Your guide to horizontal directional drilling (HDD)
Sometimes you need to drill beneath a road, a waterway, or some other obstacle that creates an engineering challenge for those used to downward drilling. Through the process of horizontal directional drilling (HDD), you can get your project done without disruption. But what exactly does HDD entail? Let’s explore this useful technique, the tools required to make it happen, and the reasons why it’s become such a popular drilling method.
If you need drill bits for your HDD operation, OK Bit has what you’re looking for. We offer a huge variety of new and rerun HDD bits. If you know what you’re looking for, contact us today to see if we have your bit in stock. If you aren’t sure, our experts will be happy to advise you on the best tool for the job.
How does horizontal directional drilling work?
There are three primary steps to horizontal directional drilling:
- Pilot hole drilling
You’ll start HDD by drilling a small diameter pilot hole. Next, you’ll pump drilling fluid through the drill pipe to the bit, where high-pressure jets will help the bit grind soil ahead of the drill stem. This fluid carries cuttings back to the pit at the entrance of the drill rig.
Next, you’ll pre-ream the pilot hole until it’s a sufficient size to install product lines. You’ll pull the reamer back and rotate it while pumping drilling fluid, which will cut and remove debris to make the hole bigger. Additives like Bentonite are often used to ensure a stable hole.
- Pipe pullback
Once your hole is pre-reamed, it’s time to pull back the pipe. Your reamer and drill rod will be able to swivel, preventing any torsional stress from the rotating drill string’s transfer to the product pipe.
What kinds of projects is HDD good for?
HDD is the best technique for installing a variety of types of underground infrastructure. It’s commonly used for:
- Telecommunication cables
- Fiber optic cables
- Oil and gas pipelines
- Water pipelines
- Sewer pipelines
- Electrical cables
If your project doesn’t fit any of the above categories, that doesn’t mean HDD isn’t your best option. Because of its versatility, the drilling industry is finding new applications all the time. Our experts can help you decide if it’s right for you.
The advantages of HDD:
- Uninvasive – HDD allows you to install pipes and other utilities underground without disrupting anything above them on the surface. This is why it’s the most popular method for drilling in urban and suburban areas.
- Easier to get permits – HDD creates less of a disturbance than the trench method and requires less equipment and people, so getting permits is a simpler process.
- Cost efficient – For most projects, HDD is also cheaper than alternatives. You need fewer workers, less fuel, and fewer pieces of equipment. Additionally, there are little to no costs involved with restoring the surface after installation.
- Faster – Horizontal drilling is more efficient, so the process is faster. You also don’t have to spend time restoring the surface afterward. Because the pipeline is deeper than with the trench method, you’re also less likely to have to fix it or do maintenance.
What are the best soil types for HDD?
Soil type plays a large role in the success of horizontal directional drilling. Soft soils do best, including clay and sand. However, if soil is too soft, this can make steering the equipment more difficult and increase risk of hydraulic fracturing.
Hard rock can work well too, but it takes longer and needs heavier-duty equipment. Soil with a lot of cobbled rock or gravel, however, can make your equipment more difficult to steer and more unstable. This increases your risk of drilling fluid return.
Choosing the best HDD drill bit for the job
Finding the right HDD drill bit can be intimidating. There are a ton of different kinds, including PDC bits, milled tooth, TCI roller cone bits, drag and shear type bits, and point attack bits. Each of these bit types has its own IADC code and set of attributes that can get more detailed than you’ll likely need them to.
Choosing the right bit is typically a four part process:
- Collect information about drill site – Start by doing an on site survey. Contact local authorities, water well drillers, construction companies, and anyone else who might be important and able to give you the information you need. The more you know, the more confidence you can have in your decision.
- Identify soil category – Take samples of the soil and analyze its materials. The texture and hardness will help inform what the right drill bit for the project will be.
- Choose a drill bit based on category – HDD bits go from softer to harder in descending order. If you need help figuring out what the right bit is for your project and soil type, our team can help you analyze your information and find the perfect bit.
- Adjust your bit as needed – You may find through the drilling process that soil type is inconsistent or other issues exist you need to adjust for. Analyzing return characteristics can help you know what adjustments might be needed.
OK Bit has the Horizontal Directional Drill Bits you need
If you’ve decided HDD is the right drilling method for your project, OK Bit can supply you with whatever bits you need to get the job done. If you aren’t sure if HDD drilling is the best choice or if you need help choosing a specific bit, our expert staff will be happy to help. Contact us today.