This paper reports
high-pressure viscosity measurements for Krytox
GPL 102 lot K2391 and tris(2-ethylhexyl) trimellitate (TOTM). These
two viscous liquids have recently been suggested as potential deepwater
viscosity standard (DVS) reference fluids for high temperature, high
pressure viscosity studies associated with oil production from ultradeep
formations beneath the deepwaters of the Gulf of Mexico. The measurements
are performed using a windowed, variable-volume, rolling-ball viscometer
at pressures between 7 and 242 MPa and temperatures between 314 and
527 K with an expanded uncertainty of 3% at a 95% confidence level.
The viscosity results are correlated using an empirical temperature/pressure-dependent
function and a modified Vogel–Fulcher–Tammann (VFT)
Equation. The present viscosity data for TOTM and Krytox GPL 102 lot
K2391 are in good agreement with the available reported data in the
literature at lower temperatures and pressures. The viscosity values
of TOTM and Krytox GPL 102 lot K2391 are 9.5 mPa·s and 25 mPa·s,
respectively, at 473 K and 200 MPa, whereas the desired DVS viscosity
value at this condition is 20 mPa·s. Although the viscosity of
Krytox GPL 102 lot K2391 is closer to the targeted value, a comparison
of the present viscosity results with data obtained for lot K1537
indicates a very large lot-to-lot variation of the viscosity for this
polydisperse perfluoropolyether oil, which represents a significant
deficiency for a DVS.