It was client demand that led DTD to develop its patent-pending technique for blind well installation. Though these wells were difficult to install, the requests for long blind horizontal remediation wells continued to pile up. The typical situation was (and still is) that a long plume either extends beneath an inaccessible area, or perhaps has migrated from the client’s property. These, and many other scenarios can make it difficult to install a double-ended horizontal well.
Blind wells, the alternative to a double-ended well, have always been a challenge and in many ground conditions their installation has been difficult or impossible. This is because during a traditional blind installation, the bore must stay open for a period while the drill rods are removed and the well materials installed. Any bore collapse during this time could prevent the successful installation. If flowing sands were present, or any non-cohesive soils, the blind installation could not be completed.
The development of DTD’s proprietary technique began several years ago and was first successfully implemented at Edwards Air Force Base during 2011. During this project DTD installed blind wells up to 1,380 feet long (for permanganate injection and air sparging) in a coarse sand and gravel. We have since installed four blind wells at an Air National Guard facility, where the remediation wells were installed through construction debris including concrete and rebar. At both sites the wells were 3-inches in diameter.
Now DTD has deployed a larger set of the same patent-pending tooling that allows us to install up to 4-inch diameter well materials. This was recently used to install the first of five blind wells at at a southern US Air Force Base.
At this particular installation, the blind remediation wells are being used to air sparge a jet fuel plume that extends beneath both taxiways and the main runway. The wells being installed vary from 1,200 to 1,450 feet in length. Blind wells of this length, in the flowing sand found on site, would be nearly impossible to install using conventional methods – but the well materials slid into place with no difficulty using the new DTD technology.