In Alberta, wells designated for abandonment must be tested to determine if there is any flow of gas through the surface casing vent. Flow rates of more than one bubble in 10 minutes must be repaired prior to abandonment.
The test must be repeated following the repair and abandonment operations to confirm that there is no gas leak prior to cutting and capping the well.
It is difficult to measure these low flow rates of gas accurately as even small amounts of back pressure on the casing can suppress the gas flow during the test and heating or cooling of the wellhead due to changing weather conditions or exposure to the sun could affect the measured flow rate.
Inaccurate measurements could lead to unnecessary operations to repair leaks that do not exist or to result in wells being abandoned with persistent low rate leaks.
How we Help
C-FER adapted a system used to measure leakage through premium connections in laboratory qualification tests to be installed on wellheads prior to abandonment.
The system monitors low rate gas flows by counting individual bubbles as they pass through a column of liquid. The well can be monitored over several hours or days to confirm the absence of gas leaks or to characterize the leak rate over time.
This information will help to ensure that even very small or intermittent flows of gas are detected and subsequently repaired and should greatly reduce the number of false positive indication of gas leaks, preventing unnecessary repair operations.