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AAPG Rocky Mountain Section Meeting

Datapages, Inc.Print this page

Application of surface geochemical survey integrated with subsurface geology and seismic data in exploration for conventional reservoirs

Abstract

Surface geochemistry can be an integral part in finding conventional petroleum reservoirs when used in conjunction with subsurface and seismic data. Surface geochemical methods presented here are iodine and soil gas results that detailed regional and specific areas for further exploration and delineation by subsurface and seismic tools. Surface geochemistry is based on the concept that vertically migrating hydrocarbons migrate upwards from a reservoir to the surface along micro-pores, micro-fractures and microunconformities. Fluids migrate as the result of simple physics of moving toward an area of decreasing pressure. Migrating petroleum compounds eventually enter the soil substrate and react with existing oxides, carbonates, metals, plants, bacteria, water and clays. These petroleum compounds cause changes in Eh, pH, deposition of or removal of radioactive, halogen and carbonate minerals. One of the pressing questions for an explorationist is whether a target defined by subsurface geology, 3D or 2D seismic contains hydrocarbons. The presence or absence of a surface geochemical anomaly can determine if exploration should stop or move forward. The lack of a surface geochemical anomaly, as defined by actual drilling case histories in the literature, indicate there is a 95% chance testing will result in a dry hole, marginal or uneconomic well. The presence of a surface geochemical anomaly, strong or weak, definitive or chaotic in shape, does not predict a productive or producible discovery. Based on published articles over the last 80 years the use of surface geochemistry can increase drilling success from 10% to 60% depending upon the area. Surface geochemistry has proven to be a very successful exploration tool when integrated with subsurface and seismic methods. Presented here will be case histories utilizing surface geochemistry with seismic and subsurface geology from the Nevada Basin and Range Province, Denver, and Williston basins; USA; Michigan Basin, Canada and the Zuunbayan and Unegt basins, China.