Reflection Survey

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Exploration Technique: Reflection Survey

Exploration Technique Information
Exploration Group: Geophysical Techniques
Exploration Sub Group: Seismic Techniques
Parent Exploration Technique: Active Seismic Techniques
Information Provided by Technique
Lithology: Rock unit density influences elastic wave velocities.
Stratigraphic/Structural: Structural geology- faults, folds, grabens, horst blocks, sedimentary layering, discontinuities, etc.
Hydrological: Combining compressional and shear wave results can indicate the presence of fluid saturation in the formation.
Thermal: High temperatures and pressure impact the compressional and shear wave velocities.
Cost Information
Low-End Estimate (USD): 26,763.332,676,333 centUSD
26.763 kUSD
0.0268 MUSD
2.676333e-5 TUSD
/ sq. mile
Median Estimate (USD): 44,946.674,494,667 centUSD
44.947 kUSD
0.0449 MUSD
4.494667e-5 TUSD
/ sq. mile
High-End Estimate (USD): 120,000.0012,000,000 centUSD
120 kUSD
0.12 MUSD
1.2e-4 TUSD
/ sq. mile
Time Required
Low-End Estimate: 1.36 days0.00372 years
32.64 hours
0.194 weeks
0.0447 months
/ sq. mile
Median Estimate: 4.45 days0.0122 years
106.8 hours
0.636 weeks
0.146 months
/ sq. mile
High-End Estimate: 12.46 days0.0341 years
299.04 hours
1.78 weeks
0.409 months
/ sq. mile
Additional Info
Cost/Time Dependency: Energy Source Needed, Source and Receiver spacing, Terrain, Size
Dictionary.png
Reflection Survey:
Seismic reflection surveys image the structure of the subsurface through the measurement of the two way travel time of reflected artificially-generated elastic waves.
Other definitions:Wikipedia Reegle


 
Introduction
Seismic reflection is the most widely-used geophysical technique.[1] The method is capable of imaging to depths of 30,000 feet, enabling a determination of geologic structure throughout a sedimentary section. The depth of investigation of a seismic reflection survey relies on the chosen active seismic source as well as the subsurface characteristics.[2]
 
Use in Geothermal Exploration
Utilizing seismic reflection data, it is possible to constrain the structure in the vicinity of a geothermal reservoir, such as faulting, fracture zones, and impermeable cap rocks, for instance. [3]Alteration mineralization due to geothermal fluid flow typically results in high velocity regions, while fracture zones may attenuate the seismic waves and cause low velocity areas.[4] Additionally, the ratios between compressional and shear wave velocities may indicate if the geothermal reservoir is steam- or liquid-dominated. [5]

The image below is from a seismic survey which was conducted for geothermal exploration in 2010 at the Pueblo of Jemez in north-central New Mexico, 22 miles southwest of the Valles Caldera. In this region, the geothermal system is hypothesized to be fault-dominated at the Indian Springs fault zone based on geological studies. An active reflection survey was performed to constrain the structure of the faults in the subsurface and develop a better understanding of the geothermal system. An accelerated weight-drop seismic source was utilized and the geophones were placed along a survey line at 50 foot separation.[6]

The figure below presents the data after processing techniques (specifically poststack time migration) were performed (left) and the preliminary interpretation of the fault system (right). At 1 second of two-way time, the approximate depth is 6000 feet. The image profile indicates the presence of west-dipping geologic structures [6]

Poststack time migration image and preliminary interpretation of seismic reflection survey at the Jemez Pueblo in New Mexico.[6]



 
Field Procedures
 
Environmental Mitigation Measures
 
Physical Properties
 
Data Access and Acquisition
See Active Seismic Techniques

Seismic reflection is the most widely-used geophysical technique and many source/receiver arrays exist. These include p-wave sources, s-wave sources, 2D studies and 3D studies. There are different approaches and data processing techniques for each method. [5][2]

The figure below shows a simplified representation of the geometry of a seismic reflection survey.

Schematic of seismic reflection wave path geometry.[7]

 
Best Practices
 
Potential Pitfalls
2-D surface seismic reflection has limitations when applied to complex geothermal areas. Processing and interpretation of 2-D seismic data may be problematic due to attenuation, scattering and lack of coherent reflectors for well-siting purposes. [4]


 
NEPA Analysis
NEPA documentation could include a Categorical Exclusion (CX) for projects conducted in areas with no resource conflicts using vibroseis trucks with no new or improvements to existing roads and trails. An Environmental Assessment(EA)would most likely be initiated for those projects with resource elements that are present with a potential to be impacted. Examples include the use of shot hole, improvement and/or construction of access roads, or cultural concerns.


Page Area Activity Start Date Activity End Date Reference Material
Reflection Survey (Deangelo, Et Al., 1999) Unspecified


Reflection Survey (Laney, 2005) Unspecified


Reflection Survey (Majer, 2003) Unspecified


Reflection Survey (Nannini, 1986) Unspecified


Reflection Survey (Ozkocak, 1985) Unspecified


Reflection Survey At Blue Mountain Geothermal Area (Fairbank Engineering Ltd, 2003) Blue Mountain Geothermal Area 1990 1990


Reflection Survey At Blue Mountain Geothermal Area (Melosh, Et Al., 2010) Blue Mountain Geothermal Area 2007 2007


Reflection Survey At Coso Geothermal Area (1989) Coso Geothermal Area 1989 1989


Reflection Survey At Coso Geothermal Area (2001) Coso Geothermal Area 2001 2001


Reflection Survey At Coso Geothermal Area (2008) Coso Geothermal Area 2008 2008


Reflection Survey At Cove Fort Area - Liquid (Toksoz, Et Al, 2010) Cove Fort Geothermal Area


Reflection Survey At Crump's Hot Springs Area (DOE GTP) Crump's Hot Springs Geothermal Area


Reflection Survey At Dixie Valley Geothermal Area (Blackwell, Et Al., 2003) Dixie Valley Geothermal Area 1975 1985


Reflection Survey At Fish Lake Valley Area (DOE GTP) Fish Lake Valley Area


Reflection Survey At Hot Pot Area (DOE GTP) Hot Pot Area


Reflection Survey At Hot Sulphur Springs Area (Goranson, 2005) Hot Sulphur Springs Area


Reflection Survey At Hot Sulphur Springs Area (Laney, 2005) Hot Sulphur Springs Area


Reflection Survey At Jemez Pueblo Area (DOE GTP) Jemez Pueblo Area


Reflection Survey At Kilauea East Rift Geothermal Area (Leslie, Et Al., 2004) Kilauea East Rift Geothermal Area 1998 1998


Reflection Survey At Lightning Dock Area (Cunniff & Bowers, 2005) Lightning Dock Area


Reflection Survey At Neal Hot Springs Geothermal Area (Colorado School of Mines and Imperial College London, 2011) Neal Hot Springs Geothermal Area 2011 2011


Reflection Survey At Neal Hot Springs Geothermal Area (Colwell, Et Al., 2012) Neal Hot Springs Geothermal Area 2011 2011


Reflection Survey At New River Area (DOE GTP) New River Area


Reflection Survey At North Brawley Geothermal Area (Even, 2012) North Brawley Geothermal Area 2011 2011


Reflection Survey At Oceanic-Marine Systems (Singh, Et Al., 1999) Oceanic-Marine Systems


Reflection Survey At Rye Patch Area (DOE GTP, 2011) Rye Patch Area


Reflection Survey At Rye Patch Area (Deangelo, Et Al., 1999) Rye Patch Area


Reflection Survey At Rye Patch Area (Feighner, Et Al., 1999) Rye Patch Area


Reflection Survey At Rye Patch Area (Gritto, Et Al.) Rye Patch Area


Reflection Survey At Rye Patch Area (Laney, 2005) Rye Patch Area


Reflection Survey At San Emidio Desert Area (DOE GTP) San Emidio Desert Area


Reflection Survey At Snake River Plain Region (DOE GTP) Snake River Plain Geothermal Region


Reflection Survey At Soda Lake Area (DOE GTP) Soda Lake Area


Reflection Survey At The Needles Area (DOE GTP) The Needles Area


Reflection Survey At Under Steamboat Springs Area (Warpinski, Et Al., 2002) Under Steamboat Springs Area


Reflection Survey At Under Steamboat Springs Area (Warpinski, Et Al., 2004) Under Steamboat Springs Area


Reflection Survey At Valles Caldera - Redondo Geothermal Area (Musgrave, Et Al., 1989) Valles Caldera - Redondo Geothermal Area 1989


Reflection Survey At Wister Area (DOE GTP) Wister Area


Reflection Survey At Yellowstone Region (Morgan, Et Al., 2003) Yellowstone Caldera Geothermal Region


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