Water detection in gas/condensate flows by SeCaP technology

Abstract

Safe and controlled operation of subsea gas/condensate flow lines depends on adequate monitoring capabilities of free water in the well stream. Accurate knowledge on the amount of water present directly determines the requirement for hydrate inhibitor injection. Free water originates from two sources; condensed water from the produced gas phase and the possible amount of formation water from the reservoir. The gas production should ideally be single phase from the reservoir, but as the temperature and the pressure are reduced in the well and flow line, both a liquid hydrocarbon phase and water will condense from the gas. Normally there is less water than condensate present, and the water cut can be lower than 10%. This means that the water often is dispersed as droplets in the condensate phase due to high velocities. The paper presents tests on a 3” Sentech WCM (WaterCutMeter), based on the Single Electrode Capacitance Probe (SeCaP) technology. These experiments were conducted at 78 bar and 0 °C in the Norsk Hydro multiphase flow loop in Porsgrunn, with the primary objective to see if this instrument was able to detect the small changes in the amount of water present at such realistic operating conditions. The results show that the SeCaP WCM was able to detect changes in water content smaller than 0.01 vol%, but the meter needs a thorough temperature correction as the signal is strongly influenced by temperature changes.