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Elisa Guasti, TNO (Netherlands)
Oscar Abbink, TNO (Netherlands)
Geel Kees, TNO (Netherlands)
Leslie Kramers, TNO (Netherlands)
Hanneke Verweij, TNO (Netherlands)
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The Netherlands represent a mature area for hydrocarbon exploration, and only challenging fields are left for finding more oil and gas. One of these critical plays is the Chalk. In this project new biostratigraphical analysis, petrophysical log interpretations, seismic fault interpretations and Petroleum Systems Modeling are combined with high resolution analyses of existing geological, geophysical, geochemical and fluid dynamic data on the Chalk.
The result of this comprehensive and integrated approach is of direct importance for establishing prospectivity of the Chalk in the Netherlands and surrounding areas. The aim of this project is to create a new exploration play concept and to assess the regional distribution of reservoirs, seals and leak points in the Chalk in the Netherlands.
The chalk represents widely extensive deposits on the continental shelf of the North Sea and it is intensely studied from the '70 onwards. The deposition of the chalk took place mainly between the Cenomanian and the Maastrichtian, with local continuation into the Danian. The chalk is a micritic limestone mainly composed by fine algae and in minor part also by larger organisms such as Foraminifera, Ostracods, fragments of bivalves, Echinoids and Bryozoa. The deposition in different paleoenvironmental settings, combined with a complex structural configuration and tectonic history are responsible for creating a wide range of differences in prospectivity.
The reservoir-quality Chalk is, generally, characterized by high porosity and low permeability. Most of the Chalk fields produce from the uppermost part of the Chalk (Maastrichtian and Danian). In contrast the lower part of the Chalk Group, and the Lower Cretaceous shales, are considered to act as a regional seal restricting flow and often preserving high overpressures in underlying units. In The Netherlands, the only producing oil and gas fields in Chalk so far discovered are the Hanze Field offshore and the Harlingen onshore.
A preliminary integrated regional study revealed that differences in sedimentary and burial history of the Dutch Chalk and resulting differences in seismostratigraphic build-up, thickness and porosity of the Chalk correspond to different fluid migration conditions in the Chalk.
To enhance the understanding of the Chalk in the Netherlands, our study builds upon the published information available, in combination with innovative techniques. The regional approach and a detailed comparison with surrounding areas allow the development of a new stratigraphic trap model for the Chalk in The Netherlands.
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