Experiments with a Wire-Mesh Sensor for stratified and dispersed oil-brine pipe flow

•Holdup fraction measurements using gamma densitometry and Wire-Mesh Sensor.•Evaluation of complex permittivity models applied to holdup measurement.•Local instantaneous oil fraction for stratified and dispersed oil-brine flow.•Estimation of oil–water interface height in stratified flow.•Observed interface curvature with either a concave or convex shape.

Two-phase oil–water flow was studied in a 15 m long horizontal steel pipe, with 8.28 cm internal diameter, using mineral oil (having 830 kg/m3 density and 7.5 mPa s viscosity) and brine (1073 kg/m3 density and of 0.8 mPa s viscosity). Measurements of the holdup and of the cross-sectional phase fraction distribution were obtained for stratified flow and for highly dispersed oil–water flows, applying a capacitive Wire-Mesh Sensor specially designed for that purpose. The applicability of this measurement technique, which uses a circuit for capacitive measurements that is adapted to conductive measurements, where one of the fluids is water with high salinity (mimicking sea water), was assessed. Values for the phase fraction values were derived from the raw data obtained by the Wire-Mesh Sensor using several mixture permittivity models. Two gamma-ray densitometers allowed the accurate measurement of the holdups, which was used to validate the data acquired with the capacitive Wire-Mesh Sensor. The measured time-averaged distribution of the phase fraction over the cross-sectional area was used to investigate the details of the observed two-phase flow patterns, including the interface shape and water height. The experiments were conducted in the multiphase-flow test facility of Shell Global International B.V. in the Netherlands.