petrowiki.org
http://petrowiki.org/PetroWiki

PetroWiki was created from the seven volume etroleum Engineering Handbook (PEH) published by the Society of Petroleum Engineers (SPE). PetroWiki preserves the PEH content in unaltered form (page names that start with PEH:), while allowing SPE's membership to update and expand content from the published version. Pages that do not have PEH: at the beginning may have started with content from the PEH, but have been modified over time by contributors to the wiki.