Development of Hydrologic Characterization Technology of Fault Zones

Abstract

Executive SummaryThis is the year-end report of the first year of the NUMO-LBNL collaborative project: Development of Hydrologic Characterization Technology of Fault Zones under NUMO-DOE/LBNL collaboration agreement, the task description of which can be found in the Appendix.Literature survey is conducted to study past works that relate geology to hydrology of fault zones. This includes study in sediments, sedimentary and crystalline (igneous and metamorphic) rocks with examples from various parts of the world. We focus on studies of hydrology of fault zones in the field and the laboratory as well as through modeling performed in all types of faults (i.e. normal, thrust and reverse, and strike-slip). We find that there is very limited amount of work on the subject, particularly in the field using borehole testing. The common elements of a fault include a core, and damage zones. The core usually acts as a barrier to the flow across it, whereas the damage zone controls the flow either parallel to the strike or dip of a fault. In most of cases the damage zone is the one that is controlling the flow in the fault zone and the surroundings. The permeability of damage zone is in the range of two to three orders of magnitude higher than the protolith. The fault core can have permeability up to seven orders of magnitude lower than the damage zone. In general, most fault studies in the literature fit into combinedconduit barrier classification by Caine et al., 1996.The main results are listed in three tables which summarize the main geological, structural and hydrological characteristics for each type of fault. At the end of the chapter, we suggest a characterization strategy for classifying faults based on available information (i.e. stress field, scaling relationship, fluid flow concentrated on one side of a fault) The fault types (normal, reverse, and strike-slip) by themselves do not appear to be a clear classifier of the hydrology of fault zones. However, there still remains a possibility that other additional geologic attributes and scaling relationships can be used to predict or bracket the range of hydrologic behavior of fault zones. We identify potential U.S. locations to conduct analogue studies and to extend the current effort on fault zone classification and development of characterization technology.Next we examine in the literature the characterization technologies employed and the information used to identify the hydrologic properties of faults. The findings are listed by the location. AMT(Audio frequency Magneto Telluric) and seismic reflection techniques are often used to locate faults. In some cases AMT results are successfully used to infer the hydrologic properties. Geochemical signatures and temperature distributions are often used to identify flow domains and/or directions. ALSM(Airborne Laser Swath Mapping) or LIDAR (Light Detection and Ranging) method may prove to be a powerful tool for identifying lineaments in place of the traditional photogrammetry. Nonetheless not much work has been done to cha...

The biases and trends in fault zone hydrogeology conceptual models: global compilation and categorical data analysis

“…In situ hydraulic tests are difficult in heterogeneous fault zones because of problems with separating the test intervals, difficulties of in situ testing the narrow fault cores, and interpreting the results (Karasaki et al . ). In hydrogeological studies, at depths <1 km below the top of the crystalline rock at research sites a large proportion of brittle faults are seen as conduits (e.g., Stevenson et al .…”

“…The faults are heterogeneous and it is difficult to assign only one simple category of the permeability structure to describe the hydraulic behavior (Shipton et al 2002). In situ hydraulic tests are difficult in heterogeneous fault zones because of problems with separating the test intervals, difficulties of in situ testing the narrow fault cores, and interpreting the results (Karasaki et al 2008). In hydrogeological studies, at depths <1 km below the top of the crystalline rock at research sites a large proportion of brittle faults are seen as conduits (e.g., Stevenson et al 1996;Bossart et al 2001;Stober & Bucher 2007;Geier et al 2012), although some of the drillhole data may not be representative of the faults tested because of heterogeneity and channeling of fracture networks.…”

Multidisciplinary database of permeability of fault zones and surrounding protolith rocks at world-wide sites

“…• drilling and in-situ hydraulic testing in parts of active fault zones on continents [38][39][40][41] ,…”

Development of Geohydrologic Model of the Wildcat Fault Zone

“…For example, contrary to LBNL and Parsons (2000), we encountered a geologic formation not expected in the boreholes drilled on the west side of the Wildcat Fault. According to the systematized investigation flow proposed in Karasaki et al (2008) and Kiho et al (2012), a geologic model would be constructed as information and data gathered by the field investigation start to come in. Then the geologic model would become the basis of a hydrologic model that honors hydraulic data obtained by passive and active hydrologic tests.…”