2004 Denver Annual Meeting (November 7–10, 2004)

Paper No. 8
Presentation Time: 3:30 PM


NISSEN, Susan E.1, MARFURT, Kurt J.2 and CARR, Timothy R.1, (1)Kansas Geological Survey, Univ of Kansas, 1930 Constant Ave, Lawrence, KS 66047-3726, (2)Allied Geophysical Laboratories, Univ of Houston, 4800 Calhoun, Houston, TX 77204-5505, snissen@kgs.ku.edu

The widespread Western Interior Plains (WIP) aquifer system has a high potential for sequestration of large quantities of CO2 in a deep saline aquifer, with the addition of value-added sequestration through enhanced oil recovery. In Kansas, the Mississippian aquifer unit of the WIP consists primarily of naturally fractured, solution-enhanced, multi-layered shallow shelf carbonates with a strong bottom water drive. On both regional and local scale, fluid flow in the Mississippian aquifer is strongly influenced by fracturing. Fractures can either be open, providing a water conduit, or shale-filled, providing a barrier to fluid flow.

New 3-D seismic attributes, including a suite of volumetric reflector curvature attributes developed at the University of Houston, have the potential to reveal subtle lineaments that can be related to fractures in the aquifer. Volumetric curvature attributes are calculated directly from a seismic data volume, with no prior interpretation required, and have been shown to be useful in delineating faults, fractures, flexures, and folds.

Volumetric curvature attributes applied to 3-D seismic surveys over the Mississippian aquifer in Kansas reveal two main lineament directions within the Mississippian, with orientations of approximately N45E and N45W. The N45E-trending lineaments parallel a down-to-the-north normal fault at the northwestern corner of one of the seismic surveys, and appear, on average, to have greater length and continuity than the N45W-trending lineaments. Fluid and pressure data tied to flow simulation suggest that the N45E-trending lineaments may be related to shale-filled fractures, while the N45W-trending lineaments may be related to open fractures that are conduits for water. Both sets of lineaments are related to karst-enhanced fracturing in the Mississippian.

Imaging of natural fractures within an aquifer system to be used for CO2 sequestration is required to maximize injection and storage of CO2 and minimize early breakthrough between wells. Also, detection of fractures is critical to evaluating the integrity of overlying seal. New 3-D seismic attributes help to locate these fractures and could become an important tool in the evaluation of potential geological sequestration sites.