June 2026 Vol. 81 No. 6
FEATURES
Proper drilling fluid testing when using a mud reclaimer on small bore projects
Tyson Smith, HDD Market Manager, Wyo-Ben, Inc.
As disposal costs continue to rise and environmental regulations become more stringent, the use of mud reclaimers and recycling systems on small bore horizontal directional drilling (HDD) projects has increased significantly. These systems help contractors reduce drilling fluid consumption, lower disposal expenses, and improve overall project efficiency. However, achieving these benefits requires more than simply running a mud recycler. Proper drilling fluid testing is essential to ensure the recycling equipment is functioning correctly, protect drilling equipment, and maintain borehole stability throughout the project.
Why Regular Fluid Testing Matters
A mud recycler is designed to remove drilled solids from the drilling fluid so that it can be reused. While the system can significantly reduce fluid costs and waste, it must be monitored regularly to ensure it is operating effectively.
Three key drilling fluid properties should be tested every hour:
- Viscosity
- Mud Weight
- Sand Content
These tests should be performed on both the dirty fluid entering the recycler and the clean fluid leaving the system. Monitoring both streams provides valuable insight into the effectiveness of the recycling equipment and helps identify potential issues before they become costly problems. Consistency is critical. Large swings in test results can indicate changes in formation conditions, equipment malfunctions, groundwater intrusion, or fluid contamination—all of which can negatively impact drilling performance and borehole integrity.
Monitoring Viscosity
Viscosity is measured using a Marsh Funnel and Cup and provides an indication of the drilling fluid's ability to suspend and transport drilled solids. For most HDD applications, viscosity typically ranges between 35 and 65 seconds per quart, although the ideal range depends on the formation being drilled. Dirty drilling fluid should generally have a higher viscosity than the clean fluid because it contains drilled cuttings. If dirty fluid exhibits a lower-than-expected viscosity, groundwater intrusion may be occurring, diluting the drilling fluid and reducing its carrying capacity. Fresh water has a 26 second viscosity, ±1 due to human error, and should be used periodically to verify that the Marsh Funnel is properly calibrated.
Keeping Mud Weight Under Control
Mud weight is measured using a mud balance or mud scale and is one of the most important indicators of drilling fluid performance.
Clean drilling fluid typically weighs between 8.4 and 8.5 pounds per gallon. Contractors should strive to keep mud weight as low as practical because heavier drilling fluids create higher downhole pressures. Elevated downhole pressure increases the risk of inadvertent returns and formation damage. Dirty fluid should have a higher mud weight than clean fluid, indicating that drilled solids are being carried out of the bore and successfully removed by the recycler.
Clay formations often present additional challenges because their ultrafine particle size can rapidly increase mud weight. Clay inhibitors like CLAYMASTER and drilling lubricants like WYO-LUBE RR are commonly used to help manage this issue. Conversely, the use of long-chain PHPA polymers and drilling detergents is generally not recommended while utilizing a mud recycler, as drilling detergent can contribute to excessive fine-solid buildup and long chain PHPAs will blind-off shaker screens and prevent drilling fluid from falling through. A high mud weight combined with low sand content often indicates the accumulation of ultrafine solids that are too small for the recycler to remove effectively. When clean mud weight approaches 10 pounds per gallon, corrective action should be taken to reduce solids loading and lower the risk of fracturing the formation or causing a bore failure. Fresh water weighs approximately 8.34 pounds per gallon and should be used regularly to verify mud balance accuracy.
Understanding sand content
Sand content testing provides a direct measurement of larger drilled solids that remain in the drilling fluid after processing. A sand content test kit should be used to monitor the efficiency of the recycling system. Dirty fluid should naturally contain a higher sand content than clean fluid. Ideally, clean drilling fluid should contain less than 0.25 percent sand.
Elevated sand content in clean fluid often points to mechanical issues within the recycling system, including:
- Damaged shaker screens
- Improper screen sealing
- Insufficient settling time
In some situations, the problem may stem from pit design. Increasing the size of the settling pit and pumping fluid from the top rather than the bottom can improve fluid quality and reduce sand carryover.
Excessive sand content can create several operational problems, including:
- Increased mud weight
- Reduced carrying capacity
- Premature wear of pumps
- Accelerated drill pipe wear
- Increased wear on downhole tooling
The importance of documentation
Hourly drilling fluid test results should be recorded throughout the project. Historical testing data can provide valuable insight into changing ground conditions, equipment performance, and fluid management decisions.
Reviewing these records after project completion often helps identify trends that contributed to successful drilling performance—or highlights issues that may have affected productivity and bore quality.
Consistent documentation also supports troubleshooting efforts when unexpected conditions arise.
Maintaining testing equipment
Accurate test results depend on properly maintained testing equipment.
All testing tools should be thoroughly cleaned after each use to prevent contamination between samples. Regular calibration, inspection, and proper storage are equally important to ensure reliable measurements.
Even small inaccuracies in testing equipment can lead to incorrect fluid treatment decisions, potentially impacting drilling performance and project outcomes.
Conclusion
Mud reclaimers have become valuable tools for contractors seeking to reduce fluid costs and manage disposal challenges on small bore HDD projects. However, their effectiveness depends on consistent monitoring and proper drilling fluid management.
By performing hourly viscosity, mud weight, and sand content tests—and maintaining accurate records—contractors can maximize recycling efficiency, protect equipment, reduce drilling risks, and improve overall project performance.
About Wyo-Ben, Inc.
Wyo-Ben, Inc. is a market leader in mining and manufacturing premium Wyoming Bentonite Clay products. Family-owned since 1951, Wyo-Ben proudly celebrates its 75th anniversary in 2026, marking three-quarters of a century of innovation, integrity, and industry leadership. Wyo-Ben serves global industries including oil and gas, water well drilling, environmental construction, hazardous wastewater treatment, cat litter, cosmetics, pharmaceuticals, and other industrial and consumer markets. Headquartered in Billings, Montana, with strategically located manufacturing facilities in Greybull, Thermopolis, Lovell, Wyoming, Billings, Montana and Toronto, Canada. Wyo-Ben ensures product availability and reliable supply. Customers count on Wyo-Ben for premium-quality products, proven performance, excellent service, and knowledgeable application specialists. Backed by decades of innovation and strong partnerships with local dealers, Wyo-Ben continues its 75-year legacy of helping customers get the job done with confidence. For more information, visit www.wyoben.com.
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