摘要
选取松辽盆地内泥岩样品和煤样进行热模拟实验,建立了两个样品成甲烷的氢、碳同位素分馏动力学模型并标定了动力学参数。分别以徐深1井区、沉降中心地质资料为例进行研究,表明两处源岩均有短期内大量生气的特点,气源岩生气期分别为距今95.5～73 Ma和距今100～73 Ma。计算得到两处源岩沙河子组暗色泥岩和煤、火石岭组暗色泥岩和煤所生天然气单独运聚成藏(自开始生烃到现今累积成藏)所对应的δD_(CH_4)和δ^(13)C_1,进而定量计算出徐深1井区源岩所生甲烷的δD_(CH_4)为-237.3‰,δ^(13)C_1为-28.8‰,沉降中心气源岩所生甲烷的δD_(CH_4)为-102.5%‰,δ^(13)C_1为-24.8‰以各区域天然气混合后的δD_(CH_4)作为来源气体的端元同位素值,根据物质平衡原理计算得到:徐深1井区源岩对该区气藏的贡献比例约占72%,沉降中心源岩的贡献比例约为28%。同理以δ^(13)C_1方法得到徐深1井区源岩对该区气藏的贡献比例约占66%,沉降中心源岩的贡献比例约为34%。氢、碳同位素分馏的化学动力学地质应用结果存在的差异与同位素分馏模型标定所用热模拟实验为不加水实验有关。
The dark mudstone sample from Shahezi Formation of the Well Du 13 and coal sample from Yingcheng Formation of the Jilin Yingcheng Coal Mine in the Songliao Basin were selected for pyrolysis, in which the chemical kinetic models of methane generated from oil and its fractionation of hydrogen and carbon isotope were constructed and calibrated. Taking geological data of Block Xushen 1 and the subsidence centre for example, the geological application indicated that both source rocks generated a large quantity of natural gas in a short time. The gas generation period of source rocks of the Block Xushen 1 was 95.5 - 73 Ma ago,and that of the subsidence centre was 100 -73 Ma ago. The corresponding values of δDCH4 and δ^13C1 of migrating and accumulating natural gas（ generated by dark mudstones and coals of Shahezi and Huoshiling Formations＇ source rocks in the both places） were calculated. And then δDCH4 of methane generating from source rocks of the Block Xushen 1 was calculated as -237.3‰, δ^13C1 as -28.8‰;δDCH4 of methane generating from source rocks of the subsidence centre was calculated as - 102.5‰,δ^13C1 as -24. 8‰. Regarding δDCH4 of the mixing natural gas as the end-member value of isotope, it could be figured out, based on the material balance principle, that the contribution of gas source rocks of the Block Xushen 1 accounted for 72% ,and that of the subsidence centre was 28%. In the same way, by means of δ^13C1, the contribution of gas source rocks of the Block Xushen 1 accounted for 66% ,and that of the subsidence centre was 34%. There was a difference between the results of geological application of hydrogen and carbon isotope fractionation chemical kinetics. The difference might be caused by the pyrolysis no-water experiment,which was used to calibrate isotope fractionation model.
出处
《地质科学》
CAS
CSCD
北大核心
2009年第2期635-644,共10页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金项目(批准号:40572079)
国家重点基础研究发展计划(编号:2009CB219308)的部分成果
关键词
氢同位素
碳同位素
气源
沉降中心
徐深1井
松辽盆地
Hydrogen isotope, Carbon isotope, Gas sources, Subsidence centre, The Well Xushen 1 ,The Songliao Basin
