Download a potential co2 storage play in skagerrak

A POTENTIAL CO2 STORAGE PLAY IN SKAGERRAK DEPOSITIONAL ENVIRONMENT AND RESERVOIR GEOLOGY OF
THE GASSUM FORMATION
Manzar Fawad*1, Caroline Sassier1, Erlend Morisbak Jarsve1, Per Aagaard1, Jan Inge Faleide1,
Lars Henrik Nielsen2, Lars Kristensen2, Per E.S. Bergmo3
1
Department of Geosciences, University of Oslo, P.O. Box 1047, Blindern 0316, Oslo, Norway
2
Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 k, Denmark
3
SINTEF, P.O. Box 4760, Sluppen, 7465 Trondheim
*e-mail: [email protected]
Keywords: CO2 Storage, Reservoir, Depositional Environment
A screening study for identifying CO2 storage plays in the Skagerrak and eastern North Sea has
revealed one large open/semi-closed dipping aquifer in the Upper Triassic Gassum Formation,
which is presently under closer study for CO2 storage. The present contribution presents
reservoir characteristics of the Gassum formation in the area north of the Fjerritslev Trough and
a corresponding reservoir model. This reservoir model is part of an ongoing interdisciplinary
project with the overall goal to establish a basis for large-scale handling of CO2 in this area,
including both regional CO2 sources and capture possibilities, transportation and infrastructure,
possible storage sites as well as legal aspects relating to the whole CCS chain. The work is
financed through Interreg/KASK (EU) and the Climit Programme together with industrial and
public funding from Sweden and Norway.
The open/semi-closed dipping aquifer is 40 km long, 25 km wide and 70-170 m thick with net
reservoir of 50 m. The proposed injection depth is 2070 m with the reservoir pinch-out 38 km
away; here the top reservoir is 610 m below sea level and has a cover of 117 m Quaternary
sediments. The southern portion of the reservoir located in Denmark can be characterized from
wells drilled for hydrocarbons and geothermal energy. The Gassum reservoir rocks are mainly
shallow marine shoreface sandstones with associated estuarine deposits possibly deposited
during sea-level low stands. To predict the reservoir facies/parameters and to make a realistic
geologic model comprising the/and area closer to Norway, a regional geological model based on
sequence stratigraphic interpretations is imperative. Using thicknesses from seismic data a
pseudo-well was generated about 50 km north of an existing well in Denmark with the objective
to predict facies. The sandstones are possibly deposited in a high stand setting assuming
sediment sourced from north. A 50% thickness erosion of highstand sandstones were assumed at
each cycle when sea level fell during a low stand. This removed thickness was compensated by
non-reservoir transgressive systems tracts sediments (possible aggrading floodplain or lagoonal
sediments). As good reservoir porosities (~20%) were found in wells in the south, porosities
towards north are expected to be higher owing to shallower depth of burial. The sealing
properties of transgressive shales overlying the low stand sandstones are also important in local
trapping and lateral distribution of the injected CO2. Furthermore the intercalation of shaly
layers and permeability heterogeneities developed in prograding sand systems may provide
additional trapping capacity to the reservoir. This geologic model as one of the likely scenario
Formatert: Engelsk (USA)
favors Gassum Formation as a potential CO2 storage reservoir in Skagerrak area and warrants to
evaluate the reservoir using other possible scenarios.