Always nice to find out you own something you didn’t know about.
Attached below is the Railroad Commission’s current map of that area with your Section 270 outlined in red. You’ll see five horizontal wells that have been permitted to cross that section, two being drilled from a location at the south end of Section 269 that joins 270 on the north, and three to be drilled from a site in Section 270 but all extending to the bottom of Section 271 that joins 270 on the south. Lot of activity there. I’m guessing the interest you own is already include in one or more of the units that Oxy has formed there.
Those wells are called the Oxy Young wells and there’s been considerable discussion about them in this Reeves County section of the Forum. Here’s a link where you can read those posts.
Before going any further in lease discussions you need to pin down exactly how much mineral interest you and your brother own there. If you haven’t tried already, I’d ask Oxy, or the landman who sent you the lease offer, to provide information on that ownership interest. If you have names of relatives you think you could have inherited that interest from you can search their names in the Reeves County deed records to locate the chain of title to that mineral interest. Here is a link to the deed records where you can do free searches. If you can’t figure out how to get started there come back here with the names you think are logical to search and someone will help you.
Once you’ve determine what you own there is a lot of information on the forum that will help you with basic questions on leasing. Enter the topic you want to search in the looking glass feature at the top of the page next to the block labeled New Topic.