Experience of Using Water Cut Meters at Samotlor and Verkhnechonskoe Fields

Abstract

Summary As the operation process moves on to the advanced stages of field development, the increase in water cut is observed; that makes it necessary to apply technologies to reduce water onset. Timely prevention of problems associated with water onset is possible due to equipment ensuring continuous monitoring and high accuracy of measured values. Modern water-cut meters based on near-infrared absorption spectroscopy can distinguish oil, water, natural gas, and gas-hydrate inhibitors such as methanol. Field testing of water-cut meters was performed by Samotlorneftegaz OJSC and Verkhnechonskneftegaz OJSC. Water-cut metes were mounted into Group Measuring Stations (GMS); the readings were displayed on the upper level of Automatic Process Control system of the company what enabled real time water-cut monitoring. Measurement accuracy was evaluated by means of comparative testing with the laboratory testing results of oil well fluid samples. To ensure stable accurate performance of the water-cut meter within the rated tolerances and ability to compare the measured values with the laboratory sample test results, it is important to maintain turbulent flow conditions: vertical velocity of min. 0.6 m/s, and horizontal velocity of 1.2 m/s. It will ensure adequate mixing. Besides, other methodological aspects are important, such as mutual alignment of the water-cut meter and sampling port, sampling frequency, mixer availability, group measuring station operating mode, etc. The economic effect of high-quality dynamic water-cut measurements (taking into account synergetic effect of other technologies) is achieved due to various factors: fewer inefficient well interventions; improving of decision-making; timely prevention of water onset; reduction of operational costs for manual sampling and laboratory analysis; incremental oil production by eliminating of premature well conversion to non-commercial stock due to poor quality measurements, and improved safety.