Mechanical and hydraulic coupling in cement–caprock interfaces exposed to carbonated brine

Walsh, Stuart; Mason, Harris E.; Frane, Wyatt L. Du; Carroll, Susan A.

doi:10.1016/j.ijggc.2014.04.001

Cited by 60 publications

(80 citation statements)

References 30 publications

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“…This hypothesis is supported by recent examinations of reactive fluid flow at debonded cement−caprock interfaces. 28,29 For the same reason, this work suggests that the use of acidic fluids in the stimulation of hydraulic fractures may have a deleterious effect on shale hydrocarbon extraction, as observed experimentally, 30 by increasing X clay on fracture surfaces.…”

Section: ■ Results and Discussionmentioning

confidence: 54%

Sealing Shales versus Brittle Shales: A Sharp Threshold in the Material Properties and Energy Technology Uses of Fine-Grained Sedimentary Rocks

Bourg

2015

Environ. Sci. Technol. Lett.

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Fine-grained sedimentary rocks (shale and mudstone) play important roles in global CO 2 abatement efforts through their uses in carbon capture and storage (CCS), radioactive waste storage, and shale gas extraction. These different technologies, however, rely on seemingly conflicting premises regarding the sealing properties of shale and mudstone, suggesting that those rocks that lend themselves to hydrocarbon extraction may not be optimal seals for CCS or radioactive waste storage, and vice versa. In this paper, a compilation of experimental data on the properties of well-characterized shale and mudstone formations is used to demonstrate that clay mineral mass fraction, X clay , is a very important variable the controls key material properties of these formations and that a remarkably sharp threshold at X clay ∼ 1 / 3 separates fine-grained rocks with very different properties. This threshold coincides with the predictions of a simple conceptual model of the microstructure of sedimentary rocks and is reflected in the uses of shale and mudstone formations for CCS, radioactive waste storage, and shale gas extraction. ■ INTRODUCTIONFine-grained sedimentary rocks (hereafter termed shales and mudstones) account for roughly two-thirds of the sedimentary rock mass. 1,2 Vast formations of these rocks play important roles in three low-carbon energy technologies that have the potential to contribute up to 70% of global CO 2 abatement efforts required to stabilize atmospheric CO 2 levels over the next half-century ( Figure 1). 3,4 In carbon capture and storage (CCS), shale and mudstone are the predominant lithologies used or considered for use as caprocks of geologic CO 2 storage sites. 4,5 In nuclear energy production, they constitute a promising option for isolating radioactive waste on time scales greater than the half-lives of long-lived radioactive fission products. 6 Finally, the transition from coal to natural gas as an energy source in North America is driven largely by hydrocarbons extracted from fine-grained sedimentary rocks. 7 These multiple emerging roles of shale and mudstone have prompted concerns about the allocation of these rocks between hydrocarbon extraction, CCS, and nuclear waste storage. 8 The technologies listed above rely on the ability of finegrained sedimentary rocks to essentially immobilize fluids (water, CO 2 , and hydrocarbons) in the subsurface. Chemical, isotopic, and fluid pressure gradients across shale and mudstone formations indicate that these rocks, at least in some cases, maintain their very low permeability (on the order of 10 −20 m 2 in core-scale laboratory experiments) over length scales of hundreds of meters and time scales of millions of years. 6,9 Figure 1. Contribution of different low-carbon energy technologies to global CO 2 emission reductions over the next century according to one scenario proposed by the Intergovernmental Panel on Climate Change (IPCC). The checkered area highlights the technologies that rely on shale and mudstone. Figure modified from ref 4. Review pubs....

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Section: ■ Results and Discussionmentioning

confidence: 54%

Sealing Shales versus Brittle Shales: A Sharp Threshold in the Material Properties and Energy Technology Uses of Fine-Grained Sedimentary Rocks

Bourg

2015

Environ. Sci. Technol. Lett.

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“…Hence deeper reservoirs could have a positive effect on CO 2 containment of the wellbore cement. In addition to the sealing effect of the pore space, carbonation of cement may also lead to improved geomechanical properties …”

Section: Discussionmentioning

confidence: 99%

Sensitivity of chemical cement alteration – modeling the effect of parameter uncertainty and varying subsurface conditions

et al. 2015

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To ensure the safety of a CO 2 storage site and containment of CO 2 in the subsurface, the integrity of wellbore materials must be maintained. Field and laboratory studies have shown CO 2 -induced reactivity of wellbore cement, but these results have to be extrapolated to the extended time span of CO 2 storage. Geochemical modeling provides a tool for the prediction of cement alteration; however, large uncertainties in input parameters exist and signifi cant variation in subsurface conditions is expected. This asks for a systematic investigation of the sensitivity of modeled cement alteration towards these factors. In this paper we report PHREEQC simulations of CO 2 diffusion into cement and subsequent chemical reactions. The sensitivity of cement alteration toward reaction rates, initial porosity, temperature/mineralogy and fl ow/no fl ow conditions were investigated. The base case model indicated that intact cement and tight interfaces between the reservoir and the cement would yield less than 1% porosity change after 300 days of diffusion. For porosity increase or degradation to occur at the cement interface, leaching/fl ow along the wellbore was required. The sensitivity scenarios yield CO 2 penetration depths between 0.3 cm and 1.4 cm after 300 days of diffusion. The maximum was reached for the high porosity (fast diffusion) scenario that facilitates CO 2 transport through the cement matrix. The minimum CO 2 penetration was for enhanced calcium silicate hydrate (C-S-H) decalcifi cation, which increases calcite precipitation, CO 2 consumption, and hence decelerates CO 2 penetration. This is related to high temperatures (and more crystalline C-S-H) or to higher kinetic rate constants used.

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“…25,26 Geomechanical and geochemical processes over the life span of the well may significantly affect the well integrity. [27][28][29][30][31][32] Moreover, the interaction of CO 2 -rich brine with well cement may rapidly degrade the integrity of the wellbore cement. 5,18,19,25,27,[33][34][35] Bachu and Bennion 25 noted that the degradation of the cement's ability to act as a barrier is directly related to its initial quality.…”

Section: Introductionmentioning

confidence: 99%

Field‐scale well leakage risk assessment using reduced‐order models

2019

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Oil wells that intersect a potential CO2 storage zone in a depleted oil and gas field may provide leakage pathways. It is essential to estimate the field‐scale leakage risk associated with these wells. In this study, a risk‐based approach is used to estimate the risk of leakage. Existing reduced‐order models for well leakage are used to quantitatively estimate well leakage rates for cased‐cemented, cased‐uncemented, and open wellbores. For each existing well that intersects the storage zone, we introduce the well leakage index (WLI), which accounts for wellbore geometry, distance from the injection well, buffer layers between the storage zone and underground sources of drinking water, and the nature of storage zone boundary type. For an initial injection well location, the total site well leakage index (SWLI) is calculated, which is the summation of the WLI for all of the wells. Next, the injector location is varied areally and SWLI is calculated for a specified number of potential injector well locations in the storage zone area. Small values for the SWLI correspond to low well leakage potential, indicating where injection well locations can be considered. The developed criterion provides a means to systemically find the areas with highest and lowest well leakage potential for a storage zone. Due to the reduced order nature of the developed method, it should be a useful tool in the planning and execution phase of the CO2 geological sequestration process. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Mechanical and hydraulic coupling in cement–caprock interfaces exposed to carbonated brine

Cited by 60 publications

References 30 publications

Sealing Shales versus Brittle Shales: A Sharp Threshold in the Material Properties and Energy Technology Uses of Fine-Grained Sedimentary Rocks

Sealing Shales versus Brittle Shales: A Sharp Threshold in the Material Properties and Energy Technology Uses of Fine-Grained Sedimentary Rocks

Sensitivity of chemical cement alteration – modeling the effect of parameter uncertainty and varying subsurface conditions

Field‐scale well leakage risk assessment using reduced‐order models

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