It has been well documented that there exist rich petroleum and mineral resources in deep (>4500 m) sedimentary formations. Despite the huge costs involved in deep sedimentary basin exploration, thousands of deep wells have been drilled over the past decades worldwide. By 2014, approximately 1600 deep oil and gas fields had been found in deep sedimentary formations. These discoveries have not only proved that there are huge quantities of petroleum resources in deep formations, but also provided rich geological information that enables us to understand much about the properties and phase behaviors of deep geofluids, their chemical reactions with surrounding rock formations, and fluid flow and circulations in deep basins. The pioneering researches on geofluids in deep basins reveal a complete new realm, and much of our previous understanding about the geofluids and their evolution based on shallow sedimentary formations might be changed in the near future. They also allow us to better define the key research directions in the basinal geofluid discipline.

The purpose of this special issue is to collate high-quality research articles as well as review papers on geofluids in deep sedimentary basins. We hope to cover the most recent development on new discoveries, new data, new methodologies, and new understandings on geofluids in deep sedimentary basins and to discuss challenges and opportunities for future resource exploration in deep sedimentary basins.

Potential topics include but are not limited to the following:

• Properties of geofluids in deep sedimentary basins
• Geofluid research methodology for deep basin environments
• Geopressure and geothermal characteristics in deep basins
• Petrology and petrophysics of deeply buried rocks and reservoirs
• Fluid flow and circulation in deep sedimentary basins
• Petroleum generation, migration, and accumulation in deep sedimentary basins
• Worldwide case studies of geofluids in deep sedimentary basins