Subsea pipeline installation is a multi-billion dollar industry. It consists of installing hundreds to thousands of kilometers of submerged pipelines from the shoreline to offshore oil rigs and platforms, as well as onshore processing facilities and natural gas compressor stations.
These pipelines are then buried into trenches that can be several meters deep and several hundred meters wide. The only way to install these pipelines is via horizontal directional drilling (HDD).
This process needs machinery like horizontal directional drilling rig, which is an essential part of the industry. However, not all HDD drill rigs can meet up with the demands of this industry, thus it’s imperative to choose the right one.
What Are The Factors To Consider When Choosing The Right Hdd Rig?
When choosing a HDD drill rig there are three main factors that should be considered such as the water depth, ground conditions and access to the site. The drill rig’s power source is also an important factor in making a decision. The majority of HDD rigs work off diesel engines which put out between 1,000 to 4,500 horsepower .
Another important factor for choosing a HDD drill rig is the number of pipeline installation passes. This is the amount of attempts it takes to get the drilling string into the required depth. A pass involves threading a certain amount of casing onto the drilling string and lowering it to set depth on each attempt before pulling back up and rethreading more casing .
The selection of HDD drill rig is also dependent on the amount of casing that needs to be installed. Casing is the steel piping that lines the outer edge of the trench and can range from 5 to 30 feet in diameter, each section weighing up to 9 tons.
There are many different types of HDD drill rigs on the market today. The two main types being land- or marine-based .
Land-based HDD drill rigs are most typically used in soil, clay and silt conditions where water depths are less than 100 feet. They have multiple sets of pipe storage racks built in so that the pipe can be easily connected and disconnected from the drilling string .
The majority of land-based HDD drill rigs have the capacity to dredge over 100,000 yards a day, which is a great advantage when considering that open cut trenching can take several weeks to complete. There are also different types of water pumps available for land-based HDD drill rigs depending on the water depth and soil conditions .
Marine-based HDD drill rigs are used for projects in nearwater environments as well as areas with very loose soils like sands or gravels, water depths between 1,000 to 5,000 feet and remote locations where transportation is limited.
There are two types of marine-based HDD drill rigs: self-propelled vessels and jack-up barges. A self-propelled vessel is permanently attached to its drilling unit, while a jack-up barge can be moved from one project to the next .
Marine HDD drill rig operators will also use what is called a wiggle stick when digging down into the seabed. The wiggle stick has three different positions; forward, neutral and reverse. When the drill rig is in forward mode it pushes the pipe into the seabed to get past any obstructions, when in neutral position the weight of the load will push it down into place, and in reverse position it pulls back on the pipe to remove any obstructions .
What Contractors Should Know?
Work with a contractor who is well-versed with the industry standards for HDD projects, or hire a firm that specializes in installation of subsea pipelines. Since the entire pipeline installation process has multi-billion dollar implications, choosing the HDD drill rig is not something that can be done lightly.
Subsequently, when choosing an HDD drill rig, contractors need to take into account various considerations that pertain to the industry they work in. The design of the machinery is a good indicator of what applications they will be used for. Making use of a faulty machine can not only waste time and money but may also damage the pipeline being laid out.
The best way to know if a machine is right for the job is to gather as much information as possible as there are various factors that will make one type of HDD drill rig better suited for a specific project than another.
Complexity, environmental conditions and price all need to be considered before making a final choice.
Even though the HDD industry has its own list of requirements, this should not prevent contractors from seeking out other machines that might be suitable for their project and needs. For example, rotary steerable systems are great for rocky terrain and uneven surfaces. This is why many firms consider it as one of the best HDD drill rigs.
All things considered, the best machines are the ones that can accomplish a job with minimum waste of both time and money, so choosing the HDD drill rig requires prudence and caution to make sure all specifications are met.