonMobil Corp. (Houston,
TX) Petroleos de Venezuela SA (Caracas, Venezuela), Shell International Exploration
& Production (Houston, TX), Total (Paris, France), and Tyco Thermal Controls
(Menlo Park, CA).
The project laid the technical foundations for thermal oil recovery from low-permeability,
fractured porous media as well as primary heavy oil recovery using the solution
gas drive mechanism. Additionally, in situ upgrading of heavy oil was shown
to be feasible using in situ combustion. The project also examined the efficiency
of reservoir heating using horizontal and multilateral wells. Finally, improved
reservoir definition techniques were developed to infer reservoir heterogeneity
from production data.
Thermal recovery, accomplished primarily by injecting steam, is the most successful
enhanced oil recovery (EOR) process. This project furthered the application
of steam injection by lending support to the technical case for thermal recovery
from low-permeability fractured formations, such as diatomite. Diatomite formations
in California alone contain 12-80 billion bbl of original-oil-in-place (OOIP),
and steam successfully unlocks these resources. Several companies are moving
ahead with steam injection pilots and projects in diatomite partially as a result
of this research. The industry, state of California, and nation would benefit
from increased production, royalty, and tax revenue.
Despite the finite nature of petroleum and gas, they remain dominant sources
of energy. This appears unlikely to change in the near future. Against this
backdrop of increasing reliance on imported oil, heavy oil (10-20° API or
940-1,000 kg/m3) is a tremendous energy resource that is not utilized to its
fullest potential. In the contiguous U.S., it is estimated that heavy oil reservoirs
hold in excess of 85 billion barrels of OOIP; in Alaska there is at least an
additional 40 billion barrels. Worldwide, there are also large heavy-oil deposits
in Canada, Venezuela, China, Indonesia, and the former Soviet Union. Moreover,
fractured reservoirs are estimated to contain 25-30% of the world's oil supply.
Many of these reservoirs, with artificial or natural fractures, contain medium
to heavy oil or tar. The central problem with heavy crude oil production is
that the oil is far more viscous than water or conventional crude oil. Because
fluid flow resistance is proportional to viscosity, high viscosity frustrates
production. The challenge was to improve industry's understanding of primary
and thermal heavy oil recovery mechanisms and to increase recovery efficiency
so that oil not producible by conventional means can be recovered. Thermal methods,
especially steam injection-where heat is used to lower oil viscosity-and carefully
engineered primary (cold) production, are the best techniques for increasing
production from heavy and fractured reservoirs.
- Developed a new technique for measuring the oil-water relative permeability
and capillary pressure characteristics of heavy oil in porous media.
- Proposed and verified a mechanism for the evolution of the wettability of
reservoir rock toward increased water wetness as a function of increasing temperature.
- Proved experimentally, the theoretical existence of two different modes of
countercurrent imbibition in multidimensional fractured rock. This discovery
led to a time-dependent formulation of the matrix-fracture transfer function
employed in dual-porosity simulation.
- Demonstrated that, with respect to heavy oil solution gas drive, oil viscosity
and composition affect significantly the coalescence of gas liberated from solution
into a continuous gas phase. Thus the gas remains dispersed and relatively immobile
within the reservoir, thereby maintaining drive energy for a significant period
of time. This observation explains, in part, the excellent recovery witnessed
in some heavy oil reservoirs under cold production.
- Developed a novel technique employing streamlines to perform history matching
of production data under geological constraints.
Current Status (October 2005)
A small business, StreamSim Technologies, is attempting to commercialize the
history-matching technique developed under this project. The company expects
to be marketing a commercial code within 3 years.
Final Report [PDF-5.59MB] - December, 2003
Hoffman, B.T., and Kovscek, A. R., "Displacement Front Stability of Steam
Injection into High Porosity Diatomite Rock," Journal of Petroleum Science
and Engineering, 46(4), 253-266 (2005). DOI:10.1016/j.petrol.2005.01.004.
Schembre. J.M., and Kovscek, A.R., "Thermally Induced Fines Migration:
Its Relationship to Wettability and Formation Damage," SPE 86937, Proceedings
of the SPE International Thermal Operations and Heavy Oil Symposium and Western
Regional Meeting, Bakersfield, CA, March 16-18, 2004.
Tang, G.Q., and Kovscek, A.R., "An Experimental Investigation of the
Effect of Temperature on Recovery of Heavy Oil From Diatomite," Society
of Petroleum Engineers Journal, 9(2), 163-179 (2004).
Sahni, A., Gadelle, F., Kumar, M., Tomutsa, L., and Kovscek, A.R., "Experiments
and Analysis of Heavy Oil Solution Gas Drive," Society of Petroleum Engineers
Reservoir Engineering & Evaluation, 7(3), 217-229 (2004).
Kovscek, A. R., and Bertin, H.J., "Foam Mobility in Heterogeneous Porous
Media I & II: Scaling Concepts" & "Experimental Observations,"
Transport in Porous Media, 52, 17-35, 37-49 (2003).
(A list of additional published articles can be obtained from the principal
investigator at email@example.com.)
Project Start: September 1, 2000
Project End: December 31, 2003
DOE Contribution: $1,453,137
Performer Contribution: $363,284 (20% of total)
NETL - Sue Mehlhoff (firstname.lastname@example.org or 918-699-2044)
Stanford U. - Anthony Kovscek (email@example.com or 650-723-1218)
CT-derived water saturation images of water imbibition in oil-saturated core
of diatomite. Times beneath the images are given in minutes.