Summing up the first newly structured year
SUCCESS 2014 in a nutshell
Following the advice of the midterm evaluation, the SUCCESS centre decided to reorganize from seven to three work packages. 2014 has been the first year with this new structure.
The aim of the SUCCESS center is to acquire sufficient knowledge for subsurface CO2 storage in a secure and lasting way. Elements are finding ways of determining the best storage locations, studying CO2 behavior in the storage, and ensuring that we have ways of detecting any leaks out of the reservoir and assessing potential environmental impacts.
Work Package leaders in FME SUCCESS, from left; Joonsang Park (WP3), Sarah Gasda (WP2) and Helge Hellevang (WP1) Reservoir
In 2014, researchers in Work package 1: Reservoir have studied near-well geochemical reactions, conducting experiments where dry CO2 was injected into salt formation water. Results show the formation of salt plugs, and this process can be modeled using a combination of methods developed in SUCCESS. Salt formation can reduce the injectivity of the reservoir, particularly under conditions of high salinity, like at the Snøhvit field.
Furthermore, in-depth studies have been carried out at the Johansen and Sognefjord formations to see what effects heterogeneities in reservoirs may have on CO2 storage. This is relevant to improve our simulations of CO2 movement, of how the CO2 dissolves in formation water, and of mineralization.
To better understand the risk of leaks we have completed seal-bypass analyses, as these systems show how liquids / fluids migrate to the surface.
Risk analysis has also been performed within a mathematical framework for representation of uncertainty, and implemented in a simplified-physics numerical model. The method produces statistics of outputs, including sensitivities with respect to input uncertainties in physical parameters.
In addition, we have worked with phase equilibria and properties of impure CO2 and the behavior of greenhouse gases affected by hydrocarbons. This can be useful if the CO2 is injected into a former oil or gas field, or to increase the recovery rate of oil mixtures. The results of the work are also valuable with regard to future use of CO2 for enhanced oil recovery.Photo: Salt forming at the vapor-side of the formation water – vapor interface and growing into the pore space, eventually leading to a complete clogging of the flow
In Work package 2: Containment we have done a mechanical analysis of sealing materials at the LYB-pilot. The results suggest that a generally fractured rock with high resistance towards stress and stretch is unlikely to form new cracks during a CO2 injection. On the other hand, existing cracks will be a primary way of increasing the injectivity in this type of rock.
Furthermore, we have completed tests and geochemical analyses on samples from the LYB reservoir. These show that – on geological timescales – there has been very little vertical migration. We therefore find it unlikely that there will be any CO2 migration during injection in this reservoir.The methodology can be used to assess the risk of vertical migration in future reservoirs.Figure: Non-linear rheology results in self-propagating high-porosity chimneys.
For the Sleipner pilot, we have made complex rheology modeling and hydro simulations showing that dense CO2 in interaction with shale as a cap rock in the Utsira Sand may have led to formation of the “chimneys” clearly seen on 4D seismic from the field. Validation of the Utsira data is ongoing.
An analysis of shallow seismic data from a small sector of the “Greater Sleipner” area has been made, revealing an extensive network of canals, fractures and gas pockets in the seal of the Utsira Sand. We are now developing a flow model based on the observations. This will enable us to evaluate the seal integrity of the entire Utsira.
Within Work package 3: Monitoring, we have initiated to combine two monitoring aspects of geophysics and the marine component. Further work on this cross-institutional activity (Development of reference geo-models and leakage scenarios) will hopefully result in a unique monitoring research platform for the CCS society. In the geophysical aspect, we have jointly interpreted gravitational and CSEM data from the Sleipner field in an attempt to estimate the actual total thickness (~ 20 m) and in situ resistivity (~ 22 m) of the CO2 plume at the time of the CSEM data collection (i.e. 2008). Through this work, we can improve surveillance methods for storage reservoirs. This will be a complementary tool to existing seismic methods. In addition, a fast CSEM 3D forward modelling tool has been developed, where only the required parts of a full 3D space are updated and efficiently simulated, e.g. for inversion.
In the marine component aspect, we have observed gas bubbles rising from the seabed at several of the abandoned wells in the Sleipner area over the past years. Samples have been analyzed and the results will be presented in an upcoming article.
A study of annual and interannual variations of carbon cycling parameters is made for Arctic as well as temperate Norwegian fjords, showing that the influence of freshwater dilution dominates over seasonal variations regarding salinity, dissolved inorganic carbon and total alkalinity. Details of biogeochemical transfer of matter at the sediment–water boundary have been modelled by a one-dimensional vertical transport-reaction model. Results confirm that seasonality in production and decay of organic matter significantly affect the redox conditions and carbon species distributions and fluxes.Photo: Sampling intact sediment with microbial mats on top at methane leaking well.