Evaluation of CO2 Storage Potential in Depleted Gas Fields, West Netherlands Basin Dutch Offshore: A Case Study of the P-18 Gas Field
CO2 capture and storage is expected to be become a serious CO2 emission reduction technology in The Netherlands, where interesting opportunities are present in the form of the concentration of major CO2 emission sources in the vicinity of the multiple depleted gas reservoirs in the Dutch offshore. An example of this situation is the nearly-depleted gas field P-18, which is located 20km offshore from the latest extension of Rotterdam’s sea port where a coal-fired power plant is being built. The reservoir in the P-18 field consists of thick (avg. 200m) and deeply buried (>3000m) fluvial and shallow-marine sandstone of the Buntsandstein Subgroup (Lower Triassic). The Solling Claystone and Röt Formations form an impermeable >100-m-thick caprock whereas the reservoir-bounding faults are acting as main sealing structures.
The study focuses on 1) developing an improved high resolution reservoir architecture geomodel (~160Km2) accounting for the inherent fluvial reservoir heterogeneities, 2) estimating the CO2 volumetric storage capacity, 3) assessing the reservoir sealing quality, and 4) evaluating the impact of the reservoir heterogeneities on the CO2 injectivity and subsequent migration from reservoir fluid flow simulations. The improved geomodel was constructed from the revision of the available 3D seismic cube, core data, petrophysical data from 8 wells and a later integration of classic fluvial facies concepts and new sequence stratigraphic correlations for the Triassic Dutch subsurface. Available production data were used to calculate the CO2 storage potential and compared with net pore volume data. Finally, the P-18 reservoir geomodel was upscaled and the dynamic simulations were carried out with Shell In-house MoRes simulator.
The improved P-18 geomodel helped to understand the impact of factors such as lateral connectivity, petrophysical properties and reservoir heterogeneities critical to modeling the CO2 dynamic flow behavior and storage capacity of the P-18 field. A better sealing quality assessment was possible because an improved mapping of fault size and throw was achieved, and the detailed reservoir architecture model showed the juxtaposition of reservoir intervals with impermeable overburden rocks. This study provided an important insight into the uncertainties in the geomodel (e.g., offset in position and dip of faults) in CO2 volume storage calculation, sealing quality assessment and fluid flow simulation.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California