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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 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 flowour 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
 

Containment

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.
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.

 

Monitoring

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.

Sampling intact sediment with microbial mats on top at methane leaking well.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.
 

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