ABSTRACT: Associations among Landsat Thematic Mapper Data, Biogeochemical Anomalies, Hydrocarbon Microseepage and Oilfield Production Patterns in the Uinta Basin, Utah

Steven A. Young, Roger M. McCoy, Keith Clem

LANDSAT data can be analyzed to extract information pertinent to geologic exploration for oil and gas. Previous studies relied heavily

on synoptic coverage that LANDSAT data provided for the structural and stratigraphic interpretations in areas of interest. Criticism has been made of many of these analyses, suggesting that they were too qualitative, too weak on data, and too strong on speculation. It has only been in recent years that researchers have begun to augment remote sensing techniques with data sets from geophysics, structural analysis, stratigraphic basin analysis, geochemistry, and biogeochemistry.

The occurrence of natural fracture systems in subsurface rock is responsible for a significant portion of petroleum production in the Uinta basin, Utah. The Uinta basin of northeast Utah has long been recognized as one of the most petroliferous basins in the United States because of the exposures around the basin of thick oil shales, gilsonite dikes, and tar sands. The Altamont-Bluebell oil field in particular produces crude oil from a highly overpressured series of naturally fractured, low porosity, Tertiary lacustrine sandstones.

The purpose of this study is to determine the feasibility of developing a technique for combining remotely sensed data with biogeochemical, geochemical, geophysical, and structural data for identifying petroleum microseepage and subsequently for hydrocarbon exploration. This study was undertaken by first looking at the regional pattern of LANDSAT derived lineaments. As a result, a six township area within the Altamont-Bluebell oil field was chosen for further analysis. A detailed analysis was undertaken in order to evaluate the associations between LANDSAT-derived lineaments and the occurrence of hydrocarbons in the Altamont-Bluebell oil field, Utah.

The process of causing microseepage of hydrocarbons from oil accumulations upward to the surface is not well understood, but there is ample evidence of its occurrence. It is generally accepted that vertical microseepage is common and can produce a variety of near-surface phenomena thus leading to the possibility for detection of subsurface hydrocarbon accumulations. Leaking hydrocarbons promote the development of reducing conditions, thereby initiating chemical reactions in the strata overlying the reservoir. For example, seeping hydrocarbons provide reducing conditions sufficient enough to enable divalent iron and manganese to be organically complexed or absorbed on solids in the soils. These bound or absorbed elements in the divalent state are then assimilated by plants.

Various studies have shown that soils and plants growing over hydrocarbon accumulations at depth have greater amounts of reduced manganese and iron than the vegetation not over the producing area. Another study successfully mapped hydrocarbon microseepage induced mineralogic alteration in the surface rocks of Lisbon Valley, Utah, using LANDSAT Thematic Mapper data.

Preliminary results from our investigation suggest that the combination of techniques used appear to have positive results in successfully identifying and delineating the oil field and could prove to be a valuable method for future hydrocarbon exploration.

AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990