SEMI-AUTOMATED APPROACH TO MAPPING SMALL SCALE STRUCTURES FOR OIL AND GAS EXPLORATION ALONG THE SOUTHERN CINCINNATI ARCH USING PYTHON AND GIS APPLICATIONS

The oil and gas production in south-central Kentucky and northern Tennessee is primarily from fractured reservoirs in Ordovician carbonates. Some of these reservoirs have been associated with hydrothermally dolomitized zones that occur along negative flower structures resulting from lateral movement along deeper reactivated basement faults, similar to the Albion-Scipio trend. The outcrop surface expression of these structures appear as synclinal features, which can be easily identified on structure contour maps. Unfortunately, producing structure contour maps from surface geologic maps and well data can be time consuming, particularly if no digital data are available and manual entry of data points is required. Here a semi-automated process for generating structure contour maps from surface and subsurface geologic data was developed in Python™, facilitating the analysis of large datasets. This process was then used to generate regional structure contour maps spanning from central Kentucky, to northern Alabama along the southern portion of the Cincinnati arch, a regional scale structural high, and the superimposed Nashville and Jessamine domes that separate the Appalachian and Illinois petroleum producing basins.

Due to the large volume of data available for this study, we developed a semi-automated process for data collection, cleaning, and cross-verification using Python™ and ArcGIS™. This process was used to compile data from 887 published and unpublished digital 1:24,000-scale geologic quadrangle maps acquired from the Tennessee Geological Survey, Kentucky Geological Survey, USGS, and Alabama Geological Survey. Subsurface data from 24,833 wells were also compiled from oil and gas well logs, mineral exploration boreholes, resource summary reports, and state oil and gas well databases. We then generated structure maps of key surfaces and identified multiple sets of map-scale folds across the study area. Along the southern Nashville dome these folds frequently trend N-S, with a second set trending NW-SE at a similar orientation to a series of faults. E-W-trending folds occur on the flanks of the Jessamine dome. The synclinal features associated with these folds may be similar to those with basement fault associated dolomitized zones and as a result are potential targets for oil and gas exploration.