We all use Schlumberger's handy glossary to look sh*t up, so why have a fatty reference book?
It's an A to Z reference of every literally every slang term, equipment, process, tool and beyond that is relevant to the oil patch. Frankly, even with the power of google, you're not going to be able to track down archaic industry terminology like "moose pasture" (crappy lease acreage). I cannot overemphasize how comprehensive this book is.
Industry terminology varies alot by region, not to mention country to country. If you've ever found yourself trying to sort out terminology, whether for writing a paper, procurement or whatever else engineering minutia you got handed, this book will be very helpful. It's also very nicely illustrated, many excellent diagrams are included to visually explain some of the terms. Especially for equipment, this resource is invaluable. It has an entry for everything: adamantine drill bit, padeye, hydra hook, over shot grab, gumbo buster et al.
If you're a young engineer, this book will make you seem much more smarter and experienced that you really are because you know the difference between a guide shoe and float shoe.