The Physical and Chemical Nature Of Supercritical Fluids At - PowerPoint PPT Presentation

The Physical and Chemical Nature Of Supercritical Fluids At Drillable Depths By Robert Fournier

Critical point pure water Critical point 10 wt% NaCl 10 wt% NaCl in gas in equilibrium with brine

Water 374°C circulation 221 bars Brittle Plastic domain Domain Heat conduction

λ = fluid P f /lithostatic P r

Water 374°C circulation 221 bars Brittle Plastic domain Seismicity Self sealing Heat conduction

Fournier (1982) Quartz Solubility in Water Two-phase field liquid plus steam

Fournier & Potter (1982)

Calculation of Quartz Solubilities For Steam-Gas Mixtures or Brines Instead of the specific volume of pure water: Use the specific volume of the mixture times the weight fraction of water in the mixture

Fournier (1982) Quartz Solubility in Water (or brines or gas) Two-phase field liquid plus steam e

Shibue (1997)

Critical pt. H 2 O Critical pt. 10 wt% NaCl Condensation pt curves Boiling pt curves

Brines boil and become more concentrated Salt dissolved in gas or “steam” becomes less with increasing temperature or decreasing concentrated (brine condenses) with increasing pressure temperature or decreasing pressure C = CP 10 wt% NaCl

Gas + Solid Salt

(Na + + K + ) Cl - Fournier & Thompson (1993) (Na+K) or (equivalents/Kg)

NaCl + H 2 O = NaOH + HCl° 2NaCl + SiO 2 + H 2 O = Na 2 Si 2 O 5 + 2HCl° Na 2 Si 2 O 5 is less soluble at higher temperatures

_ ++

From Bischoff, Rosenbauer, & Fournier (1996)

CaCl 2 + 2H 2 O = Ca(OH) 2 + 2HCl° With silica present that reacts with Ca(OH) 2 , expect a greater yield of HCl° CaCl 2 + SiO2 + H 2 O = CaSiO 3 + 2HCl°

Generation of HCl During Alteration of Plagioclase to Alkali Feldspar and/or Epidote 2Anorthite + 2 Qtz +NaCl + H 2 O = Albite + Epidote + HCl° 2Anorthite + 2 Qtz +KCl + H 2 O = K-Feldspar + Epidote + HCl° 3Anorthite + 2 Qtz + 2CaCl 2 + 2H 2 O = 2Epidote + 4HCl°

Least Principal Stress is the Lithostatic Load

Water circulation 374°C Brittle region 221 bars 125°C per km Plastic region 500°C per km Heat conduction

The Physical and Chemical Nature Of Supercritical Fluids At Drillable Depths By Robert Fournier

Least Principal Stress is the Lithostatic Load