Consultancy
OGS can conduct studies on behalf of clients to assist in the evaluation of potential CO2 storage projects which range from screening studies to support for license applications.
You can use OGS to supplement your subsurface expertise or to provide reservoir engineering human resources you don’t have in-house.
OGS has built experience in all three store types, namely:
A brief description of some of these studies follows.
Closed Saline Aquifer
OGS has worked closely with CarbonCuts to assist with the license application for the Ruby project, which is targeting the Rødby structure in Lolland, onshore southern Denmark. The top reservoir horizon is shown in the figure below taken from a GEUS report.
Rødby is a four-way dip closure in the Bunter Sandstone Formation whose crest is close to one of the two wells drilled in the structure, Rødby-1, at 1075 m TVDSS. Whilst this well, drilled in the late 1950s has a suite of logs, they are not comprehensive nor of the quality that can be obtained nowadays.
From the limited data (of the top surface map and the Rødby-1 log), a set of simulation models were constructed. Working closely with the CarbonCuts’ geoscience professionals, numerous sensitivities were undertaken to evaluate subsurface risk. A particular focus was on downside risk on the commerciality from a low storage mass.
Don’t hesitate to contact us if you think we can help you with your closed saline aquifer project.
Open Saline Aquifer
OGS has worked with TGS to evaluate an Open Saline Aquifer (OSA) in the Norwegian Sea, offshore of Bergen, see figure below which is Fig 5-059 from the NPD CO2 Atlas. This area has a set of west-east dipping thick sandstone layers of variable quality interspersed with shales. The major risk associated with OSAs is whether the CO2 will be contained, or could it escape back to the surface?
The size of these structures (area > 5000 km2, net sands > 500 m) means it’s not practical, nor desirable, to build full field simulation models. However, given the density difference between the injected CO2 and the native brine, the former will, given an available flow path, always migrate upwards, by-passing much of the aquifer volume. The presence of heterogeneity at all scales will disperse the CO2 plume, thereby promoting dissolution and residual trapping to ensure long term storage. OGS have developed a novel workflow which concentrates on smaller scale elements of the OSA, which can be modelled separately at finer resolution to capture these effects more accurately.
Don’t hesitate to contact us if you think we can help you with your open saline aquifer project.
Depleted Gas Field
The Hamilton gas field in the southern part of the East Irish Sea, UK, is the structure cited for storage by the HyNet CCS project. It was extensively studied by the Energy Technology Institute (ETI) in 2015/16 and much of the data, including an Eclipse simulation model, are freely available. OGS decided to use this model and data to improve their understanding of storage in depleted gas fields.
Two simulation models have been developed to date. The first is a full field model (of just over 400,000 active grid cells) in which the 20+ years of production history is modelled using a multi-gas formulation. After a shut-in period, CO2 is then injected until the reservoir pressure returns to its pre-production value. The CO2 properties are provided via a look-up table and the reservoir mixing follows molar volume weighting, i.e. Amagat’s Law.
The second simulation model focusses on the near well bore region in which the concern is reservoir temperature. Well modelling software was used to estimate bottom hole temperature. The simulation grid uses a logarithmically varying grid to capture pressure and temperature changes in the well vicinity, to study the likely degree of cooling which must constitute a hydrate risk(T < 0 °C).
Don’t hesitate to contact us if you think we can help you with your depleted gas field project.