Geothermal exploration in Oregon, 1986

Priest, George; Woller, Neil; Blackwell, David; Gannett, Marshall

The general level of leasing activity was similar to last year's level. Drilling activity increased partly as a result of the U.S. Department of Energy (USDOE) Cascade Deep Thermal Gradient Drilling Program, a cooperative effort between USDOE and industry. Drilling of intermediated-depth (1.2 to 1.5-km-deep) diamond core holes continued to be the dominant for m of exploration in 1986. All drilling occurred either at Newberry volcano or in the high Cascades. Holes generally need to be relatively deep to be sure of penetrating the blanket of cold ground water that masks deep heat flow in these two areas. The most exciting news from the drilling programs is the discovery of temperatures of 107.1 C at 405-m depth in California Energy's MZI-11A hole on the southeast flank of Mount Mazama (Crater Lake area). Other publicly available data from the Cascade and Newberry drilling programs indicate that, in most cases, the holes could have gotten reliable temperature-depth data at depths of as little as 0.65 km. Drilling through the cold water blanket or "rain curtain" may therefore be somewhat easier than previously thought. Original permit requirements prompted California Energy Company to elect to suspend drilling on its MZI-11A hole. Possible alternatives to these requirements are being studied by the U.S. Bureau of Land Management (USBLM). Possible classification of the heat flow anomalies in the floor of Crater Lake as "significant thermal features" by the federal government may have future regulatory impacts on geothermal development on Mount Mazama. New age data from the U.S. Geological Survey (USGS) indicate that the silicic volcanic highland west of Bend may be much younger than previously thought. An average K-Ar age of about 0.3 million years (Ma) was obtained on an ash flow that was probably erupted from the highland. The 24-km-wide highland could therefore harbor still-hot magma bodies and associated hydro-thermal systems. Direct use of the geothermal fluids continued to expand slowly in 1986, and more expansion is expected in 1987. Most of the activity is occurring at Klamath Falls, La Grande, Lakeview, and Vale. Oregon Trail Mushroom Company, a new $8.5million fresh-pack operation, utilized the 107 C water at Vale for heating. Klamath Falls expanded its district heating system. Use of geothermal heat for a greenhouse and for residential heating continued at Lakeview. New developments are planned at Olene Gap near Klamath Falls.

Geothermal exploration in Oregon, 1986

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