Abstract: Conceptual Models in Geothermal Hydrology

W. K. Summers

A conceptual model of a natural thermal system is an attempt to quantify the components, processes, and products of that system. This paper considers the characteristics of an ideal conceptual model of a natural thermal system and reviews the features of modern thermal areas that a conceptual model should explain.

A review of the models promulgated shows that they include one element from each of the following groups:

Group A, Heat source:
(1) A deep-seated heat source (not necessarily a magma); (2) a magma chamber; and (3) intrusive or extrusive igneous activity.

Group B, Fluid type or source:
(1) No fluid; (2) fluid derived from the heat source (juvenile water, metamorphic water, "hydrothermal" solution magmatic waters); (3) formation fluids, connate waters; (4) meteoric ground water; and (5) some combination of 2, 3, or 4.

Group C, Heat transfer:
(1) Heat transfer by conduction only; (2) heat transfer by mass transport of fluids; (3) heat transfer by true convection; (4) heat transfer by combinations of 1, 2, or 3.

Group D, Reason for fluid movement:
(1) No movement; (2) true convection in a temperature-driven cell; (3) gravity potential; (4) osmotic or electro-osmotic potential; (5) compaction of overburden; (6) driving energy from unspecified source; and (7) combinations of 2-6.

The diversity of models comes about because the distinctions between the components, processes, and products are not usually clear and because individual modelers emphasize different phenomena.

AAPG Search and Discovery Article #90979©1975 AAPG – SEPM Rocky Mountain Sections Annual Meeting, Albuquerque, New Mexico