TORR ™-The Next Generation of Hydrocarbon Extraction From Water
Authors: Plebon M.J. 
Published: March 2010

EARTH (Canada) Corporation is commercializing a revolutionary development in oil/water separation at the Global Petroleum Show. TORR- (Total Oil Remediation and Recovery) removes free-floating and emulsified oils in water without the need for heat or chemicals. No waste is created from this technology. Treated water can reach non-detectable hydrocarbon limits and the recovered oil is of low water content. The introduction of TORR- is a significant breakthrough for water treatment solutions for SAGD, conventional oil and gas production water, environmental remediation, and any other applications where oily water is a concern.

Introduction

Oil and grease are present at numerous commercial, industrial and government sites. The presence of oil poses a severe challenge for oily water remediation technologies. Oil and grease must generally be removed from wastewater since those materials can foul instruments and equipment, interfere with other processes, and may accumulate in unwanted areas causing a hazard or performance problem. Furthermore, oil and grease are very damaging to the environment and could cause a significant environmental issue.

In upstream oil and gas production, oily production water increases as the asset ages to a level where the asset may no longer be economical to operate. The management and treatment of the increasing produced water will play a significant role in the overall economics of the facility.

Basic Separation Theory

The removal of oil and grease from produced waters can be accomplished by the use of several well-known and widely accepted techniques. However, the performance of any given separation technique will depend entirely on the condition of the oil-water mixture. Present techniques for the separation of oil from water are based on their difference of density. Stoke's Law states that rising velocity (Vr) is a function of the square of the oil droplets' diameter:

Vr = gd2 (ρw - ρo)/18 η

where Vr = rise velocity of oil droplet

g = acceleration due to gravity

ρw = density of water

ρo = density of oil

d = oil particle diameter

η= viscosity of water

From Stoke's Law, it can be seen that droplet size has the largest impact on the rising velocity rate. Consequently, the bigger the droplet size, the less time it takes for the droplet to rise to a collection surface, and thus the easier it is to treat the water. The oil in the produced water can be present as free-oil and/or emulsified and/or dissolved states in different proportions. This oil droplet size distribution is one of the most important factors affecting the design of oil-water separators.

Free-oil is defined as an oil droplet of 150 microns, which will float immediately to the surface due to its large size and high rise velocity. Emulsion is oil which is dispersed in the water in a stable fashion due to its small diameter and having a low rise velocity.

Emulsions can be classified into two categories: mechanical and chemical emulsions. Mechanical emulsions are created through the process of pumping large pressure drops through chokes and control valves.