Devon Canada Sahtu Gravity Survey 2007
Principal Investigator: Millman, Peter M (5)
Licence Number: 14247
Organization: Devon Canada Corporation
Licenced Year(s): 2007 2006
Issued: Sep 14, 2007
Project Team: (Field Operation Manager, Excel Geophysics), (Technician 1 , Excel Geophysics), (Technician 2, Excel Geophysics), (Helicopter Pilot 1, Sahtu Helicopters), (Helicopter Pilot 2, Sahtu Helicopters), (Wildlife Monitor, Local Community), (Gravity Meter Operator 1, Excel Geophysics),

Objective(s): The objective of this project is to identify geophysical anomolies that will warrant additions to exploration activity (seismic surveys).

Project Description: The objective of this project is to identify geophysical anomolies that will warrant additions to exploration activity (seismic surveys).

Three helicopters will be required for this project. Two Hughes 500’s will be used as longline helicopters to collect gravity data. The Hughes 500 is ideal for this longline operation as the helicopter is small and maneuverable. The third support helicopter will be used for operations such as GPS base set-up and slinging fuel to remote fuel caches. This helicopter will be either a Bell 205. Each helicopter will be equipped with a survival kit, FM/UHF/VHF radios, and navigation equipment.

The survey area covers a total area of 5,436 km². The program will require 1,432 gravity stations (data points) at a spacing of approximately 2 km. An average production rate of 80 stations per day has been anticipated. With reasonable operating conditions the project will be completed in approximately three weeks.

This survey will be conducted from the air using helicopters. The project team will mobilize daily from Deline. Using the support helicopter a network of three to five GPS base stations will be set in optimum locations around each day’s survey area. The LaCoste & Romberg remote reading gravity meter will be used to acquire the data and will be suspended about 50 m below a helicopter. The gravity meter weighs approximately 45 kg (100 lbs).
The location of the gravity stations are preloaded into the helicopter navigation system. The pilots and operators look for the best location to set the meter down within 200 m of the station. If the location cannot be obtained due to terrain constraints the location will be altered. While the helicopter hovers the gravity meter is gently lowered to the ground and read remotely by an operator in the helicopter. Natural clearings in forested areas of only a few meters in diameter are required for the meter to be placed on the ground. This process can be used in very rough terrain and has been used by Devon for extensive gravity programs during the fall of 2006 and 2007 in the Sahtu Settlement Area, and in the Southeast Yukon and Southwest NWT during the fall of 2003. Similar equipment will be used on the proposed 2007 project.

Once the meter is on the ground a reading can be acquired in approximately 5 minutes. After the reading is complete the helicopter lifts the meter and moves on to the next station approximately 2 km away. This operation does not require any personnel to be on the ground at the data points.

Remote fuel caches of Jet A fuel (205 L drums) will be required in the survey area. Fuel cache size will typically be 10 drums (2,050 L) and will be managed to ensure they never exceed 18 drums (3,690 L). The fuel caches will be established in an appropriate location using the support helicopter. The fuel caches are set up one to two days prior to working in the area and empty barrels are returned within 72 hours. A daily record will be kept of how many barrels are at each site and each site will be inspected to ensure no barrels are left. The precise location of each fuel cache will be recorded and photographed and the locations provided to the Sahtu Land and Water Board in compliance with Section 7 of the Mackenzie Valley Land Use Regulations.

Results will be communicated in a written summary of project activities.

Fieldwork will be conducted from September 14 to October 12, 2007 near the communities of Norman Wells, Tulita and Deline and range as follows:Latitude 64.9 N to 66.2 N Long 124.2 W to 126 W.