| 湘中邵阳凹陷二叠系龙潭组页岩含气性特征与气体成因 |
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| 引用本文： | 张国涛,陈孝红,张保民,李海,陈林.湘中邵阳凹陷二叠系龙潭组页岩含气性特征与气体成因[J].地球科学,2019,44(2):539-550. |
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| 作者姓名： | 张国涛 陈孝红 张保民 李海 陈林 |
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| 作者单位： | 中国地质调查局武汉地质调查中心, 湖北武汉 434023 |
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| 基金项目： | 中国地质调查局基础地质调查项目No.12120115005601中国地质调查局油气基础性公益性地质调查项目No.DD20160194 |
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| 摘 要： | 针对湘中地区邵阳凹陷二叠系龙潭组页岩气资源评价，部署了页岩气调查井2015H-D3井，通过现场解析气等相关样品测试定量分析了页岩含气性特征及其影响因素，并借助气体稳定碳、氢同位素对气体成因进行了初步探讨.结果显示:钻深从150 m处开始出现气显，随深度增加，解析气含量呈现先逐渐增大后减小的趋势，300~425 m为最高含气层段，累计厚度达125 m，现场解析气含量全部大于0.5 m3/t，最高为2.35 m3/t，平均1 m3/t，证实龙潭组具良好页岩气资源潜力.当埋深大于300 m时，解析气含量受有机碳含量控制，而埋深小于300 m时，解析气含量并不简单受控于有机碳含量，而是受到保存条件的严重制约.气体碳、氢同位素测试显示δ13C1介于-29.87‰~-36.82‰，平均为-34.52‰，δ13C2介于-29.45‰~-31.02‰，平均为-30.09‰，δD1介于-131.20‰~-178.40‰，平均为-167.40‰.气体成因分析揭示龙潭组页岩气属热成因中的油型气类型.基于沉积现象判断龙潭组为海陆过渡相环境，与氢同位素判断结果基本吻合，但目前还无法确定具体判定区间.
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| 关 键 词： | 湘中地区 龙潭组 海陆过渡相 页岩气 碳、氢同位素 |
| 收稿时间： | 2018-12-14 |
Gas-Bearing Characteristics and Origin Analysis of Shale Gas in Longtan Formation,Permian, Shaoyang Sag,Central Hunan |
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| Abstract: | In order to evaluate shale gas resources potential in the Permian Longtan Formation, Shaoyang sag, Central Hunan, a shale gas survey well-2015H-D3 was done in this study. The gas-bearing properties and its influencing factors were quantitatively analyzed by the well on-site desorption with other related tests, combined with gas stable carbon and hydrogen isotopes, preliminary discussion on the origin of hydrocarbon gas is made. The gas logging values become abnormal from the depth of 150 m, and the gas content of desorption firstly increases gradually and then decreases with the increase of depth. 300-425 m is the highest gas-bearing zone, with a cumulative thickness of 125 m. The gas content of desorption is all over 0.5 m3/t, the highest value is 2.35 m3/t, with an average value of 1 m3/t, indicating that the Longtan Formation has a good potential for shale gas exploration. The gas content of desorption is controlled by organic carbon content while the depth is more than 300 m, and the desorption gas content is not simply constrained by organic carbon content but rather restricted by the preservation conditions while the buried depth is less than 300 m. The gas carbon isotope test shows that δ13C1 is between -29.87‰ and -36.82‰ with the average value of -34.52‰, δ13C2 is between -29.45‰ and -31.02‰ with the average value of -30.09‰, and δD1 is between -131.2‰ and -178.4‰ with the average value of -167.4‰. The gas origin analysis reveals that the shale gas in Longtan Formation belongs to the type of oil source gas in thermal genesis. It can be determined that the Longtan Formation is the transitional environment through sedimentary phenomena, which is consistent with the results of hydrogen isotope, but it is still unable to determine the specific judgment interval. |
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