Factors to Consider in Choosing the Right Drill Pipe for an HDD Project
The primary step to performing a horizontal directional drilling job is securing the best fit drill pipe for the specific operation being conducted. A poor fit undermines the performance of the entire horizontal directional drilling equipment and severely affects production results. That’s why it’s important to ensure that the correct drill pipe is used for the project.
The use of a drill pipe, as part of a drilling rig, is to guide the drill bit in its rotation, much like how a straw works with your drink. The drill bit must be able to rotate freely and smoothly within the hollow cavity of the drill pipe without compromising its integrity or that of the borehole itself.
However, with the wide range of drill pipes available in the market today, it can be difficult to choose which one is best suited for any drilling project. For this reason, it’s best to create a checklist of factors that will potentially affect the productivity of the project as well the efficiency of the drill rig.
When drilling a pilot hole for an extended reach HDD project, torsional stiffness is a critical factor to consider. For example, a 6 5/8-in., 27.70 lb/ft, S-135 drill pipe with a.362-in. wall thickness will twist 59 percent less than a 5-in., 19.50 lb/ft, S-135 drill pipe with the same wall thickness. This is especially important while trying to keep the mud motor and drill bit on the high side, or clock-face, at the end of a 5,000-foot pipe string.
Most HDD installers prefer to utilize API-style connections like 4 1/2-in. IF, 5 1/2-inches full hole, or 6 5/8-inches full hole since they are common and well-tested in the field. These connections are available with a double shoulder feature or in their conventional configuration.
The double shoulder variants of these connections give a secondary shoulder at the end of the pin. This strengthens the connection by around 30% and helps prevent over-torque if slip torque occurs downhole.
There are other available connections, but they frequently come with their own set of challenges, such as re-cut serviceability and cross-over subs, stabbing/alignment issues, adapters, or accessories availability.
Size of the pipe
Another factor to consider is the size of the drill pipe. Selecting one that is too big or small will only compromise its rigidity and strength, leading to damage caused by poor performance.
Typically, for most HDD projects, the use of 4 1/2-inch, 6-inch or 8-inch sizes are more than sufficient to penetrate through soft soils and achieve the best possible ground penetration rates.
Type of material used
The drill pipe is made up of different types of materials with varying degrees of strength. For instance, 4 1/2-inch pipes are usually made up of stainless steel material with added molybdenum. This alloy is known for its strength and durability, making it suited for most HDD projects.
When utilized on rock crossings, hard banding can extend the life of drill pipe. Consult your vendor about the many types and placements of hard banding. For HDD projects, some manufacturers or suppliers can recommend different types of hard banding as well as where the hard banding should be placed (special features).
The manufacturer of the horizontal directional drilling equipment is also an important aspect to consider. This plays a crucial role in ensuring that your drill pipe can support proper rotation of the drill bit. The best manufacturer of drill pipe is a company that manufactures high-quality items for contractors and construction companies.
Make sure to compare prices from various manufacturers before making your purchase to get the best deal. If you are still unsure about the type of drill pipe to use for your project, consult a drilling contractor or construction professional.