Tuesday, October 23, 2007

The Golden Zone

A new report titled Simplifying oil and gas exploration confidently claims "The Golden Zone is about to become a key concept in the petroleum and gas industry." The report details the theory developed over a period of ten years based on a database covering 120,000 productive oil fields. The report is the effort of researchers in Stavanger, Norway - former senior researcher, now dean, Per Arne Bjørkum at the Faculty of Technology and Science at the University of Stavanger, and the researchers Paul Nadeau and Olav Walderhaug at Statoil. That project has determined that 90% of all oil and gas deposits on earth occur in the so-called Golden Zone, a zone in the earth's crust where temperatures are in the range 60-120C.[1]

The depth of this zone varies considerably from one location to another around the world. In some locations this is at depths of 1-2km. These are called warm reservoirs. In cold reservoirs the golden zone is at depths of 4-8km. The differing depths are largely a function of historic plate tectonic activity, cold reservoirs being closely associated with subduction zones. Warm reservoirs are most likely to occur in conjunction with, but not exclusive to, tectonic spreading zones such as rift valleys and sub-oceanic spreading ridges like the mid-Atlantic ridge.[7]

The temperature zone associated with the Golden Zone occurs commonly throughout the world. This does not, however, mean that all parts of the Golden Zone will contain oil and natural gas deposits. It just means there is a greater probability which should reduce the cost and risk associated with oil and gas exploration, especially for deep water reserves. Capitalizing on this theory and reducing exploration costs, however, will require the development of new and improved technology for sensing and measuring the geothermal gradient (the rate of increase in temperature per unit depth in the earth).[5]

This new theory does not preclude the discovery of oil or natural gas in zones where the temperature is outside the 60-120C range. Oil does occur in lower temperature zones but this oil is generally heavier and of poorer quality. At the moment there is not a great deal of refining capacity around the world for handling this heavier oil.[1] The theory also does not negate the occurrence of tar-sands/oil-sands. These deposits are not really oil, however, but rather a type of bitumen which must be processed into synthetic oil.

At first glance it would appear that this study and theory should usher in a new era of more efficient, less costly oil and natural gas exploration that should result in the discovery of vast new hydrocarbon reserves. One analysts suggests, "This new understanding represents perhaps one of the main advances in petroleum geology."[5] This would clearly be bad news from a global warming perspective. Over-exuberance, however would be misplaced. What this theory does is effectively obliterate one of the cornucopian hopes of the oil and gas industry that to find more oil all they have to do is drill deeper.

Essentially this theory says that oil will not occur at depths below the Golden Zone which contains almost all of today's oil fields. According to the research team, "Reservoirs within geologic traps which occur in this zone contain an exceptional number of the discovered giant and super giant accumulations."[2] As the report suggests, "The hope of finding much more oil the deeper we drilled into the basement of the sedimentary basins, is about to fade." It would also seem to nullify the abiotic oil theory which suggests that oil is being perpetually generated at the earth's mantle, the layer of the earth's crust immediately above the outer core.

Where the theory will have the greatest positive impact for the oil and gas industry is in the exploration for sub-oceanic - particularly deep water - reserves. Deep water exploration is tremendously difficult and expensive and anything that helps reduce the exploration risk is a bonus for the oil industry. The theory is unlikely to result in the discovery of many new giant or super-giant fields on land, however. New land-based fields are becoming extremely rare.

Certainly the oil and gas industry, and politicians in every developed and developing nation, will probably latch onto this new theory. Cautionary notes in the research papers will be ignored as the theory is touted as proof that we are about to enter a new golden age of oil discovery and that peak oil proponents are out to lunch. That will be the front page news. The reality that the theory does not allow business as usual to be prolonged will be buried on the back page, if it appears as well. My perception is that this theory is little more than an explanation of the location and occurrence of existing fields, not the road map to tomorrow's fields.
1) Simplifying oil and gas exploration
2) Golden Zone Implications for Global Exploration
3) New Theory Predicts Location Of Oil And Gas Reserves
4) New Theory Predicts Location Of Oil And Gas Reserves
5) The Golden Zone
6) Geothermal gradient
7) Geothermal Gradient

No comments: