Mining Publication: Methane Content of Gulf Coast Domal Rock Salt

Large-scale methane releases in domal salt mines have resulted in ignitions and mine fatalities as recently as 1979. Several past studies have implied that hazardous methane occurrences in U.S. salt domes are distributed neither uniformly nor randomly, but are geologically controlled and potentially predictable. A first step by the Bureau of Mines in addressing the problem of methane in domal salt mines required development of a new test to determine volumes of gases in solid salt samples. This report considers the results achieved when 80 domal salt samples were tested for gas content by dissolution in a controlled atmosphere chamber. Criteria were organized to delineate salt types based on geological occurrence. The presence of higher hydrocarbons was most common in samples containing larger quantities of methane. The presence of higher hydrocarbons appears to be useful in detecting methane hazards where some methane may be lost before gas content testing. An exploratory rotary and/or core drilling program, dissolution testing for gas content, and up-to-date geologic mine mapping could allow a mine operator to assess methane hazards in domal salt.