Chemical and isotopic tracers of the contribution of microbial gas in Devonian organic-rich shales and reservoir sandstones, northern Appalachian Basin
Chemical and isotopic tracers of the contribution of microbial gas in Devonian organic-rich shales and reservoir sandstones, northern Appalachian Basin
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DOI：
10.1016/j.apgeochem.2010.01.001
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发表时间：
2010-03-01
影响因子：
3.4
通讯作者：
McIntosh, Jennifer C.
中科院分区：
文献类型：
--
作者：
Osborn, Stephen G.;McIntosh, Jennifer C.
在这项研究中，阿巴拉契亚盆地北方边缘泥盆纪富含有机质的页岩和储集砂岩中天然气和地层沃茨的地球化学和成因（纽约西部、俄亥俄州东部、宾夕法尼亚州西北部和肯塔基州东部）进行了研究。另外的样品从密西西比州伯里亚砂岩中收集，志留纪Medina砂岩和奥陶纪特伦顿/黑河组油气威尔斯井比较在沿着Like伊利的泥盆纪富含有机物的页岩中，浅层地下水中的溶解气体含有可检测到的甲烷（0 01-50 55 mol%），具有低Δ C-13-CH 4值（-74.68至-57.86份每千份），没有更高的链烃，微生物气体的典型特征。这些地下水只有中等碱度（1.14-8.72 meq/kg）和相对较低的溶解无机C（DIC）的δ C-13值（-248至-06ppm）。表明微生物产甲烷作用是有限的。北方阿巴拉契亚盆地泥盆系富含有机质的页岩和砂岩中的大多数天然气在深度（>168 m）具有低的CH 4/乙烷和丙烷比率（3-35摩尔%; C-1/C-2 + C-3）和高的CH 4的δ C-13和δ D值（分别为-53 35至-40 24份/千份和-315 0至-174 6份/千份）。随着深度、储层年龄和热成熟度的增加，这些气体的分子和同位素特征表明，CH 4是通过生热过程产生的。DIC的高δ C-13值（-10ppm）、碱度略微升高（高达12.01 meq/kg）和低SO 4值（
In this study, the geochemistry and origin of natural gas and formation waters in Devonian age organic-rich shales and reservoir sandstones across the northern Appalachian Basin margin (western New York, eastern Ohio, northwestern Pennsylvania, and eastern Kentucky) were investigated Additional samples were collected from Mississippian Berea Sandstone, Silurian Medina Sandstone and Ordovician Trenton/Black River Group oil and gas wells for comparison Dissolved gases in shallow groundwaters in Devonian organic-rich shales along Like Erie contain detectable CH4 (0 01-50 55 mol%) with low delta C-13- CH4 values (-74.68 to -57.86 parts per thousand) and no higher chain hydrocarbons, characteristics typical of microbial gas Nevertheless, these groundwaters have only moderate alkalinity (1.14-8.72 meq/kg) and relatively low delta C-13 values of dissolved inorganic C (DIC) (-24 8 to -0 6 parts per thousand). suggesting that microbial methanogenesis is limited The majority of natural gases in Devonian organic-rich shales and sandstones at depth (>168 m) in the northern Appalachian Basin have a low CH4 to ethane and propane ratios (3-35 mol%; C-1/C-2 + C-3) and high delta C-13 and delta D values of CH4 (-53 35 to -40 24 parts per thousand, and -315 0 to -174 6 parts per thousand, respectively). which increase in depth, reservoir age and thermal maturity, the molecular and isotopic signature of these gases show that CH4 was generated via thermogenic processes Despite this, the geochemistry of co-produced brines shows evidence for microbial activity. High delta C-13 values of DIC (-10 parts per thousand), slightly elevated alkalinity (up to 12.01 meq/kg) and low SO4 values (