NAPENews Magazine September 2022 Edition

Possible location of Caritas
University Well Bore
(A er Onuoha and Dim, 2017)
Conceptual Depositional Model/Schematic Cross-section
MITIGATION: Short-term
Short term (3 days to 1 Week):
Construction of a temporarily gas diverter, with a shut-in valve
leading to a gas-lift hose.
Once shut-in only for seconds, the ame will go out without oxygen,
then the valve is immediately opened before gas build-up, then
vented or tapped by mobile gas tankers. This can be constructed in
Enugu
Note that the increasing height of gas ow (as would be simulated
in a well test, suggest increased downhole connectivity /
overpressure and relatively major source)
MITIGATION: Middle-term
Middle-term (2 Week to 1 month):
If the situation does not abate after 1 Week
Quick Shallow Seismic acquisition and Processing (approximately 1000m depth)
extending further away to look ahead laterally and vertically, to verify the structure and
source of leak, which is possibly: Shallow Gas Pocket, Fractured/Coal Seam Methane,
or Reservoir Gas.
The type of gas (most likely methane) was not ascertained before the ame, and may
be ascertained after ame is controlled using the diverter.
Note that the increasing radius of ow gives an inference in the nature of the upper
layer, suggesting weak upper cover and forced shut-in may lead to more problems.
Measures currently being used, such as re service water hose, sand ll, etc., will not
extinguish the re.
Disclaimer: This is a quick look based on notes taken at site and reported as an initial mitigation proposal in the emergency.
Orientations, azimuth and dips were estimated for situating an offset relief well, and benchmarks used.
NAPENEWS AUG/SEPT 2022 16