Horizontal wells continue to advance in remediation industry,
Horizontal well technology, originally developed for use in the oil and gas industry, has continued to advance and be adapted for environmental remediation applications across all industries. The technology is a proven, reliable tool with unique advantages that can significantly improve the effectiveness of remediation projects.
Horizontal wells (wells that are turned horizontally at depth, providing access to unconventional sources of reserves) have been used in petroleum exploration and recovery since the early 1930s, and for environmental investigation and remediation beginning in the late 1980s. Yet the adoption of horizontal wells by the remedial business has been relatively slow. This is likely because the technology is perceived by many as rarely employed, expensive, and fraught with implementation challenges.
In reality, the technology has advanced significantly over the past two decades and is continuing to improve. For example, one drilling company recently developed a tool that has made the installation of “blind” wells (wells with only one entrance) in unconsolidated materials less problematic, thereby reducing the footprint on the ground surface (by eliminating the second access point associated with “continuous” wells) and the length of drilling.
What are the advantages of horizontal wells for remediation?
Horizontal wells can be used for almost any remedial application, including soil vapor extraction, groundwater/leachate extraction, recovery of non-aqueous phase liquids, bioventing, air sparging, bio-sparging, and other injections to promote in situ degradation. From an environmental perspective, the advantage of using horizontal wells to reach under areas, such as landfills and urban areas, including buildings and infrastructure (railways, streets, runways, etc.) is clear, and despite the higher per-foot cost, the use of horizontal wells can often offer significant savings over vertical wells.
Despite the higher per-foot cost, the use of horizontal wells can offer significant savings over vertical wells.
Other advantages include:
- Improved targeting of contaminated media: Most plumes are elongated, and barrier technologies are typically linear. Why install multiple vertical wells when a single horizontal well can cover the same area?
- Minimization of above- and below-ground infrastructure: Running pipes, conduits, and wires to multiple vertical wells is expensive and can be disruptive to site operations. The use of horizontal wells can significantly reduce the amount of surface infrastructure and related expense.
- Improved remediation efficiency: Horizontal wells can be constructed with much longer screen lengths within the zone of contamination, thereby maximizing flow through the contaminated zone and improving contaminant removal, amendment delivery, or both.
While horizontal wells offer many advantages, there are also design and implementation challenges, so support from an experienced and knowledgeable consultant and drilling company is important. OBG has evaluated the potential use of horizontal wells at many sites over the past two decades, and has successfully designed, installed, and used horizontal wells to achieve the remediation objectives of clients, including for Fortune 500 companies. Recent and continued improvements in the technology should lead to many more horizontal well installations.
OBG experts present to the U.S. Army Corps of Engineers
Last month, environmental experts from OBG talked about using horizontal wells to achieve remediation goals with the U.S. Army Corps of Engineers' Philadelphia District during a lunch & learn event.
“Horizontal wells are a great, cool technology that many of us have not used.” – U.S. Army Corps of Engineers' Philadelphia District
OBG, with longtime partner Directed Technologies Drilling (DTD), discussed a history of the technology, as well as types, applications, advantages, and challenges.
About Michael Hall: Michael Hall, PG is a Division Manager at OBG and expert in site investigation and remediation. With more than 27 years of experience, Mr. Hall has managed a wide range of environmental programs involving the integration of technical disciplines and significant regulatory interpretation and negotiation. He has managed large and complex site investigation and remediation programs under RCRA, CERCLA, and a variety of state cleanup programs, and developed innovative investigations that have provided rapid, cost-effective site characterization. An author of nearly a dozen technical papers and publications, Mr. Hall also has extensive experience with facility closure, repurposing and redevelopment, environmental compliance and permitting, and wetlands delineation and mitigation.
About Ralph Morse: Ralph Morse, CPG is a Technical Manager at OBG and expert in site investigation and remediation. With more than 27 years of experience, Mr. Morse has managed a wide range of environmental programs for Fortune 500 industries and municipal, state, and federal agencies involving contaminants such as organic solvents, heavy metals, PCBs, pesticides, and semi-volatile organic compounds. He has specific expertise in complex hydrologic and chemically complex site investigations and has received specialized training in the fields of fractured bedrock and DNAPL investigations and remediation. Mr. Morse has co-authored several technical papers and publications, including topics on hydraulic monitoring, bioremediation, and innovative site investigation technologies.