Title

Organic acid concentration thresholds for ageing of carbonate minerals: Implications for CO2 trapping/storage

Document Type

Journal Article

Publication Title

Journal of Colloid and Interface Science

Publisher

Elsevier B.V.

School

School of Engineering

RAS ID

27505

Comments

Originally published as:

Ali, M., Al-Anssari, S., Arif, M., Barifcani, A., Sarmadivaleh, M., Stalker, L., ... & Iglauer, S. (2019). Organic acid concentration thresholds for ageing of carbonate minerals: Implications for CO2 trapping/storage. Journal of Colloid and Interface Science, 534, 88-94.

Original article available here.

Abstract

Hypothesis

CO2 geological storage (CGS) involves different mechanisms which can store millions of tonnes of CO2 per year in depleted hydrocarbon reservoirs and deep saline aquifers. But their storage capacity is influenced by the presence of different carboxylic compounds in the reservoir. These molecules strongly affect the water wetness of the rock, which has a dramatic impact on storage capacities and containment security. However, precise understanding of how these carboxylic acids influence the rock’s CO2-wettability is lacking.

Experiments

We thus systematically analysed these relationships as a function of pressure, temperature, storage depth and organic acid concentrations. A particular focus was on identifying organic acid concentration thresholds above which storage efficiency may get influenced significantly.

Findings

These thresholds (defined for structural trapping as a water contact angle θ > 90°; and for capillary trapping when primary drainage is unaffected, i.e. θ > 50°) were very low for structural trapping (∼10−3–10−7 M organic acid concentration Corganic) and extremely low for capillary trapping (10−7 M to below 10−10 M Corganic). Since minute organic acid concentrations are always present in deep saline aquifers and certainly in depleted hydrocarbon reservoirs, significantly lower storage capacities and containment security than previously thought can be predicted in carbonate reservoirs, and reservoir-scale models and evaluation schemes need to account for these effects to de-risk CGS projects.

DOI

10.1016/j.jcis.2018.08.106

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