Abstract
The evolution of the pore space of mudrocks induced by drying shrinkage and effective stresses is of importance to several areas of research. Drying is a prerequisite for most mudrock characterization methods, while effective stresses have a direct impact on mudrocks properties such as permeability, compressibility, and strength. Mercury porosimetry intrusion has been widely utilized to show that drying shrinkage and effective stresses lead to the collapse of large pores only (~ > 50 nm), while small pores (~ < 50 nm) remain unaffected. However, the validity of mercury porosimetry intrusion-derived pore size distributions is greatly doubted in the literature due to the fact that most pores in mudrocks are not directly accessible to the surrounding mercury. This study follows a different approach by utilizing a suite of methods including imaging by transmission electron microscopy and scanning electron microscopy at cryogenic temperature after high-pressure freezing (cryoSEM), and gravimetric porosity measurements to investigate the influence of volumetric changes on the pore space of mudrocks. Contrary to previously published results, we show that volumetric changes induced by drying and effective stresses lead to the collapse of pores of all sizes. Furthermore, we show that porosity measured from SEM images is dependent on SEM resolution and reveals only a fraction of the actual porosity. These results provide valuable insights used to interpret the results of characterization methods requiring drying and modeling of effective stress influence on the properties of mudrocks.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4290-4304 |
| Number of pages | 15 |
| Journal | Journal of Geophysical Research: Solid Earth |
| Volume | 124 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1 2019 |
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Keywords
- CryoSEM
- Gulf of Mexico mudrocks
- drying shrinkage
- effective stress application
- mudrock porosity
- pore space evolution
ASJC Scopus subject areas
- Geophysics
- Geochemistry and Petrology
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
Cite this
}
Impact of Drying and Effective Stresses on the Pore Space and Microstructure of Mudrocks. / Deirieh, Amer; Chang, Irene Y.; Casey, Brendan; Joester, Derk; Germaine, John T.
In: Journal of Geophysical Research: Solid Earth, Vol. 124, No. 5, 01.05.2019, p. 4290-4304.Research output: Contribution to journal › Article
TY - JOUR
T1 - Impact of Drying and Effective Stresses on the Pore Space and Microstructure of Mudrocks
AU - Deirieh, Amer
AU - Chang, Irene Y.
AU - Casey, Brendan
AU - Joester, Derk
AU - Germaine, John T.
PY - 2019/5/1
Y1 - 2019/5/1
N2 - The evolution of the pore space of mudrocks induced by drying shrinkage and effective stresses is of importance to several areas of research. Drying is a prerequisite for most mudrock characterization methods, while effective stresses have a direct impact on mudrocks properties such as permeability, compressibility, and strength. Mercury porosimetry intrusion has been widely utilized to show that drying shrinkage and effective stresses lead to the collapse of large pores only (~ > 50 nm), while small pores (~ < 50 nm) remain unaffected. However, the validity of mercury porosimetry intrusion-derived pore size distributions is greatly doubted in the literature due to the fact that most pores in mudrocks are not directly accessible to the surrounding mercury. This study follows a different approach by utilizing a suite of methods including imaging by transmission electron microscopy and scanning electron microscopy at cryogenic temperature after high-pressure freezing (cryoSEM), and gravimetric porosity measurements to investigate the influence of volumetric changes on the pore space of mudrocks. Contrary to previously published results, we show that volumetric changes induced by drying and effective stresses lead to the collapse of pores of all sizes. Furthermore, we show that porosity measured from SEM images is dependent on SEM resolution and reveals only a fraction of the actual porosity. These results provide valuable insights used to interpret the results of characterization methods requiring drying and modeling of effective stress influence on the properties of mudrocks.
AB - The evolution of the pore space of mudrocks induced by drying shrinkage and effective stresses is of importance to several areas of research. Drying is a prerequisite for most mudrock characterization methods, while effective stresses have a direct impact on mudrocks properties such as permeability, compressibility, and strength. Mercury porosimetry intrusion has been widely utilized to show that drying shrinkage and effective stresses lead to the collapse of large pores only (~ > 50 nm), while small pores (~ < 50 nm) remain unaffected. However, the validity of mercury porosimetry intrusion-derived pore size distributions is greatly doubted in the literature due to the fact that most pores in mudrocks are not directly accessible to the surrounding mercury. This study follows a different approach by utilizing a suite of methods including imaging by transmission electron microscopy and scanning electron microscopy at cryogenic temperature after high-pressure freezing (cryoSEM), and gravimetric porosity measurements to investigate the influence of volumetric changes on the pore space of mudrocks. Contrary to previously published results, we show that volumetric changes induced by drying and effective stresses lead to the collapse of pores of all sizes. Furthermore, we show that porosity measured from SEM images is dependent on SEM resolution and reveals only a fraction of the actual porosity. These results provide valuable insights used to interpret the results of characterization methods requiring drying and modeling of effective stress influence on the properties of mudrocks.
KW - CryoSEM
KW - Gulf of Mexico mudrocks
KW - drying shrinkage
KW - effective stress application
KW - mudrock porosity
KW - pore space evolution
UR - http://www.scopus.com/inward/record.url?scp=85065790281&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85065790281&partnerID=8YFLogxK
U2 - 10.1029/2018JB016513
DO - 10.1029/2018JB016513
M3 - Article
VL - 124
SP - 4290
EP - 4304
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
SN - 2169-9313
IS - 5
ER -