A Laboratory Investigation of Steam Adsorption in Geothermal Reservoir Rocks

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Some vapor-dominated geothermal reservoirs and low-permeability gas reservoirs exhibit anomalous behavior that may be caused by surface adsorption. For example, geothermal reservoirs in the Larderello area of Italy and reservoirs in the The Geysers Geothermal Field, California produce little, if any, liquid. Yet to satisfy material balance constraints, another phase besides steam must be present. If steam adsorption occurring in significant amounts is not accounted for, the reserves will be grossly under-estimated. In addition, well tests may be misinterpreted because the pressure response is delayed owing to the adsorbed material leaving or entering the gaseous phase.In the present research the role of adsorption in geothermal reservoirs is investigated. Two sets of laboratory equipment were constructed to measure adsorption isotherms of cores from Berea sandstone, Larderello, and The Geysers. Seven experimental runs were completed using nitrogen on the low temperature apparatus at -196C. Eight runs were conducted using steam on the high temperature apparatus at temperatures ranging from 150C to 207C. The largest specific surface area and the greatest nitrogen adsorption isotherm were measured on the Berea sandstone, followed by a core from Larderello and then The Geysers. Difficulties in determining whether a system had reached equilibrium at the end of each step lead to questions regarding the magnitude of adsorption measured by the steam runs. Nevertheless, adsorption was observed and the difficulties themselves were useful indicators of needed future research.


Type of resource text
Date created March 1988


Author Luetkehans, Jeralyn
Primary advisor Miller, Frank G.
Primary advisor Ramey Jr., Henry
Degree granting institution Stanford University, Department of Petroleum Engineering


Subject School of Earth Energy & Environmental Sciences
Genre Thesis

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Luetkehans, Jeralyn. (1988). A Laboratory Investigation of Steam Adsorption in Geothermal Reservoir Rocks. Stanford Digital Repository. Available at: https://purl.stanford.edu/pf873tj2515


Master's Theses, Doerr School of Sustainability

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