by Bill Ball
Introduction
For decades, the oil and gas industry has relied on traditional practices to handle oil-water separation. However, as technology advances, it has become clear that many long-held beliefs, particularly around retention time and separation efficiency, need to be reassessed. In this post, we’ll explore some of the most impactful innovations in oilfield separation, including the application of Stokes’ Law, the significance of retention time, and the game-changing HWSB® Skim Tank.
How Stokes’ Law Shapes Oilfield Separation
Stokes’ Law, formulated by physicist George Stokes in the 19th century, is a key principle behind oil-water separation. The law explains how immiscible fluids (fluids that don’t mix, like oil and water) separate based on their density, gravity, and viscosity. Simply put, the size of oil droplets and their density relative to the surrounding water determines how quickly they rise to the surface.
In modern oilfield operations, understanding Stokes’ Law is essential for designing efficient separation systems. The law shows that larger droplets separate faster, while smaller droplets take more time. Therefore, improving separation efficiency often involves finding ways to increase droplet size or prevent droplets from being broken into smaller particles during processing.
The Reality of Retention Time vs. Separation
Another common myth in oilfield separation is the belief that more retention time automatically leads to better separation. Retention time refers to the amount of time a fluid spends in a separation vessel before being discharged. While longer retention times can help, they aren’t the only factor at play.
In fact, research has shown that if the fluid velocity inside the separation vessel is too high, no amount of retention time will help. Fluids tend to follow the path of least resistance, and if oil droplets are forced to move too quickly, they don’t have enough time to rise and separate from the water. Therefore, achieving optimal separation is about balancing retention time with proper fluid distribution and velocity control.
The HWSB® Skim Tank: A Game-Changer for Oil-Water Separation
The HWSB® (Hydrodynamic Water Separation Breakthrough) Skim Tank is a revolutionary piece of technology designed to replace outdated equipment like gunbarrel tanks. This system is engineered specifically to handle the high water cuts seen in modern oilfield operations, where large volumes of water must be processed to recover even small amounts of oil.
What makes the HWSB® Skim Tank so effective is its ability to slow water velocity and allow oil droplets to coalesce and rise to the surface. With no moving parts and minimal maintenance, this system has been proven to recover over 99.9% of entrained oil, making it a highly efficient solution for 21st-century oil production. Its performance has led to widespread adoption across the industry, with over 4,000 units in operation today.
Addressing High Water Cuts with Modern Technology
In today’s oilfields, high water cuts are the norm rather than the exception. Wells often produce far more water than oil, and traditional separation systems struggle to keep up. The key to efficient separation lies in technology like the HWSB® Skim Tank, which is designed to handle these challenging conditions.
Modern systems focus not only on improving oil recovery but also on enhancing water quality. Water disposal is a significant cost in oil production, and reducing the amount of oil in the water helps avoid environmental penalties and lowers operational costs. By investing in technology that can handle high water cuts, operators can improve both their bottom line and their environmental footprint.
Conclusion
The oil and gas industry is at a turning point where innovation is no longer optional—it’s essential. By applying the principles of Stokes’ Law, optimizing retention time, and adopting modern systems like the HWSB® Skim Tank, oil producers can greatly enhance their separation processes. Moving beyond the myths of the past will lead to more efficient, cost-effective, and environmentally responsible operations in the future.
Read the technical paper, Separation in Oilfield Operations “Myths versus Realities”
Bill Ball is a senior staff consultant to KBK Industries with over 50 years of oilfield engineering experience and holder of twenty-three oil and gas industry related US patents. His credentials represent the culmination of a lifetime of breakthroughs and innovations. Bill’s twenty-three US process equipment patents speak to this. His first patent has become an industry “game changer.” It is the industry’s first true oil-water separation “skim tank”, the “HWSB”. Today there are over 3,500 HWSB® skim tanks separating and capturing oil that used to be injected and lost forever. Bill resides in Bixby, a suburb of Tulsa, Oklahoma.