The Relationship Between Geothermal Fluid Flow and Geologic Context: A Global Review (GRC Poster)

Geothermal fluid flow is related to geologic context from the global or district scale down to the reservoir scale. We present a discussion of that relationship which is based on a review of high-temperature geothermal reservoirs worldwide. Initially we focus on large-scale geological controls on productive geothermal reservoirs, such as the role crustal-scale structural discontinuities play in localizing highly productive geothermal reservoirs.

We present maps showing the relationship between large-scale geological features and the locations of productive geothermal reservoirs in five case study districts:

1. The Taupō Volcanic Zone in New Zealand,

2. The Great Sumatra Fault in Indonesia,

3. The East African Rift System that hosts geothermal development in Kenya and Ethiopia,

4. The spreading plate boundary that bisects Iceland, and

5. The Great Basin in the Western US.

We review the control geological context has on the natural state reservoir geometry and demonstrate that the degree of influence a geological discontinuity (e.g., structure, contact zone or unit with high hydraulic potential) has on reservoir geometry, typically reflects how focused that resource is. Focused reservoirs have high well-to-well temperature gradients and complex thermal geometry. Broad reservoirs with low temperature gradients between wells show less influence from geological discontinuities in the natural state. In this poster we include cross-sections of seven geothermal reservoir case studies that illustrate the range of convection cell geometry and its relationship to geologic context.

Please refer to the companion paper for additional discussion a full list of references:

Wallis, I.C., Rowland, J.V., Dempsey, D.E., 2018, The relationship between geothermal fluid flow and geologic context: A global review, GRC Meeting, Reno.

The material presented here also draws on:

Wallis, I.C., Rowland, J. V., Cumming, W., and Dempsey, D. E., 2017, The subsurface geometry of a natural geothermal reservoir, New Zealand Geothermal Workshop: Rotorua, New Zealand.

Links to both papers are provided below.