Measure formation water pH without contamination effects

Water pH is measured with the InSitu pH reservoir fluid pH sensor by injecting dye into the formation fluid being pumped through the flowline of the InSitu Fluid Analyzer system. The pH is calculated with 0.1-unit accuracy from the relevant visible wavelengths of the dye signal measured by an optical fluid analyzer.

Making the measurement at reservoir conditions avoids irreversible pH changes that occur when samples are brought to the surface, as acid gases and salts come out of solution with reduced temperature and pressure and routine laboratory flashing of the sample.

InSitu pH sensor measures the fluid pH across the entire flowline cross section, making it more robust than potentiometric methods of measurement, which are compromised when oil and mud foul electrode surfaces. Direct pH measurements with dye also avoid the limitations of resistivity measurement in monitoring contamination, which requires a sufficient resistivity contrast between the filtrate and formation water.