Geological features, major discoveries and unconventional petroleum geology in the global petroleum exploration

Large and extra-large oil/gas fields are mainly distributed in Tethys areas, passive margins, foreland thrust belts, and craton basins in the world. Unconventional oil/gas fields are mainly distributed in foreland slopes, basin (depression) centers, craton synclines, and tundra. Since the 21st century, the major exploration discoveries across the globe have been mainly concentrated in the deep water area of passive margins, carbonate rock, lithologic-stratigraphic zone, foreland thrust belt, mature exploration area, new basin and unconventional oil/gas reservoir (field). These major discoveries involve conventional and unconventional oil/gas resources. The conventional oil geology stresses the oil/gas migration and reservoir-forming rules in individual traps; the unconventional oil geology focuses on unconventional resources, reservoir, reservoir-formation and technologies. The geological features, classification program, research content, evaluation method and exploration phase of unconventional oil/gas reservoirs (fields) are different from those of conventional ones. Research should be strengthened on unconventional oil geology to develop unconventional oil geological theories.