I thought I will chip in since I had just a somewhat similar experience:
- Moved from the #1 MNC in my field (based on revenues) to somewhere #30+ down the line (new employer role is a more of a niche player)
- Previous role had 3 direct reports. New role individual contributor,.
- New employer was bleeding for last 2 years when I was talking to them
- Increase in salary was about 18%, not factoring bonuses (for my industry bonus is quite quite heng suay but previous employer was consistently paying out about 2 months since I was there)

My eventual reasons to move:
1. Change in product of which new employer is top 2-3 in that space (like I said niche player). so an opportunity to expand at least horizontally and hopefully be more employable.
2. Financially, I figured I will at worse break-even if there are no bonuses. Also, the company was also seem to be turning the corner based on publicly available information.
3. There's also some shortage in the market at the moment for what I do so I figure I could go elsewhere if it really goes tits up at the new employer.

For the OP:
- My advice is that you really need to think about why this role is attractive to you since your financial upside somewhat limited like in my case.
- You didn't say whether you are currently from the O&G industry but if you are not, I will be very cautious since the GM does not seem to indicate if there is a plan for the business to survive the current downturn. (I am not from the industry so I can't judge what can be done but companies should at least have a plan.)
- What is your risk-mitigation plan if this goes bad in 12 months? Can you find another role somewhere else relatively easily or even go back to your current company? Alternatively, do you think the new role will make you even more employable in the future?