Given your background, I think the best approach, if possible, is to try to get a referral to the specific practice (O&G in your situation). If your resume goes directly to the Principal / Partner and they are interesed to interview you, they would ask the HR to set up the interviews. This would give you a better chance than going through the typcial application route.
8 years experence is still okay an not uncommon for indutry hires. You might start with a (senior) consultant role first if you don't have much experience managing projects. You just need to be comfortable with the fact that many of your peers would be a few years younger than you. This is really personal / individual, so only you can decide for yourself whether you'd be okay or not.
Given your background, I think the best approach, if possible, is to try to get a referral to the specific practice (O&G in your situation). If your resume goes directly to the Principal / Partner and they are interesed to interview you, they would ask the HR to set up the interviews. This would give you a better chance than going through the typcial application route.
8 years experence is still okay an not uncommon for indutry hires. You might start with a (senior) consultant role first if you don't have much experience managing projects. You just need to be comfortable with the fact that many of your peers would be a few years younger than you. This is really personal / individual, so only you can decide for yourself whether you'd be okay or not.