Integrated Investigations of Faulting in Carbonate Strata
This profile view of Hidden Valley fault zone at waterfall looking west southwest shows a synthetic dip in the footwall damage zone, and conjugate normal faulting in both footwall and hanging wall.
A Southwest Research Institute (SwRI) Project
Project Motivation and Scope
The permeability architecture of faults in carbonate rocks is of fundamental importance to hydrocarbon reservoir performance, but the architecture remains poorly understood. We will characterize the deformation features that develop in faulted carbonate rocks and integrate structural analysis with lithologic and hydrologic characterization.
The project will generate a quantitative data set of normal fault characteristics in carbonate strata and their effects on permeability.
This low-altitude aerial photograph of Canyon Lake Gorge shows traces of faults and locations of springs, pools, and infiltration points in a channel. View is to the east northeast, along the strike of the Hidden Valley fault.
Detailed work will be conducted on the recently exhumed Hidden Valley fault, which cuts the Cretaceous Glen Rose formation of south-central Texas. Additional work on faults within the Cretaceous strata of south-central and west Texas will provide a context for the interpretation and application of the detailed work. The Hidden Valley fault is representative of structures that are common in carbonate oil reservoirs and the unique site permits us to study the interplay between structure, rock type, and fault-zone hydraulic properties.
Specific Project Tasks
Stratigraphic and Lithologic Characterization
- Develop detailed measured sections of hanging wall and footwall
- Measure natural gamma ray log
- Characterize textures and quantify clay content of host lithologies
- Structural Analysis
- Analyze mechanical stratigraphy
- Produce detailed maps of outcrop scale structural elements
- Perform microstructural analysis
- Develop a digital geologic framework model from field mapping and borehole data
- Well Infrastructure
- Drill, core, log, and complete wells as multi-level piezometers in the hanging wall and footwall of Hidden Valley fault
- Hydrologic Characterization
- Assemble water-level data for Canyon Lake and local water wells
- Monitor springs, seeps, and influent/effluent surface water bodies
- Measure water flow rates within Canyon Lake Gorge
- Monitor water pressures at multiple intervals in monitoring wells
- Geomechanical Characterization
- Conduct tests to characterize geomechanical properties of representative lithologies from the Hidden Valley fault exposure
- Perform numerical geomechanical simulations using finite element and distinct element methods to simulate deformation associated with Hidden Valley fault
Photomicrographs of fault rock in Cretaceous limestone, from a fault in the the Balcones fault system in Central Texas, illustrates stylolites, vein fill, and twinning of vein calcite.
carbonate strata • permeability architecture • carbonate rock faults • hydrocarbon reservoir performance • deformation features • lithologic characterization • hydrologic characterization • normal fault characteristics • Hidden Valley fault • Cretaceous Glen Rose formation • stratigraphic characterization