4.2.4 The Kingsnorth project (UK)

As mentioned in the previous section, all information in this section results from an analysis of the published FEED study on the Kingsnorth project.

The EON Kingsnorth project considered storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere in the depleted(hydrocarbon reservoir) one where production is significantly reduced Hewett gas field, again a Bunter SandstoneSand that has turned into a rock due to geological processes formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it at about 4 km depth, in the southern part of the UK sector of the North Sea. The demonstration phaseDemonstration phase means that the technology is implemented in a pilot project or on a small scale, but is not yet economically feasible at full scale of the project was limited to a maximum of 20 million tonnes of CO2Carbon dioxide and is required to be completed by 2029. InjectionThe process of using pressure to force fluids down wells of CO2Carbon dioxide was expected to be performed entirely in gaseous phase for the duration of the demonstration phaseDemonstration phase means that the technology is implemented in a pilot project or on a small scale, but is not yet economically feasible at full scale.

Like for the P18-4 reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids of the ROAD project, the targeted Lower Bunter reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids does not have an active aquiferAn underground layer of fluid-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) with significant permeability to allow flow support and will in principle be underpressured at the start of injectionThe process of using pressure to force fluids down wells. There is no connection (expected) between the lower and upper Buntsandstein reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids. Currently the inclusion of the Upper Bunter in the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere complex is under consideration, since this reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids represents a potential CO2Carbon dioxide storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site as wellManmade hole drilled into the earth to produce liquids or gases, or to allow the injection of fluids. Note, that the Upper Bunter reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids does have active aquiferAn underground layer of fluid-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) with significant permeability to allow flow support. For the design of the monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions plan, inclusion of the Upper Bunter reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids has been taken into account as much as possible.

Below the Bunter reservoirs are potential reservoirs separated by the Lower Bunter shaleClay that has changed into a rock due to geological processes and sealing sections of the Zechstein formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it. Communication between these lower reservoirs and the target reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids has been identified as an issue to further investigate, particularly through wells penetrating the lower reservoirs and plugged at the level of the sealAn impermeable rock that forms a barrier above and around a reservoir such that fluids are held in the reservoir between the two reservoirs.

Above the Upper Bunter various other sealing formations, that can act as secondary seals, have been identified.

The monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions plan is in a very early stage of development, and it was mentioned, that refinement was envisaged prior to the start of the project. Therefore no references to remediation methods are made at this stage yet.

The monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions plan is riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event based, with as main risks identified:

• Wells (with old/exploration wells a greater riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event than new drilled wells);
• Faults and Fractures (induced by injectionThe process of using pressure to force fluids down wells);
• Upper Bunter caprockRock of very low permeability that acts as an upper seal to prevent fluid flow out of a reservoir sealAn impermeable rock that forms a barrier above and around a reservoir such that fluids are held in the reservoir leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column;
• Upper Bunter aquiferAn underground layer of fluid-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) with significant permeability to allow flow dissolution/mixing;
• Upper Bunter aquiferAn underground layer of fluid-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) with significant permeability to allow flow ingress into Lower Bunter.

For each of the issues, parameters and measurement needs have been identified and the relevance of each monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions method has been detailed for different scenarios. The scenarios include:

1. InjectionThe process of using pressure to force fluids down wells of high pressure CO2Carbon dioxide into Low Pressure ReservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids: replacement of residual, low pressure, hydrocarbon gas by higher pressure CO2Carbon dioxide in the Lower Bunter;
2. InjectionThe process of using pressure to force fluids down wells of Dense Phase CO2Carbon dioxide into the Upper Bunter: replacement of residual low pressure gas by dense phase CO2Carbon dioxide in the Upper Bunter;
3. Completed injectionThe process of using pressure to force fluids down wells into Upper Bunter and Lower Bunter, pre abandonment(wells) Actions taken to ensure permanent isolation of the fluids and pressures of exposed permeable zones within a well from the surface and from lower pressured zones;
4. Completed injectionThe process of using pressure to force fluids down wells into Upper Bunter and Lower Bunter, post abandonment(wells) Actions taken to ensure permanent isolation of the fluids and pressures of exposed permeable zones within a well from the surface and from lower pressured zones.

For these scenarios monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions plans have been detailed out further based on measureable parameters.

From the technological perspective, a full overview has been made of possible monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions techniques including their sensitivity and accuracy. The current monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions program proposed (but still to be detailed further) is based on bringing together the identified riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event based monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions parameters and the technical monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions feasibility.

It encompasses the following essential monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions programme: continuous measurements of pressure, temperature and flowrates for all wellManmade hole drilled into the earth to produce liquids or gases, or to allow the injection of fluids heads, downhole pressure and temperature measurements for all wells; CO2Carbon dioxide sampling on the seabedBoundary between the free water and the top of the seabottom sediment and at the injectionThe process of using pressure to force fluids down wells facility during the operational and post abandonment(wells) Actions taken to ensure permanent isolation of the fluids and pressures of exposed permeable zones within a well from the surface and from lower pressured zones phase; 4D baseline seismic, repeated seismic on estimated time schedule (e.g., every 5 years), microseismic (optionally together with vertical seismic profileA two-dimensional seismic image of the subsurface, VSP) and wireline logging.

A number of recommended monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions techniques, that reduce the riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event associated with unplanned migrationThe movement of fluids in reservoir rocks localisation, have been identified: for selected wells techniques as distributed temperature sensor, casingA pipe which is inserted to stabilise the borehole of a well after it is drilled strain detection, micro-seismic/in-wellManmade hole drilled into the earth to produce liquids or gases, or to allow the injection of fluids geophones (close to legacy wells or faults with highest reactivation riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event) and optionally time-lapse controlled sourceAny process, activity or mechanism that releases a greenhouse gas, an aerosol, or a precursor thereof into the atmosphere electromagnetic methods (CSEM) are proposed.

Finally the use of dedicated monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions wells is mentioned, though not firmly included in the proposed monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions plan at this stage of the project.

The most striking difference of the monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions program proposed for Kingsnorth compared to ROAD is probably the stronger emphasis on geophysical monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions (time-lapse seismic, CSEM) from the surface to track CO2Carbon dioxide in the reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids and the use of microseismic monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions. Currently not sufficient detail is available on the expected responses of both monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions methods in terms of monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions the CO2Carbon dioxide injectionThe process of using pressure to force fluids down wells processes in the reservoirA subsurface body of rock with sufficient porosity and permeability to store and transmit fluids.