The project goal is to develop an improved understanding and tools for the management of reservoirs. The geomechanics approach to the characterization, stimulation, and production of oil reservoirs involves the characterization of natural fracture systems, the measurement of in situ stress, the development of an understanding of the evolution of stress state with reservoir production, and the determination of the mechanical and transport properties of reservoir rocks and fracture systems and how those properties change with the evolving stress state.
This project was funded through DOE's Natural Gas and Oil Technology Partnership Program. The Partnership Program establishes alliances that combine the resources and experience of the nation's petroleum industry with the capabilities of the national laboratories to expedite research, development, and demonstration of advanced technologies for improved natural gas and oil recovery.
Sandia National Laboratories
Reservoirs are dynamic systems that are constantly changing during their production history. Primary hydrocarbon production of a reservoir will reduce the pore pressure, increase the effective stresses and alter the formation permeability and fracture flow characteristics. Improving reservoir management requires the characterization of reservoir fracture networks, meaningful mechanical property and permeability data that are obtained under realistic reservoir conditions, and an improved capability to integrate coupled mechanical-fluid flow effects into reservoir production models.
The key elements in the application of this geomechanics approach to the characterization, stimulation, and production of oil reservoirs are the characterization of natural fracture systems, the measurement of in situ stress, an understanding of the evolution of stress state with reservoir production, and the determination of the mechanical and transport properties of reservoir rocks and fracture systems and how those properties change with the evolving stress state.
The goal of this program was to develop a better understanding of how geomechanics (rock deformation, fracturing, and in situ stress) affects the optimal management of reservoir production and to develop tools based on improved understanding that would allow engineers to better manage production and avoid problems.
The major results from this project are in three areas:
The benefits resulting from this work are many. It has resulted in several partnerships with industry (most notably, with BP, Phillips, ExxonMobil, BHP, Chevron, Conoco, Halliburton, and Unocal) to support the development and implementation of methods that have significantly reduced drilling and production costs in the Gulf of Mexico. The project efforts also have resulted in the elucidation of phenomena, such as the formation of compaction bands, that can be demonstrated to have potentially significant effects on long-term reservoir production, if not addressed through careful production planning and management. This fundamental work also has spawned numerous research efforts at technical institutions and universities across the country to better understand the conditions leading to the formation of heterogeneous compaction or shear states. Related efforts to assist production companies in the Gulf of Mexico has led to drill hole stabilization methods saving millions of dollars.
Recent work entails:
Although the project was completed, related industry research on compaction banding continues.
Cooper, S.P., Lorenz, J.C., and Goodwin, L.B., Lithologic and structural controls on natural fracture characteristics-Teapot Dome, Wyoming, Sandia National Laboratories Technical Report, SAND2001-1786, 2001.
DiGiovanni, A. A., Fredrich, J. T., Holcomb, D. J., and Olsson, W. A., Micromechanics of Compaction in an Analogue Reservoir Sandstone, Pacific Rocks 2000, Girard, Lieberman, Breeds and Doe (eds), Balkema, Rotterdam, pp. 1153, 2000.
Lorenz, J.C., Sterling, J.L., Schecter, D.S., Whigham, C.L., Jensen, J.L., Natural Fractures in the Spraberry Formation, Midland Basin, TX: The Effects of Mechanical Stratigraphy on Fracture Variability and Reservoir Behavior, American Association of Petroleum Geologists Bulletin, v. 86, p. 505-524, 2002.
Lorenz, J.C., and Cooper, S.P., Interpreting Fracture Patterns in Sandstones Interbedded with Ductile Strata at the Salt Valley Anticline, Arches National Park, Utah, Sandia National Laboratories Technical Report, SAND2001-3517, 2001.
Olsson, W. A., and Holcomb, D.J., Compaction localization in porous rock, Geophysical Research Letters, v. 27, 3537-3540, 2000.
Olsson, W. A., Theoretical and experimental investigation of compaction bands in porous rock, J. Geophys. Res., 104, 7219-7228, 1999.
Olsson, W. A., Quasistatic propagation of compaction fronts in porous rock, Mechanics of Materials, 33, 659-668, 2001.
Holcomb, D. J., and Olsson, W. A., Compaction localization and fluid flow, J. Geophys. Res., 2002.
Olsson, W. A., Origin of Luders bands in deformed rock, J. Geophys. Res., v. 105, pp. 5931-5938, 2000.
Olsson, W. A., Lorenz, J.C., and Cooper, S.P., A Mechanical Model for Multiply Oriented Conjugate Deformation Bands, J. Structural Geology, v. 26, 325-338, 2004.
$340,000 (8.5% of total)