Analysing the role of caprock morphology on history matching of Sleipner CO₂ plume using an optimisation method

Abstract

Geological carbon storage is a promising solution to reduce the CO2 concentration in the atmosphere to ameliorate the effects of global warming from the greenhouse effect. Among feasible storage options, deep saline aquifers are believed to have the largest storage capacity for the gas collected from industrial processes. The first CO2 storage project at a commercial scale in a saline aquifer is in the Sleipner field of the Utsira storage formation in Norway. The long ongoing storage operation in the Sleipner field has been the subject of several past studies attempting to recreate the observed injected CO2 plume migration behaviour. History matching is a method to adjust the input parameters of the model in a way to minimise the mismatch between the simulated and the actual production data in reservoir engineering and applicable to carbon sequestration. Typical parameters adjusted in history matching are porosity, absolute and relative permeability data. In this study, we used an adjoint‐based optimisation tool and showed the importance of caprock morphology in finding an accurate plume match. Using a set of synthetic models, we initially minimised the mismatch between the observed and simulated CO2 plume outline by modifying the caprock topographical details. After testing the optimisation tool on the synthetic models, we applied the methodology to the Sleipner benchmark 2019 model and improved the plume match by locally adjusting caprock elevation within seismic detection limits. We subsequently improved the match by calibrating porosity, permeability, CO2 density and injection rate together in an experiment in which we calibrated all the parameters, including the caprock morphology, to find a better match. The results showed an improvement of around 8% (compared with the original model) in the plume match resulting from an average absolute elevation change of 3.23 m in the model while keeping the other parameters constant. Calibrating the porosity, permeability, CO2 density and injection rate resulted in a 5% improvement in the match, and once caprock morphology was included in the optimisation process, the match improvement increased by 16%. We changed the caprock elevation within a range lower than the seismic detection limit, and results showed that even a few metres variations in the elevation have significant impacts on the plume migration and trapping mechanism in the Sleipner model. The method presented in this work results in a better match than the original seismic data for the Sleipner model. © 2020 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons, Ltd.

Quantitative evaluation of the joint effect of uncertain parameters in CO2 storage in the Sleipner project, using data-driven models

“…While the impact of CO2 impurity on plume migration was negligible, the study showed that raising the average storage site temperature to 46 o C improves the history matching results. A recent history matching study on Sleipner 2019 benchmark model (Ahmadinia, M.& Shariatipour, 2020) showed an improvement of around 8% in the plume match resulted by an absolute elevation calibration of 3.23 meters in the caprock. Calibrating porosity, permeability, CO2 density and injection rate all together resulted in 5% improvements in the match, and once caprock elevation was adjusted too, the match increased by 16%.…”

Storage Sites for Carbon Dioxide in the North Sea and Their Particular Characteristics

“…Ahmadinia and Shariatipour [89,90] found that slight variation of the topography of the interface between the caprock and the upper reservoir, within the aforementioned limits on seismic resolution, led to substantial improvement in the agreement between Darcy flow simulations and the observations of plume distribution.…”

A study on the impact of storage boundary and caprock morphology on carbon sequestration in saline aquifers

“…A good storage candidate will have a secure and very low permeable caprock (extremely tight formation), a large pore volume, good permeability and good pressure connectivity over long distances so the injection will not result in a significant pressure build‐up 38 . Moreover, several parameters, including the presence and size of structural traps, 25,39 the planned amount of injected CO 2 40,41 , likely migration paths, 39 migration speed 42 and the pressure build‐up, 43,44 must be taken into account while characterising a potential storage reservoir 27 . Based on the structural characteristics of the site, the lateral and vertical migration of the CO 2 can be predicted.…”

“…88 The results showed that the plume development has two stages, the first occurring in the full thickness of the aquifer and the second at the top of the site. Several studies have investigated the effect of the caprock on the overall carbon storage process in realistic 8,28,29,41 and synthetic [24][25][26][27][89][90][91] models. The effect of tilt, permeability anisotropy and rugosity, namely the roughness of the surface, with the main focus on the aquifer and caprock interface, were studied previously.…”