The process from drilling to final product is a long trip. Start by reading ISA 5.1 for instruments or the P&ID legend sheet. I know, sometimes it is hard to find a P&ID legend sheet. All projects should have one. Many don't. This approach gets the instrumentation symbology out of the way.
It sounds as though you have familiarity with the mechanical machinery such as pumps and compressors. More on equipment if not. If you do not know devices such as pressure differentia (flow) and pressure transmitters visually, consider visiting a skid fabricator, plant, job site or instrument representative warehouse for that purpose. This applies more easily for valves. Many warehouses are available to get a grasp of ball or gate valves, flange classes, etc. If pipe sizes are not clear (NPS 1/2 has no relationship to 1/2-inch inside or outside) then any piping warehouse or even a hardware store can help.
I am least able to address drilling. However, API publishes some neat training material that is great for this end of the business. Exploration and drilling are known as upstream -- way up stream. Gas and oil gathering, separation, and treating in an oil-patch setting are still upstream. We all define upstream and downstream differently. Downstream includes gas processing, refining and all of the gas/liquid petro-chemical processes. Plastic pellots are way down stream.