Evidence for composite hydraulic architecture in an active fault system based on 3D seismic reflection, time‐domain electromagnetics and temperature data

Abstract

Fault hydrology is a topic of scientific and practical importance but considerable uncertainty exists regarding the nature of structural controls on fluid flow. Here we use seismic reflection and timedomain electromagnetic data to develop a three-dimensional model of hydraulic architecture in a predominantly dip-slip normal fault system and we predict the architectural elements based on subsurface fluid flow patterns inferred from near-surface temperature measurements. Our observations indicate the presence of high-permeability flow paths parallel to fault planes in poorly-lithified sediments. These results are best explained using a combination of elements from commonly accepted conceptual models of fault architecture, a finding that exhibits the heterogeneous nature of the geologic materials comprising the site. These insights may be useful as a guide to future studies of active fault systems, where multiple-mode investigations (geophysical, hydrologic, thermal, geochemical) will be required to better understand subsurface fluid/fault interactions.

Cluster Analysis as a Tool for Evaluating the Exploration Potential of Known Geothermal Resource Areas

“…An exploration well drilled by Anadarko Petroleum to a depth of 451 m in 1989 flowed at a rate of 400 gpm and a temperature of 152°C (Cummings et al, 1993). Cation geothermometry indicates equilibration temperatures around 200°C (Cummings et al, 1993;Koski and Wood, 2004), and studies indicate hydrothermal discharge in the basin is fault controlled (Fairley and Hinds, 2004;Anderson and Fairley, 2008;Hess et al, 2009), with strong lateral variations in fault permeability tending to channelize subsurface flow into localized "fastflow" pathways (Fairley and Hinds, 2004;Fairley, 2009). Environmental restrictions on development in the Alvord Basin have discouraged further commercial exploration in the basin, but the area provides an important source of data for testing models of geothermal systems.…”

17. High-Resolution Seismic Imaging of Near-Surface Fault Structures within the Upper Rhine Graben, Germany

“…Fault systems are important targets in fields of exploration geophysics because they have a significant impact on hydrocarbon migration and trapping (Knipe et al, 1998;Manzocchi et al, 1998;Walsh et al, 1998;Krawczyk et al, 2007), ore mineralization (Blundell et al, 2002;Zhang et al, 2003), and regional hydrogeology (Haneburg and Hawley, 1996;Bense and van Balen, 2003;Hess et al, 2009). More recently, fault systems also have been considered to be valuable hydrogeothermal reservoirs for heat and energy extraction.…”

The Effects of Fault‐Zone Cementation on Groundwater Flow at the Field Scale

“…One of the most common means of predicting fault sealing potential is by estimating the shale-gouge ratio (Yielding et al 1997). Additional methods for estimating fault seal potential in unlithified sediments, focus primarily on: (1) the juxtaposition of hydrostratigraphic units, (2) cataclasis developing a low permeability fault core, or (3) particulate flow developing zones of mixed character adjacent to the fault core (Heynekamp et al 1999;Rawling et al 2001;Sigda and Wilson 2003;Minor and Hudson 2006;Rawling and Goodwin 2006;Caine and Minor 2009;Hess et al 2009;De Boever et al 2011;Loveless et al 2011). In systems where cementation is the dominant process reducing fault zone permeability, predictions of fault seal that do not account for cementation are likely to be unsound.…”