Geophysical methods are essential for logging and seismic exploration, and recently electromagnetic methods have also been used in exploration and production. Most universities do not offer specific courses in petroleum geology/geophysics and only a few have a Masters or Ph.D. programmes in this field. Oil companies therefore recruit many geologists with little training in these subjects. In this book we have tried to give a basic introduction to disciplines relevant to petroleum exploration and we have also included some aspects of petroleum production. Consequently, geophysical exploration is of importance not only to geophysicists but also to geologists, physicists, engineers and archaeologists. The book covers the physical principles, methodology, interpretational procedures and fields of application of the various survey methods.