Carbon-13 variations in fluids from the Cerro Prieto geothermal system

Conference · Tue Aug 10 04:00:00 EDT 1982

OSTI ID:7369511

Janik, C J; Nehring, N L; Huebner, M A; Truesdell, A H

The carbon isotope compositions of CO/sub 2/ in steam from Cerro Prieto production well have been measured for 1977, 1979, and 1982. Variations in the delta/sup 13/C values are caused by production-related changes in the chemical and physical parameters of the geothermal system. In 1977, most CO/sub 2/ in the reservoir was isotopically light (delta/sup 13/C = -6.4 +/- 0.4). Heavier CO/sub 2/ was produced from wells in the center of the field (M5,M26,M27) due to deposition of isotopically light calcite caused by near-well boiling. In 1979 nearly all well showed relatively heavy CO/sub 2/, probably due to expansion of aquifer boiling and calcite precipitation. In 1982, many wells in the central part of the field were shut in. The amount of drawndown decreased and as temperatures and pressures near the wells increased, the boiling zones collapsed. The CO/sub 2/ in the fluid then exchanged with the precipitated calcite and became isotopically lighter. The sensitivity of carbon isotopes to calcite precipitations caused by aquifer boiling and to reequilibration with this deposited calcite upon decrease of boiling suggests use as an indicator of these aquifer processes. Surficial CO/sub 2/ of thermal origin was collected in 1981. Generally, the carbon-13 contents were close to CO/sub 2/ from production wells except for high-temperature mud pots and fumaroles containing isotopically light CO/sub 2/ derived from near surface alteration of organic matter.

• Research Organization: Geological Survey, Menlo Park, CA
• OSTI ID: 7369511
• Report Number(s): CONF-8208109-Vol.2-7; ON: DE87003674
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150302* -- Geothermal Exploration & Exploration Technology-- Geochemical Techniques & Surveys
150904 -- Geothermal Engineering-- Geothermal Reservoir & Well Performance
CARBON 13
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CERRO PRIETO GEOTHERMAL FIELD
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMISTRY
EVEN-ODD NUCLEI
FLUIDS
GEOCHEMISTRY
GEOTHERMAL FIELDS
GEOTHERMAL FLUIDS
GEOTHERMAL WELLS
Geothermal Legacy
ISOTOPES
LIGHT NUCLEI
NUCLEI
OXIDES
OXYGEN COMPOUNDS
ROCK-FLUID INTERACTIONS
STABLE ISOTOPES
VARIATIONS
WELLS