Preprint Article Version 1 NOT YET PEER-REVIEWED

Experimental Investigation of Mechanical Properties of Black Shales after CO2-Water-Rock Interaction

Qiao Lyu 1,2,3 , P.G. Ranjith 3 , Xinping Long 1,2,* , Bin Ji 1,2
  1. School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
  2. Key Laboratory of Hubei Province for Water Jet Theory & New Technology, Wuhan 430072, China
  3. Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Melbourne 3800, Australia
Version 1 : Received: 5 August 2016 / Approved: 5 August 2016 / Online: 5 August 2016 (12:35:12 CEST)

A peer-reviewed article of this Preprint also exists.

Lyu, Q.; Ranjith, P.G.; Long, X.; Ji, B. Experimental Investigation of Mechanical Properties of Black Shales after CO2-Water-Rock Interaction. Materials 2016, 9, 663. Lyu, Q.; Ranjith, P.G.; Long, X.; Ji, B. Experimental Investigation of Mechanical Properties of Black Shales after CO2-Water-Rock Interaction. Materials 2016, 9, 663.

Journal reference: Materials 2016, 9, 663
DOI: 10.3390/ma9080663

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 & 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 sub-/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 sub-/super-critical CO2. Compared to intact samples, 30-days’ saturation causes reductions of 56.43% in UCS and 54.21% in Young’s modulus for sub-critical 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 intact samples to 50.9% for samples saturated in water with sub-critical 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 sub-/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 intact samples.

Subject Areas

shale; CO2-water-rock interaction; mechanical properties; crack propagation; microstructure

Readers' Comments and Ratings (0)

Discuss and rate this article
Views 141
Downloads 115
Comments 0
Metrics 0
Discuss and rate this article

×
Alerts
Notify me about updates to this article or when a peer-reviewed version is published.