Ann: Hydrocarbon gas recovered & evaluation program forward plan, page-433

It depends what mechanism is causing the coals to wash out. Patchawarra coals are very cleaty and increasing the mud weight was usually the fix when they caused problems with logging tools

From memory in M1 the mechanism causing hole deterioration was thought to be the mud weight being too high and close to fracture gradient. Cracks were being induced in the wellbore and made worse by being banged around by the drill string. If the same mechanism is going on in M2 then the coals are probably undergoing fracturing as well...theyd most likely frack before the shales and sands.

A vertical well will help as tools wont be as prone to lying on low side of the hole and you have a better chance of getting past any ledges.