Horizontal directional drilling (HDD), also known as cross-well borehole drilling, is a subset of directional drilling that has the same goal as its vertical (vertical isomer) counterpart; to reach target zones of interest across an existing wellbore.
A hdd drilling machine is used frequently in the oil, gas, and geothermal industries to drill wells that deviate from the vertical plane. This process can be used to drill horizontal, slanted, and diagonal wells. The goal is to drill an intersecting wellbore that can be used for multiple purposes and easier and more efficient production.
An additional benefit of horizontal directional drilling is the ability to bore a well in areas that would be deemed too difficult or expensive to drill using traditional methods. For example, drilling a well through a mountain or into an area with highly congested highways would be nearly impossible to drill with conventional methods.
There is also the ability to drill through reservoirs that are considered “un-drillable” using traditional methods. An example of this would be an aquifer that lies below a body of water, a reservoir that lies below a body of highly dense salt, or a reservoir under a river bed.
The capability of drilling horizontal wells presents several challenges for the directional driller. There is the common challenge of keeping the drill bit on path during drilling. Another issue is keeping the well on path while also maintaining a constant slope while drilling. There is also the challenge of keeping accurate records while drilling in an unfamiliar lateral direction and keeping accurate records on the target depths of each section.
Recent advances in directional drilling technology have helped to overcome the challenges of horizontal directional drilling. Specifically, advanced directional sensors combined with advanced telemetry systems provide the ability to maintain proper slope and direction while also having the ability to correct deviations in real-time.
Cross-well drilling is an example of horizontal directional drilling
An example of a cross-well directional well would be a Driller’s, Cross Drilling. This type of drilling has the potential to earn two production zones at the same time. One wellbore is drilled that can be produced both horizontally and vertically without significantly affecting production rates.
Another type of cross-well directional drilling is called a Sidewall Drilling
Much of the success in drilling a horizontal well depends on using a grapnel to keep the drill bit on track. This is considered difficult because when using traditional techniques for directional drilling, there is little or no feedback from the actual drill bit.
Advancements in directional sensors, combined with telemetry systems, provide the ability to monitor the position of the drill bit while drilling and make necessary corrections to stay on track. These advancements have helped to overcome the challenges of horizontal directional drilling while also increasing drilling efficiency.
Regardless of the type of drilling, HDD is the way to go for many
A major advantage of the HDD is the time and cost savings. In addition, the HDD is an excellent alternative for many situations. An excellent example of this would be for wells that are considered un-drillable or drilling in areas where access is extremely difficult or impossible.
The choice is clear for many; HDD is the way to go for horizontal directional drilling. The benefits and increased efficiency far outweigh any disadvantages and provide an overall increase in production.