Changes

Although shale-oil plays with oil stored in open-fractured shale have been pursued for more than 100 yr, organic-rich and low-permeability shales and hybrid shale-oil systems are now being pursued based on knowledge and technologies gained from production of shale-gas resource systems and likely hold the largest untapped oil resource potential. Whereas fractured and hybrid shale-oil systems have the highest productivity to date, organic-rich tight shales are the most difficult to obtain high oil flow rates because of ultra-low permeability, typically high clay and low carbonate contents, and organic richness whereby adsorption plays a role in retention of petroleum.

Although shale-oil plays with oil stored in open-fractured shale have been pursued for more than 100 yr, organic-rich and low-permeability shales and hybrid shale-oil systems are now being pursued based on knowledge and technologies gained from production of shale-gas resource systems and likely hold the largest untapped oil resource potential. Whereas fractured and hybrid shale-oil systems have the highest productivity to date, organic-rich tight shales are the most difficult to obtain high oil flow rates because of ultra-low permeability, typically high clay and low carbonate contents, and organic richness whereby adsorption plays a role in retention of petroleum.

A special, but separate, shale resource system is oil shale. It is preferred to refer to oil shale as a [[kerogen]] resource system or as kerogen oil as it does not contain sufficient amounts of free oil to produce, but must be heated to generate oil from kerogen either in the subsurface or after mining and retorting. This 2d part of chapter 1 will only discuss shale-oil resource systems that have already generated petroleum because of geologic heating processes.

A special, but separate, shale resource system is [[oil shale]]. It is preferred to refer to oil shale as a [[kerogen]] resource system or as kerogen oil as it does not contain sufficient amounts of free oil to produce, but must be heated to generate oil from kerogen either in the subsurface or after mining and retorting. This 2d part of chapter 1 will only discuss shale-oil resource systems that have already generated petroleum because of geologic heating processes.

With the remarkable success in locating and producing shale-gas resource systems, an overabundance of gas has reduced its current economic value and there has been an exploration and development shift toward locating producible shale-oil resource systems. Recent announcements of the oil resource potential of several shale-oil resource systems have substantiated the volume of oil they contain, for example, 5.88253 times 107 m3 (370 million bbl of oil equivalent [BOE]) in the [[Barnett shale play|Barnett Shale]], 1.430886 times 107 m3 (90 million BOE) in the Bakken Formation core area, and 1.430886 times 108 m3 (900 million BOE) in the Eagle Ford Shale.<ref name=EOGResources2010 /> However, the keys to unlocking these high volumes of oil are not fully understood or developed to date.

With the remarkable success in locating and producing shale-gas resource systems, an overabundance of gas has reduced its current economic value and there has been an exploration and development shift toward locating producible shale-oil resource systems. Recent announcements of the oil resource potential of several shale-oil resource systems have substantiated the volume of oil they contain, for example, 5.88253 times 107 m3 (370 million bbl of oil equivalent [BOE]) in the [[Barnett shale play|Barnett Shale]], 1.430886 times 107 m3 (90 million BOE) in the Bakken Formation core area, and 1.430886 times 108 m3 (900 million BOE) in the Eagle Ford Shale.<ref name=EOGResources2010 /> However, the keys to unlocking these high volumes of oil are not fully understood or developed to date.