Using Geothermal Play Types as an Analogue for Estimating Potential Resource Size

Katherine Young, Rachel Terry

Research output: Contribution to conferencePaper


Blind geothermal systems are becoming increasingly common as more geothermal fields are developed. Geothermal development is known to have high risk in the early stages of a project development because reservoir characteristics are relatively unknown until wells are drilled. Play types (or occurrence models) categorize potential geothermal fields into groups based on geologic characteristics. To aid in lowering exploration risk, these groups' reservoir characteristics can be used as analogues in new site exploration. The play type schemes used in this paper were Moeck and Beardsmore play types (Moeck et al. 2014) and Brophy occurrence models (Brophy et al. 2011). Operating geothermal fields throughout the world were classified based on their associated play type, and then reservoir characteristics data were catalogued. The distributions of these characteristics were plotted in histograms to develop probability density functions for each individual characteristic. The probability density functions can be used as input analogues in Monte Carlo estimations of resource potential for similar play types in early exploration phases. A spreadsheet model was created to estimate resource potential in undeveloped fields. The user can choose to input their own values for each reservoir characteristic or choose to use the probability distribution functions provided from the selected play type. This paper also addresses the United States Geological Survey's 1978 and 2008 assessment of geothermal resources by comparing their estimated values to reported values from post-site development. Information from the collected data was used in the comparison for thirty developed sites in the United States. No significant trends or suggestions for methodologies could be made by the comparison.
Original languageAmerican English
Number of pages7
StatePublished - 2015
EventGeothermal Resources Council 2015 Annual Meeting - Reno, Nevada
Duration: 20 Sep 201523 Sep 2015


ConferenceGeothermal Resources Council 2015 Annual Meeting
CityReno, Nevada

NREL Publication Number

  • NREL/CP-6A20-66437


  • electric potential
  • exploration
  • geology
  • geothermal
  • geothermal occurrence models
  • heat in place
  • Monte Carlo
  • OpenEI
  • parameters
  • play types
  • probability distribution
  • recoverable heat
  • reservoir characteristics
  • resource assessment
  • resource potential
  • resource size
  • risk
  • temperature
  • USGS
  • volume


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