Integrating shallow and deep data to understand the spatial ristribution of reservoirs for energy storage in the Utrecht Science Park.

Abstract

High-temperature aquifer thermal energy storage (HT-ATES) offers a potential solution to the seasonal imbalance between heat supply and demand in urban heating and is included in the future low CO2 initiatives proposed for the Utrecht University. To create such a system inside the Utrecht Science Park (USP), Utrecht University, detailed characterization of the subsurface using all the available data is required. Therefore, old and new well logs or reprocessed to advanced, high resolution 2D seismics, were analyzed and interpreted to provide the best litho-stratigraphic, structural and kinematic analysis possible. The aim of the MSc Thesis is to provide a complete geological, structural, litho-stratigraphic analysis of the eastern Utrecht region where the USP is situated, for improvement of the existing subsurface models (DGM, REGIS II) and minimization of the underground uncertainty for implementation of thermal storage facilities. A total of nine normal faults were identified in the area around the Utrecht Science Park (USP) with trendingNW-SE, except ofone majorfaultwhich shiftsfromNNW- SSE to WNW-ESE in the western part of the area of interest. Ten depth maps of shallow formations were interpreted and correlated across the seismic sections from the base of the North Sea Super Group (NSSG) upwards. Fault and stratigraphic interpretation were subsequently used as the base for the construction of a new velocity model to infer the True Vertical Depth (TVD) of each shallow horizon. The main target for HT-ATES is the Maassluis formation, early Pleistocene and the Oosterhout formation, Pliocene, which occur approximately between 150m and 280m. Chrono- and litho-stratigraphic correlation for both formations, was finally conducted, using the available well and seismic data, to propose a conceptual depositional model for the late Miocene-Pleistocene. The model predicts that the Maassluis and Oosterhout formation have been deposited in a prograding delta,shallow marine, near-coastal (Maassluis) to delta front (Oosterhout) environment, with shallow and coarsest deposits in the coastal zone. This deltaic depositional environment during the late Miocene gently prograded seaward towards the northwest before it shifted towards the west, during the Pliocene-Pleistocene, with strong, high-angle seaward progradation to aggradation patterns.