Cation geothermometry in oil field waters

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6038441

Smith, L K; Dunn, T L; Surdam, R C ^[1]

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1. Univ. of Wyoming, Laramie, WY (United States)

The assumptions used in the development of cation ratio geothermometers are: (1) the ratios of the cations are controlled by cation exchange between solid silicate phases, (2) aluminum is conserved in the solid phases, and (3) neither hydrogen ions nor CO[sub 2] enter into the net reactions. These assumptions do not apply to oilfield waters where organic species are present and commonly abundant. Nine different published cation geothermometers of Na/K, Na-K-Ca, Na-K-Ca-Mg, and Mg/Li were applied to 309 water samples from both oilfield and geothermal wells. None of the cation geothermometers predicted consistent or accurate temperatures for the oilfield waters. Plots of measured v. predicted temperature for oilfield water samples gave correlation coefficients of less than 0.35. In contrast, those same plots for geothermal water samples within the same temperature range gave correlation coefficients between 0.45 and 0.95. This analysis suggests that the presence of organic species exerts a strong control on the cation ratios. Organic species form complexes of varying stability with the cations. This, in turn, changes the relative concentrations of the cations in solution over that which is expected when cation exchange between silicate phases controls the ratios. Organic complexes also strongly affect pH and P[sub CO[sub 2]]. The buffering capacity of the organic complexes in the 80-120 C temperature range strongly affects the solubility of the carbonate minerals. That in turn affects the Ca[sup 2+] in solution and thus the temperature predicted by the Na-K-Ca geothermometers. Future development of an empirical cation geothermometer for oilfield waters must accommodate the presence of organic species and their control on various mineral solubilities.

• OSTI ID: 6038441
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
15 GEOTHERMAL ENERGY
150301 -- Geothermal Exploration & Exploration Technology-- Geophysical Techniques & Surveys
BRINES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
COMPLEXES
FLUIDS
GEOLOGIC DEPOSITS
GEOTHERMAL FLUIDS
GEOTHERMAL WELLS
GEOTHERMOMETERS
GEOTHERMOMETRY
MATTER
MEASURING INSTRUMENTS
MINERAL RESOURCES
MINERALS
OIL FIELDS
ORGANIC MATTER
OXIDES
OXYGEN COMPOUNDS
PARTIAL PRESSURE
PERFORMANCE
PETROLEUM DEPOSITS
PH VALUE
RESERVOIR TEMPERATURE
RESOURCES
SOLUBILITY
THERMOMETERS
WELLS