Multiphase flow metering (MPFM) technology is gaining popularity and becoming the main well rate testing mechanism in some regions of the world. Yet, their application in measuring the flow rates of high gas-oil-ratio (GOR) and/or high gas volume fraction (GVF) wells has always been a challenge. A remote field located in the Southeastern part of Saudi Arabia commenced its production in the late 90's from a thin oil column lying between a large gas-cap and a water aquifer. Although, 84% of the thin-oil-column producing wells are horizontal and multilateral wells with extended reservoir contact, the gas-cap gas breakthrough and production from these wells have increased gradually; resulting in an increase in the wells GOR.Currently, 35% of the wells are producing at high GOR ranging between 2,000 and 6,000 SCF/STB with a GVF reaching as high as 98%.

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Scale precipitation is a common phenomenon that is a result of chemical reactions that usually occur during hydrocarbon production. It is one of the most common challenges in the oil and gas industry, especially for remote offshore fields. Scale crystals usually cause production losses due to the deposition of scale on the subsurface and surface of equipment and will damage instruments, reduce functionality and increase measurement uncertainties. Deposition of scale influences the performance of multiphase flow meters (MPFM) based on electrical impedance and gamma ray density measurements. Several oil wells of an offshore field located in Arabian Gulf, which commenced its production in 2013 from a heavy oil column lying above a large water aquifer, faced scale build up. The field has encountered a period of water injection prior to its production startup to ensure that reservoir pressure is maintained. The fluid flow rate tests of these wells are conducted through MPFMs. This paper presents the work performed, remedial actions and procedures implemented to maintain MPFM's measurement accuracy in a precipitation environment. This paper will also address the methodology for detecting scale deposition using MPFM measurements compared to scale laboratory detection experiments and water geochemical analysis. The paper will recommend the lessons learned of cleanup operations guidelines for affected MPFMs for calibration purposes.

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