Step-out Well

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Exploration Technique: Step-out Well

Exploration Technique Information
Exploration Group: Drilling Techniques
Exploration Sub Group: Exploration Drilling
Parent Exploration Technique: Exploration Drilling
Information Provided by Technique
Lithology: Drill cuttings are analyzed to determine lithology and mineralogy
Stratigraphic/Structural: Fractures, faults, and geologic formations that the well passes through are identified and mapped
Hydrological: Identify aquifers, reservoir boundaries, flow rates, fluid pressure, and chemistry
Thermal: Direct temperature measurements from within the reservoir
Step-out Well:
A well drilled outside of the proven reservoir boundaries to investigate a possible extension of the known reservoir. Also known as an out step well or delayed development well.
Other definitions:Wikipedia Reegle

A step-out well is a type of exploratory well drilled outside of the known reservoir to search for an extension of the reservoir or even a new nearby reservoir. These wells have a high degree of risk and are also known as a wildcat in the oil and gas industry.[1] They are used to find another productive zone within an already producing field, or to extend the parameters of the known field.
Use in Geothermal Exploration
In geothermal exploration a step-out well is used to help define the reservoir and improve the reservoir model.[2]

Field Procedures
A step-out well is drilled some distance from the known reservoir for exploration purposes but drilling procedures are similar to that of Development Drilling. Also see Production Wells

Data Access and Acquisition
A successful step out well was drilled at the Blue Mountain Geothermal Area. The Step-out well is 58-15 and was drilled 1.2 km west of the known geothermal reservior at the time.[2]

Best Practices
A step-out well should be drilled where there is some evidence of a permeable formation linked with the main reservoir. The well should be drilled in a location to where if it is an unsuccessful production well it might still be useful as an injection well.
Potential Pitfalls
A step-out well may result in lost time and money.

  1. Liberty Pioneer educational materials. Industry Terms and Definitions [Internet]. 2007. [cited 2013/10/08]. Available from:
  2. 2.0 2.1 Glenn Melosh, John Casteel, Kim Niggeman, Brian Fairbank. 2008. Step-Out Drilling Results at Blue Mountain, Nevada. In: GRC Transactions. GRC Annual Meeting; 2008/10/05; Reno, Nevada. Davis, California: Geothermal Resources Council; p. 49-52

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