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Results
CCUS in Mature Fields: How Core-to-Log Data-Driven Analytics Enhances Mechanistic Models for the Purpose of Reservoir and Caprock Mineralogical Characterization
Pirrone, Marco (Eni S.p.A.) | Di Maggio, Federica (Eni S.p.A.) | Reolon, Dario (Eni S.p.A.) | Borghi, Massimiliano (Eni S.p.A.) | Mele, Maurizio (Eni S.p.A.)
Abstract This paper discusses how an integrated data-driven analytics (DDA), mechanistic petrophysical and mineralogical modeling can enhance the characterization of reservoirs selected for Carbon Capture, Utilization and Storage (CCUS) projects. The approach makes use of exhaustive core datasets to generate synthetic mineralogical curves at wells, hence expanding the available log information. This allows a robust and complete quantitative analysis of storage and sealing intervals through a DDA-informed physics-based methodology. The growth of interest around CCUS pushes towards in-depth analyses of reservoir layers, as well as of the sealing ones. In brown fields the available open-hole (OH) logs might not be enough for a detailed lithological and petrophysical characterization, which is mandatory to establish the storage capacity of the assets. Hence, the proposed methodology starts from X-Ray Powder Diffraction (XRD) core data representative of the field under investigation for both reservoir and non-reservoir sections. Next, DDA is used to generate synthetic volumetric fractions of given minerals after an ensemble learning relating core mineralogy and selected logs. The DDA-based log mineralogy and the other available OH logs are then input for conventional mechanistic models to obtain final petrophysical and mineralogical properties. The added value is demonstrated through a real case study, where a CCUS project is ongoing for a mature field. From the mineralogical standpoint, experimental studies performed for several cored wells show a wide composition variety with different coexisting phases including carbonates, silicates, feldspars, micas and clays. The main criticality is represented by the OH log datasets that are often incomplete and ineffective to provide a straightforward formation evaluation consistent with the complexity highlighted by core analyses. Therefore, after the calibration of the ensemble learner with hundreds of XRD data, high-frequency dielectric and reprocessed nuclear logs, the DDA steps have been successfully applied to about a hundred wells for obtaining synthetic mineralogical curves. These augment the information of the available measured logs and allow the definition of a physics-based interpretation model able to properly characterize both the reservoir and caprock layers. In addition, the most reactive facies to carbon dioxide are recognized and represent another significant step forward to evaluate the sealing efficiency and integrity over time at field scale. The presented workflow is deemed able to provide a strong mineralogical and petrophysical characterization template in case of incomplete/not exhaustive wellbore dataset. The outcomes are fundamental for several aspects in CCUS projects, including reservoir modeling, geomechanics, geochemistry, monitoring phases and risk management.
- Geology > Geological Subdiscipline > Mineralogy (1.00)
- Geology > Mineral > Silicate > Tectosilicate (0.37)
- Geology > Mineral > Silicate > Phyllosilicate (0.36)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Health, Safety, Environment & Sustainability > Environment > Climate change (1.00)
Abstract The Gorgon Project off north-west coast of Australia plans for the injection of more than 2 trillion cubic feet (TCF) of reservoir CO2. For this purpose, the Dupuy Formation under Barrow Island has been selected as the target reservoir, as it is interpreted to have sufficient capacity, containment and injectivity. In order to gather information to narrow a number of key reservoir uncertainties, the Gorgon Project Joint Venture participants decided to drill a well through the proposed injection target. This paper describes the log and core acquisition programmes of the ‘Gorgon CO2 Data Well’ and shows why the information obtained in this well is essential for the success of the project. The CO2 injection project has been extensively documented and subjected to public comment as part of the Gorgon Project Environmental Impact Assessment Process. Following this process the Western Australian Environmental Protection Authority found that the environmental risks associated with the carbon dioxide injection project were acceptable and recommended that CO2 injection must proceed as an integral component of the Gorgon Project. The pre-CO2 Data Well Dupuy Formation log data base was of mixed quantity, quality and vintage, resulting in wide ranges of key subsurface uncertainties. The logging programme for the well was designed to answer questions about lithology, mineralogy and reservoir quality in order to reduce the impact of the ranges of these uncertainties. Logs ran included nuclear magnetic resonance (NMR), image, dipole sonic, spectroscopy, tri-axial induction logs as well as a comprehensive formation tester program including a number vertical interference tests and medium-scale formation fracture tests, known as ‘mini-fracs’. Pre-CO2 Data Well routine and special core analysis was also very limited in the proposed injection target, so an extensive core program was undertaken. The analysis on the 500m of CO2 Data Well core consisted of a comprehensive set of routine core measurements, permeability at different scales, geochemical analyses, petrography, NMR, mercury injection capillary pressure (MICP) and electrical measurements. As well as providing updated and additional input data to static and dynamic models, the data acquired in the CO2 Data Well has resulted in a shift in reservoir modelling focus as well as giving the team an improved understanding of the reservoir. Some examples of how this was manifested are as follows:- Observed variations in core permeability were analysed and explained through a series of detailed core and log analyses - this has had a direct impact on the modelled distribution of injected CO2 through various parts of the aquifer. - Core and log evidence have significantly narrowed the range of uncertainty in residual oil saturation (Sor) and reduced its absolute value to zero for most of the reservoir, resulting in a reduction in the number of planned wells. - Geomechanical tests on core in combination with insitu tests in the CO2 Data Well have greatly increased the understanding of the geomechanical properties of the Dupuy Formation, resulting in increased confidence in containment of the injected CO2.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Geological Subdiscipline > Petrology > Petrography (0.48)
- Europe > Norway > Barents Sea > Hammerfest Basin > License 100 > Block 7121/7 > Snøhvit Field (0.99)
- Europe > Norway > Barents Sea > Hammerfest Basin > License 100 > Block 7121/7 > Askeladd Field (0.99)
- Europe > Norway > Barents Sea > Hammerfest Basin > License 100 > Block 7121/7 > Albatross Field (0.99)
- (53 more...)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- (3 more...)