Overburden Analysis and Seal Integrity Study for CO2 Sequestration in the North Sea (OASIS)

OASIS (Overburden Analysis and Seal Integrity Study for CO2 Sequestration in the North Sea) is a research project funded by the Research Council of Norway under the CLIMIT programme. The CLIMIT programme is a Norway's national programme for research, development, piloting and demonstration of CO₂ capture and storage (CCS) technologies for power generation and other industrial sources.

Figure: Map showing three potential CO2 storage sites of Smeaheia, Heimdal and Utsira in the North Sea (left). The depth map of the Sognefjord Formation (the main sandstone reservoir in the Smeaheia area, Source: Gassnova) based on a combination of the low density 2D seismic and high density 3D seismic interpretations (right).

Figure: Map showing three potential CO₂ storage sites of Smeaheia, Heimdal and Utsira in the North Sea (left). The depth map of the Sognefjord Formation (the main sandstone reservoir in the Smeaheia area, Source: Gassnova) based on a combination of the low density 2D seismic and high density 3D seismic interpretations (right). (See better version)

About the project

In the OASIS project we will focus on Smeaheia area (one of the three potential sites that evaluated by Equinor) which has been appointed the full-chain CO₂ storage site for the federal NORCCS project (See figure).

Objectives

The objectives of the project are:

To suggest a seismic data derived 3D geomechanical model focusing on the overburden and seal rocks. For geomechanical input the dynamic elastic moduli will be directly computed from the seismic inverted volumes, whereas static elastic moduli will be computed using statistical relations. Uncertainties in the geomechanical input due to lack of the information will be treated as probabilistic input for the simulation for a quantitative risk assessment. The input will be precisely adjusted by additional information such as well log, geological information, geomechanics lab data etc.
To develop a comprehensive understanding of the interactions between geophysical and mechanical behavior of CO₂ storage formation and cap rock.
Use combined information to predict various risks involved with the injection and storage of CO₂ i.e. the present state of stress in the study areas, presence of critically stressed faults, assessment of safe pressure level to avoid leakage by seal damage, or through fractures and/or fault movement under perturbation of pore pressure, predict injection pressure, and direction of induced fracture in case of injection pressure goes above the formation/seal integrity etc.

Researchs tasks

For a safe CO₂ storage, the seal above a potential reservoir and the overburden are extremely important. The seal rock integrity and the overburden rocks will be analysed for the proposed CO₂ storage site "Smeaheia" in order to identify critically stressed faults to predict slip on potential active faults as a function of pore pressure change or build-up, evaluate risk for fracturing, and risk of vertical and lateral CO₂ migration. This makes the project directly applicable and of benefit to existing and future large-scale CO₂ storage projects on the Norwegian Continental Shelf (NCS).

Reliably determining distribution and predicting future movement of CO₂ underground continue to be challenging, but are necessary in the planning and managing of current and future CO₂ storage projects. In terms of seal and overburden, the following information are required in order to ascertain a safe CO₂ storage:

Sufficient thickness of the overburden
Sufficient thickness of the seal/cap rock
Mechanical strength and integrity vis-a-vis injection pressure
Degree of brittleness of the seal/cap rock
Present pore pressure and stress regime within the overburden
Presence of fracture and fault location and orientation
Critically stressed faults
Possible thermos-chemical interaction of CO₂ with the seal rock
Direction of CO₂ plume migration, and
Well integrity (not in present study) and optimum well trajectory through the overburden.

The project’s objectives will be achieved by an interdisciplinary research involving laboratory experiments, petrophysical-geophysical analysis and theoretical/computational modelling. To address project objectives, the research activities are subdivided into three work packages (WP) that deal with seal and overburden characterization (WP1), G&G work (WP2), and geomechanical modelling, calibration and iterations, predictions and sensitivity analysis (WP3).

The seismic data coverage provides us with information from the surface down to a depth below the potential reservoir. Therefore, it can be an excellent source of information of the overburden and seal rock, such as presence and orientation of faults and fractures etc. From seismic inversion the overburden seal-rock characterization information (i.e. brittleness, fluid, sedimentary facies etc.) can be obtained. Furthermore, dynamic elastic moduli obtained by seismic inversion can be used as input to a field scale 3D geomechanical model.

Collaboration

The project will be carried out as a collaborative effort between the University of Oslo (UiO), Norwegian Geotechnical Institute (NGI), Norwegian Computing Center (NR), Curtin University (CU), National Oceanography Centre (NOC), Colorado School of Mines (CSM) and two industry partners TOTAL and Equinor. It will involve experience and young scientists from all partner institutions and will recruit 1 Researcher, 1 PhD Research Fellow and 3 MSc students who will work on the different tasks under the mentorship of the Senior Researchers. The combined knowledge base and track record of the senior and young scientists, and their dedicated integrated efforts, warrant leading edge results from the project.

Research partners

Department of Geosciences, University of Oslo (UiO), Norway
Curtin University (CU), Perth, Australia
Colorado School of Mines (CSM), Golden, CO, USA
Norwegian Computing Center (NR), Oslo, Norway
Norwegian Geotechnical Institute (NGI), Oslo, Norway
National Oceanography Centre (NOC), Southampton, UK

Industry partners

Financing

The name of the project is 'Overburden Analysis and Seal Integrity Study for CO2 Sequestration in the North Sea', in Norwegian: Studier av overdekning og forseglingsintegritet ved CO2-lagring i Nordsjøen.

The project is funded by the Research Council of Norway in the CLIMIT programme, with NFR-project number 280472. Additional funding is acknowledged from Equinor and Total (TotalEnergies).

The project duration of the OASIS is from 2018 to 2022.

Rahman, Md Jamilur; Fawad, Manzar & Mondol, Nazmul Haque (2024). Potential secondary seals within overburden: Observation from the CO<inf>2</inf> storage sites Aurora and Smeaheia, northern North Sea. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 133, p. 1–13. doi: 10.1016/j.ijggc.2024.104101. Full text in Research Archive
Rahman, Md Jamilur; Fawad, Manzar & Mondol, Nazmul Haque (2022). Influence of Rock Properties on Structural Failure Probability—Caprock Shale Examples from the Horda Platform, Offshore Norway. Energies. ISSN 1996-1073. 15(24). doi: 10.3390/en15249598. Full text in Research Archive
Rahman, Md Jamilur; Johnson, James Ronald; Fawad, Manzar & Mondol, Nazmul Haque (2022). Characterization of Upper Jurassic Organic-Rich Caprock Shales in the Norwegian Continental Shelf. Geosciences. ISSN 2076-3263. 12(11). doi: 10.3390/geosciences12110407. Full text in Research Archive
Rahman, Md Jamilur; Fawad, Manzar & Mondol, Nazmul Haque (2022). 3D Field-Scale Geomechanical Modeling of Potential CO<inf>2</inf> Storage Site Smeaheia, Offshore Norway. Energies. ISSN 1996-1073. 15(4). doi: 10.3390/en15041407. Full text in Research Archive
Fawad, Manzar & Mondol, Nazmul Haque (2022). Monitoring geological storage of CO2 using a new rock physics model. Scientific Reports. ISSN 2045-2322. 12. doi: 10.1038/s41598-021-04400-7. Full text in Research Archive
Rahman, Md Jamilur; Fawad, Manzar; Choi, Jung Chan & Mondol, Nazmul Haque (2022). Effect of overburden spatial variability on field-scale geomechanical modeling of potential CO2 storage site Smeaheia, offshore Norway. Journal of Natural Gas Science and Engineering. ISSN 1875-5100. 99. doi: 10.1016/j.jngse.2022.104453. Full text in Research Archive
Rahman, Md Jamilur; Choi, Jung Chan; Fawad, Manzar & Mondol, Nazmul Haque (2021). Probabilistic Analysis of Draupne Shale Caprock Reliability of the Alpha Prospect - A Potential Co2 Storage Site in the Smeaheia Area, Northern North Sea . In Røkke, Nils Anders & Knuutila, Hanna K (Ed.), TCCS–11. CO2 Capture, Transport and Storage. Trondheim 22nd–23rd June 2021. Short Papers from the 11th International Trondheim CCS Conference. SINTEF akademisk forlag. ISSN 978-82-536-1714-5. p. 127–134. Full text in Research Archive
Aker, Eyvind; Kjønsberg, Heidi; Fawad, Manzar & Mondol, Nazmul Haque (2021). Estimation of Thickness and Layering of Johansen and Cook Sandstones at the Potential Co2 Storage Site Aurora . In Røkke, Nils Anders & Knuutila, Hanna K (Ed.), TCCS–11. CO2 Capture, Transport and Storage. Trondheim 22nd–23rd June 2021. Short Papers from the 11th International Trondheim CCS Conference. SINTEF akademisk forlag. ISSN 978-82-536-1714-5. p. 19–26. Full text in Research Archive Show summary
We have estimated the reservoir sand thickness and internal layering in the Aurora area, a planned geological CO2 storage site in the northern North Sea. The results are obtained by stochastic Markov chain Monte Carlo (MCMC) simulations on probabilistic lithology and fluid distributions in the subsurface. The probabilistic distributions are obtained by inverting the seismic data in a Bayesian framework. The inversion is using angle-dependent pre-stack seismic data and the linearized seismic forward model of Aki and Richards to estimate the posterior probabilities of lithology and fluid classes (facies) in the subsurface. The facies are defined from well log data by identifying depth intervals with distinct elastic responses to seismic waves. The inversion methodology and the MCMC simulations are developed and implemented by the Norwegian Computing Center. The planned CO2 storage reservoir comprises the Johansen and Cook sandstones belonging to the Early Jurassic Dunlin Group. The injection site (well 31/5-7) is located south and west of the Troll field in the northern North Sea and is currently being developed by Equinor in partnership with Total and Shell as part of the Northern Light project. The seismic inversion is mapping structural details like faults and internal layering of the sandstones, and the MCMC simulations estimate the probability of sand thickness and expected layering. Results show that the Johansen Formation sandstone has a tendency of layering towards the west and largest thickness to the east in the inversion area. The sandstone in the Cook Formation is generally thinner, and probability maps indicate that it pinches out to the east. Cumulative thickness distributions provide low (P90), median (P50), and high (P10) thickness maps of both Johansen and Cook Formation sandstones. The presented methodology defines a functional workflow for quantifying the thickness uncertainty and possibly internal layering of the reservoir sands. Such results may provide important input for future field development strategies and CO2 migration predictions.
Rahman, MD Jamilur; Choi, Jung Chan; Fawad, Manzar & Mondol, Nazmul Haque (2021). Probabilistic analysis of Vette fault stability in potential CO2 storage site Smeaheia, offshore Norway. International Journal of Greenhouse Gas Control. ISSN 1750-5836. 108. doi: 10.1016/j.ijggc.2021.103315. Full text in Research Archive
Fawad, Manzar; Rahman, MD Jamilur & Mondol, Nazmul Haque (2021). Seismic-derived geomechanical properties of potential CO2 storage reservoir and cap rock in Smeaheia area, northern North Sea. The Leading Edge. ISSN 1070-485X. 40(4), p. 254–260. doi: 10.1190/tle40040254.1.
Choi, Jung Chan; Liu, Zhongqiang; Lacasse, Suzanne & Skurtveit, Elin (2021). Leak-Off Pressure Using Weakly Correlated Geospatial Information and Machine Learning Algorithms. Geosciences. ISSN 2076-3263. 11(4). doi: 10.3390/geosciences11040181. Full text in Research Archive
Fawad, Manzar; Rahman, MD Jamilur & Mondol, Nazmul Haque (2021). Seismic reservoir characterization of potential CO2 storage reservoir sandstones in Smeaheia area, Northern North Sea. Journal of Petroleum Science and Engineering. ISSN 0920-4105. 205. doi: 10.1016/j.petrol.2021.108812. Full text in Research Archive
Fawad, Manzar; Hansen, Jørgen André & Mondol, Nazmul Haque (2020). Seismic-fluid detection-a review. Earth-Science Reviews. ISSN 0012-8252. 210. doi: 10.1016/j.earscirev.2020.103347. Full text in Research Archive Show summary
Since the advent of seismic imaging techniques, the dream of geophysicists has been to identify the fluid effect and be able to accurately map hydrocarbon from the brine within a target reservoir. The usage of bright spots (strong reflection amplitudes) as an indicator of hydrocarbon was the earliest recognition of the direct role played by the pore fluids in seismic signatures. Further development of new techniques had a strong correlation with the increase in computing power and advances in seismic acquisition and processing techniques. In this review, we touch upon the relevant theory developed more than 100 years ago, and then review the methods developed over five decades leading to the quantitative interpretation of seismic data for fluid detection. We also carried out a case study to compare selected fluid identification methods applied to a complex reservoir within an oil and gas field in the Barents Sea. The impedance-based methods “CPEI-Curved Pseudo-elastic Impedance” and “LMR-Lambda-Mu-Rho” inversion provided better results compared to other techniques, highlighting the critical influence anomalous lithologies have on such screening attributes.
Falcon-Suarez, Ismael; Livo, Kurt; Callow, Ben; Marin-Moreno, Héctor; Prasad, Manika & Best, Angus (2020). Geophysical early warning of salt precipitation during geological carbon sequestration . Scientific Reports. ISSN 2045-2322. 10(1). doi: 10.1038/s41598-020-73091-3. Full text in Research Archive Show summary
Sequestration of industrial carbon dioxide ( CO 2) in deep geological saline aquifers is needed to mitigate global greenhouse gas emissions; monitoring the mechanical integrity of reservoir formations is essential for effective and safe operations. Clogging of fluid transport pathways in rocks from CO 2-induced salt precipitation reduces injectivity and potentially compromises the reservoir storage integrity through pore fluid pressure build-up. Here, we show that early warning of salt precipitation can be achieved through geophysical remote sensing. From elastic P- and S-wave velocity and electrical resistivity monitoring during controlled laboratory CO 2 injection experiments into brine-saturated quartz-sandstone of high porosity (29%) and permeability (1660 mD), and X-ray CT imaging of pore-scale salt precipitation, we were able to observe, for the first time, how CO 2-induced salt precipitation leads to detectable geophysical signatures. We inferred salt-induced rock changes from (i) strain changes, (ii) a permanent ~ 1.5% decrease in wave velocities, linking the geophysical signatures to salt volume fraction through geophysical models, and (iii) increases of porosity (by ~ 6%) and permeability (~ 7%). Despite over 10% salt saturation, no clogging effects were observed, which suggests salt precipitation could extend to large sub-surface regions without loss of CO 2 injectivity into high porosity and permeability saline sandstone aquifers.
Rahman, MD Jamilur; Fawad, Manzar & Mondol, Nazmul Haque (2020). Organic-rich shale caprock properties of potential CO2 storage sites in the northern North Sea, offshore Norway. Marine and Petroleum Geology. ISSN 0264-8172. 122. doi: 10.1016/j.marpetgeo.2020.104665. Full text in Research Archive Show summary
Assessment of the geomechanical properties of organic-rich shale caprocks is critical for a successful CO2 storage into a saline aquifer. In this study, we investigated the geochemical properties of the organic-rich shale caprocks of the Draupne and Heather formations, overlying the potential sandstone reservoirs of Sognefjord, Fensfjord, and Krossfjord formations in the northern North Sea, offshore Norway. The caprock’s depositional variations within the sub-basins are established by analyzing the gamma-ray shape and stacking patterns. The effect due to differences in depositional environments, on the caprock compaction behavior is investigated by integrating petrographical analysis of core and cutting samples from 3 wells and by rock physical analysis of wireline log data from 27 exploration wells. Three rock physics templates are used where the wireline log data are interpreted using the published background trends. The effect of kerogen type, maturation level, and deposition environment on caprock properties within the study area are also evaluated. Moreover, the caprock property, such as brittleness, is estimated by using four mineralogy and elastic property-based, empirical relations, which is a quantitative measure of caprock property with respect to changes in stress-state. Finally, the seismic inversion method is assessed for the possibility of extracting caprock properties from surface seismic data. Regardless of compaction processes, the results indicate that the Heather Formation is mechanically stronger than the Draupne Formation. However, both formations appear to be ductile in nature. The depositional environments control the mineralogical composition and fabric of the Draupne and Heather formations, which influence the caprock properties significantly. Results also show that the effect of TOC on caprock properties is insignificant in the study area. The brittleness of the organic-rich shale caprocks in the study area follows a different trend compared to the published trends. We also observed an excellent correlation between the log-derived elastic properties and geomechanical parameters. Still, it is difficult to assess the caprock elastic properties from seismic due to the overlap of data clusters. The evaluation of caprock geomechanical behaviors is challenging as these properties are site-specific and also influenced by other factors such as exhumation, in-situ stress conditions, the existence of natural fractures, and their orientations.
Fawad, Manzar & Mondol, Nazmul Haque (2019). AVO Modelling Considering Various Caprock and Reservoir Scenarios for Potential CO2 Storage in Smeaheie Area, Northern North Sea, 6th EAGE Shale Workshop 2019, Bordequx, France 28 April - 1 May 2019 . European Association of Geoscientists and Engineers (EAGE). ISSN 978-1-5108-8666-7. Full text in Research Archive Show summary
We have performed a comparative study of undrained triaxial testing with five different laboratories, to explore the reproducibility of test results. Opalinus Clay was sourced as testing material from a borehole at the Mont Terri URL. Cores were vacuum-sealed, and resin impregnated immediately after recovery. Systematic determination of basic properties such as water content, grain density and bulk mineralogy of specimens after testing assisted in diagnostic test evaluation. A detailed testing protocol was requested to avoid specimen damage during initial loading («swelling») and to verify specimen saturation. A balanced pore fluid was used for testing, and a consolidation phase was performed to reach specific target effective stress levels prior to the shear phase. One laboratory deviated from these protocols, as it did not use an external pore fluid. Instead, specimens were brought to variable saturation levels in a desiccator prior to assembling them into the rig. For specimens with almost identical basic properties, the test results were indeed found to be in very good agreement, despite the different procedures applied. Differences in test results can be attributed to material heterogeneity. The study provides compelling evidence that robust triaxial testing can be achieved with shales.

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Rahman, Md Jamilur; Fawad, Manzar & Mondol, Nazmul Haque (2022). Lateral distribution of the upper Amundsen shale in potential Co2 storage site Aurora, northern North Sea.
Rahman, Md Jamilur; Fawad, Manzar & Mondol, Nazmul Haque (2022). Potential Effect of Biot’S Coefficient on Rock Failure in CO2 Storage Site Smeaheia, Northern North Sea.
Fawad, Manzar & Mondol, Nazmul Haque (2019). Geological and Geophysical investigation of CO2 storage site Smeaheia in the northern North Sea. SEG technical program expanded abstracts. ISSN 1949-4645. p. 3285–3289. doi: 10.1190/segam2019-3215406.1. Show summary
For a subsurface CO2 storage it is imperative to evaluate the reservoir, seal and overburden viability to avoid any storagerelated problems, or subsequent leakage risks. Whereas, in case of a hydrocarbon trap, the presence of oil and gas itself validates a working reservoir, seal and overburden system. The upper Jurassic Sognefjord Formation is a potential CO2 storage formation overlain by the Heather and Draupne Formations considered to be the cap rocks in the Smeaheie area within the northern North Sea. In this study, we extracted spectral decomposition and similarity attributes at various levels from the top reservoir to the sea floor from a 3D seismic survey covering the area. The attributes facilitated to identify various fault systems and surface features. A prestack seismic inversion was also carried out to obtain elastic property cubes, i.e. acoustic impedance, Vp/Vs ratio, and density. These elastic properties showed changes as a function of compaction and will be used to build a geomechanical model in the next stage of the study. The geological and geophysical properties derived from the seismic attributes, well logs and laboratory measurements of cores/cuttings will be used to calibrate the model.

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Published Sep. 14, 2018 2:02 PM - Last modified Jan. 22, 2023 7:12 PM

Contact

Nazmul Haque Mondol, Professor and Project leader

Participants

Md Nazmul Haque Mondol University of Oslo
Manzar Fawad University of Oslo
Md Jamilur Rahman University of Oslo
Jens Jahren University of Oslo
Alvar Braathen University of Oslo
Jan Inge Faleide University of Oslo
Per Aagaard University of Oslo
Knut Bjørlykke University of Oslo
Roy Helge Gabrielsen University of Oslo

Detailed list of participants

Publications

Publications from the OASIS-project Mar. 25, 2022 1:37 PM