This is the first book I purchased when finding out about the upstream oil industry.
It is well written, not too technical yet introduces the industry from the formation of hydrocabons through to exploration, drilling and production in a logical structured manner.
Diagrams are clear, text is concise, and the glossary is particularly useful for a newcomer.
I cannot recommend it highly enough. Skim read it first to get the feeling of the upstream environment, then read thoroughly for an excellent grounding. There's a lot of material, so I found it useful to insert little bookmarks at the particularly useful points I am pursuing.