Publication Date

5-2014

Advisor(s) - Committee Chair

Michael T. May (Director), Kenneth W. Kuehn, Jun Yan

Degree Program

Department of Geography and Geology

Degree Type

Master of Science

Abstract

Paleovalleys associated with the Mississippian-Pennsylvanian unconformity have been identified as potential targets for hydrocarbon exploration in the Illinois Basin. Though there is little literature addressing the geologic factors controlling hydrocarbon accumulation in sub-Pennsylvanian paleovalleys basin-wide, much work has been done to identify the Mississippian-Pennsylvanian unconformity, characterize the Chesterian and basal Pennsylvanian lithology, map the sub-Pennsylvanian paleogeology and delineate the pre-Pennsylvanian paleovalleys in the Illinois Basin. This study uses Geographic Information Systems (GIS) to determine the geologic factors controlling the distribution of hydrocarbon-bearing sub-Pennsylvanian paleovalley fill in the Illinois Basin. A methodology was developed to identify densely-drilled areas without associated petroleum occurrence in basal Pennsylvanian paleovalley fill. Kernel density estimation was used to approximate drilling activity throughout the basin and identify “hotspots” of high well density. Pennsylvanian oil and gas fields were compared to the hotspots to identify which areas were most likely unrelated to Pennsylvanian production. Those hotspots were then compared to areas with known hydrocarbon accumulations in sub-Pennsylvanian paleovalleys to determine what varies geologically amongst these locations. Geologic differences provided insight regarding the spatial distribution of hydrocarbon-bearing sub-Pennsylvanian paleovalleys in the Illinois Basin. It was found that the distribution of hydrocarbon-bearing paleovalleys in the Illinois Basin follows structural features and faults. In the structurally dominated portions of the Illinois Basin, especially in eastern Illinois along the La Salle Anticlinal Belt, hydrocarbons migrate into paleovalleys from underlying hydrocarbon-rich sub- Pennsylvanian paleogeology. Along the fault-dominated areas, such as the Wabash, Rough Creek and Pennyrile Fault Zones, migration occurs upwards along faults from deeper sources. Cross sections were made to gain a better understanding of the paleovalley reservoir and to assess the utility of using all the data collected in this study to locate paleovalley reservoirs. The Main Consolidated Field in Crawford County, Illinois, was chosen as the best site for subsurface mapping due to its high well density, associated Pennsylvanian production, and locally incised productive Chesterian strata. Four cross sections revealed a complex paleovalley reservoir with many potential pay zones. The methodology used to locate this paleovalley reservoir can be applied to other potential sites within the Illinois Basin and to other basins as well.

Disciplines

Geochemistry | Geographic Information Sciences | Geology

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