Horizontal Directional Drilling

Horizontal Directional Drilling is a method of installing utility pipelines and conduits under a wide variety of surface obstacles. First developed in the 1970s, this technique combines those used in conventional road boring with those found in oil and gas directional drilling. This method is now very popular for oil, water, natural gas and waste water pipelines as well as conduits for power and fiber optic cables. The main benefit is the ability to install these services without using traditional trenching methods, avoiding unnecessary environmental impact and providing additional security.

HDD Data

Process

  • SITE INVESTIGATION AND DESIGN – Includes the site survey, locations of existing pipelines and services, and a geological investigation. Placement and equipment are then determined.
  • PILOT HOLE DRILLING – A Pilot hole is drilled from the entry point to the exit point along the pre-determined profile and direction.
  • HOLE ENLARGEMENT – In most cases pilot hole enlarging, also known as “pre-reaming,” will be necessary. This is required to provide a bore diameter large enough for the pipeline to be installed in the drilled crossing.
  • PULLBACK – The pipeline is pre-assembled and placed on rollers. A reamer is then connected to the drill pipe to enlarge the bore. The drill pipe is pulled back to the entry point until the pipeline is completely installed.

Benefits

  • A single location area can be used to install different pipes
  • Less invasive, protects the ecosystem and adjacent areas.
  • More secure than traditional open cut.
  • Weather will not impact directly on the process.
  • Limited disruption, ideal for sites such as roadways, railways, recreational facilities, waterways and areas of high population density.
  • Ability to drill beneath surface obstructions or ongoing site operations.

For most HDD applications, the drilling tools and rig equipment are individually designed for each job. Pipe selection is a critical part of this process. TSC HDD manufactures a wide range of pipe suitable for most HDD projects. By offering 3 1/2″ OD to 7 5/8″ OD with connection configurations matching the design requirements, TSC HDD is one of the largest suppliers to this specialized industry. Tungsten carbide hard-banding and non-standard lengths are available on request.

Drill Pipe

TSC HDD manufactures a full line of drill pipe in nominal sizes from 2 7/8″ to 7 5/8″ in E, X, G and S grades and with a wide range of API and non-standard wall thicknesses. Sour service grades are also available by special request.

The raw material supplied to TSC HDD is manufactured by reputable tube and tool joint suppliers at industry recognized facilities. All of these products are thoroughly inspected upon receipt to verify that they meet TSC HDD specifications. Specially selected steels with stringent cleanliness requirements provide enhanced fracture toughness that translates into greater safety margins for the end user.

Connections

TSC HDD provides pipe with API threaded connections for each of the various sizes. In addition, compatible double shoulder connections are available. This connection uses a standard API thread form with a secondary internal shoulder. It offers significantly improved torque performance over conventional API connections.

Design

The life of the drill string is maximized by designing pipe that is resistant to fatigue. Fatigue stress is primarily concentrated in areas where there is a sudden change in geometry. In drill pipe this is the upset area adjacent to the tool joint weld. It consists of a transition from the thin cross-sectional area of the drill pipe body to the thick cross-sectional area of the tool joint. The longer and smoother the manufacturer can make the upset transition area the better it is for resisting stress concentrations. This is done by making the transition zone between the body of the pipe and the tool joint as smooth and gradual as possible. Using the company’s proprietary forge practices, TSC HDD is able to manufacture an extended internal upset with a shallow run-out angle that blends seamlessly into the pipe body’s internal diameter. This greatly improves the pipe’s performance and helps to ensure it will not fail in this stress prone region. To reduce fatigue even further, TSC HDD also grinds both the internal and external diameters of the assembled pipe adjacent to the weld line.

Tool joint forgings are required to meet or exceed API specifications. Prior to assembly, each tool joint is inspected to guarantee dimensional properties and tested to make sure they provide proper mechanical integrity. Tool joints are normally supplied two inches longer than standard API lengths providing additional re-cut capability and greater service life. Longer lengths can also be supplied by special request.