Directional Technologies, Inc. expands international experience with installation of horizontal remediation wells in Australia.
By: Kyle Carlton, PG, Senior Geologist
During the summer of 2017, Directional Technologies, Inc. was provided with the unique opportunity to partner with several Australian and American companies to successfully design and install horizontal remediation wells in Australia. As a technology company with 27 years of horizontal well system experience, Directional Technologies was selected for the team based on our knowledge for designing horizontal well layouts and well screen design engineering expertise.
Background:
Source remediation was necessary at an active manufacturing facility near Sydney in New South Wales. A plume of dissolved volatile organic compounds was previously found to be migrating off-site. Prior to the summer of 2017, remedial measures included a vertical air-sparge/soil vapor extraction remediation system installed on the boundary of the site to prevent further contamination migration. Remediation at the source was the next phase of work, and access to the source area posed significant challenges due to the infrastructure and surface obstructions of the facility. Directional Technologies and horizontal wells were chosen to provide in-situ chemical oxidation (ISCO) of the source zone.
Challenges:
The project posed several significant challenges as the target zones for the horizontal wells were beneath multiple types facility infrastructure and high traffic areas:
- Locating: Both underground and above ground chemical storage tank along with an emulsion processing unit were in-line with the well paths. Each posed different challenges, but all had to be safely accessed and circumvented by Directional Technologies’ field crews to accurately track the drill bit using the walk-over locating system.
- Directional Drilling: The target zones for the horizontal wells were off-set from the actual entry location which required a compound curved bore path leading up to the start of screen.
- Horizontal Drill Rig Setup: Forklift and vehicular traffic essential to facility operations could not be impeded. Therefore, the directional drill rig was staged in a peripheral location to ensure minimal disturbance to vehicle traffic patterns, which lead to the compound curve well paths.
Other items that were unique to this international project included the 17-hour time difference between central standard time and Sydney standard time. Real-time Standard to Metric conversions in the field were vigilantly applied to distances, depths, pipe diameters, pressures, and volumes. Additionally, Australian regulations for health, safety, and environmental waste disposal had to be fully understood and followed.
Solutions: Horizontal Injection Wells
Directional Technologies’ installed the horizontal wells beneath the surface obstructions while avoiding subsurface utilities and the underground storage tanks. The horizontal remediation wells were installed via blind method, meaning exit locations for the wells were not required. Blind horizontal wells further minimized disturbance to facility operations.
Horizontal Well Design and Remediation System Details: The horizontal wells were installed so that the screen sections were at depths of approximately 8 meters (26 feet) below ground surface (bgs). This target depth ensured successful injection below the groundwater table at 4.8 to 5.2 meters (15.7 feet to 17.0 feet) bgs.
Injection Strategy and Results
The three (3) horizontal remediation wells were utilized for injection of a Modified Fenton’s Reagents (MFRS) consisting of a stabilized hydrogen peroxide and chelated ferrous sulphate combination into the saturated zone of the subsurface formation. The remediation system consists of two progressive cavity pumps connected to 34,000 liters (9,000 gallons) tanks capable of injecting tens of thousands of liters of reagent into the subsurface over relatively short periods of time.
Three total injection events were conducted in August 2017, November 2017, and February 2018 for an approximately total of 130,000 gallons injected into the target zone. The injection successfully influenced the groundwater by creating groundwater mounding of 40 centimeters (16 inches) and temperature increases observed at nearby groundwater monitoring wells.
After only 6 months of operation, an estimated 36% of the mass in the target zone has been remediated.
This project received the 2018 Outstanding Innovation Advancing the Land & Groundwater Industry Award from the Australasian Land & Groundwater Association (ALGA) for Australia’s 1st Installation of Horizontal Wells for ISCO.
Directional Technologies, Inc. has 27 years of horizontal remediation well installation experience, with thousands of horizontal remediation wells installed. Whether your next project is Stateside, Down Under, or “Across the Pond”, don’t hesitate to contact us to experience the advantages of horizontal remediation wells.