Vacuum-based filtration is a viable alternative to shale shakers

Fig. 1. The MudCube is a vacuum-based filtration system that removes solids from the drilling fluids, and it avoids some of the limitations of Shale shakers.

The first line of defense in replenishing drilling fluids and separating rock particles during drilling operations is the solids control system. Foremost among such systems are shale shakers, where, through G-force vibrations, solids are filtered out for overboard discharge or treatment. The cleaned mud is then incorporated back into the active fluid system and reused to continue drilling the well.

Yet, shale shakers today come with a number of limitations. The high G-forces, for example, tend to break down the drilled solids into fine particles, reducing the amount of solids removed and increasing the solids content in the drilling fluids. High volumes of mud are also lost, leading to increased drilling waste. In addition, shale shakers often result in a poor working environment, with personnel exposed to high noise levels and vibrations, as well as oil and vapor emissions.

It is with these issues in mind that Cubility, a Norwegian company, will showcase an alternative to shale shakers, called the MudCube, Fig. 1. This new solids control solution is leading to improved operational efficiencies, reduced drilling fluid costs, enhanced mud quality, and improved HSE solution. As such, this system provides a viable alternative to shale shakers, which have been used in the industry since
the 1930s.

The MudCube is a vacuum-based filtration system, which removes solids from the drilling fluid and has a lower deckload than traditional shakers. Rather than relying upon a high G-force to separate mud and the drilled solids, drilling fluids are vacuumed through a rotating filter belt, using high airflow for more effective separation of the cuttings from the fluid. The rotating filter belt carries drilling fluid and drilled solids forward while air, at 20,000 lpm, is pulled through the filter belt, taking with it the drilling fluid.

Fig. 2. Offering a relatively compact size, the MudCube can help operators meet regulatory and environmental requirements, at a cheaper disposal cost.

The cleaned drilling fluid is returned to the active mud system, and the drilled solids—carried forward on the filter belt—are discharged either directly overboard (if they meet environmental discharge regulations) or to a cuttings handling system. The use of vacuum and airflow, as opposed to high G-forces, also leads to a much-improved HSE environment. MudCube also uses water-knives, installed on the inside of the vertical part of the filter belt, to remove any cuttings or clay that may have “stuck” to the belt. Pneumatic micro-vibrators are installed underneath the filter belt to create resonance and improve conductance. The MudCube’s solids removal efficiency can be as high as 90%. 

The system’s improved separation capabilities lead to better-quality mud, fewer chemicals required to maintain its properties, and more mud recycled back to the mud tanks, to be reused for drilling. In addition to cost-savings achieved through the reduced use of chemicals, there are also the operational benefits of high-quality drilling fluids with stable mud properties, leading to improved drilling efficiencies on the rig, and a decrease in non-productive time (NPT).

The MudCube generates substantially drier cuttings, with lower oil content, and substantially cheaper disposal, Fig. 2. In the Gulf of Mexico, for example, the regulatory limit for oil on cuttings, to allow for the disposal of cuttings directly to the sea, is 6.9%. The MudCube can deliver that requirement.

Since its introduction to the market, the system has been adopted on offshore rigs in the North Sea, Middle East, Far East, and North and South America.