There really is no question here. If the oil company has purchased the land they own it. Since the ranchers have been operating under permits in the past they understand they don't own it. It is not clear to my why there can't be an amicable arrangement. The oil operation, I'm assuming it's a fracking operation, only takes up a few acres. Fence it off and lease the rest. Work a deal with the ranchers to do the fence.

This shouldn't be hard but then again, I almost forgot, there are lawyers involved now.

Never mind.