Using fault tree analysis in the Al-Ahmadi town gas leak incidents

The gas leak incidents that occurred in Al-Ahmadi, Kuwait, were considered to be unprecedented phenomena worldwide. Three gas explosions occurred between January 2010 and November 2010: two occurred at different houses that were connected to the Kuwait Oil Company natural gas network in north Al-Ahmadi, and one occurred at a house in south Al-Ahmadi that was not connected to the network. These explosion incidents triggered an immediate investigation. The fault tree analysis was used to identify the type and the source of the leaking gas and to determine how the leaking gas reached the surface. Four different source hypotheses were investigated: leaks from the natural gas network, leaks from the sewer network, leaks from wells and boreholes in and around the town of Al-Ahmadi, and leaks from underground geological formations. The study concluded that the leaking gas in the Al-Ahmadi incidents was natural gas and of geological origin. The natural gas gradually migrated from deep hydrocarbon reservoirs upwards through cap-rock fractures. The gas collected in the Dammam formation and soil near the surface and then leaked into the air. The analysis and the results of this investigation can serve as a useful reference if any similar gas leak incidents happen elsewhere.