Unloading induced absolute negative pore pressures in a low permeable clay shale

Khaledi, Kavan; Hamdi, Pooya; Winhausen, Lisa; Jalali, Mohammadreza; Jaeggi, David; Amann, Florian

doi:10.1016/j.enggeo.2021.106451

Cited by 12 publications

(2 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The following test case describes this scenario and was motivated by the example presented in Khaledi et al [2021]. It focuses on a core drilling experiment in Opalinus clay.…”

Section: Momas Benchmark: Phase Appearance Testmentioning

confidence: 99%

Extended analysis of benchmarks for gas phase appearance in low-permeable rocks

Grunwald,

Nagel,

Pitz

et al. 2023

Preprint

View full text Add to dashboard Cite

This manuscript presents a comprehensive study on the numerical simulation of gas transport in clay rock, with a specific focus on the transition of the transport regime from single-phase to two-phase conditions.Our code demonstrates the capability to cover this transition seamlessly, without relying on common approaches such as the use of persistent primary variables or the switching of primary variables. To validate our approach, two benchmark tests were conducted.The first benchmark replicates a well-known scenario in the field of radioactive waste disposal, where gas injection induces a transition from single-phase to two-phase flow.The second benchmark simulates a core drilling experiment, where the mechanical unloading of a fully saturated domain results in the appearance of a gas phase. In addition to analyzing primary quantities, a comprehensive set of secondary variables was introduced to gain deeper insights into the model's operation and enhance understanding of the underlying processes.By plotting these secondary variables alongside the primary quantities, a comprehensive understanding of the system's behavior during the transition of flow regimes was obtained. The primary objective of this work is to improve our understanding and confidence in the model used for simulating large repository systems.By successfully capturing the transition from single-phase to two-phase gas transport, our study provides valuable insights into the behavior of gas in clay rock.This enhanced understanding lays the groundwork for utilizing the model effectively in large-scale repository simulations, contributing to the advancement of the field of gas transport in clay rock.

show abstract

“…The following test case describes this scenario and was motivated by the example presented in Khaledi et al [2021]. It focuses on a core drilling experiment in Opalinus clay.…”

Section: Momas Benchmark: Phase Appearance Testmentioning

confidence: 99%

Extended analysis of benchmarks for gas phase appearance in low-permeable rocks

Grunwald,

Nagel,

Pitz

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…The nature of shale pore networks, including pore morphology, connectivity, and distribution (both in organic matter and mineral hosts), is a key factor affecting subsurface transport and storage in shales for the recovery of CH 4 as a transitional fuel, − storage of H 2 , , sequestration of CO 2 , and geomechanical behaviors like tunnel excavation and slope engineering. − Different experimental techniques have been used to characterize the pore structure of shales . The currently available imaging tools for high-resolution three-dimensional (3D) analysis of rock samples include nondestructive instruments, such as X-ray computed tomography (CT), and destructive instruments such as dual beam Focused Ion Beam and Scanning Electron Microscope (FIB-SEM) tomography. , However, the higher resolution provided by advanced imaging techniques such as FIB-SEM and nano-CT inevitably limits the study field-of-view (FOV).…”

Section: Introductionmentioning

confidence: 99%

Assessment of Pore Connectivity and Representative Elementary Volume Size in Marine-Continental Transitional Shale

Xie,

Li,

Elsworth

et al. 2023

Energy Fuels

View full text Add to dashboard Cite

Directly obtaining representative pore structure information is important to understand subsurface shale gas storage and production, while acquiring large-scale and highresolution images using a single imaging tool is plausible as there is always a trade-off between the resolution and field-of-view. We report a new method to define representative elementary volumes (REV) of a shale pore system and define pore structural parameters of diameter, surface area, porosity, and other features. Automated ultrahigh resolution scanning electron microscopy, integrated with a modular automated processing system (MAPS), was used to image pore distribution in two dimensions. Focused ion beam (FIB) milling was further utilized to construct a true three-dimensional digital image, on which the REV analysis was then carried out. The results show that (i) pores are mainly developed in organic matter (OM) and as interparticle inorganic pores and (ii) the diameter of inorganic pores is slightly larger than those in OM. The pore network coordination number, representing the average number of pores that are connected to a specific pore, indicates that the pores can be either clustered within mainly OM pores or more widely connected by slit-like pores and throats in minerals. Extracting cubic sub-blocks, ranging from 500 to 5000 nm in edge dimension, defines the minimum REV as ∼4000 nm, as measured using minimum and maximum pore sizes, surface areas, and shape factors. Combined FIB and MAPS provide insight into pore morphology and connectivity at multiple scales with the reconstructed digital rock used to determine representative REV sizes. Such results are useful in understanding the pore structure in shales and for the rapid acquisition of pore structure distributions.

show abstract