Global S&T Development Trend Analysis Platform of Resources and Environment
DOI | 10.1306/02271816507 |
Effects of internal gradients on pore-size distribution in shale | |
Obasi, Christian; Pashin, Jack | |
2018-09-01 | |
发表期刊 | AAPG BULLETIN
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ISSN | 0149-1423 |
EISSN | 1558-9153 |
出版年 | 2018 |
卷号 | 102期号:9页码:1825-1840 |
文章类型 | Article |
语种 | 英语 |
国家 | USA |
英文摘要 | In porous media, effects of internal gradient caused by magnetic susceptibility contrast between the matrix and infilling fluid shifts transverse relaxation time (T-2) to shorter time, resulting in imprecise classification of pore sizes. In shale, details of the effects of paramagnetic and clay minerals that induce the internal gradients are poorly understood. We measured a brine mixture with a granular form of minerals, including kaolinite, montmorillonite, glauconite, illite, pyrite, celadonite, and chamosite, to infer contributions of each to T-2 relaxation in shale. Nuclear magnetic resonance (NMR) response of these samples was used to calculate the total mean logarithm of T-2 (T-2ML) and volume of water in the samples. Additionally, physical properties such as magnetic susceptibility, specific surface area, and elemental composition were acquired. Pore geometry, magnitude of internal gradients, pore-size distributions, and secular regimes in which the media relaxed (based on their shortest characteristic time scales) were characterized from these properties. These time scales measure the behavior of the relaxation regimes such as longitudinal relaxation time-to-T-2 ratio and dependence of relaxation rate on echo spacing (t(E)). Glauconite illite, pyrite, chamosite, and kaolinite grouped into a small-pore system, whereas montmorillonite and celadonite grouped into large-pore systems. A free diffusion regime governed secular relaxation for kaolinite; a motional-averaging regime governed montmorillonite, celadonite, and large tE chamosite; whereas a localization regime dominated the rest of the minerals. We conclude that understanding the effects of internal gradients in shale is important to quantify the shortening of T-2ML, which leads to overestimation of bulk fluid volume and, thus, underestimating NMR permeability when used as an input into permeability estimator equations. |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000445705200007 |
WOS关键词 | NUCLEAR-MAGNETIC-RESONANCE ; NMR RELAXATION ; TRANSVERSE RELAXATION ; DEPENDENCE ; DIFFUSION ; PROTONS ; SPHERES ; FLUIDS ; WATER |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/24516 |
专题 | 地球科学 |
作者单位 | Oklahoma State Univ, Boone Pickens Sch Geol, 105 Noble Res Ctr, Stillwater, OK 74078 USA |
推荐引用方式 GB/T 7714 | Obasi, Christian,Pashin, Jack. Effects of internal gradients on pore-size distribution in shale[J]. AAPG BULLETIN,2018,102(9):1825-1840. |
APA | Obasi, Christian,&Pashin, Jack.(2018).Effects of internal gradients on pore-size distribution in shale.AAPG BULLETIN,102(9),1825-1840. |
MLA | Obasi, Christian,et al."Effects of internal gradients on pore-size distribution in shale".AAPG BULLETIN 102.9(2018):1825-1840. |
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