BELT, JOHN Q. JR. and GARY K. RICE
GeoFrontiers Corporation, Dallas, TX
Abstract: Low-Cost Quantified Fluorescence Analysis of Soils Helps Evaluate the Hydrocarbon Potential of Oil and Gas Prospects
Fluorescence analysis of near-surface soils and sediments detects the Polynuclear Aromatic Compounds (PAC) associated with petroleum seepage. Transfer of PAC-containing petroleum at depth into the near-surface requires macro-fractures. Quantifying and mapping PAC displays petroleum seepage along fracture migration pathways. Therefore, mapping elevated PAC concentrations shows the approximate location of macro-fractures at the surface.
A PAC concentration ordered plot determines background (insignificant) versus anomalous (significant) concentrations. Increased slope in the ordered plot determines mapping boundary for anomalous concentrations. Color-filled contour maps are constructed using these parameters. A single line of data may be depicted as a mapped profile line. Reconnaissance data is usually displayed as a bubble or dot map.
Mapped PAC data should be integrated with available subsurface geology and geomorphology. The comparison of drainage patterns with elevated concentration trends often reveal a subsurface migration pathway. Integrating PAC data with available geological information helps the explorationist evaluate the hydrocarbon potential of a prospect. Areas appearing more prospective should be evaluated with additional geochemical and/or geophysical tools.
Examples illustrating faults, differential loading and compaction fractures, shelf edge fractures, and the quantifying statistical quality control process will be presented.
AAPG Search and Discovery Article #90918©1999 AAPG Southwest Section Meeting, Abilene, Texas