The Discovery of Helium Gas in South Ganga Basin, Sagar Division M P India - Juniper Publishers

 Recent Advances in Petrochemical Science - Juniper Publishers

Opinion

A rare Discovery of the Helium and Petroleum Gas in more than 54 Tube wells in and around Sagar Town in Sagar Division (1993 to 2015 period) in the rocks of Upper Rewa sandstone of the Vindhyan Super group. The discovery of the Rare Gas Helium in hydrocarbon rich zone in the tube wells in agricultural field in the Villages in Sagar division of M P is a unique finding in rocks of the Vindhyan Super Group, in the history of Earth Science in India. The depth of tube wells is varying in 300 feet to 1000 feet. On the basis of Geochemical & Stable Isotopic analyses of the soil, water and gas samples held at Geochemical Lab of KDM IPE, ONGC, Dehradun and National Geophysical Research Institute (NGRI) Hyderabad, it is remarkable to note that average values of rare gas helium contents varies from 0.34 % to 0.732 % along with the 72% to 99 % of methane and ethane, and minor amount of oxygen, nitrogen and CO2 gases in the hydrocarbon rich zone are recorded. In the west central part of the Vindhyan Basin around sagar area is characterized by the presence of the Helium along with hydrocarbon gas in Upper Sandstone rocks of Rewa group, which was overlain by the Deccan trap Basaltic lava flow, iot6 is acting as trap or cover rocks over theses gaseous sandstone.

The occurrence of the various inlier of the Vindhyan rocks are contain the Helium and hydrocarbon gases. In variably we do not get the gas during the mansoon period, after the mansson period, after Nov. every year there is leakages of both the gases coming from the tube wells. The part of the Vindhyan basin, which is not covered with the Deccan trap basalt, do not have any chances of storing these gases/rare gases. During the intrusion of the Dome structure of Jabera area in Damoh Distt, about 140km east of the study are, must be responsible for the generation of these gases by the fractionation under high temperature & pressure condition. These gases were formed in the later phase of folding in the Lower, Middle and Upper Vidhyan rocks. In the gently folded rocks around Sagar area also containing these gases. The stable Isotopic analysis suggests the stable isotope δ C13 value the values for the methane is - 43.6 per mil w. r. t. to - 54.9 per mil w.r.t. PDB and for the Ethane gas is --24.9 to --26.4 per mil w. r. t. PDB in the gas samples collected in the saturated sodium chloride solution in the glass bottles at various sites in Sagar & Damoh District.

The occurrence of rare helium gas in the Hydrocarbon rich zone is reported first time in Jan 2007 from the tube wells of Sagar Distt, which were geochemically and stable isotopically analyzed in the labs of KDMIPE Dehradun & NGRI Hyderabad. The gaseous hydrocarbon analysis shows the presence of moderate to low concentration of methane (C1) 1 to 104 ppb, Ethane(C2)-1 to 14 ppb, Propane(C3) 1 to 10 ppb, i- Butane (i C4) 1 to 9 ppb and n Butane (nC4) 1 to 8 ppb in the soil samples collected from different locations. The Isotopic composition of the hydrocarbon gases are governed by their source of characteristic. In case of the thermogenic gases the maturity of the parent kerogen at the time of gas generation also affect the isotopic composition of the gas. The migration does not appear to affect the isotopic signature of the hydrocarbon gases, although due to diffusion through imperfect seals in a reservoir, isotopically lighter 12C methane may preferentially escape leaving behind isotopically behavior gas in a reservoir. Biogenic and Thermogenic gas can be distinguished based on molecular and isotopic composition.

The Biogenic gases are depleted in higher hydrocarbon gas, like ethane, propane, butane etc. The methane is biogenic gas if the isotopic value of the δ C13 -55%. The helium gas in the Upper Sandstone of Rewa group of of rocks of the Vindhyan Super Groupare generated from thermal cracking of U238 (U238- Pb206 + He) and Kerogen. No mixing with any biogenic gas taken place after the generation of thermogenic gases. The Result of the soil gas and stable isotopic analysis of Ethane gas in these samples δ C13value are ranging from -24.9 per mill w.r.t. PDB and -26.9 per mill w.r.t. PDB are indicative that this gas is of thermogenic origin, which must have been formed at very high temperature & pressure condition in the deeper horizon of the Great Vindhyan sedimentary basin of late Proterozoic (> 600 m.y.) period

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