Shale gas desorption behavior and carbon isotopic variations of gases from canister desorption of two sets of gas shales in south China
Shale gas desorption behavior and carbon isotopic variations of gases from canister desorption of two sets of gas shales in south China
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南方两套含气页岩页岩气解吸行为及碳同位素变化
DOI：
10.1016/j.marpetgeo.2019.104127
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发表时间：
2020-03
影响因子：
4.2
通讯作者：
Jiao Weiwei
中科院分区：
文献类型：
--
作者：
Ma Yong;Zhong Ningning;Yao Lipeng;Huang Haiping;Larter Steve;Jiao Weiwei
对重庆东部下志留统龙马溪组和下寒武统水井沱组4个页岩样品进行了储层和高温（90 °C）条件下的罐式解吸实验，研究了页岩气的释放行为及其解吸气体化学和同位素组成的变化。储层温度下释放的天然气占储层和高温下总解吸气的比例以及解吸速率表明，龙马溪页岩气比水井沱页岩气更容易释放。扫描电镜（SEM）观察沿着低温CO2和N2吸附结果表明，龙马溪页岩中富含2-100 nm的有机质孔隙，而水井沱页岩中有机质以发育良好的微孔（<2 nm）为特征。高比例的有机质托管的微孔和高TOC含量，再加上连接不良的有机质托管的孔隙网络，导致在水井沱页岩中的吸附气体的优势和随后的气体释放困难。随着解吸程度的增加，CO2/CH 4和C2 H6/CH 4的比值均增加，而C2 H6/CH 4的比值先增加后减小。页岩吸附能力的差异以及甲烷、C2 H6和CO2分子大小的变化是导致解吸气化学组成变化的主要原因。随着温度的升高，解吸甲烷碳同位素值迅速富集，龙马溪页岩和水晶沱页岩的碳同位素值分别高达13.7-16.2‰和9.1-10.2‰。在升高的温度（60和90 °C）下，观察到类似的趋势，但解吸的气体最初是13 C耗尽的。通过同位素分馏和质量平衡计算，页岩气原位δ 13 CCH 4值与储层温度下罐式解吸第5 h时的解吸气δ 13 CCH 4值基本一致。这通常对应于42-70%的潜在可用气体从页岩中释放的阶段。因此，新获得的岩心样品的罐解吸的页岩气含量和气体化学数据为理解页岩气在油田中的生产行为提供了有价值的地球化学信息。
Four shale samples from the Lower Silurian Longmaxi Formation and the Lower Cambrian Shuijingtuo Formation in the eastern part of Chongqing, SW China, were subjected to canister desorption experiments at reservoir and elevated temperatures (up to 90 °C) to investigate shale gas release behaviors and their variations in chemical and isotopic compositions of desorbed gases. Both the ratios of gas released at reservoir temperature to the total desorbed gas at reservoir and elevated temperatures and the desorption rates suggest that the Longmaxi shale gas is more easily released than the Shuijingtuo shale gas. Scanning electron microscope (SEM) observation, along with low temperature CO2and N2adsorption results, suggests that organic matter hosted pores with diameters of 2–100 nm are rich in the Longmaxi shales, whereas well-developed micropores (<2 nm) are characteristics of the organic matter in the Shuijingtuo shales. High proportions of organic matter hosted micropores and high TOC contents, coupled with a poorly connected organic matter hosted pore network, result in the dominance of adsorbed gas in the Shuijingtuo shales and subsequent difficulty for gas release. Both the CO2/CH4and C2H6/CH4ratios of the incrementally collected desorbed gas, increase with the extent of desorption, whereas the C2H6/CH4ratio increases first and then decreases after a peak. The changes in chemical composition of desorbed gas with desorption process are mainly caused by both the difference of adsorption capacity of shales and the varying molecular sizes of CH4, C2H6and CO2. Carbon isotopic values of incrementally collected desorbed methane become rapidly13C-enriched as desorption proceeds at reservoir temperatures, and up to 13.7–16.2‰ and 9.1–10.2‰ for the Longmaxi and Shuijingtuo shales respectively. At elevated temperatures (60 and 90 °C), a similar trend was observed but the desorbed gas is initially13C-depleted. Isotopic fractionation and mass balance calculations of lost gas and desorbed gas suggest that the in situ δ13CCH4values of shale gas were approximately represented by the δ13CCH4values of desorbed gas collected at the 5th hour of canister desorption at reservoir temperature. This corresponds typically to a stage when 42–70% of potentially available gas is released from the shale. Thus shale gas content and gas chemistry data from canister desorption of freshly obtained core samples provides valuable geochemical information for understanding shale gas production behavior in the field.
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影响因子：
4.2
作者：
Yong Ma;N. Zhong;Lijun Cheng;Z. Pan;Na Dai;Zhang Yu;Liu Yang
通讯作者：
Yong Ma;N. Zhong;Lijun Cheng;Z. Pan;Na Dai;Zhang Yu;Liu Yang
影响因子：
1.8
作者：
Zhong Ningning
通讯作者：
Zhong Ningning
影响因子：
4.2
作者：
Shangbin Chen;Yanming Zhu;Yong Qin;Hongyan Wang;Honglin Liu;Junhua Fang
通讯作者：
Shangbin Chen;Yanming Zhu;Yong Qin;Hongyan Wang;Honglin Liu;Junhua Fang
DOI：
--
发表时间：
1981-03
期刊：
--
影响因子：
--
作者：
W. P. Diamond;J. R. Levine
通讯作者：
W. P. Diamond;J. R. Levine
影响因子：
3.5
作者：
Bowker, Kent A.
通讯作者：
Bowker, Kent A.