AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Evaluation of CO2 Sequestration Potential in Ozark Plateau Aquifer System (OPAS) in Southern Kansas - Initial Studies
(1) Kansas Geological Survey, University of Kansas, Lawrence, KS.
(2) Charter Consulting, Miramar, FL.
(3) Bittersweet Energy, Inc., Wichita, KS.
(4) Consultant, Hanover, KS.
(5) Department of Geology, Wichita State University, Wichita, KS.
(6) Department of Geology, Kansas State University, Manhattan, KS.
(7) Hedke-Saenger Geoscience, Ltd., Wichita, KS.
(8) Geophysical Consultant, Mc Louth, KS.
(9) Koger Remote Sensing, Ft. Worth, TX.
(10) Geological Consultant, Houston, TX.
The Paleozoic-age Ozark Plateau Aquifer System (OPAS) in southern Kansas is centrally located to multiple major point sources of CO2 emissions and is considered a prime candidate for CO2 sequestration. The OPAS consists of the thick (>800 ft) and deeply buried (>3500 ft) Arbuckle Group saline aquifer and overlying Mississippian carbonate reservoirs, such as Wellington field (Sumner County), many of which are in various stages of depletion. The Arbuckle saline aquifer consists of siliceous dolomite with interbedded shales, and appears to be well suited for supercritical CO2 sequestration because multiple regional caprocks isolate it from shallow freshwater aquifers. Demonstration of CO2-EOR potential in depleted Mississippian fields should spur infrastructure development for commercial scale CO2 sequestration in the OPAS.
This study focuses on 1) developing a regional (≈ 20,000 mi2) geomodel for the Arbuckle saline aquifer, 2) constructing a local geomodel of the Mississippian reservoir and the underlying Arbuckle saline aquifer at Wellington field, 3) estimating the CO2 sequestration capacity of the OPAS, and 4) evaluating CO2-EOR potential of Wellington field. The regional Arbuckle geomodel was constructed utilizing wireline logs from 95 type wells and 1400 key wells, 5 cores, DSTs, and gravity/magnetic and remote sensing data. The detailed Wellington geomodel integrates existing geologic and engineering data with newly acquired data: multi-component 3D seismic survey (10 mi2), gravity/magnetic surveys, and core and wireline logs from 2 wells drilled to basement.
The regional Arbuckle geomodel has helped to understand factors, such as lateral continuity of Arbuckle strata including caprocks and shale beds, and relationship between underpressurization and hydraulic connectivity to the outcrop (northwestern flank of Ozark Uplift), critical to modeling sequestration capacity of the OPAS. Arbuckle flow units, indentified by depth-constrained cluster analysis of petrophysical data and mapped over a 9-Township area over a monoclinal structure, were used in simulation studies, with CO2 injected in bottom Arbuckle flow unit, to demonstrate sequestration of significant tonnage of CO2 by solution, residual gas saturation, and mineralization. Intermediate shaly layers in Arbuckle appear to prevent vertical migration of free-phase CO2 to the lowermost caprock. Simultaneous brine injection from shallow Arbuckle flow-units increased residual gas trapping of CO2.