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Impact of Ageing in Supercritical CO2 on Mineralogy, Geochemistry and Geomechanical Properties of Preserved Clay Rich CaprocksNormal access

Authors: D.N Dewhurst, M.D Raven, A Giwelli, S Firns, S.S Md Shah and S.S M Ali
Event name: Asia Petroleum Geoscience Conference and Exhibition 2017
Session: Session 1: IOR/EOR
Publication date: 20 November 2017
DOI: 10.3997/2214-4609.201802832
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 3.12Mb )
Price: € 20

Preserved clay-rich caprocks from a potential CO2 storage site in the Sarawak basin offshore Malaysia were characterised for mineralogy, major element geochemistry and geomechanical properties before and after ageing for up to six months in supercritical CO2 under high temperature and pressure conditions. The S4 shale was dominated by quartz and mixed later illite-smectite, with subsidiary kaolinite and illite plus close to 10% siderite. The S6 shale is also dominated by quartz and mixed later illite-smectite, with lesser kaolinite, smectite illite. The mineralogy of the bulk rock and less than 2 micron fractions did not change with ageing in sCO2 across steps of 1, 4 and 6 months. The major element geochemistry and physico-chemical properties such as cation exchange capacity and specific surface area also did not change. However, geomechanical properties changed significantly after ageing for six months, with both strength and static Young’s modulus increasing significantly. The change in strength is attributed to the loss of pore water during the ageing process.

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