Completed Study
Geologic Characterization of Fractured Reservoir Block Size Using Microcrack Data
Stephen E. Laubach and Jon E. Olson (Department of Petroleum and Geosystems Engineering, The University of Texas at Austin), principal investigators; assisted by Yuan Qiu, Zeno Philip, and Jon Holder
  The goals of this project, funded by the Advanced Research Program of the Texas Higher Education Coordinating Board, included characterization of fracture arrays in sedimentary rocks, relating the fracture characteristics to fluid-flow observations, and relating fracture characteristics to the bedding architecture of the sedimentary rocks. Naturally fractured reservoirs represent a large but poorly understood resource in the State of Texas as well as in other hydrocarbon-producing provinces throughout the world. Reservoir-scale fracture networks are difficult to characterize because fracture spacing is typically many times the diameter of a conventional borehole, so that in most cases well bores miss fractures. Because these fractures may nevertheless profoundly influence reservoir behavior, this sampling problem poses a serious challenge to fracture characterization and simulation. This project involved geomechanical modeling and other advanced modeling and characterization methods to improve prediction of

fracture attributes in the interwell region. The project successfully used microstructural fracture proxies to define the location of horizons having conductive fractures on a scale suitable for use in reservoir simulation. These results have been used to specify the vertical dimension of simulator cellblocks. Geomechanical modeling, calibrated with subsurface fracture observations and new rock property tests, specifies the spacing of fracture clusters in a way that can be used to define the lateral extent of cellblocks.


Olson, J., Hennings, P. H., and Laubach, S. E., 1998, Integrating wellbore data and geomechanical modeling for effective characterization of naturally fractured reservoirs: EUROCK '98, Society of Petroleum Engineers, p. 475–485.

Laubach, S. E., 1997, A method to detect natural fracture strike in sandstones: American Association of Petroleum Geologists Bulletin, v. 81, no. 4, p. 604–623.

For more information, please contact Steve Laubach, principal investigator. Telephone 512-471-6303; e-mail
February 2003