Radial Horizontal Well System Targets Specific LNAPL Viscosities in Multiple Product Plume

Directional Technologies, Inc. designed and installed a radial horizontal well system of six blind horizontal wells, with over 200 feet total of horizontal screen, in less than two weeks at site with a multi-product plume while the site’s shipping department activities continued – business as usual. 

A multiple product plume under an active paint facility includes No. 6 Oil, No. 4 Oil, mineral spirits and lube oil. Contrasting viscosities can cause preferential flow, complicating LNAPL recovery efforts that are required by the state environmental agency. The plume is under a building, and installation of vertical wells would be costly, not only because of the large number of concrete pad penetrations and conveyance pipe installation but also because it would interrupt operations of the active business. Horizontal well drilling was chosen and six horizontal wells were installed instead, radiating from a central directional drilling location in the shipping department. The central directional drilling location kept the footprint of drilling operations to a minimum, and the six horizontal wells were installed as blind wells, like spokes of a wheel. All six wellbores were drilled through a 20-by-10-foot, decommissioned underground storage tank beneath the central drilling location, and the wellheads were completed within this tank, conveniently placing surface equipment for all six wells, including piping and oil-water separation, inside the tank. Since the wells were drilled blind, there was no need to exit at ground surface at the far end of the wells. Instead, each well terminated in the target zone at the distal endpoint of the well screen, eliminating unnecessary horizontal well drilling and surface construction.

The wells were completed with 6-inch, schedule 80 PVC pipe, with conventional slots appropriate for LNAPL recovery. Each well was equipped with a down-hole pump that can easily be moved to the optimal location for efficient LNAPL recovery. The ability to adjust the pump location along the horizontal screen allows continuous optimization of recovery in response to changing positions of the multiple LNAPL phases with contrasting viscosities. This flexibility avoids or greatly delays the need for installing new well points that are often required in vertical LNAPL recovery well fields as the LNAPL distribution changes.

Directional Technologies, Inc. installed the six horizontal wells, with over 200 feet total of horizontal screen, in less than two weeks. Forklifts moved, unimpeded, during those two weeks, allowing the shipping department to continue business as usual. Operation and maintenance of the LNAPL recovery system will likewise not impede operations at the paint facility. The centralized location of surface equipment in the underground tank at the center of the “wheel” of horizontal recovery wells will cut the time required for O&M activities to a fraction of what would have been required for an equivalent vertical well LNAPL recovery system dispersed within the building.