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U.S. Department of Energy
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Simulation of steam transport in vapor-dominated geothermal reservoirs

Technical Report ·
OSTI ID:7239654

A numerical model of steam transport through a porous medium is presented and applied to a hypothetical geothermal reservoir in order to explain observed production characteristics. A vapor-dominated geothermal reservoir is conceptualized as a one-dimensional column of porous or highly fractured rock initially filled with a mixture of saturated steam and liquid water under high pressure. A simple finite-difference technique is used to solve the flow and energy equations simultaneously for temperature and pressure. Analysis involves evaluation of pressure, temperature, and liquid-water saturation distributions when steam is produced at either constant discharge or constant pressure. Constant pressure is considered to be a more realistic condition for geothermal systems and permits computation of the discharge-versus-time relation. Comparisons of computed saturation profiles with previously published results lead to the conclusion that movement in the liquid phase can be neglected at low moisture contents. Production characteristics that can be explained with this model include: temperature and pressure changes when steam is produced at constant or variable discharge, temperature- and discharge-versus-time variations when steam is produced at constant pressure, and the existence of superheated steam. Results also demonstrate that temperature changes due to fluid expansion or compression may be significant when dealing with superheated steam.

Research Organization:
Geological Survey, Menlo Park, Calif. (USA)
OSTI ID:
7239654
Report Number(s):
USGS-OFR-76-607
Country of Publication:
United States
Language:
English