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.

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The technique and procedure described here can be performed with LandMapper ERM-01 or ERM-02 (set in resistivity mode). The electrode spacings provided in this example are identical to Landviser's supplied "big manual VES" cable set made to measure 16 layers of topsoil down to approximately 9 m. The worksheet for pre-set electrode spacings in such cable re-calculating measured resistivities to 1D VES profile can be downloaded as Manual 1D VES workbook (MS Excel format).

Other electrode spacings are possible for custom-made cable arrays to reach deeper profiles. For example, we developed and tested with LandMapper a 60m-long cable, measuring down to ~ 20 m for one custom hydrology project. 

This manual VES technique is most convenient to use with three people. Follow step-by-step instructions below. If you need further help, do not hesitate to contact Landviser, LLC @ +1-609-412-0555 or info@landviser.com. Register on our site and download 7 related publications and software!

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Electrical geophysical methods were successfully used for exploration of gas and oil fields (Kalenev, 1970). However, the methods are not widely used for estimation of the soil pollution with petroleum products (Znamensky, 1980; Pozdnyakov et al., 1996a). The possibility of using the methods of electrical resistivity to evaluate the places of petroleum pollution or natural petroleum and gas deposits is based on highly different resistivities of soil and petroleum products. Petroleum and various products of petroleum manufacture, such as oil, gasoline, bitumen, and kerosene have very high electrical resistivity compared with soils. Electrical resistivity of petroleum varies from 10⁴ to 10¹⁹ ohm m (Fedinsky, 1967), whereas resistivity of petroleum-saturated sand is much lower (2200 ohm m) (Znamensky, 1980), but is still higher than that of any non-polluted soil.

Soil pollution by the products of gas and petroleum mining was studied near Urengoi in northwest Siberia, Russia. The virgin soils, Glacic and Aquic Haplorthels, were extremely polluted with various by-products of petroleum extraction and manufacturing, such as bitumen, gasoline, kerosene, and mining brine solutions. The study area was thoroughly investigated with four-electrode profiling on 1.2-m array and vertical electrical sounding.

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