The impact of mineral dissolution on drainage relative permeability and residual trapping in two carbonate rocks

Carbon dioxide (CO2) injection into deep saline aquifers is governed by a number of physico-chemical processes including mineral dissolution and precipitation, multiphase fluid flow, and capillary trapping. These processes can be coupled, however, the impact of fluid-rock reaction on the multiphase flow properties is difficult to study and is not simply correlated to variation in rock porosity. We observed the impact of rock mineral dissolution on multiphase flow properties in two carbonate rocks with distinct pore structures. The Ketton carbonate was an ooidal limestone with a distinct bimodal pore structure whereas the Estaillades limestone was a bioclastic limestone with a wide range of pore sizes. Observations of steady state N2-water relative permeability and residual trapping were obtained at 100 bars fluid pressure and 22°C, with X-ray tomography used to estimate fluid saturation. These tests alternated with steps in which mineral was uniformly dissolved into solution from the rock cores using an aqueous solution with a temperature controlled acid. Eight alternating sequences of dissolution and flow measurement were performed, with on average 0.5% of the mass of the rocks dissolved at each stage. A sequence of mercury injection capillary pressure measurements were conducted on a parallel set of samples undergoing the same treatment to characterize the evolving pore size distribution and corresponding capillary pressure characteristics. Variations in the multiphase flow properties were observed to correspond to the changes in the underlying pore structure. In the Ketton carbonate, dissolution resulted in an increase of the fraction of pore volume made up by the smallest pores and a corresponding increase in the fraction made up by the largest pores. This resulted in a systematic increase in the relative permeability to the nonwetting phase and decrease in relative permeability of the wetting phase. There was also a modest but systematic decrease in residual trapping. In the Estaillades carbonate, dissolution resulted in an increase in the fraction of pore volume made up by pores in the central range of the initial pore size distribution, and a corresponding decrease in the fraction made up by both the smallest and largest pores. This resulted in a decrease in the relative permeability to both the wetting and nonwetting fluid phases and no discernible impact on the residual trapping. In summary, the impact of rock matrix dissolution will be strongly dependent on the impact of that dissolution on the underlying pore structure of the rock. However, if the variation in pore structure can be observed or estimated with modelling, then it should be possible to estimate the impacts on multiphase flow properties.

Date (Creation): 2016-01-01

Citation identifier: http://data.bgs.ac.uk/id/dataHolding/13607386

Point of contact

Organisation name	Individual name	Electronic mail address	Role
Imperial College London	Sam Krevor	not available	Point of contact
Imperial College London	Sam Krevor	not available	Principal investigator
Qatar Carbonates and Carbon Storage Research Centre	qccsrc@imperial.ac.uk	not available	Author
Qatar Carbonates and Carbon Storage Research Centre	qccsrc@imperial.ac.uk	not available	Point of contact

Maintenance and update frequency: notApplicable

GEMET - INSPIRE themes, version 1.0

Geology

BGS Thesaurus of Geosciences

NGDC Deposited Data
Petrophysics
UKCCS
Carbon capture and storage

dataCentre

Keywords

NERC_DDC

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Other constraints: Either: (i) the dataset is made freely available, e.g. via the Internet, for a restricted category of use (e.g. educational use only); or (ii) the dataset has not been formally approved by BGS for access and use by external clients under licence, but its use may be permitted under alternative formal arrangements; or (iii) the dataset contains 3rd party data or information obtained by BGS under terms and conditions that must be consulted in order to determine the permitted usage of the dataset. Refer to the BGS staff member responsible for the creation of the dataset if further advice is required. He / she should be familiar with the composition of the dataset, particularly with regard to 3rd party IPR contained in it, and any resultant use restrictions. This staff member should revert to the IPR Section ( ipr@bgs.ac.uk) for advice, should the position not be clear.

Language: English

Topic category

Geoscientific information

Begin date: 2016-01-01

End date: 2017-01-01

Supplemental Information: Niu, Krevor. (in review)

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No information provided.

Distribution format

Name	Version
Dicom

OnLine resource

Protocol	Linkage	Name
	http://www.bgs.ac.uk/ukccs/accessions/index.html#item120231

OnLine resource

Protocol	Linkage	Name
	http://dx.doi.org/10.5285/f75fe4a2-d7e9-44ee-a855-5f2a25c70a4c	Digital Object Identifier (DOI)

Hierarchy level: Non geographic dataset

Other: non geographic dataset

Conformance result

Title: INSPIRE Implementing rules laying down technical arrangements for the interoperability and harmonisation of Geology

Date (Publication): 2011

Explanation: See the referenced specification

Pass: No

Conformance result

Title: Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services