Figure 1.1: Petroleum exploration is a very old activity. Every petroleum-bearing basin in the world has numerous oil seeps where oil leaks up to the surface. From the time of Noah, pitch (the black glue-like substance left behind when coal tar is heated) has been used to make boats waterproof. Early uses of oil also included medication and warfare. People once believed that oil collected in large underground pools of liquid; all we needed to do was to find the pool and tap into it. Nothing could be further from the truth. Hydrocarbons are found in the pores of the reservoir rock, usually sandstones or coarse-grained limestones. Illustration by Inge Grødum, made for Geco around 1980, showing the Viking ‘Leiv’ investigating oil rock.
