Natural Gas Production From Tight Gas Formations: A Global Perspective

Abstract

Tight gas formations are part of what is usually known as unconventional gas which also includes coal bed methane, shale gas and natural gas hydrates. Tight gas formations as used in this paper refer to sandstone and carbonate reservoirs with in-situ effective permeabilities to gas equal to or smaller than 0.1 md. In petroleum provinces in North America some tight gas reservoirs are found in basincentered or continuous gas accumulations. Others are found in low permeability reservoirs in conventional structural, stratigraphic or combination traps usually referred to as sweet spots. A limited amount of information suggests that tight gas formations are generally found in older rocks in the same petroleum provinces where conventional gas is produced. This observation, supported by various examples and illustrated with a gas resource pyramid, permits using conventional gas formations as a proxy for the presence of tight gas in basins and petroleum provinces throughout the world. A variable shape distribution (VSD) model leads to the conclusion that there is a significant potential endowment in tight gas formations that rivals the endowment from conventional gas accumulations (15,100 tcf). Thus, tight gas formations have potential to provide a significant contribution to global energy demand estimated at approximately 722 quads by 2030. It is recommended to actively pursue research and development of this potential. The economic and technical challenges involved in commercialization of this vast untapped resource are many and overcoming them will depend on a multi-disciplinary approach involving geoscience, engineering and economics. In particular, resource characterization and production technologies will be discussed and areas for future research presented.