Slim Holes

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Exploration Technique: Slim Holes

Exploration Technique Information
Exploration Group: Drilling Techniques
Exploration Sub Group: Exploration Drilling
Parent Exploration Technique: Exploration Drilling
Information Provided by Technique
Lithology: If core is collected
Stratigraphic/Structural: If core is collected
Hydrological: Fluid flow and water chemistry
Thermal: Thermal gradient or bottom hole temperature
Cost Information
Low-End Estimate (USD): 100.0010,000 centUSD
0.1 kUSD
1.0e-4 MUSD
1.0e-7 TUSD
/ foot
Median Estimate (USD): 169.8916,989 centUSD
0.17 kUSD
1.6989e-4 MUSD
1.6989e-7 TUSD
/ foot
High-End Estimate (USD): 200.0020,000 centUSD
0.2 kUSD
2.0e-4 MUSD
2.0e-7 TUSD
/ foot
Time Required
Low-End Estimate: 0.0132802124833997 day3.635924e-5 years
0.319 hours
0.0019 weeks
4.363109e-4 months
/ foot
Median Estimate: 0.00998801438274071 day2.734569e-5 years
0.24 hours
0.00143 weeks
3.281483e-4 months
/ foot
High-End Estimate: 0.00893655049151028 day2.446694e-5 years
0.214 hours
0.00128 weeks
2.936033e-4 months
/ foot
Additional Info
Cost/Time Dependency: Costs increase with depth over time, and deeper holes require larger initial core size (e.g., Delahunty et al 2012). Cost is also affected by drilling regulations for geothermal test wells, which may require casing string cemented in to a percentage of total depth; these rules typically require 1" cement annulus, which may require reaming of hole to attain.
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Slim Holes:
Slim holes are typically drilled using a diamond coated bit, core samples are often collected, and reservoir properties measured. Slim holes can range from 3-6’’ in diameter and be significantly cheaper than traditional wider rotary drilled holes.
Other definitions:Wikipedia Reegle


 
Introduction
Drilling costs are considered to be the largest expense for developing a geothermal power facility. Slim holes can be a cheaper way to characterize the geothermal resource than traditionally wider exploratory wells (Finger, et al., 1999). Pritchet (1995; 1996) conducted compelling research on the feasibility of small scale geothermal power plants (100-1,000 kWe) using slim holes as production wells to promote remote resource development in undeveloped regions. However, due to the small diameter of slim holes flow rates are not sufficent for large scale power output per well, and are therefore considered to be associated with exploratory drilling.
 
Use in Geothermal Exploration
Slim holes are very commonly considered to be synonymous with core holes, however, there can be slim holes that do not recover core samples. Slim holes are usually drilled to recover core, take water samples, measure thermal and fluid flow properties (Garg and Combs, 1993). Once the reservoir has been adequately defined and slim holes happen to be in an optimal location and depth, they can be used for observation and monitoring of the geothermal reservoir during production (Hinchliffe).

Slim holes offer a significant advantage because lost circulation zones can be drilled through with no problems (aside from loss of drilling fluids/mud), without stopping to cure the lost circulation (e.g., Delahunty et al 2012).

Costs increase with depth over time, and deeper holes require larger initial core size (e.g., Delahunty et al 2012). Cost is also affected by drilling regulations for geothermal test wells, which may require casing string cemented in to a percentage of total depth; these rules typically require 1" cement annulus, which may require reaming of hole to attain.

 
Related Techniques
Core Holes are a related technique because they are drilled specifically to recover core samples, while slim holes very often recover core samples. When core samples are recovered they are considered to be the same, utilizing the same drilling techniques.
 
Field Procedures
Slim holes require less of a footprint for drilling, smaller rig, less water, and can mobilize much quicker than traditional wide rotary holes (Hinchliffe).










Page Area Activity Start Date Activity End Date Reference Material
Slim Holes At Alum Area (DOE GTP) Alum Geothermal Area


Slim Holes At Alvord Hot Springs Area (Combs, Et Al., 1999) Alvord Hot Springs Area


Slim Holes At Black Warrior Area (DOE GTP) Black Warrior Area


Slim Holes At Blue Mountain Area (Warpinski, Et Al., 2002) Blue Mountain Area


Slim Holes At Blue Mountain Geothermal Area (Fairbank Engineering Ltd, 2003) Blue Mountain Geothermal Area 2002 2004


Slim Holes At Crump's Hot Springs Area (DOE GTP) Crump's Hot Springs Geothermal Area


Slim Holes At Fish Lake Valley Area (Deymonaz, Et Al., 2008) Fish Lake Valley Area


Slim Holes At Flint Geothermal Area (DOE GTP) Flint Geothermal Area


Slim Holes At Fort Bliss Area (Combs, Et Al., 1999) Fort Bliss Area


Slim Holes At Fort Bliss Area (DOE GTP) Fort Bliss Area


Slim Holes At Gabbs Valley Area (DOE GTP) Gabbs Valley Area


Slim Holes At Glass Buttes Area (DOE GTP) Glass Buttes Area


Slim Holes At Hawthorne Area (Sabin, Et Al., 2010) Hawthorne Area


Slim Holes At Hot Pot Area (DOE GTP) Hot Pot Area


Slim Holes At International Geothermal Area, Japan (Combs, Et Al., 1999) International Geothermal Area Japan


Slim Holes At Jemez Pueblo Area (DOE GTP) Jemez Pueblo Area


Slim Holes At Maui Area (DOE GTP) Maui Area


Slim Holes At New River Area (DOE GTP) New River Area


Slim Holes At Newberry Caldera Area (Combs, Et Al., 1999) Newberry Caldera Area


Slim Holes At Newberry Caldera Area (DOE GTP) Newberry Caldera Area


Slim Holes At Reese River Area (Henkle & Ronne, 2008) Reese River Area


Slim Holes At Salt Wells Area (Combs, Et Al., 1999) Salt Wells Area 1980 1980


Slim Holes At Salton Sea Area (Sabin, Et Al., 2010) Salton Sea Area


Slim Holes At Silver Peak Area (DOE GTP) Silver Peak Area


Slim Holes At Snake River Plain Region (DOE GTP) Snake River Plain Geothermal Region


Slim Holes At Steamboat Springs Area (Combs, Et Al., 1999) Steamboat Springs Area


Slim Holes At Steamboat Springs Area (Warpinski, Et Al., 2002) Steamboat Springs Area


Slim Holes At Steamboat Springs Area (Warpinski, Et Al., 2004) Steamboat Springs Area


Slim Holes At Vale Hot Springs Area (Combs, Et Al., 1999) Vale Hot Springs Area

Document # Analysis
Type
Applicant Geothermal
Area
Lead
Agency
District
Office
Field
Office
Mineral
Manager
Surface
Manager
Development
Phase(s)
Techniques
DOI-BLM-CA-170-02-15 EA Mammoth Pacific Long Valley Caldera Geothermal Area BLM BLM Central California District Office BLM Bishop Field Office BLM Geothermal/Exploration Exploration Drilling
Exploratory Well
Slim Holes
Drilling Methods
DOI-BLM-NV-B020-2010-0106-CX CX Sierra Geothermal Power Alum Geothermal Area Bureau of Land Management BLM Battle Mountain District Office Bureau of Land Management Bureau of Land Management Geothermal/Exploration Hyperspectral Imaging
Magnetotellurics
Slim Holes
Z-Axis Tipper Electromagnetics
Magnetic Techniques
DOI-BLM-NV-W010-2010-0043-CX-2 CX Geothermal Technical Partners McGee Mountain Geothermal Area Bureau of Land Management BLM Winnemucca District Office BLM Humboldt River Field Office Bureau of Land Management Bureau of Land Management Geothermal/Exploration Geophysical Techniques
Slim Holes
Thermal Gradient Holes
Well Testing Techniques
EA-NV-030-07-006 EA Ormat Technologies Inc Carson Lake Corral Geothermal Area Bureau of Land Management BLM Carson City District Office BLM Stillwater Field Office Bureau of Land Management BLM
Bureau of Reclamation
Geothermal/Well Field Exploration Drilling
Slim Holes
Thermal Gradient Holes
GFO-04-236b, GFO-10-367 Chena Hot Springs Resort Chena Geothermal Area DOE Golden Field Office Geothermal/Exploration Slim Holes
NV-063-EA06-098 EA Sierra Geothermal Power Reese River Geothermal Area Bureau of Land Management BLM Battle Mountain District Office BLM BLM Geothermal/Exploration Slim Holes
Thermal Gradient Holes


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