New Solution for Managing Drilling Fluid on HDD Jobsites

Mud recyclers are increasing jobsite productivity by cutting cumbersome disposal rituals.

During the horizontal directional drilling (HDD) process, water and other fluids are a necessity. For example, drilling fluids such as bentonite and polymers can play an important role in stabilizing hydrostatic pressure, managing drill-bit temperature and limiting formation damage. This mixed material generates a by-product often referred to as “drilling mud.”

Drilling mud can be a messy business. Once underground utilities are installed, it’s the responsibility of the contractors to clean up the excess drilling mud. Specifically, in many regions federal regulations require drilling mud to be cleaned and disposed of properly. And while physical extraction and disposal of drilling mud is possible, it’s a time-consuming and costly hassle for many utility contractors.

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To combat this often cumbersome process, advanced technology is now available that allows contractors to recycle HDD fluid. By removing large cuttings, rocks, sand and fine particles, the cleaned fluids can be reused throughout the drilling process. This provides benefits for contractors and the environment.

Micro Recycling System Benefits

By recycling HDD fluid, contractors can significantly reduce their operational costs. In the past, because recycling equipment was typically manufactured for large operations with 100,000 lbs of pullback or higher, smaller utility projects were limited in their recycling efforts.

Today, however, new “micro” recycling systems — self-contained units that clean and re-circulate fluids through the bore hole — are making drilling fluid recycling possible for these smaller projects. These micro systems are compact enough to work in urban areas and meet the needs of standard-size directional drills. Additionally, because a large volume of today’s drilling takes place in urban areas, the system can be quickly moved from one jobsite to the next with relative ease.

Time and resources that were once spent on hauling and disposing drilling mud are now reduced through these mud-recycling units. Some units, in fact, provide full-fluid transportation, automated controls and leveling screens, which can help prevent overflows and arduous cleanups for contractors.

Contractor Savings

As the water crisis continues to challenge businesses in California and elsewhere, many businesses are looking to relieve environmental pressures through sustainable practices. Nevertheless, decreased water consumption and recycling efforts can also retain profits for many contractors — a win-win for contractors and the environment. While fluid recycling is becoming increasingly common due to advances in HDD technology, contractors are pursuing the process for a variety of reasons.

Cost is one key driver. The cost of additives and disposal fees for 1,000 gals of drilling fluid can range from up to $600 or more — and this does not include water and transportation costs.

Also, because drilling fluid is being recycled during the pumping process, lower fluid volumes mean fewer additives and less water consumption. For example, an operation with a 30,000-lb pullback drill unit may pump 20,000 gals of fluid throughout the project. Yet, when a micro recycling system is used, the actual fluid loss may only be 1,500 gals of drilling fluids throughout the entire operation. And because reduced drilling fluid lowers the number of vac systems and trucks needed for mud extraction, it can also lower fuel costs substantially.

Using fewer additives, water and transportation resources can save contractors hundreds to thousands of dollars throughout the drilling process.

Additionally, most HDD projects use a stand-alone mud-mixing system, employing more machines throughout the operation. Mud-recycling systems, however, can also mix fluids and reduce the need for a vacuum trailer or truck, requiring fewer machines and operators.

Environmental Relief

Emissions, drilling fluids and water consumption are diminished during the HDD process with recycling systems, shrinking its carbon footprint. Fluid cleanup, however, is still a necessity.

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For that reason, Oklahoma State University conducted a study on the chemical and physical properties of HDD fluid residue and its environmental effect from land application. A total of 56 samples from 28 different states were received, testing total solids, pH, salts, plant-available nutrients and trace metals. The study found that 100 percent of the samples had no chemically limiting effect preventing land application. In other words, all would be safe to apply to land with no negative effects. To evaluate the effects of land application, researchers applied various rates of HDD fluid residuals on vegetated and bare soils. After weeks observing the controlled test sites, it was concluded that land applications up to 50 tons of solids per acre are a viable option for HDD fluid disposal, given that a driller does not bore through a contaminated site.

Agricultural application may not seem the most obvious choice for HDD fluid disposal, but this research suggests that it is a practical option. “Mud farming” is increasingly used in various parts of the country where regulations allow, with contractors paying farmers to apply the fluids to the farmlands with no expected negative results.

The Future for HDD Jobsites

When utility contactors break down their biggest operational hindrances during the drilling process, mud disposal often tops the list. Yet, what was once a messy and cumbersome cleanup process — involving excess machinery, labor, and rising water and additive costs — is now much improved with drilling recycling units.

Some units today, such as the Ditch Witch MR90, mix fluids, recycle mud and can be transported full of fluid. These combined components mean utility contractors are handling less tedious disposal steps and ultimately increasing jobsite productivity.

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And although HDD fluid recycling still requires a skilled operator for maximum efficiency, the benefits of increased hole velocity include increased production, improved tooling life and reduced risk of inadvertent returns. For utility contractors, this means fewer trips to haul water supplies and dispose of fluids. For the environment, this means less water consumption and additive and landfill use after the process is complete. Overall, the recycler’s investment is recovered by the savings achieved, making it an increasingly appealing option for HDD industry professionals.

Seth Matthesen is senior product manager, directional drills, fluid systems and mud recyclers at Ditch Witch.
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