Comparison of Inline Produced Water Monitors

Abstract

Produced water represents the largest waste stream in the oil and gas production industry. Water drawn up from oil and gas formations contains many substances, the disposal of which is heavily regulated. Offshore oil platforms must ensure that these regulations are met with great accuracy, as the disposal of the water means its reintroduction into the environment. For this reason it is essential that hydrocarbon measuring equipment be effective and accurate when deployed on these platforms. A pilot scale project was designed to test and compare four instruments currently employed on offshore oil platforms. The project compared the instruments for accuracy, responsiveness, maintenance requirements, and fouling by manipulating four variables. The variables tested were flow rate through the instruments, particulate and gas addition to the produced water, hydrocarbon and production chemical spiking, and heat addition. Each variable was manipulated one at a time, but their lingering effects (such as particles) were not removed due to the design of the system. Instrument readouts were compared with lab tested produced water samples taken from the system stock using infrared technology. A ranking system was devised to compare the monitors in the categories of accuracy, precision, maintenance requirements, and reliability. This system was used to determine which monitor was the most effective in terms of those categories and this project.