But, what about the other end of the scale – relatively short wells that need to be installed in constrained sites? There are many small sites where a small rig can be used to install short horizontal wells cost effectively, thereby bringing the advantages of minimal surface disturbance and maximizing treatment.
In December 2015, DTD completed just such a project at an east coast Department of Defense Air Station. Two wells, each less than 170 feet in length, were installed to remedy historical fuel, oil and solvent contaminated groundwater. HDD allowed placement of over 200 feet of In-Situ Chemical Oxidation (ISCO) injection screen in direct communication with the contaminant zone beneath the tarmac where maintenance and flight operations take place.
The drill rig selected for this project was one of the smallest in DTD’s inventory – a Vermeer 10×15 Navigator. A rubber track-mounted rig with a length of only a little over 15 feet, the rig is supplied with drilling fluid from an attached 50-gal single-pass mud tank. The rig is easily portable, very maneuverable, and may be tucked into a small corner of a busy site. Despite its relatively diminutive size, the rig is capable of installing wells to 200 feet or more in favorable drilling conditions.
In use, the drill is set up behind a small entry pit, excavated to contain the return drilling mud and cuttings generated as the boring is advanced. The mud is usually conveyed to a nearby rolloff container by a pump and hoses. However at this Air Station, a rolloff could not be placed nearby due to space constraints, and the drilling site being on the flight line.
To adapt to this requirement, DTD worked with the consultant to place a rolloff at an acceptable location, then used a small, low-profile vacuum trailer to periodically remove accumulated drilling fluid and transfer it to the rolloff for longer-term containment while the project progressed. Later, the fluid would be characterized and transported from the site. The project proceeded swiftly, with both wells successfully installed within four days of mobilization to the site.
Large projects or small, horizontal directional drilling provides innovative ways to enable treatment at a variety of site categories and situations. For more information, contact DTD.