Geo-microbial and light gaseous hydrocarbon anomalies in the near surface soils of Deccan Syneclise Basin, India: Implications to hydrocarbon resource potential
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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DOI：
10.1016/j.petrol.2012.01.010
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发表时间：
2012-04
影响因子：
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通讯作者：
M. A. Rasheed;M. Kalpana;M. V. Prasanna;M. Lakshmi;T. Madhavi;D. Tiwari;D. J. Patil;A. M. Dayal;S. V. Raju
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作者：
M. A. Rasheed;M. Kalpana;M. V. Prasanna;M. Lakshmi;T. Madhavi;D. Tiwari;D. J. Patil;A. M. Dayal;S. V. Raju
德干Syneclise盆地被认为是地质上具有石油和天然气储量前景的盆地;然而，该盆地的大部分被德干圈闭覆盖，阻碍了中生界油气目标的勘探。在这些地区，根据地下积聚的碳氢化合物的微渗漏进行地表地球化学勘探可能是有利的。应用地表化探方法对德干隆起进行了油气资源潜力评价。吸附的土壤气体的气相色谱分析表明，C1至C4烃的存在。土壤吸附气体的浓度范围分别为甲烷（C1）=1 ~ 483 ppb，乙烷（C2）=1 ~ 83 ppb，丙烷（C3）=1 ~ 38 ppb，正丁烷（nC 4）=1 ~ 60 ppb，正丁烷C2+=1 ~ 129 ppb。C1和C4组分之间的散点图描绘了线性趋势，表明所有气体均来自同一来源。采用气相色谱-燃烧-同位素比值质谱法（GC-C-IRMS）测定了吸附甲烷的碳同位素组成。甲烷的δ 13 C1值与维也纳PeeDee Belemnite（VPDB）相比，变化范围为−39.9至−19.9‰。碳同位素比值分布模式代表了热源烃类气体的同位素特征。丙烷氧化细菌（POB）数量在1.0× 102 ~ 12.8× 105 cfu/g土壤之间。在Aurangabad、Ahmednagar、Shirdi、阿科拉、布萨瓦尔和印多尔地区及其周围发现的吸附轻气态烃和丙烷氧化细菌异常被认为是未来油气研究和勘探的前景。
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 C1to C4hydrocarbons. The concentrations of adsorbed soil gasses ranged for methane (C1)=1 to 483ppb, ethane (C2)=1 to 83ppb, propane (C3)=1 to 38ppb, butane (nC4)=1 to 60ppb and ΣC2+=1 to 129ppb, respectively. The scatter plots between C1and C4components 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 δ13C1varied from −39.9 to −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 1.0×102and 12.8×105cfu/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.