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Electrical Geophysical Methods to Evaluate Soil Pollution from Gas and Oil Mining

transect across bitumen polluted soil and brune collectorElectrical 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.

VES profiles of oil polluted soil and permafrost

Four-electrode profiling was conducted for a transect through the most common pollution features within the area. Figure shows a clear distinction between non-polluted areas and areas with bitumen or brine pollution. The salty mining solutions can decrease resistivity of Gelisols to 20-50 ohm m, and wetland formed with salty mining solutions is outlined by the lowest resistivity in the profile.  The places polluted by bitumen, on contrary, have the very high resistivity, about 3000 ohm m. Non-polluted soils are indicated by resistivity of about 1000-1500 ohm m.

The variation in electrical resistivity indicating the pollution distribution in soil profiles can be seen on VES profiles. Pollution by heavy fraction of petroleum, such as bitumen appeared at the top part of soil profile and was indicated by electrical resistivity as high as 6´105 ohm m (Fig. 2c). The pollution by salty mining solutions lowered soil electrical resistivity. The resistivity of the soil near the stream where brine mining solution was discharged, varied from 50 to 200 ohm m (Fig. 2b). The surface soil at the brine collector has resistivity as low as 20 ohm m (Fig. 2d), while the electrical resistivity of the native pergelic soils was about 1000 ohm m at the surface (Fig. 2a). Some non-polluted native soils shown increase in electrical resistivity up to 8000 ohm m at the AB/2=2.4 m (about 0.6-m depth) indicated the presence of permafrost in soil profile (Fig. 2a). The depth of the permafrost was verified by soil excavation.                                                                                                      

Soil

Electrical resistivity

-— ohm m ——

 
 

Surface layers of non-polluted Gelisols

2 *102 – 2*103

 

Permafrost

4*103 – 8*103

 

Polluted by bitumen and other heavy fraction of oil

1*105 – 6*105

 

Polluted by gasoline

1*104 – 4 *104

 

Polluted by salty mining water

2 – 2 *102

 

Table shows the average values of electrical resistivity of natural non-polluted soils (Glacic and Aquic Haplorthels) and soils polluted during petroleum and gas mining in northwest Siberia. In this particular case the pollution by petroleum products highly increased the soil electrical resistivity, whereas brine solutions used for the mining considerably decreased soil resistivity.

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Mapping soils polluted during oil and gas mining

Location

Urengoj 65° 57' 27" N, 78° 23' 4.2" E

Electrical geophysical

Electrical geophysical methods used in the past for gas and oil exploration led to soil pollution with residual compounds. This way not only the soil is polluted, but also the groundwater. If your want your water to be clean, you must find other methods to extract oil and gas, this way you'll be healthy and you're going to minimize your environmental impact.

Although we value any

Although we value any difference in opinion, blank statements like that are very un-scientific. Electrical geophysical methods used for oil/gas exploration could not possibly polute the environment, on the contrary, they can save unnecessary soil excavation during initial stages of land development. However, excavation for oil/gas which proceeds afterwards is a whole different story and very often results in leftover oil spills and pollution. That is what we studied with our methods to better plan cleanup activities on the site.

Disclaimer: Landviser, LLC does not necessary endorse links/opinions appearing in comments on our site. Unappropriate links will be censored out from the posts. And considering your link - using plastic Christmass trees made from non-renewable resources in lie of live trees (which, by the way, are grown by local farmers and do not contribute to deforestation, on the contrary, they sequester carbon while grown ~5 years) is not as environmentally savvy as it might seem. We need to consider many sides of a problem before fanatically accusing "bad guys".:)

Larisa Golovko (Pozdnyakova), Ph.D. - President of Landviser, LLC

Scientists find that rising

Scientists find that rising levels of man-made pollution.The World Bank has reluctantly censored a report revealing that pollution. Click www.n8fan.net for more information. MARIZ www.n8fan.net

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