An Integrated Imaging Study of the Pore Structure of the Cobourg Limestone—A Potential Nuclear Waste Host Rock in Canada

Hu, Zhazha; Lu, Shuangfang; Klaver, Jop; Dewanckele, Jan; Amann-Hildenbrand, Alexandra; Gaus, Garri; Littke, Ralf

doi:10.3390/min11101042

Cited by 7 publications

(4 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is a challenge to evaluate the pore structure of tight oil reservoirs due to the broad PSD, with a significant portion being nanoscale pores and substantially constricted pore throats [5][6][7][8]. However, the pore network system composed of pore bodies and their connecting throats controls the crucial storage space of hydrocarbon and the significant flowing pathway during petroleum accumulation and extraction.…”

Section: Introductionmentioning

confidence: 99%

Pore Size Distribution Characterization by Joint Interpretation of MICP and NMR: A Case Study of Chang 7 Tight Sandstone in the Ordos Basin

Liu

You

et al. 2022

Processes

Self Cite

View full text Add to dashboard Cite

Pore size distribution characterization of unconventional tight reservoirs is extremely significant for an optimized extraction of petroleum from such reservoirs. In the present study, mercury injection capillary pressure (MICP) and low-field nuclear magnetic resonance (NMR) are integrated to evaluate the pore size distribution of the Chang 7 tight sandstone reservoir. The results show that the Chang 7 tight sandstones are characterized by high clay mineral content and fine grain size. They feature complex micro-nano-pore network system, mainly composed of regular primary intergranular pores, dissolved pores, inter-crystalline pores, and micro-fractures. Compared to the porosity obtained from MICP, the NMR porosity is closer to the gas-measured porosity (core analysis), and thus can more accurately describe the total pore space of the tight sandstone reservoirs. The pore throat distribution (PTD) from MICP presents a centralized distribution with high amplitude, while the pore size distribution (PSD) derived from NMR shows a unimodal distribution or bimodal distribution with low amplitude. It is notable that the difference between the PSD and the PTD is always related to the pore network composed of large pores connecting with narrow throats. The PSD always coincides very well with the PTD in the very tight non-reservoirs with a much lower porosity and permeability, probably due to the pore geometry that is dominated by the cylindrical pores. However, a significant inconsistency between the PSD and PTD in tight reservoirs of relatively high porosity and low permeability is usually associated with the pore network that is dominated by the sphere-cylindrical pores. Additionally, Euclidean distance between PSD and PTD shows a good positive correlation with pore throat ratio (PTR), further indicating that the greater difference of pore bodies and pore throats, the more obvious differentiation of two distributions. In summary, the MICP and NMR techniques imply the different profiles of pore structure, which has an important implication for deep insight into pore structure and accurate evaluation of petrophysical properties in the tight sandstone reservoir.

show abstract

Section: Introductionmentioning

confidence: 99%

Pore Size Distribution Characterization by Joint Interpretation of MICP and NMR: A Case Study of Chang 7 Tight Sandstone in the Ordos Basin

Liu

You

et al. 2022

Processes

Self Cite

View full text Add to dashboard Cite

show abstract

“…The microstructure of rocks can often influence their macroscopic mechanical properties to a great extent; a number of studies have been carried out using SEM to investigate the structural morphology [29], porosity [30,31], and fractal dimensions [32,33] of rocks. Due to the anisotropic behavior of rocks, it is very difficult to study the geometric distribution and distribution laws of the pores.…”

Section: Fractal Characteristicsmentioning

confidence: 99%

Microscopic Damage to Limestone under Acidic Conditions: Phenomena and Mechanisms

Xing-ming

Luo

et al. 2022

Sustainability

View full text Add to dashboard Cite

In an acidic environment, the mineral components in rock begin to break down. As a result, the microstructure will be damaged, and then the mechanical properties will deteriorate, which will eventually have a negative effect on engineering stability. In order to study acid damage’s effect on this kind of rock, limestone samples were acidified for 0 days, 5 days, 10 days, 15 days, and 20 days. The microstructure changes in the limestone after acidification were studied via the wave velocity test and electron microscope scanning, and the damage deterioration mechanism was revealed. The results show that the acoustic signal of acidified samples has an obvious absorption effect at high frequency, and the surface pore structure of acidified samples shows fractal characteristics. The P-wave velocity, main peak amplitude, and fractal dimension of the acidified samples did not gradually decrease with time; however, there was a short-term strengthening phenomenon during immersion, which was mainly caused by the formation of CaSO4 crystals.

show abstract

“…The rock pore structure refers to the type, size, distribution, and interconnection of pores and throat in rocks. The pore is the reservoir space where a fluid exists in a rock, and the throat is an important channel to control fluid seepage in a rock. , Limestone is a porous rock widely used in heavy oil thermal recovery, underground storage of nuclear waste, underground coal gasification, and other projects. − The mineral composition, pore, and throat of limestone undergo complex changes under the action of high temperature. In order to explore their changes, some studies have been conducted.…”

Section: Introductionmentioning

confidence: 99%

“… 17 , 18 Limestone is a porous rock widely used in heavy oil thermal recovery, underground storage of nuclear waste, underground coal gasification, and other projects. 19 − 21 The mineral composition, pore, and throat of limestone undergo complex changes under the action of high temperature. In order to explore their changes, some studies have been conducted.…”

Section: Introductionmentioning

confidence: 99%

Pore Structure Evolution and Failure Mechanism of Limestone in the Taiyuan Formation of the Ordos Basin under High Temperature

Kong,

Yin,

Chen

et al. 2024

ACS Omega

View full text Add to dashboard Cite

The study on the destruction of the limestone microstructure after hightemperature treatment has a significant value in the airtightness and safety of underground high-temperature geotechnical engineering. In order to truly simulate the influence of the underground high-temperature environment on limestone, taking seven groups of limestones of the Taiyuan Formation in the Ordos Basin as examples, we carried out a high-temperature (25−1200 °C) heating experiment of limestone in an argon atmosphere. The pore structure of limestone after the high temperature is studied based on scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), porosity, and permeability, and the change in the fractal dimension of the limestone pore structure was discussed based on the thermodynamic fractal theory, combined with X-ray diffraction (XRD) and thermogravimetry differential scanning calorimetry (TG-DSC), the variation of mineral composition with temperature is characterized, and the evolution mechanism of the limestone microstructure under high temperature is discussed. The results show that the evaporation of pore water does not destroy the lattice structure of limestone minerals; however, with the increase of temperature, the complete decomposition of dolomite and calcite occurs, along with the tensile fracture of calcite crystals under the effect of swelling stress. Moreover, the new minerals generated by the decomposition products under the effect of temperature severely damage the crystal structure, leading to the rapid increase of porosity and permeability. The comprehensive results show that the decomposition, expansion, and recrystallization of calcite and dolomite minerals after 800 °C led to the development of limestone macropores and fissures, increased the pore throat radius, enhanced the pore connectivity, simplified the pore structure, and sharply increased the permeability; thus, 800 °C can be used as the critical temperature to change the limestone pores and fractures. The research results can provide data support for subsurface high-temperature geotechnical engineering.

show abstract

An Integrated Imaging Study of the Pore Structure of the Cobourg Limestone—A Potential Nuclear Waste Host Rock in Canada

Cited by 7 publications

References 44 publications

Pore Size Distribution Characterization by Joint Interpretation of MICP and NMR: A Case Study of Chang 7 Tight Sandstone in the Ordos Basin

Pore Size Distribution Characterization by Joint Interpretation of MICP and NMR: A Case Study of Chang 7 Tight Sandstone in the Ordos Basin

Microscopic Damage to Limestone under Acidic Conditions: Phenomena and Mechanisms

Pore Structure Evolution and Failure Mechanism of Limestone in the Taiyuan Formation of the Ordos Basin under High Temperature

Contact Info

Product

Resources

About