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    Making sense of HDD drilling fluids


    Why drilling fluid is essential to HDD and the mixing process

    Drilling fluids are the secret sauce on horizontal directional drilling (HDD) jobs. Drilling fluids can also be one of the most misunderstood aspects of drilling operations. Every member of your crew working around drilling operations should understand what drilling fluid is, how to mix it, the type of additives they should use for various soil conditions, how to determine pumping and pullback rates, as well as how to make adjustments on the job.

    This series of short articles will help take some of the mystery out of drilling fluids, beginning with why it is essential to HDD operations and ways to mix it.

    Why drilling fluid is important
    Here are a few of the reasons drilling fluids are used on HDD projects:

    ·  Helps extract cuttings: Failure to remove cuttings from the bore path can result in inadvertent returns (frac-out), limit distance length the drill can pilot bore, heave ground surfaces above the drill head and lead to product pullback failures.

    ·  Creates downhole stability: Drilling fluid helps the drill path keep its shape during the drilling process. Using the right type of fluid additive is also important to help a drilled hole maintain its shape when working in different soil types (drilling in sand for example).

    ·  Cools and lubricates tooling: Downhole tooling temperatures can rise quickly without the use of drilling fluids. Drill head temperatures rising above 220° Fahrenheit will permanently damage the transmitter that gives critical depth and pitch data. Drilling fluids also help keep tooling clean and reduce pullback/rotational torque pressures required to pilot out and pull product back through. 

    Drilling fluid viscosity
    You’ve now learned why using drilling fluid is essential, but it's also necessary to understand having the right viscosity (thickness) of drilling fluid.

    Drilling fluid that is too thin or light can limit the amount of cutting returns. You may still get the majority of returns, but heavier cuttings can sink to the bottom of the bore (creating a cuttings bed) and not be flushed out. After a while, this cuttings bed can create return flow issues during the rest of the drilling process (which can result in excessive product stress and inadvertent returns).

    Drilling fluid that is too thick can result in additional downhole pressure to get fluid to flow and eventually lead to inadvertent returns. Fluids follow the path of least resistance, and if the fluid is too thick — that direction is typically towards the surface.

    To check that you have the right viscosity, it’s important to measure it every time you mix up a batch of drilling fluid. You will need a Marsh funnel and cup, following these steps.

    1.  Start by filling your cup up to the fill line with drilling fluid.

    2.  Next, plug the hole in the bottom of your funnel with your finger and pour the fluid through the funnel’s screen (ensure you are wearing proper safety gloves).

    3.   There shouldn’t be any clumps of material left behind on the screen. If there is, your drilling fluid is likely not mixed correctly or fully hydrated (more on that next). Repeat until drilling fluid crests the top fill line (just under the screen) of your Marsh funnel.

    4.  Now, place the empty cup below the funnel and start a stopwatch as you remove your finger from the bottom of the funnel. You want to stop counting when the drilling fluid crests the top fill line (32 oz [.9 kg]) of your cup. This number is your drilling fluid viscosity measurement.

    You should aim for a viscosity rate of between 45 and 60 seconds for most drilling applications.

    Mixing processAlways make sure the person assigned to drilling fluid mixing is fully trained on the proper steps.

    On every new job, you should check pH levels from your water source. Drilling fluid additives (bentonite and polymers) mix better with a pH level range between 8 to 9. Municipal water will typically measure around that range. However, if you’re using water from a pond or well, the pH level will likely fall below that range. Adding soda ash will help raise the pH levels and help you use less drilling fluid products.

    When you’re ready to mix your additives with the water, powders like bentonite must be added to the hopper and liquids should be poured directly into the tank.

    Every Vermeer fluid mixing system is equipped with a bag cutter next to the hopper. Use it to split and empty the whole bag into the hopper at once. Doing it this way, instead of cutting it with a knife and slowly sifting material into the hopper, will help reduce dust levels and help prevent air from getting into the system.

    When adding bentonite, make sure it’s sent through the venturi and hopper at full throttle. You want to get the maximum implosion through the venturi to mix the product well. After enough bags of bentonite are added, keep product mixing through the venturi for approximately 10 minutes until it’s thoroughly broken up and hydrated.

    If you plan to add a polymer, you’ll need to wait until the bentonite is completely mixed (10 minutes). Adding a polymer too soon or out of sequence can cause the bentonite to ball up in the tank rendering it ineffective.

    The final step is to check the drilling fluid viscosity. If it's too thick, add additional water or thinners; if it is too thin, add more drilling fluid additives.

    A few housekeeping notes
    Mixing drilling fluid doesn’t have to be a messy job. Make sure you’re cleaning your mixing system’s hopper and venturi regularly to help prevent clogs. Also, make sure you’re washing your tank often. If there is polymer residue left in the tank when you go to mix up your next batch of drilling fluid, you could end up with small balled-up clumps of bentonite in your tank.

    Future articles of “Making sense of HDD drilling fluids” will cover the steps to calculate reamer pullback drill rates and explain the different types of drilling fluid additives available. For more information about drilling fluid mixing or the MUD hub, reach out to your local dealer, or visit Vermeer.com. 

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    Spring maintenance for horizontal directional drills


    Hey drillers — Are you starting a big project this spring? Do you have your HDD ready? If not, it’s time to get to it. 

    Spring is the best time of year to give your drill rig a thorough inspection, perform routine maintenance and address any potential issues. The checklist below will give you a little more direction about what maintenance you should be doing this spring. Make sure to refer to your operator's and maintenance manuals for specific information about each of these features on your HDD. 

    General inspection

    • Make sure the operator presence system is functioning correctly
    • Grease the machine’s lubrication points
    • If your machine has a cab, top off your windshield wiper fluid and check the cabin air filter
    • Inspect the Rollover Protection System (ROPS)–if you notice any bending, cracking, breaks or signs of flexing, call your Vermeer dealer
    • Make sure there’s no damage or signs of abrasion to the electrical harness
    • Check the horn and the backup alarm system
    • Test the parking brake
    • Check the emergency shutoff switch operation
    • Look through your racks of drill rods and pull out any rods that show signs of wear or are damaged
    • Inspect, clean and grease vises
    • Verify that the machine’s greaser is working properly
    • Test the Strike Alert System and the Remote Lockout System

    Engine and drivetrain

    • Check and top off engine oil
    • Inspect the air filter — replace if necessary
    • Check coolant level and condition
    • Clean the radiator/grille of any debris
    • Drain the water/fuel separator
    • Check the planetary oil level and look for any signs of leakage


    • Check your hydraulic fluid levels 
    • Make sure the controls are working correctly
    • Inspect the hoses and components for leaks and damage
    • Check the vise cylinder pressure and operation of vises
    • Test the machine’s thrust/pullback and rotation pressures
    • Check the operation of shakedown units

    Also, review your Vermeer operator’s manual, which covers prepping the work area, preparing the machine, required personal protective equipment (PPE) and safety warnings.

    There you have it — a quick list of components you should be inspecting, maintaining and repairing this spring. Spending a little time now on preventive maintenance can save you time down the road as the days get longer, and you’re busy working.

    Getting in touch with your local Vermeer dealer is easy through our dealer locator, or if need an operator’s manual for your drill, you can fill out the form here.

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    HDD 101: Teaching engineers about directional boring


    What makes a driller’s blood boil?

    Sure, there are a few things. But one that is sure to frustrate horizontal directional drilling (HDD) crew members is a project designed by an engineer who does not have a good grasp on HDD methods.

    Samuel Ariaratnam is trying to help you out.

    He’s a professor and the program chair for construction engineering at Arizona State University. Without fail, the young engineers he teaches know very little about horizontal directional drilling prior to taking his construction engineering and management class.

    Here are the ways he’s getting the next generation of civil and construction engineers to understand the potential of HDD and preparing them to properly design an HDD project:

    • HDD-specific assignments, including readings and writing essays, researching a challenging project and giving a presentation on it, and designing an underground project. That last one does not have to incorporate HDD, but students often pick it as the installation method.
    • A class trip to HDD jobsites, arranged by a local Vermeer dealer.
    • Making sure his students are aware of the following benefits of directional boring compared with other installation methods:
      • It is very efficient from a productivity perspective.
      • It can be less disruptive than other underground construction methods.
      • It has environmental advantages, including lower carbon emissions.

    Ariaratnam estimates that on a scale of 1 to 10, the general knowledge of horizontal directional drilling among civil engineers is a 3 or 4. That can lead to poorly designed projects, or HDD not even being included in bid documents.

    Ariaratnam is working to change that.

    “I see a huge future in horizontal directional drilling,” he says. “We have a long way to go in raising awareness about HDD, but that’s a positive thing too because we have a huge market to capture.”

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    Arkansas contractor takes on collapsed sewer job in industrial park


    Take an industrial park with a 60-year-old clay pipe sewer line buried 10 feet below ground, add a road nearby that is highly traveled, and throw in a line break that has created a sinkhole big enough to hide a small car. The result? A real problem.

    That was the situation facing Pete Charlton, Vice President and General Manager of Gastony Directional Boring, Inc., in Fort Smith, Arkansas. Charlton founded the company in 1999 and has done many jobs in “pipe rehabilitation”—boring for sewer, gas, water, and electric lines primarily from Fort Smith north to the Missouri/Arkansas border. He and his eight employees were in the process of completing a project for the city of Fort Smith to replace many of that city’s older sewer lines when an emergency situation popped up in neighboring Van Buren, Arkansas.

    Van Buren, a city of about 20,000 on Arkansas west-central border, is nestled at the foot of the Ozark Mountains. Van Buren features an industrial park that houses, among other companies, Simmons Foods, a poultry processing plant that releases about 200,000 gallons of wastewater each day in the industrial park’s sewer main. About 60 feet of an old clay sewer line had collapsed beneath the industrial park and formed a huge hole at the intersection of Co-op Drive and 28th Street, a roadway that carries significant truck traffic every day. Another factor in this problem is that the Arkansas River is nearby and tends to flood the area.

    Plans were already in the works to spend $1 million to $2 million to raise the road, but no work had yet been accomplished. City officials knew if the river spilled over into this area now, they would have a giant mess.

    “We were asked by the city engineers to bring in our camera truck to provide video of the collapsed pipe in order to determine the exact location and extent of the collapse,” says Charlton. “We went through from both sides of the collapse, and determined that somewhere between 60 and 80 feet of the pipe was simply gone.”

    He speculates the missing pipe collapsed and was washed away by the 200,000 gallons of scalding water that rushes through the pipes each day from the poultry plant. Heavy truck traffic and the old age of the pipe also contributed significantly to the development of the sinkhole.

    In order to position the camera into the pipe, the crew used nearby manholes to get under the street and reach the collapsed area. Upon review of the videotape, the Van Buren Utilities Commission Board did not waste any time.

    “This was an emergency. We got the job because we have done a lot of work rehabilitating pipe in Van Buren,” Charlton notes. “There are a lot of large companies in that industrial park. If that sewer went out or the street caved in it would have created several major problems. We submitted a price to do the work and the Board and engineers then said, ‘Get it done.’”

    In all, about 400 feet of pipe needed to be replaced. Getting the new HDPE SDR 20-inch pipe in was the next challenge. The new 20-inch pipe came in 40-foot lengths. Charlton rented a fusing machine from ISCO, fusing the pipe above ground as it was pulled through the 400-foot bore.

    Preparation was the key to getting this job done quickly and efficiently. In order to complete the project, Simmons Foods agreed to a 24-hour plant shutdown beginning on a Saturday morning. Charlton, Jeromy Dutra (his supervisor of ten years), and the Gastony crew spent two days prior to the shutdown prepping the job site. This included excavating the entry and exit pits, setting up 6-inch bypass pumps, positioning traffic control signs, and excavating a pit along the road by the manhole. Simmons Foods and several smaller companies agreed to shut off their water supply and not discharge water once the project began. Charlton and his crew had the next 24 hours to complete the job.

    Charlton decided to burst the old clay pipe using a HammerHead® impactor, a Vermeer® NAVIGATOR® D36x50 Series II horizontal directional drill, which he had purchased about six months before this job, and a 24-inch reamer to break up the clay pipe and collapsed material that was left.

    “We bored through 60 - 80 feet that were simply gone — the pipe was full of dirt,” Charlton says.

    “The impactor was an important part of the process,” he says. “That old 18-inch pipe was so thick that it had to be dealt with and removed. We used a bio-degradable bore gel to slurry up the water and make sure the pipe pulled through smoothly,” Charlton says.

    Charlton and his crew also had to negotiate the new line through an existing manhole. Since the city didn’t want the street dug, Gastony reamed out the manhole and made it big enough to pull in the 20-inch pipe. Once the pipe was in place they grouted the area around the pipe.

    “Using HDPE pipe was an important consideration for this project,” Charlton says. “We often install HDPE around processing plants, because the caustic acid that comes from the plants doesn’t affect the HDPE pipe at all.”

    The expected life of the new HDPE system in simulated tests is more than 100 years. According to Charlton, older cast iron pipes develop calcium deposits, significantly reducing pipe capacity. “Nothing clings to HDPE pipe,” he says.

    The city’s main objective was to replace the old 18” clay pipe with 20” HDPE pipe with minimal interruption to the traffic. “They didn’t want traffic stopped, and it didn’t,” Charlton says. The poultry plant was able to find a silver lining to the downtime, using it to update and maintain some of its manufacturing technology.

    The entire project — which cost $68,000 — took just over ten hours. Charlton says he had estimated that it could be completed in six hours. Why the time difference? “Everything worked as we expected, but it was just slower going,” he says. “It went inch by inch, slow but smooth. It just took a little longer to pull in the larger pipe.” Compared to past jobs, Charlton says he would rate it as “up there” among some of the toughest.

    “Gastony has had jobs boring under rivers and swimming pools, but the pipe sizes on those jobs were all between 4- to 24-inch,” he says.

    Charlton’s advice to other contractors who might be considering a similar job is simple: know the costs of running your boring machine. “There are boring contractors who do not take into consideration what all the expenses are to just to turning the boring machine on,” he says. “In addition to diesel fuel, labor, trucks, insurance, and cost of materials, there are many other expenses to consider. Other expenses might include site restoration, depth of pipe, size of pipe, and the cost of excavating to tie in laterals and mains to the manholes.”

    In the end, the customer—the city of Van Buren and its residents—got what they wanted: the integrity of the road was maintained, traffic was not stopped at a busy intersection, and the dangerous problem was fixed. And the Gastony Directional Boring team has a job that will go down in its books as one of its toughest.

    Gastony D.B.I. is one of several companies owned by Forsgren, Inc., a fourth-generation heavy civil contractor, located in Fort Smith, Arkansas. Forsgren, Inc. was started in 1936 by three brothers. 

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