Archive for August, 2011

10
Aug
11

Shale Oil & Gas

Conventional hydrocarbon  refers to oil/gas accumulated in reservoirs ( mostly sandstones) with air permeability over 1×10-3 µm2 or formation permeability over 0.1×10-3 µm2  Unconventional hydrocarbon refers to oil/gas in reservoirs with air permeability under 1×10-3 µm2  or formation permeability under 0.1×10-3 µm2. The later accounts for greater than 80% of the total resources, such as shale gas, coal bed methane, shale oil etc. Off late interest in unconventional shale gas has increased manifold due to escalating oil prices and declining conventional resources.  Along with the interest, geological understanding of the mechanism of accumulation of shale gas/oil and advancement in  recovery technology is drawing every country’s attention in exploration of these resources. Horizontal, multi stage fracturing of shale bed will yield economical quantities of gas and oil. Major portion of shale gas is stored in matrix pore space within the rock. These pores could be micro or nano size pores. Induced fractures can provide migration pathway for the pore-locked gas and enhance recovery of this energy source.  

 Exploratory shale gas well inCooperbasin has recently produced 2 million standard cubic feet of gas. Perhaps,Chinacould be the second country to produce oil/gas from oil shale.

 Oil shales are rich in kerogen. These shale formations are wide spread in the world. By retorting oil shale, oil can be extracted or the shale can be used as fuel to generate steam that can be used to run the electric turbines.  Waste disposal is a problem due to high content of phenols,  polynuclear aromatic hydrocarbon etc.

 The Oligocene and Early Miocene Formations bordering Tibetand Nepalin the upper HimalayanProvincecontains extensive occurrence of oil shale beds with high values of TOC, S2 and HI indicating as potential source rock for oil, reports a recent scientific publication  from theUniversity ofGeosciences,Beijing. The extension of the same/equivalent  Formations are found inAssam andKutch. The Assam Barail Formation does contain oil, gas deposits and encloses several beds of oil shales. Perhaps,China could be the second country to produce hydrocarbons  from oil/gas shales. Thus forChina,Tibet is a strategic place with abundant natural resources extending from uranium to geothermal. Uranium deposits are found north of Ladakh while the entire Himalayan geothermal belt extends from Ladakh to Yangbajing, running parallel to the Tibetan-Nepal border. Oil shale technology has givenChina the technique of extracting hydrocarbons through horizontal drilling. This same technology can be used to extract geothermal waters for generating power.China is already generating 28 MWe from its Yangbajing geothermal field (from shallow wells). A large number of exploratory wells are capped and ready for possession by the investors. With the occurrence abundant natural resources, including the recently commissioned hydro power,  in conjunction with net work of railways at this altitude of 5000 m,Tibet plays an important role in Chinese economy.