Geo-microbial and light gaseous hydrocarbon anomalies in the near surface soils of Deccan Syneclise Basin, India: Implications to hydrocarbon resource potential

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• 作者：M.A. Rasheed ; ^{rasheedmicro@rediffmail.com} ; M.S. Kalpana ; M. Veena Prasanna ; M. Lakshmi ; T. Madhavi ; Devleena Mani Tiwari ; D.J. Patil ; A.M. Dayal ; S.V. Raju¹
• 关键词：adsorbed soil gas ; hydrocarbons ; Deccan Syneclise Basin ; propane-oxidizing bacteria
• 刊名：Journal of Petroleum Science and Engineering
• 出版年：2012
• 出版时间：April, 2012
• 年：2012
• 卷：84-85
• 期：Complete
• 页码：33-41
• 全文大小：2031 K

文摘

Deccan Syneclise Basin is considered geologically prospective for oil and gas reserves; however, a major part of the basin is covered by the Deccan Traps, hindering the exploration of Mesozoic hydrocarbon targets. Surface geochemical prospecting, based on micro-seepage of hydrocarbons from subsurface accumulations, could be advantageous in such areas. Surface geochemical prospecting method was applied in Deccan Syneclise for evaluation of hydrocarbon resource potential of the basin. The gas chromatographic analyses of adsorbed soil gasses showed the presence of C₁ to C₄ hydrocarbons. The concentrations of adsorbed soil gasses ranged for methane (C₁) = 1 to 483 ppb, ethane (C₂) = 1 to 83 ppb, propane (C₃) = 1 to 38 ppb, butane (nC₄) = 1 to 60 ppb and ¦²C_2 + = 1 to 129 ppb, respectively. The scatter plots between C₁ and C₄ components depict linear trend indicating that all the gasses are derived from the same source.

The carbon isotope composition of adsorbed methane was measured using Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS). The values for methane ¦Ä¹³C₁ varied from ?#xA0;39.9 to ?#xA0;19.9?versus the Vienna PeeDee Belemnite (VPDB). The carbon isotope ratio distribution pattern represents isotopic characteristics pertaining to hydrocarbon gasses derived from thermogenic sources. The propane oxidizing bacteria (POB) ranged between 1.0 ¡Á 10² and 12.8 ¡Á 10⁵ cfu/g of soil. The adsorbed light gaseous hydrocarbons and propane oxidizing bacterial anomalies found in and around Aurangabad, Ahmednagar, Shirdi, Akola, Bhusawal and Indore areas are considered to be promising for future hydrocarbon research and exploration.