WorldWide Drilling Resource

19 WorldWide Drilling Resource ® JUNE 2013 From Slant to Horizontal: The Evolution of HDD Adapted from Information Provided by NaturalGas.org Directional drilling has been around for decades, with the first patent issued to Robert E. Lee in 1891. Actively used today, the process originally known as “slant drilling” has evolved over the years thanks to modern day technology. Defined as the process of drilling a curved well to reach a target not directly beneath the rig, directional drilling has been used since the beginning of the 20th century. Slant drilling, also known as traditional directional drilling is a proce- dure where a contractor drills the well at a vertical angle, instead of straight into the earth. With this type of drilling, it can take up to 2000 feet for the well to finally bend into the proper angle. Current tech- nology allows directional operators to drill not only at an angle, but to turn the drill at a 90-degree angle in a very short dis- tance. This process is modern day HDD (horizontal directional drilling). With the evolvement of directional drilling, also came the advancement of horizontal wells. Today, drilling profes- sionals can drill up to three different types of horizontal gas wells: short-, medium-, and long-radius. Short-radius wells are perfect for recovering natural gas or oil from an already developed well. These wells are the ‘sharpest turning’ with curving at 25 to 45 feet. They can easily be dug outward from an already vertically drilled well, and can be used to drill into nonconventional formations including coalbed methane. To reach a target a long distance from the drill site or when drilling in reser- voirs spaced apart underground, medium- radius wells are typically used. These curve between 300 to 700 feet with the horizontal portion of the well measuring up to 3500 feet, allowing access to numer- ous deposits at the same time. Long-radius wells are primarily used to retrieve gas and oil offshore where it is economical to drill outward from a sin- gle platform. It curves between 1000 to 4500 feet and extends the greatest dis- tance horizontally. Several technological advancements were crucial for traditional slant drilling to become the modern horizontal drilling, including steerable downhole motors and borehole telemetry (measurement while drilling) technology. This important inno- vation will likely continue to advance as Graphic courtesy of United States Geological Survey. new applications begin to take advan- tage of this developing technology. The August issue deadlines are: Space Reservation - June 25 th . Ad Copy - Display & Classified - July 1 st .