Effective solids control improves drilling fluid performance and reduces waste management costs. The right systems can raise flow rates, reduce dilution, and decrease the amount of additives that need to be used, removed and discarded. Shakers remove solids from drilling mud as it passes over the surface of a vibrating screen. This initial screening is necessary for downstream hydro cyclones and centrifuges to become overloaded beyond their design capacity.
Increased Flow Rates
As the drilling industry evolves, rigs must run more intensely at higher speeds and drill on pads. This creates challenges for rig equipment that processes the mud. Having reliable solids control centrifuges system is critical to achieving these results. The earth goes through several processing stages before it reaches the drilling hole. This includes the shale shaker with vibrating panels separating larger solids, a degasser and vacuum pumps that remove gasses, a desilter that filters the fluid and removes even smaller debris, and a centrifuge for final mud processing.
Most conventional systems rely on a series of hydro cyclones to filter the mud and remove ultrafine particles that are too small to be classified as formation or drilled solids (also known as low gravity solids or LGS) and weighting agents, such as barite. The centrifuge can then replace these smaller particles in the mud for reuse.
Traditionally, centrifuges in weighted drilling fluid applications remove low-gravity solids (often called LGS) from the mud system. This is accomplished by eliminating the desired-sized barite particles from the mud stream and discarding the centrifuge overflow, often referred to as central.
This practice is flawed for many reasons, but a few include: The discarded barite is costly to replace with fresh barite and lowers the center’s average particle size, resulting in an accelerated decline in drilling fluid quality. Additionally, the centrifuge overflow is rich in colloidal solids that traditional centrifuging cannot separate without increasing mud dilution. An enhanced solids control system designed to fit the specific rig program allows for the maximum amount of valuable barite to be returned to the drilling fluid while minimizing dilution. This reduces the need for mud makeup and accelerated wear on bits, mud pumps and other equipment.
The right mechanical solids control system and a sound drilling fluid management program can significantly reduce waste volumes and related costs. These systems are critical for achieving environmental and regulatory compliance while protecting the environment, reducing HSE risks, and mitigating waste disposal liability.
Drill cuttings are separated from the drilling mud with vibrating screens as the earth passes over them. Particles smaller than the screen openings are discarded into mud tanks, while the larger particles continue over the screens and off to the side of the rig, where they’re collected as drilling waste.
When the solids control equipment isn’t properly sized to match the drilling conditions, it can lead to excessive dilution, excess mud disposal, and higher water haul-off costs. In these situations, a rotary drum centrifuge can significantly improve efficiency by decreasing the feed solids rate to the cyclones and bowl centrifuges. This results in lower dilution and mud consumption rates and increased efficiency for all downstream equipment.
Modern solids control systems use a closed-loop system that prevents mud waste from entering the rig site environment. This prevents surface water or groundwater contamination, reducing HSE risk and associated liabilities. In addition to eliminating mud waste from the site, these cuttings management technologies minimize the quantity of drilling waste requiring transportation by truck.
The mud waste generated from the drilling operation is collected on shale shaker screens, then pumped into centrifuges for separation. The resulting barite-rich slurry is returned to the active drilling fluid system, maximizing efficiency and reducing costs.