A system-based approach for solids control

Othman Soliman, founder, SC DrillTech, explains why treating solids control as an integrated processing system rather than as a collection of individual equipment can lead to meaningful gains in drilling performance, cost control and operational efficiency

In drilling operations worldwide, solids control remains one of the most critical yet frequently misunderstood elements of well construction. For decades, operators and contractors have evaluated solids control performance through the narrow lens of individual equipment: shaker screen API ratings, hydrocyclone separation cut points, or centrifuge bowl speed. While these metrics are not without value, they reveal only fragments of a much larger picture. The reality is that solids control must be measured, managed, and optimised as an integrated system — not as a collection of standalone machines.

The pitfalls of siloed metrics

When a rigsite team focuses solely on individual equipment performance, the results can be deceptively reassuring. A shale shaker may be running at its rated capacity, hydrocyclones may be delivering the expected underflow density, and the centrifuge may be operating within manufacturer specifications — yet the drilling fluid remains laden with fine solids, dilution rates are climbing, and non-productive time (NPT) is increasing.

This paradox occurs because each piece of solids control equipment is designed to remove a specific particle size range within a continuous processing chain. Shakers address the coarse fraction, hydrocyclones (desanders and desilters) target the medium range, and centrifuges handle the fine and ultra-fine solids. If any stage is misaligned — whether through improper feed distribution, incompatible screen selection, or fluid rheology that overwhelms downstream units — the entire system fails to deliver its collective potential.

The system approach: fluid volume, solids loading and retention time

A system-based evaluation begins with three fundamental parameters:
• fluid volume processed
• solids loading at each stage, and
• retention time across the surface system.

First, the total circulating volume must pass through the solids control equipment in a manner that matches each unit's design capacity. Overloading the shaker with high flow rates forces fine solids past the screens and into the active system, increasing the burden on hydrocyclones and centrifuges that were never intended to handle such volumes. Conversely, underutilisation of equipment leads to poor agitation and settling, creating dead zones where solids accumulate.

Second, solids loading must be tracked progressively. The mass of solids removed by the shaker directly influences the efficiency of the hydrocyclone bank. If the shaker is not removing coarse solids effectively, hydrocyclone nozzles plug prematurely, cone pressure drops, and separation efficiency collapses. Similarly, if hydrocyclones fail to remove medium solids, the centrifuge is forced to process a higher concentration of solids than its design allows, increasing wear and reducing fluid recovery.

Third, retention time across the surface system determines whether solids have sufficient opportunity to be removed before re-entering the wellbore. A system with inadequate surface volume, poor compartment agitation, or bypassed equipment will recirculate drilled solids regardless of how well individual units perform in isolation.

Impact on drilling performance and cost

Measuring solids control as a system directly affects two of the most closely watched metrics in drilling economics:
• rate of penetration (ROP) and
• dilution cost.

Excessive fine solids in the drilling fluid increase plastic viscosity and yield point, creating a thicker fluid column that reduces hydraulic efficiency at the bit. The result is lower ROP, higher equivalent circulating density (ECD), and an elevated risk of lost circulation or wellbore instability — particularly in the narrow margin windows common to deepwater, high-pressure high-temperature (HPHT), and unconventional formations globally.

From a cost perspective, every barrel of fluid diluted to control solids concentration represents a direct expense. When the solids control system operates as a cohesive unit, the volume of dilution required drops significantly. Field data from operations across multiple continents has consistently shown that improving overall system efficiency — rather than upgrading a single piece of equipment — yields the greatest reduction in dilution volumes and associated disposal costs.

Practical implementation on the rig

Transitioning to a system-based approach does not require capital-intensive overhauls. It begins with baseline measurements: capture the mass and particle size distribution of solids removed at each stage, compare it to the theoretical solids generated by the bit, and identify gaps.

Next, ensure that equipment is sequenced and sized correctly for the anticipated solids profile. A high-rate well in unconsolidated sands requires a different shaker screen and hydrocyclone configuration than a directional well in hard limestone. Fluid rheology must be managed to support — not hinder — mechanical separation.

Finally, establish clear accountability across the rigsite team so that solids control is treated as a shared objective rather than the sole responsibility of the mud engineer or solids control technician.

For operators and drilling engineers looking to stay ahead of evolving solids control practices, further technical resources and insights into system optimisation are available at SC DrillTech (https://scdrilltech.com), where continuous field-based research on solids control development is published to support industry advancement.

Conclusion

The complexity of modern drilling environments worldwide demands a shift in how solids control performance is judged. Individual equipment metrics will always have their place, but they cannot tell the full story. Only by evaluating shakers, hydrocyclones, centrifuges, and drilling fluids as a single, interdependent processing system can operators unlock meaningful gains in drilling performance, cost control, and operational efficiency. The question is no longer whether each machine is working — it is whether the system as a whole is winning.

Othman Soliman is the founder of SC DrillTech, an independent technical platform dedicated to Solids Control and Drilling Waste Management, with over 25 years of international field experience.