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Abstract: The offshore gas fields in The Netherlands provide a storage capacity of about 1 Gt, which will become available over the next few decades. Existing production facilities may be re-used for injection. Uncertainties in storage capacity, injection rates and time of availability require an analysis of the feasibility of storing CO2 at the rates currently projected for the period 2015–2050. This paper investigates the availability of storage capacity and the feasibility of injecting CO2 at the rate that current capture scenarios foresee. The cost of storage in depleted gas fields is estimated, assuming either re-use of existing installations or the construction of new platforms and wells. Unit cost of storage, non-discounted, in the range of 10 € /t CO2 is feasible for larger fields; costs for small fields are estimated to range up to 40 € /t CO2. Constructing new, dedicated facilities is not always the more expensive option, due to sometimes long hibernation times and higher operational cost of existing facilities. Two capture scenarios are used for the Rotterdam and Amsterdam areas, with captured volumes increasing to 25 Mt/yr or 40 Mt/yr. In both cases, injection rate limitations become apparent when 70–75% of the storage capacity is used, which is around 2055 and 2045, respectively. To ensure continuity of storage, alternatives for storage in offshore gas fields need to be in place by then. [Copyright &y& Elsevier]

Abstract: The onshore Barendrecht CO2 storage project in the densely populated West of the Netherlands is designed to prevent CO2 to migrate out of the deep underground through geological formations and outside of wells. Achieving maximum safe containment is facilitated by selecting depleted gas fields as CO2 storages having stored natural gas over millions of years. This also allows choosing a final storage pressure that is lower than the ambient natural pressure in the surrounding rock formations. The inverse pressure gradient prohibits potential outflow from the storage reservoir. Additional proven safety barriers are the existence of sealing caprocks and large saline aquifers that overlie the storage reservoir. These saline aquifers alone have the capacity to sequester multitudes of the CO2 volumes that are planned to be stored in the depleted gas reservoirs. It is widely accepted that wells hold the main potential of forming a migration path. In the case of Barendrecht this would mainly mean potential migration of reservoir fluids of overlying formations into the CO2 storage reservoir as pressure equalization–returning to a natural equilibrium as existed prior to start of gas production without any overpressures–is not expected to occur before hundreds to thousands of years. Nevertheless assessing the evolution of current and future well integrity with CO2 injection is crucial for ensuring containment of the injected CO2 during injection and in the long term. The Barendrecht fields have respectively two and three drilled and completed wells penetrating the CO2 storage reservoir. This paper describes the most relevant subsurface related highlights from various studies that were carried out in connection with the Barendrecht CO2 storage project. [Copyright &y& Elsevier]

Abstract: Over the past few years several geochemical evaluations of CO2 storage in Dutch potential reservoirs are carried out, including predictions of the short- and long-term impact of CO2 on the reservoir using geochemical modelling. The initial mineralogy of the reservoir is frequently obtained from core analysis and is then used to compute the formation water composition. In this paper geochemical modelling with TOUGHREACT is used to predict and compare the short- and long-term geochemical impact of CO2 injection into three reservoirs. The mineralogical composition of these reservoirs is an assemblage based on commonly observed minerals from the Buntsandstein and Rotliegend formations. These formations contain potential onshore and offshore CO2 storage locations in the Netherlands. The results predict drying out and salt precipitation in the near-well area, due to water evaporation by the injected dry CO2. Several mineral transformations are predicted, dominated by the transformation of albite into dawsonite, thereby fixing CO2. Due to the relatively low density of dawsonite, the porosity significantly decreases, which can lead to a pore pressure increase. Disabling of dawsonite precipitation in the simulations, thereby taking into account the ongoing debate on dawsonite stability, only shows a small increase of the porosity. Future (experimental) work should be focused on dawsonite occurrence for accurate predictions of the long-term reservoir integrity. [Copyright &y& Elsevier]

Abstract: This paper describes the development and application of an methodology to screen and rank Dutch reservoirs suitable for longterm large scale CO2 storage. The screening is focused on off- and on-shore individual aquifers, gas and oil fields. In total 177 storage reservoirs have been taken into consideration (139 gas fields, 4 oil fields and 34 aquifers, with a total storage potential of about 3200 Mt CO2). These reservoirs have been selected from over five hundred potentially suitable CO2 storage reservoirs. The total number of storage reservoirs has been reduced by applying preconditions with associated threshold values. Nevertheless, the number of reservoirs is still significant and limits the possibility to use any pair-wise comparison method (e.g. Multi-Criteria programs such as Bosda or Naiade). Therefore, a excel tool has been developed based on linear aggregation. The tool screens the reservoirs based on three criteria: storage potentials, costs and effort needed to manage risk. [Copyright &y& Elsevier]