Salinity and flow regime independent multiphase flow measurements

Sætre1,2, G. A. Johansen1,2 and S. A. Tjugum3,2

1Dept. of Physics and Technology, University of Bergen, Norway, Camilla.Satre@ift.uib.no
2The Michelsen Centre for Industrial Measurement Science and Technology, Norway
3Roxar Flow Measurements, Bergen, Norway

ACCEPTED FOR PUBLICATION IN FLOW MEASUREMENT AND INSTRUMENTATION (June 2010)

ABSTRACT

For oil production fields, there is a need for downhole measurements of the gas/water/oil multiphase flow. In extreme conditions a relatively simple, robust, and non-intrusive system will be appropriate. A measurement setup that combines multiple gamma beam (MGB) and dual modality densitometry (DMD) measurements, would be able to determine the gas volume fraction (GVF) independently of the flow pattern, and monitor changes in water salinity. MGB measurements of gamma-ray transmission along multiple sections across the oil pipe will provide information on the flow pattern. Whereas the DMD principle will give information on changes in salinity from a combination of transmission and scattering gamma-radiation measurements. In this work we present the results from MGB and DMD measurements of a multiphase flow with high-speed gamma-ray tomograph measurements as reference for the flow pattern. The MGB measurements should enable us to distinguish between stratified or wavy/slug and annular or slug flow. Flow patterns with several minor components distributed evenly over the measurement cross section, like bubble flow, will be interpreted as homogeneous flow. The DMD measurements can be used to monitor salinity changes of the water component for intervals where the GVF is low and the water cut of the liquid is high. Combined with other gauges for water cut measurements, the MGB and DMD measurement setup should improve the multiphase flow measurements, and enable increased oil/gas recovery and production water monitoring.

Keywords gamma-ray densitometry, flow regime identification, gas volume fraction, salinity measurement