Book excerpt: Used by corporate training departments and colleges worldwide, this is the most complete upstream guide available. Contents: The nature of gas and oil The Earth's crust - where we find time Deformation of sedimentary rocks Sandstone reservoir rocks Carbonate reservoir rocks Sedimentary rock distribution Mapping Ocean environment and plate tectonics Source rocks, generation, migration, and accumilation of petroleum Petroleum traps Petroleum exploration - geological and geochemical Petroleum exploration - geophysical Drilling preliminaries Drilling a well - the mechanics Drilling problems Drilling techniques Evaluating a well Completing a well Surface treatment and storage Offshore drilling and production Workover Reservoir mechanics Petroleum production Reserves Improved oil recovery.