Abstract:

Abstract:  The pH of fluids play an important role in the dynamics and equilibrium between minerals and fluids at high temperature and pressure. This article reviews various methods of pH determination of aqueous fluids at elevated pT conditions. These methods include potential measurement and electrical conductivity measurement of electrochemical cell and calculation of pH from fluid compositions. Over the past few decades considerable progress has been made in developing practical potentiometers for measuring pH in high temperature aqueous solutions. Platinumhydrogen electrodes are very precise for pH measurement of various solutions at relative low temperatures. Potentiometer based on ceramic membrane such as yttriastabilized zirconia(YSZ)membrane sensor is one of the most significant achievements in high temperature potentiometer. Using chemical analyses and 25 ℃ pH measurements, the pH and distribution of aqueous species at high temperature can be calculated by solving simultaneous mass action equations for complexes equilibria and mass balance equations. Numerical errors and uncertainties in thermodynamic data and analytical errors can effect these computed values. Electrical conductance measurements of aqueous solutions at high temperatures and pressures provide unique information concerning the extent of ionic interaction of ions in solutions. From the results of electrical conductance measurements of aqueous solution we can obtain pH values at relative high temperature and pressures.

Key words:

Key words: aqueous fluids; pH value; high temperature and pressure