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COTEC – CO2 containment and monitoring techniques

Science of sub-surface CO₂ storage derives mainly from small scale projects with injections in human time-scales. Projects not been operational long enough to fully assess flow and/or seepage at longer time scales relevant for subsurface CO₂ sequestration (e.g. > 10 kY). A critical concern in CCS is how to account for features that are detrimental to subsurface storage containment and are at scales below seismic resolution, such as seeps along faults. With the COTEC project we aim to get better knowledge about CO2 containment and monitoring techniques.

Fig. 1 – The COTEC project will mainly focus on the Little Grand Wash Fault south of Green River, Utah, USA (see yellow square), in the vicinity of the San Rafael Swell Monocline (Modified from Zuchuat et al. 2019a).

Fig. 1 – The COTEC project will mainly focus on the Little Grand Wash Fault south of Green River, Utah (yellow square), in the vicinity of the San Rafael Swell Monocline (Modified from Zuchuat et al. 2019a). | Larger map 1000px.

About the project

The impacts of Carbon Capture and Storage (CCS) on mitigating climate change appears more and more crucial (Bui et al., 2018), and Norway has become, over the past decade, one of the leading nations with respect to subsurface CO₂ storage, due in part to its high-level competence in characterization of sub-surface reservoirs.

Reservoirs in the North Sea are matured for CO₂ storage; however, key questions around plume migration mechanisms and pressure linked to site integrity have been raised for both the Sleiper and Snøhvit cases, as well as for the Longyearbyen CO₂ lab and Svelvik pilots. Many examples of fluid escape have been documented in the offshore subsurface environment (e.g. seismic chimneys), and active or relict natural seeps on land offer informative analogues to subsurface fluid migration.

Of note are the natural seeps in east-central Utah, USA (Fig. 1) that are easily accessible and represent suitable onshore counterparts to the offshore fluid escape features, with a specific focus on the Little Grand Wash Fault by Crystal Geyser (Fig. 2), a few kilometres south of Green River. Analysis of these seeps will improve our understanding of geological and geomechanical factors controlling subsurface CO₂ containment and the expression of fluid escape in geophysical images.

Fig. 2 – CO2 has been leaking along the Little Grand Wash Fault in east-central Utah for the past 114 kyr at least, resulting in the near-surface precipitation of travertine, as visible on this geomodel. The schematic A-A’ cross-section illustrate the impact of the Little Grand Wash Fault on the Jurassic and Cretaceous stratigraphy of the area — Fig. 2 – CO₂ has been leaking along the Little Grand Wash Fault in east-central Utah for the past 114 kyr at least, resulting in the near-surface precipitation of travertine, as visible on this geomodel. The schematic A-A’ cross-section illustrate the impact of the Little Grand Wash Fault on the Jurassic and Cretaceous stratigraphy of the area. Larger legend 1000px.

Objectives

The multidisciplinary COTEC-project will address the challenge by collecting surface and subsurface datasets at mesoscopic scales that, through upscaling, will be implemented in seismic investigations and reservoir-seal models (Fig. 3).

$Fig. 3 – Acquisition of a seismic refraction profile across the Little Grand Wash Fault, east-central Utah, view to the South. Photo: Ivar Midtkandal$

Fig. 3 – Acquisition of a seismic refraction profile across the Little Grand Wash Fault, east-central Utah, view to the South. Photo: Ivar Midtkandal

The project builds upon previous studies (COPASS project; Skurtveit et al., 2017; Sundal, 2017; Midtkandal et al 2018; Zuchuat et al. 2018; 2019a; 2019b) but is also relevant for analogous settings such as the Norwegian Continental Shelf (e.g. e.g. Aurora and Smeaheia CO₂ storage prospects, offshore Norway).

Overall, this next research phase specifically focuses on the detailed, post-depositional history of the Jurassic interval in east-central Utah, addressing one fundamental question: what are the thresholds for detecting CO₂ seeps in the subsurface? This encompasses more targeted questions:

What does the fault core and the fault damage zone of the leaking Little Grand Wash Fault consist of?
What is the detailed geological footprint of CO₂ flow along strata, faults, and fractures?
How did the CO₂ flow migrate through a heterogeneous and transitional, faulted reservoir-seal complex?
Can seepage from the storage compartments and fluid saturation be identified by seismic imaging?

Financing

The COTEC project was granted financing from the Norwegian Research Council (grant number 295061). This project is also linked to other ongoing research activity in Norway and the USA, and there is a close association toward other Norwegian and US-based federal and private funds.

The COTEC project timeframe is from from May 2019, with 4 years duration, ending in 2023.