I'm on the onshore side.
Learn process flow. Multiple ways to skin a cat but here's a general diagram we share internally with non facilities folk.
Ask if you can review old project AFEs to get an idea on cost estimating. Get familiar with P&IDs. If there are opportunities to attend Process Hazard Analysis (PHA) or HAZOP study try and attend. Learn about safety systems and how your facilities shut down based on different scenarios. Ask if there are any opportunities in to learn IHS Piper (pipeline modeling) or ProMax. We use ProMaX alot to optimize process flow and mitigate hyrdates. Promax has free online training. Ask your direct boss if you can attend one of these if it fits with the schedule. Online courses here:
https://www.bre.com/Training-Sessions.aspxI'd recommend BRE 101 Oil and Gas, BRE 102 Upstream Facilities, BRE 251 Pipelines, BRE 261Equipment Rating and Sizing, and BRE 203 Hydrate Prevention.
Know the differences and applications between back pressure valves and pressure regulating valves. You'll learn operator competency is an issue. Read this
https://kimray.com/training/back-pressure-regulator-vs-pressure-reducing-regulator-whats-difference Try and ask as many questions you can about design, scheduling projects, cost estimating, risk analysis and process optimization.