Cenozoic Shale Formations as a New Frontier Area – detecting shallow natural gas fields

Guest post by Dr. Leonid Anisimov, Principal Scientist of Lukoil-Engineering, Volgograd, Russia. VolgogradNIPImorneft – scientific center of the LUKOIL Oil Company for the South Volga, Caspian Region and Middle East.

Shalow gas accumulations in shale deposits are unconventional energy resources. However those are hazardous objects for drilling especially in the offshore areas.
Seismic is a principal instrument to detect shallow gas pockets but electromagnetic methods may have advantage. The presentation below shows principal geography and techniques for detection and development of shale gas fields. A pilot project of Landviser LLC in using VES for monitoring accumulation and release of methan in peat bogs of Eastern Siberia is attached.

Shallow recent sediments as a new target for the resource potential estimation: pro and con

Positive:

Shallow setting

Great size of gas pockets

Simple detection. Many oil and gas fields have been found by drilling anomalous bright spots in younger sediments.

Negative:

Low pressure

Special conditions for prospective accumulations: Presence of sandy lenses and layers are needed

Seeps show the shallow gas migration and accumulation

Deltaic and lacustrine facies dominate in the Cenozoic source rocks instead of marine facies in the ancient periods

Cenozoic source formations

Majority of Neogene source rocks are shales associated with large deltaic systems extending from onshore to deepwater.

Examples include the Ob (West Sybiria), Volga (Caspian Sea) Mackenzie delta (Alaska), the Mississippi (Gulf of Mexico), the Orinoco (Caribbean), the Amazon (southern Atlantic), the Niger (West Africa), the Nile (Mediterranean), the Indus (Arabian Sea), the Ganges (Bay of Bengal), the Yangtze (South China Sea)

Majority of Paleogene source rocks are shales associated with large intermountain and foreland systems:

Examples includes Green River in the USA, Maykop Suite Russia, Polish and Ukrainian Carpathians, the Subathu Formation in the NW Himalaya, the Caspian–Black Sea–Mediterranean Corridor

Gas accumulations in the Nile delta

Cenozoic shallow gas accumulations in the Netherlands.Geological setting. TNO data

Paleogene oil accumulation in Green River shale formation, Uinta Basin

Acoustic anomalies from seismic line: intercalation of ‘gas curtains’ with ‘acoustic. Shallow gas accumulation in sediments of the Patos Lagoon, Southern BrazilJAIR WESCHENFELDER1 et al, 2006

Shallow gas in Derweze, Turkmenistan. “Door to Hell” is a large hole with diameter of 70 m. Gas is still burning today

Assessed shale gas basins around the World (Wikipedia). Russia is an absolute block in the shale gas basins estimation

Offshore Sakhalin. Shallow gas accumulation in the resent sediments(V.Lomtev et al.)

Chirp profiles showing various acoustic anomalies in the Korean Strait. Seepages with plumes in the water column are characterized by vertical smearing and disturbed seafloor reflection. (Pukyong National University, Busan, Korea)

Northern Caspian. Location of shallow oil and gas fields,seeps in the Pliocene sediments

Northern CaspianShallow gas detection by seismic exploration

Vertical Electrical Sounding to Monitor Shallow Gas Accumulation and Release in Peat Bogs(Pozdnyakov et al., 2000)

Fracture permeability vs. depth in the Paleogene shale formation, Chechen Region

Chechen RegionMaykop shale of 2000 m in thick is a seal for the Cretaceous oil accumulation.This is a possible target for the unconventional oil resourcesOil invasion to the overlaid shale. Shale undercompaction is detected by decreasing rock density

Shallow Gas History: From “Hazards” to “Resources”

Is it a significant sector of the future gas industry?

Cite this presentation as:

Leonid Anisimov. “Cenozoic Shale Formations as a New Frontier Area”. Houston, TX: WorldOil, 2012.

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