Look guys, if CAT was caused by methane 'bubbles' in the atmosphere, then there would be so much methane up thar that the ozone layer would be history and we would all be coughing and spluttering. CAT comes from airflow. Aeroplanes would be registering higher exhaust temperatures if they ran into one of these 'methane clouds', the burning characteristics of the engines would change. It is a hypothesis that does not work out.
Oil platforms are placed over oil and gas fields and pricking the surface. Not surprisingly they might get more than they bargained for. But if all the 'proof' you can come up with is this, then sorry, but it doesn't happen. Theoretically a ship can sink if the SG of the water it's in is reduced by numerous gas bubbles, but watch my lips, it does not happen! Because you theorise it may does not mean it does. Bringing up bad examples (Cameroon) does not provide 'proof'. Spend your energies on something constructive! This is totally unproven nonsense.