Experimental investigation of mechanical properties of black shales after CO2-water-rock interaction

Qiao Lyu, Pathegama Gamage Ranjith, Xinping Long, Bin Ji

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The effects of CO2-water-rock interactions on the mechanical properties of shale are essential for estimating the possibility of sequestrating CO2 in shale reservoirs. In this study, uniaxial compressive strength (UCS) tests together with an acoustic emission (AE) system and SEM and EDS analysis were performed to investigate the mechanical properties and microstructural changes of black shales with different saturation times (10 days, 20 days and 30 days) in water dissoluted with gaseous/super-critical CO2. According to the experimental results, the values of UCS, Young's modulus and brittleness index decrease gradually with increasing saturation time in water with gaseous/super-critical CO2. Compared to samples without saturation, 30-day saturation causes reductions of 56.43% in UCS and 54.21% in Young's modulus for gaseous saturated samples, and 66.05% in UCS and 56.32% in Young's modulus for super-critical saturated samples, respectively. The brittleness index also decreases drastically from 84.3% for samples without saturation to 50.9% for samples saturated in water with gaseous CO2, to 47.9% for samples saturated in water with super-critical carbon dioxide (SC-CO2). SC-CO2 causes a greater reduction of shale's mechanical properties. The crack propagation results obtained from the AE system show that longer saturation time produces higher peak cumulative AE energy. SEM images show that many pores occur when shale samples are saturated in water with gaseous/super-critical CO2. The EDS results show that CO2-water-rock interactions increase the percentages of C and Fe and decrease the percentages of Al and K on the surface of saturated samples when compared to samples without saturation.

Original languageEnglish
Article number663
Number of pages15
JournalMaterials
Volume9
Issue number8
DOIs
Publication statusPublished - 6 Aug 2016

Keywords

  • CO-water-rock interaction
  • Crack propagation
  • Mechanical properties
  • Microstructure
  • Shale

Cite this

@article{8c8f1b624a4449808197d410be9047c1,
title = "Experimental investigation of mechanical properties of black shales after CO2-water-rock interaction",
abstract = "The effects of CO2-water-rock interactions on the mechanical properties of shale are essential for estimating the possibility of sequestrating CO2 in shale reservoirs. In this study, uniaxial compressive strength (UCS) tests together with an acoustic emission (AE) system and SEM and EDS analysis were performed to investigate the mechanical properties and microstructural changes of black shales with different saturation times (10 days, 20 days and 30 days) in water dissoluted with gaseous/super-critical CO2. According to the experimental results, the values of UCS, Young's modulus and brittleness index decrease gradually with increasing saturation time in water with gaseous/super-critical CO2. Compared to samples without saturation, 30-day saturation causes reductions of 56.43{\%} in UCS and 54.21{\%} in Young's modulus for gaseous saturated samples, and 66.05{\%} in UCS and 56.32{\%} in Young's modulus for super-critical saturated samples, respectively. The brittleness index also decreases drastically from 84.3{\%} for samples without saturation to 50.9{\%} for samples saturated in water with gaseous CO2, to 47.9{\%} for samples saturated in water with super-critical carbon dioxide (SC-CO2). SC-CO2 causes a greater reduction of shale's mechanical properties. The crack propagation results obtained from the AE system show that longer saturation time produces higher peak cumulative AE energy. SEM images show that many pores occur when shale samples are saturated in water with gaseous/super-critical CO2. The EDS results show that CO2-water-rock interactions increase the percentages of C and Fe and decrease the percentages of Al and K on the surface of saturated samples when compared to samples without saturation.",
keywords = "CO-water-rock interaction, Crack propagation, Mechanical properties, Microstructure, Shale",
author = "Qiao Lyu and Ranjith, {Pathegama Gamage} and Xinping Long and Bin Ji",
year = "2016",
month = "8",
day = "6",
doi = "10.3390/ma9080663",
language = "English",
volume = "9",
journal = "Materials",
issn = "1996-1944",
publisher = "MDPI",
number = "8",

}

Experimental investigation of mechanical properties of black shales after CO2-water-rock interaction. / Lyu, Qiao; Ranjith, Pathegama Gamage; Long, Xinping; Ji, Bin.

In: Materials, Vol. 9, No. 8, 663, 06.08.2016.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Experimental investigation of mechanical properties of black shales after CO2-water-rock interaction

AU - Lyu, Qiao

AU - Ranjith, Pathegama Gamage

AU - Long, Xinping

AU - Ji, Bin

PY - 2016/8/6

Y1 - 2016/8/6

N2 - The effects of CO2-water-rock interactions on the mechanical properties of shale are essential for estimating the possibility of sequestrating CO2 in shale reservoirs. In this study, uniaxial compressive strength (UCS) tests together with an acoustic emission (AE) system and SEM and EDS analysis were performed to investigate the mechanical properties and microstructural changes of black shales with different saturation times (10 days, 20 days and 30 days) in water dissoluted with gaseous/super-critical CO2. According to the experimental results, the values of UCS, Young's modulus and brittleness index decrease gradually with increasing saturation time in water with gaseous/super-critical CO2. Compared to samples without saturation, 30-day saturation causes reductions of 56.43% in UCS and 54.21% in Young's modulus for gaseous saturated samples, and 66.05% in UCS and 56.32% in Young's modulus for super-critical saturated samples, respectively. The brittleness index also decreases drastically from 84.3% for samples without saturation to 50.9% for samples saturated in water with gaseous CO2, to 47.9% for samples saturated in water with super-critical carbon dioxide (SC-CO2). SC-CO2 causes a greater reduction of shale's mechanical properties. The crack propagation results obtained from the AE system show that longer saturation time produces higher peak cumulative AE energy. SEM images show that many pores occur when shale samples are saturated in water with gaseous/super-critical CO2. The EDS results show that CO2-water-rock interactions increase the percentages of C and Fe and decrease the percentages of Al and K on the surface of saturated samples when compared to samples without saturation.

AB - The effects of CO2-water-rock interactions on the mechanical properties of shale are essential for estimating the possibility of sequestrating CO2 in shale reservoirs. In this study, uniaxial compressive strength (UCS) tests together with an acoustic emission (AE) system and SEM and EDS analysis were performed to investigate the mechanical properties and microstructural changes of black shales with different saturation times (10 days, 20 days and 30 days) in water dissoluted with gaseous/super-critical CO2. According to the experimental results, the values of UCS, Young's modulus and brittleness index decrease gradually with increasing saturation time in water with gaseous/super-critical CO2. Compared to samples without saturation, 30-day saturation causes reductions of 56.43% in UCS and 54.21% in Young's modulus for gaseous saturated samples, and 66.05% in UCS and 56.32% in Young's modulus for super-critical saturated samples, respectively. The brittleness index also decreases drastically from 84.3% for samples without saturation to 50.9% for samples saturated in water with gaseous CO2, to 47.9% for samples saturated in water with super-critical carbon dioxide (SC-CO2). SC-CO2 causes a greater reduction of shale's mechanical properties. The crack propagation results obtained from the AE system show that longer saturation time produces higher peak cumulative AE energy. SEM images show that many pores occur when shale samples are saturated in water with gaseous/super-critical CO2. The EDS results show that CO2-water-rock interactions increase the percentages of C and Fe and decrease the percentages of Al and K on the surface of saturated samples when compared to samples without saturation.

KW - CO-water-rock interaction

KW - Crack propagation

KW - Mechanical properties

KW - Microstructure

KW - Shale

UR - http://www.scopus.com/inward/record.url?scp=84984599956&partnerID=8YFLogxK

U2 - 10.3390/ma9080663

DO - 10.3390/ma9080663

M3 - Article

VL - 9

JO - Materials

JF - Materials

SN - 1996-1944

IS - 8

M1 - 663

ER -