A Hydrologic Model Based on Deep Test Data from the Walker "O" No. 1 Well, Terminal Geyser, California
- Key words
- Exploration; Reservoir Engineering; USA; California; Mt. Lassen National Park; Chemical Analysis; Temperature; Temperature Gradient; Geothermometers; Faults; Flow Tests; Aquifer; Bottom Hole Temperature
- Location
- Lassen, California
- Conference
- Geothermal Resources Council Transactions
- Year
- 1981
- Session
- Exploration; Temperature gradients; Well logging; Well testi
- Language
- English
Abstract
The Shasta Forest No. 1 Well (remained Walker "O" No. 1) at Terminal Geyser, California was reentered and deepened from 1258 to 4008 feet. Temperature logs indicated the well penetrated a laterally flowing thermal aquifer between 1400 and 2200 feet. Large amounts of drilling fluids were lost in that zone. Maximum temperature in the well (10 months after drilling) was 348°F at 2000 feet. A large "reversed" temperature gradient zone occurs below 2400 feet. Bottom hole temperature is 256°F. After completion, the well was flowed for about five hours with nitrogen injection at 2000 feet. Samples taken throughout the flow indicated that fluids lost during drilling were not completely recovered. Salinity increased steadily during the flow period. Ratios of Na, K, and Ca were nearly constant, however, and application of Na-K and Na-K-Ca geothermometers indicate these fluids were in equilibrium with rocks at a temperature of 448°-449°F.
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