Upper Jurassic Sandstones: Detailed sedimentary facies analyses, correlation and stratigraphic architectures of hydrocarbon bearing shoreface complexes in the Dutch offshore area
Publieke samenvatting / Public summary
Summary
This
project involved investigating Upper Jurassic and Lower Cretaceous intervals in
the eastern part of the Dutch offshore area to provide new insights into the
regional and local stratigraphic, depositional and syn-depostional settings. The
project strongly improved understanding of the Upper Jurassic and Lower
Cretaceous in the Dutch offshore by providing a tectono-stratigraphic framework
based on modern concepts of sequence stratigraphy and syn-depositional tectonic
models.
Background
Despite
having numerous known reservoirs, the Upper Jurassic and Lower Cretaceous
stratigraphic interval still held key questions regarding depositional
environments and the preservation of sandy strata. The local and regional
correlation of these strata required new analysis and insights. The study area
encompassed three main structural provinces, the Dutch Central Graben (DCG),
the Terschelling Basin (TB) and the Step Graben (SG), and five platforms, the
Cleaver Bank High (CBH), the Central Offshore Platform (COP), the Friesland
Platform (FP), the Ameland Block (AB) and the Schill Grund High (SGH).
Project
objective
This
project sought to update and increase knowledge on the distribution and
stratigraphic architecture of the Upper Jurassic to Lower Cretaceous reservoir
sands in the areas mentioned. It further aimed to decrease uncertainties
related to the occurrence, spatial distribution and facies of these sandstones,
and build new and robust depositional, stratigraphic and tectono-stratigraphic
models based on new biostratigraphic, facies, sequence stratigraphic and
structural information. Other goals included relating reservoir/field scale
results to key stratigraphic and tectono-stratigraphic events, interpreting
core material to better understand the depositional environments encountered, obtaining
new time lines to better constrain the local and regional correlation between
wells, and to correlate key stratigraphic intervals throughout the study area
using standard well correlation techniques combined with seismic interpretation
along the same sections.
Project
results
The results
obtained from the combination and integration of various analytical techniques were
used to produce a new stratigraphic and tectono-stratigraphic model for Upper
Jurassic and Lower Cretaceous rock in the northern and eastern part of the
Dutch offshore area. The project strongly improved understanding of the Upper
Jurassic and Lower Cretaceous in the Dutch offshore by providing a
tectono-stratigraphic framework based on modern concepts of sequence
stratigraphy and syn-depositional tectonic models. The use of regional seismic
and well-correlation panels helped to better constrain the three main
depositional sequences identified in the study area as well as their varying
preservation potential between the Dutch Central Graben, the Terschelling
Basin, the Step Graben and their surrounding platforms. The project did not include
any substantive seismic mapping such as time structure, isopach or attribute
mapping, leaving those for a follow up project.