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Increased Oil Recovery
from the Chalk Fields in the
Danish North Sea Sector
Oil in the Danish part of the North Sea is
mainly found in chalk reservoirs. Chalk is
characterized by having high porosity but
low permeability – in other words: it can
contain a lot of oil, but the oil is hard to extract.
Due to the poor permeability it is only
possible to extract a certain amount of the
oil – currently the average rate of extraction
is around 23%. If it was possible to increase
that rate by only 1%, the extra production
over a one year period would supply Denmark
with enough oil to cover the national
oil based energy demand for approximately 2
years. This Offshore Center Danmark project
looked into the challenges connected with
increasing the extraction rate.
The project ran from 2005 to 2007. The
preliminary results were presented at an open
Sub-soil Technology conference in Esbjerg in
February 2007.
Two research institutions – Aalborg University
Esbjerg (AUE) and Geological Survey
of Denmark and Greenland (GEUS) – have
been working on two technologies for the
Increased Oil Recovery
60 Offshore Center Danmark
Yearbook 2008
(IOR) with the subsequent laboratory experiments
and/or numerical modelling.
AUE has focused on Microbial Permeability
Profi le Modifi cation (MPPM), which encompasses
in situ injection of nutrients to the
reservoir micro-organisms, whereas GEUS
has worked on CO2 injection.
AUE was investigating possibilities for
MEOR (Microbial Enhanced Oil Recovery)
implementation in the Danish chalk fi elds.
Microbe adaptation to salinity, formation
water, reaction with molasses, reaction of
microbial fl uid with chalk and gas leakage
has been tested.
GEUS has made a laboratory installation of
reservoir rig for simulation of water fl ooding
and the CO2-enriched fl ooding experiments.
The experiments were made to determine
the saturation evolution of a sample during
a predetermined and precisely controlled
sequence of events.
The project was co-funded by Danish
Ministry of Science, Technology and
Innovation, and was coordinated by Offshore
Center Danmark, with partners
including Ramboll Oil and Gas, GEUS
and Aalborg University (Esbjerg
Institute).
The companies supporting the
project included Noreco, Hess Denmark,
and Baker Oil Tools.
The results of the project were described
in two reports, which can
be obtained at Offshore Center
Danmark. ■