Portland State University. Department of Geology
Robert B. Perkins
Date of Award
Master of Science (M.S.) in Geology
1 online resource (xii, 172 pages)
For this thesis I applied classical and multi-component geothermometry techniques to new water chemistry data from Breitenbush Hot Springs, Oregon and the Wind River Valley, Washington. A total of 20 well, spring, and stream samples from Breitenbush Hot Springs and 4 spring samples from the Wind River Valley were collected and analyzed for major, minor, and select trace anions and cations, as well as stable oxygen and hydrogen isotopes. I used two computer programs, GeoT and RTEst, to conduct multi-component geothermometry reservoir condition estimation on each water sample. Water chemistry data from Breitenbush Hot Springs indicates a range of thermal, nonthermal, and mixed waters in wells and springs. Isotope data from Breitenbush Hot Springs indicates that thermal water is a mix between "andesitic waters" (6-10%) and meteoric water (90-94%) from the crest of the Oregon Cascades. Classical and multi-component geothermometry conducted for Breitenbush samples for this thesis suggest a reservoir temperature of approximately 137º C, which is close to the bottom hole temperature recorded in the nearby 2,457 meter deep SUNEDCO well of 141º C, but contrasts with previous applications of geothermometry which estimate a reservoir temperature between 170 and 180º C for the system. Reservoir estimates from this thesis for the Wind River Valley hot spring samples range from 80 to 100º C, which is consistent with previous studies. Multi-component geothermometry optimization indicates a loss of CO2 (i.e. degassing) during the water's ascent at both Breitenbush Hot Springs and the Wind River Valley, and that dilution from nonthermal water occurs in some samples from both areas. Multi-component geothermometry estimates were generally consistent between RTEst and GeoT; inconsistencies were primarily due to differences between the thermodynamic databases used for each program.
Malkemus, Donnel Alexander, "Geothermometry of Two Cascade Geothermal Systems" (2016). Dissertations and Theses. Paper 3369.