Effect of Diagenesis on Geomechanical Properties of Organic-Rich Calcareous Shale: A Multiscale Investigation
Effect of Diagenesis on Geomechanical Properties of Organic-Rich Calcareous Shale: A Multiscale Investigation
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DOI：
10.1029/2020jb021365
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发表时间：
2021-07-01
影响因子：
3.9
通讯作者：
Cubillas, P.
中科院分区：
文献类型：
--
作者：
Charlton, T. S.;Goodarzi, M.;Cubillas, P.
本研究调查了埋置至100摄氏度-180摄氏度的富含有机物的钙质页岩的成熟度系列的纳米至岩心尺度地质力学性质，重点是：（a）有机物的机械性质;（B）页岩复合物在微观和岩心尺度下的弹性响应和各向异性;以及（c）蠕变响应。原子力显微镜被用来以纳米级分辨率靶向干酪根，并且发现弹性刚度随着热成熟度从未成熟样品中的5.8 GPa增加到成熟样品中的11.3 GPa。页岩基质的纳米压痕测试表明，成岩作用是确定体积弹性的关键因素，在较高的热成熟度下，碳酸盐胶结作用越来越强烈，导致响应更强。一个多尺度模型，制定高档的弹性性能从纳米级固体粘土矿物的微裂纹复合材料在核心规模，与良好的预测相比，压痕和三轴结果的微观和核心规模的刚度。蠕变模量和粘土/干酪根含量之间存在负相关性，与较高热成熟度的样品相比，在纳米压痕测试中观察到的未成熟粘土和富含干酪根的样品中的蠕变位移更大。
This study investigates the nano to core-scale geomechanical properties of a maturity series of organic-rich, calcareous shales buried to 100 degrees C-180 degrees C, with a focus on: (a) the mechanical properties of organic matter; (b) the elastic response and anisotropy of the shale composite at micro and core scale; and (c) the creep response. Atomic force microscopy was used to target kerogen at nanoscale resolution, and it was found that the elastic stiffness increased with thermal maturity from 5.8 GPa in an immature sample to 11.3 GPa in a mature sample. Nanoindentation testing of the shale matrix showed that diagenesis is a key factor in determining the bulk elasticity, with increasingly intense carbonate cementation at higher thermal maturities contributing to a stiffer response. A multiscale model was formulated to upscale the elastic properties from nanoscale solid clay minerals to a microcracked composite at core scale, with good predictions of the micro and core-scale stiffness in comparison to indentation and triaxial results. A negative correlation was found between the creep modulus and clay/kerogen content, with greater creep displacement observed in nanoindentation tests in the immature clay- and kerogen-rich sample compared to samples of higher thermal maturity.