Exploration Drilling

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Exploration Technique: Exploration Drilling

Exploration Technique Information
Exploration Group: Drilling Techniques
Exploration Sub Group: Exploration Drilling‎
Parent Exploration Technique: Drilling Techniques
Information Provided by Technique
Lithology: Identify lithology and mineralization, provide core samples and rock cuttings
Stratigraphic/Structural: Retrieved samples can be used to identify stratigraphy and structural features such as fracture networks or faults
Hydrological: -Water samples can be used for geochemical analysis

-Fluid pressures can be used to estimate flow rates

Thermal: -Temperatures can be measured within the hole

-Thermal conductivity measurements can be done on retrieved samples.

Dictionary.png
Exploration Drilling:
Exploratory drilling is the Initial phase of drilling for the purpose of determining the physical properties and boundaries of a reservoir.
Other definitions:Wikipedia Reegle


 
Introduction
Exploration drilling is an important step before development drilling should take place. Exploration drilling is essential for obtaining actual temperature measurements, rock samples, and retrieving fluid samples for chemical analysis. Geophysical methods can give valuable and useful information about the subsurface, which is very important when determining the best locations for drilling; however, in order to obtain actual temperature and fluid measurements, samples need to be obtained via exploratory drilling. There are several different exploratory drilling techniques: core holes, exploratory wells, slim holes, and thermal gradient holes. These exploratory drilling methods are used because they are far less expensive than drilling a full sized production well. Exploratory drilling utilizes drill holes which are normally not as deep, smaller, and quicker to drill compared to production and injection wells. This allows for important subsurface data to be gathered at less cost so better informed decisions can be made about how to proceed in development. Exploration drilling provides the most accurate information during the exploration phase, but it is also the most expensive method, in many cases it is the final phase of exploration.
 
Use in Geothermal Exploration
Exploratory drilling is essential for determining if a geothermal reservoir is capable of producing sufficient hydrothermal fluids for power generation. Exploratory drilling is used for building accurate reservoir models based on hard evidence from what is observed down hole. Exploratory drilling can define reservoir boundaries, estimate production potentials, characterize the subsurface geology, and provide essential fluid geochemical data.

 
Field Procedures
Field procedures vary depending on which type of exploratory drilling is being done. Typically a drill rig for exploratory drilling is much smaller and portable compared to production well drill rigs. The figure below is an example of a drill rig for drilling core holes

Drilling for core samples in New Zealand [1]

 
Environmental Mitigation Measures
Exploratory drilling requires a small amount of land for the drilling area. Roads are usually required in order to transport the drill rig and other equipment to the site. In environmentally sensitive areas such as rain forest or endangered species habitats precautions need to be taken before exploratory drilling can commence because small amounts of deforestation may be required and noise may disturb native species. Exploration drilling may make aquifers more vulnerable to degradation and contamination by connecting aquifers at different elevations and by potentially allowing surface water to enter the aquifers. Suitable precautions will differ from site to site.[2] Wetlands and waterways are also susceptible to exploratory drilling. Unless preventative measures are taken there is potential for contamination from drilling fluids draining into nearby water supplies and entering the environment. An understanding of the hydrogeology of the area is necessary before exploratory drilling should take place.



 
Best Practices
For all drilling operations careful planning is a critical step before drilling begins. Many factors need to be taken into consideration, such as geographic location, drilling equipment, cost, schedule, well parameters, etc. Drilling near a source of water is often very beneficial otherwise water for the drilling mud has to be transported to the site which can be very expensive.[3] Site accessibility is also very important to take into consideration. Large trucks carrying heavy equipment need to have reasonable access to the site and there needs to be enough space at the site for all the equipment and supplies. Drilling during calm times of the year is very important; climate extremes of hot and cold and high precipitation can affect the mud system, the equipment, and make work condition miserable, ultimately resulting in slower drilling progress and higher expenses.[3]
 
Potential Pitfalls
Exploratory drilling is the most expensive part of exploration and often times it can be difficult to predict the costs due to unexpected problems associated with drilling. Loss of drilling fluid is the most common and expensive problem during exploratory drilling and accounts for over 20% of the costs in exploratory wells.[3] Another pitfall of exploratory drilling is the unpredictability of a well. Some wells can be unstable and collapse or have cementing problems or blowouts which can result in lost effort, time, and money.








 
References
  1. SonicSampDrill. Geotechnical Drilling in New-Zealand [Internet]. 2013. [cited 2013/10/01]. Available from: http://www.sonicsampdrill.com/news/geotechnical-drilling-in-new-zealand.htm
  2. Government of Western Australia (Department of Mines and Petroleum). 2002. Guidelines for the Protection of Surface and Groundwater Resources During Exploration Drilling. N\A: N/A.
  3. 3.0 3.1 3.2 John Finger,Doug Blankenship (Sandia National Laboratories). 2010. Handbook of Best Practices for Geothermal Drilling. Albuquerque, New Mexico: Sandia National Laboratories. Report No.: SAND2010-6048.


No exploration activities found.



      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-CA-EA-2002-??? EA Calpine Corporation (Calpine) and CPN Telephone Flat Inc. (CPN) Glass Mountain Geothermal Area BLM BLM BLM Geothermal/Well Field Exploration Drilling
      Thermal Gradient Holes
      DOI-BLM-ID-220-2009-EA-3709 EA Agua Caliente, LLC Raft River Geothermal Area BLM BLM Twin Falls District Office Burley Field Office BLM BLM Geothermal/Exploration Exploration Drilling
      DOI-BLM-NV-B020-2011-0026-EA EA Ram Power Silver Peak Geothermal Area BLM BLM Battle Mountain District Office BLM BLM Geothermal/Exploration Drilling Techniques
      Exploration Drilling
      Well Testing Techniques
      DOI-BLM-NV-C010-2010-0006-EA EA Ormat Technologies Inc Gabbs Valley Geothermal Area BLM BLM Carson City District Office BLM Stillwater Field Office BLM BLM Geothermal/Exploration Downhole Techniques
      Drilling Techniques
      Exploration Drilling
      Well Testing Techniques
      DOI-BLM-NV-C010-2010-0008-EA EA Magma Energy Soda Lake Geothermal Area BLM BLM Carson City District Office BLM Stillwater Field Office BLM BLM Geothermal/Exploration Downhole Techniques
      Drilling Techniques
      Exploration Drilling
      Well Testing Techniques
      DOI-BLM-NV-C010-2010-0010-EA EA Terra-Gen Power LLC Dixie Valley Geothermal Area BLM BLM Carson City District Office BLM Stillwater Field Office BLM BLM Geothermal/Exploration Downhole Techniques
      Drilling Techniques
      Exploration Drilling
      Well Testing Techniques
      DOI-BLM-NV-C010-2011-0001-EA EA Terra-Gen Power LLC Coyote Canyon Geothermal Area Bureau of Land Management BLM Carson City District Office BLM Stillwater Field Office Bureau of Land Management Bureau of Land Management Geothermal/Power Plant Exploration Drilling
      Observation Wells
      Well Testing Techniques
      DOI-BLM-NV-C010-2011-0501-EA EA Gradient Resources Patua Geothermal Area BLM BLM Carson City District Office BLM Stillwater Field Office
      BLM Sierra Front Field Office
      BLM BLM
      Bureau of Reclamation
      Geothermal/Well Field Development Drilling
      Exploration Drilling
      Well Testing Techniques
      DOI-BLM-NV-C010-2012-0029-EA EA Ormat Technologies Inc Tungsten Mountain Geothermal Area BLM BLM Carson City District Office BLM Stillwater Field Office BLM BLM Geothermal/Well Field Downhole Techniques
      Drilling Techniques
      Exploration Drilling
      Well Testing Techniques
      DOI-BLM-NV-W010-2010-0004-EA EA Terra-Gen Power LLC New York Canyon Geothermal Area BLM BLM Winnemucca District Office BLM Humboldt River Field Office BLM BLM Geothermal/Exploration Well Testing Techniques
      Exploration Drilling
      DOI-BLM-NV-W010-2011-0001-EA EA Ormat Technologies Inc Grass Valley Geothermal Area BLM BLM Winnemucca District Office BLM Humboldt River Field Office BLM BLM Geothermal/Exploration
      Geothermal/Well Field
      Development Drilling
      Exploration Drilling
      Well Testing Techniques
      DOI-BLM-OR-P000-2010-0003-EA EA Davenport Power LLC Newberry Caldera Geothermal Area BLM BLM Prineville District Office BLM United States Forest Service Geothermal/Exploration Drilling Techniques
      Exploration Drilling
      Passive Seismic Techniques
      Seismic Techniques
      Well Testing Techniques
      DOI-BLM-UT-W020-2010-042-EA EA Ormat Technologies Inc Drum Mountain Geothermal Area BLM BLM West Desert District Office BLM BLM Geothermal/Exploration Development Drilling
      Exploration Drilling
      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
      NEPA Process for Geothermal Power Plants in the Deschutes National Forest EIS Cal Energy Newberry Caldera Geothermal Area USFS
      BLM
      Geothermal/Exploration
      Geothermal/Well Field
      Geothermal/Power Plant
      Exploration Drilling
      Exploratory Boreholes
      Production Wells
      Thermal Gradient Holes


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