Frictional properties of simulated shale-coal fault gouges: Implications for induced seismicity in source rocks below Europe's largest gas field
Frictional properties of simulated shale-coal fault gouges: Implications for induced seismicity in source rocks below Europe's largest gas field
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模拟页岩煤断层泥的摩擦特性：对欧洲最大气田下方烃源岩诱发地震活动的影响
DOI：
10.1016/j.coal.2020.103499
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发表时间：
2020-06
影响因子：
5.6
通讯作者：
Spiers Christopher J.
中科院分区：
文献类型：
--
作者：
Liu Jinfeng;Hunfeld Luuk B.;Niemeijer Andre R.;Spiers Christopher J.
我们报告了21个摩擦滑动实验进行模拟断层泥页岩煤混合物制备。我们的目的是调查当地煤层涂抹的摩擦性能和诱发地震的潜力断层切割下格罗宁根天然气藏（荷兰）的上石炭统源岩的影响。我们使用了从格罗宁根储层下方采集的页岩/粉砂岩岩心，以及与格罗宁根源岩中当地存在的煤年龄和来源相似的波兰烟煤。在100 °C和40 MPa有效正应力的近原位条件下，采用0.1 ~ 100 μm/s的滑动速度和各种孔隙流体，进行了速度步进、恒速、滑动-保持-滑动（SHS）和滑动-卸载-滑动（SUS）模式下的摩擦实验。含0-50体积%煤的样品显示摩擦系数约为0.45，具有轻微的滑动减弱。含煤量≥50 vol%的样品表现出明显的滑动弱化，从峰值摩擦值~0.47到~0.3，无论实验条件如何，这可能反映了弱富煤剪切带中的应变局部化，可能伴随着煤分子结构的变化。然而，再滑动实验（SUS）表明，滑移弱化仅限于小的初始位移（2-3 mm），并且在滑移再激活期间不会发生。在（近）稳定状态下，几乎所有的实验在原地应力，孔隙水压力（15 MPa）和温度条件下进行表现出稳定，速度强化行为，无论煤含量。相比之下，在干燥和气体饱和（CH 4，氩气）条件下，或使用水在1个大气压，50：50（体积%）页岩煤混合物显示速度弱化，甚至粘滑。我们的研究结果意味着，故障在格罗宁根石炭纪页岩粉砂岩序列是不容易诱发地震成核在原位条件下，即使当含煤或煤富集涂抹。然而，在所研究的滑动速度下控制煤摩擦的机制仍然不清楚，并且在地震滑动速度下煤摩擦的演化仍然未知。
We report 21 frictional sliding experiments performed on simulated fault gouges prepared from shale-coal mixtures. Our aim was to investigate the effects of local coal seam smearing on the frictional properties and induced seismogenic potential of faults cutting the Upper Carboniferous source rocks underlying the Groningen gas reservoir (Netherlands). We used shale/siltstone core recovered from beneath the Groningen reservoir plus Polish bituminous coal of similar age and origin to coals locally present in the Groningen source rocks. We performed friction experiments in velocity stepping, constant velocity, slide-hold-slide (SHS) and slide-unload-slide (SUS) modes, under near in-situ conditions of 100 °C and 40 MPa effective normal stress, employing sliding velocities of 0.1–100 μm/s and a variety of pore fluids. Samples with 0–50 vol% coal showed friction coefficients ~0.45, with minor slip weakening. Samples with ≥50 vol% coal showed marked slip-weakening from peak friction values of ~0.47 to ~0.3, regardless of experimental conditions, presumably reflecting strain localization in weak coal-rich shear bands, possibly accompanied by changes in coal molecular structure. However, re-sliding experiments (SUS) showed that slip-weakening is limited to small initial displacements (2–3 mm), and does not occur during slip reactivation. At (near) steady state, almost all experiments performed at in-situ stress, pore water pressure (15 MPa) and temperature conditions exhibited stable, velocity strengthening behaviour, regardless of coal content. By contrast, under dry and gas-saturated (CH4, Argon) conditions, or using water at 1 atm, 50:50 (vol%) shale-coal mixtures showed velocity-weakening and even stick-slip. Our results imply that faults in the Groningen Carboniferous shale-siltstone sequence are not prone to induced earthquake nucleation at in-situ conditions, even when coal-bearing or coal-enriched by smearing. However, the mechanisms controlling coal friction remain unclear at the sliding velocities studied, and the evolution of coal friction at seismic slip velocities remains unknown.
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DOI：
10.5860/choice.28-1579
发表时间：
2016
期刊：
--
影响因子：
--
作者：
Leon Bieber
通讯作者：
Leon Bieber
影响因子：
2.8
作者：
J. Spetzler;B. Dost
通讯作者：
J. Spetzler;B. Dost
影响因子：
3.1
作者：
K. Oohashi;T. Hirose;T. Shimamoto
通讯作者：
K. Oohashi;T. Hirose;T. Shimamoto
影响因子：
3.9
作者：
Majer, Ernest L.;Baria, Roy;Asanuma, Hiroshi
通讯作者：
Asanuma, Hiroshi
影响因子：
--
作者：
DIETERICH, JH
通讯作者：
DIETERICH, JH