Not sure where you would find them listed, but best net would be to talk to anyone you know in Oil and Gas. You would most likely be looking for a large Operating Company.
Quick explanation of industry structure
-Upstream: typically everything from in the ground to the wellhead/production facilities also known as E&P (exploration and production)
-Midstream: typically from wellhead/production facilities to terminals/refineries etc
-Downstream: from refineries to distribution/retail/end user
Within upstream, you have 2 major components.
-Operators/E&P Companies: these are the companies that actually own and produce oil and Nat gas assets, Fewer people work for operators in our industry but for security i would guess this is your best bet. Think Exxon, BHP, EOG, Anadarko, Marathon, Conoco etc
-Service companies: majority of upstream jobs are here, these are companies that help operators get oil/gas out of the ground. But I'm not sure they hire a lot of security but I could be wrong. Think Halliburton, Schlumberger, FracTech etc.
These is a very crude (pun intended) explanation of how the industry is structured that you might find useful.