DRILLING & PRODUCTION
New method for treating drilling fluids
Cubility’s new MudCube system is a departure from traditional methods of treating drilling fluids on offshore facilities.
Since the 1930s, conventional solids control systems have been pieced together to address one new situation after another, seldom reflecting a holistic approach to the total system. Shale shakers can be associated with noise, vibrations, fumes, oil mist, high screen costs, and a tendency to lose mud due to blinding or on cuttings.
Improvements with the equipment generally focus on higher gravitational forces, requiring stronger frames, bigger motors, and more metal. Significant advances in screen technology have translated into higher costs, heavier weights, and multi-screen applications to handle larger waste volumes. As a result, changing screens and maintaining the equipment has become more complex, requires larger work areas, and increases in labor.
The MudCube is quite different than the shale shaker and provides a new option to drilling operations. Instead of relying upon force to shake mud off cuttings, the drilling fluids are vacuumed through a rotating screen belt that separates the cuttings from the fluid in a more efficient manner. Air-knives in the MudCube also help dry the cuttings to reduce waste.
According to Cubility, the MudCube provides a number of advantages, including:
- Gentle filtration with a single screen (no pre-scalping needed)
- Lower screen costs
- Lower system weight and smaller footprint
- Equipment consolidation options (i.e., shakers, degasser, dryer, ventilation system)
- Decreased risk
- Minimal employee contact with fluid, mist, gasses (e.g., H2S)
- Improved control over environmental discharge(s)
- Dryer cuttings
- Fewer screen changes
- Reduced waste stream
- Reduced noise and vibration.
The MudCube system also has automated clean screening, eliminating pressure washing, and a secondary filtration system that never allows cuttings to pass through damaged screens into the active system. All fluid is returned to the active system with a known volume displacement pump, giving an accurate volume signal, and removes the need for gravity discharge or long troughs. This approach to drilling fluid treatment can open new possibilities in rig designs.
The system also has touch-screen automation that displays the following information in real-time:
- Kick detection
- Losses detection
- Fluid density/viscosity/temperature measurement
- Screen condition.
Screens are easily changed with minimal working room. The screens weigh approximately 7 lb (3.2 kg) and can be changed in less than five minutes per unit. When compared with a shale shaker, over the life of the unit this reduces the labor required to change screens by half in most cases.
Cubility’s main office, and research and development center is outside Stavanger, Norway, in Sandnes. The center has a flow loop capable of handling water-base, oil-base, or completion fluids. The center has a maximum flow rate of 475 gallons/minute (gpm) (1,798 liters/min) and can simulate flowline temperatures up to 185 °F (85 °C) while logging all information in real time.
Based on Cubility’s internal testing, each MudCube can process more than 475 gpm in 1.55 specific gravity (1.55 gm/cu cm) oil-base fluid, with API 170 mesh screens. Early tests with low weight water-based fluids exceeded 700 gpm utilizing API 140 screens. They also say that during internal testing, they can reduce the oil on cuttings retention up to 69% but they believe the real tests needs to be performed in a live offshore operating environment.
Current tests are under way in the first installation, offshore Norway, with results expected by mid-year. Cubility targets system delivery to the market as early as the fourth quarter of this year.