Horizontal environmental well designs have advanced to include installation of multiple well screens in single boreholes, allowing different treatment options in different locations along the same borehole path. Designs with complex compound curves have been successfully installed using gyroscopic steering tools (GST). GSTs also enable safe installation at sites with numerous underground utilities.
Walkover locating techniques with new electronic systems (DCI F5) and improved extended range sondes are now in use. This technology vastly increases the depth of installation for horizontal wells.
Biopolymer drilling fluids have proven effective at sites with difficult drilling conditions. Biopolymers break down, minimizing formation damage and improving contact of the well screens with the surrounding formation. Wells 1800 feet long (580 m) have been installed in loose or heaving sands.
Long blind wells can be installed inside large-diameter drill rods. Lengths of successfully installed horizontal environmental wells have been extended significantly. In 2008, a 1,000-foot long (322 m) well would be considered "long." Now wells 2000 feet long (644 m) are routinely installed.
Steerable air hammers have been used to install well materials in challenging conditions, such as gravel, cobbles and bedrock. Steerable air hammers allow drillers to drill without drilling mud in certain conditions, resulting in wells with limited formation damage and that are ideally suited for extraction technologies.
Horizontal wells have been integrated into new remedial designs that are more efficient and sustainable, e.g., removal of volatile vapors from the subsurface, incineration of the vapors, and reinjection of waste heat to warm air in the subsurface.
