An article on “The Effect of Shear on Produced Water Treatment” by John Walsh was recently published by SPE. The article focusses on the effect shear has on the oil droplet size in a produced water system. The conclusions in the article is in line with the experience Typhonix has with shear. The main factor determining the intensity of the shear exerted on the fluids is the energy dissipation rate. The article describes the effect of the energy dissipation rate on the droplet size. It confirms the experience of Typhonix that shear is not necessarily negative. High intensity shear as seen in choke and control valves can be reduced by designing a valve to minimize the energy dissipation rate. The Typhoon Valve is mentioned as a promising candidate in this field, referring to the pilot test results that showed a 50% reduction in the OiW concentration downstream of the separator compared to a conventional choke valve. The article also describes that low intensity shear can be utilized to promote coalescence of the oil droplets, increasing the downstream separation efficiency. This principle is utilized with success by Typhonix in the coalescing pump design.

The author, John Walsh, has nearly 30 years of experience in water treatment of which over 20 years in Shell. He is the president and managing director of the Produced Water Society.

The complete article can be found on the SPE website and is a good starting point for engineers designing/optimizing separation or produced water treatment systems with regards to shear.