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The AAPG/Datapages Combined Publications Database

Environmental Geosciences (DEG)

Abstract

Environmental Geosciences, V. 22, No. 3 (September 2015), PP. 7583

Copyright copy2015. The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

DOI: 10.1306/eg.06191515004

Characterizing initial-state conductivity distribution at a CO2 injection site with airborne, surface, and borehole electromagnetic induction methods

Lucie Costard1 and Jeffrey G. Paine2

1Bureau of Economic Geology, The University of Texas at Austin, University Station, Box X, Austin, Texas 78713; Institut für Geowissenschaften, Abteilung Geophysik, Christian-Albrechts-Universität zu Kiel, Otto-Hahn-Platz 1, 24118 Kiel, Germany; [email protected]
2Bureau of Economic Geology, The University of Texas at Austin, University Station, Box X, Austin, Texas 78713; [email protected]

ABSTRACT

Electromagnetic (EM) methods were used to characterize (1) the general near-surface geology and stratigraphy and (2) the initial electrical conductivity distribution at a EG15004eq1 enhanced oil recovery (EOR) site to assess and monitor possible near-surface environmental impacts of a carbon sequestration experiment. The field study was conducted at Cranfield Field, an EOR site where EG15004eq2 is being injected into a depleted oil and gas reservoir in the Cretaceous lower Tuscaloosa Formation in western Mississippi. The study focused on Tertiary and younger strata between the ground surface and maximum depths of approximately 200 m (656 ft) that host groundwater more than 3000 m (9843 ft) above the oil and gas reservoir and injection zone. It included an airborne geophysical survey collecting frequency-domain EM data, time-domain surface EM measurements, borehole logging with EM induction, natural gamma spectra, and water-level measurements. Different approaches of temperature drift corrections for the borehole EM data were compared; good results of consistent and accurate conductivity values were produced by combining both directions of a two-way (uphole and downhole) measurement. The airborne EM provided data over a large area with sufficient detail to give an overview for the subsequent surface and borehole surveys, the surface time-domain data gave insight into greater depths, and the borehole induction data provided the necessary details. These three EM methods complement each other in areal coverage, lateral and vertical resolution, and exploration depth. Together, they can provide a comprehensive near-surface characterization of the study area that is necessary to establish initial-state conditions that support future monitoring of potential EG15004eq3 migration to the near-surface environment.

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