Determination of closed porosity in rocks by small-angle neutron scattering

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• 作者：Jitendra Bahadur ; Cristian R. Medina ; Lilin He ; Yuri B. Melnichenko ; John A. Rupp ; Tomasz P. Blach and David F. R. Mildner
• 关键词：small-angle X-ray scattering ; SANS ; ultra-small-angle X-ray scattering ; USANS ; rock ; CO2 sequestration ; porosity
• 刊名：Journal of Applied Crystallography
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：49
• 期：6
• 页码：2021-2030
• 全文大小：1336K
• ISSN：1600-5767

文摘

Small-angle neutron scattering (SANS) and ultra-small-angle neutron scattering (USANS) have been used to study a carbonate rock from a deep saline aquifer that is a potential candidate as a storage reservoir for CO₂ sequestration. A new methodology is developed for estimating the fraction of accessible and inaccessible pore volume using SANS/USANS measurements. This method does not require the achievement of zero average contrast for the calculation of accessible and inaccessible pore volume fraction. The scattering intensity at high Q increases with increasing CO₂ pressure, in contrast with the low-Q behaviour where the intensity decreases with increasing pressure. Data treatment for high-Q scattering at different pressures of CO₂ is also introduced to explain this anomalous behaviour. The analysis shows that a significant proportion of the pore system consists of micropores (<20 Å) and that the majority (80%) of these micropores remain inaccessible to CO₂ at reservoir pressures.