president's message - American Association of Petroleum Geologists

Figure 3: Overview of the gas reserves and cumulative production from 1965 to 2008 (Oil and gas in The
Netherlands, 2008).
GEOLOGY AND RESERVOIRS
Hydrocarbon plays in the Netherlands range from Carboniferous to
Quaternary age. The Permian Rotliegend play is by far the most important
comprising 65% of the Dutch reserves (even if excluding the Groningen
gasfield) followed by the Triassic play. The Rotliegend play situated in the
Southern Permian Basin (Fig.2) consists of aeolian and fluvial sandstones
which are in an almost ideal position above sourcing Westphalian coal
measures (Carboniferous) and below sealing Zechstein salts. The Triassic play
consists of single or stacked reservoirs of successive sandstone and claystone
formations which have also been sourced by the Westphalian coal measures.
In contrast to e.g. their German neighbours the Dutch are blessed with high
quality reservoirs. As a consequence there is a tendency to only develop
prospects that are not considered or presumed to be ‘tight’. Recovery factors
normally range from 70 to 90% or even exceeding 95% (e.g. the Groningen
field). To give an impression of the relative easiness to produce from fields in
the Netherlands, fracjobs have been performed in only 35
production wells.
FUTURE
Because of its relative small size, its density of population and
the fact that The Netherlands is a low‐lying country there is
continuous concern about possible effects of gas production
such as land subsidence and induced microseismicity.
However, policy and ongoing technical development ensure
that gas exploration and production can be continued for many
decades.
The creaming curve shows no creaming off yet, but as the
‘easy fields’ seem to reach their end of production and
remaining reserves are declining a new impulse is needed to
develop prospects that have been left aside and to increase
exploration activities (Fig. 3, 4). High oil prices have made NAM
decide to restart the production of the heavy oil in the
Schoonebeek field in 2010. On the other side traditionally big
players in The Netherlands like NAM already give signs to
diminish their interest in the Dutch gas production. Their place
can be taken over by players who are more experienced and
willing to produce from difficult reservoirs. Especially
producing from tight reservoirs will be one of the main
challenges. A point of concern is the timing of this change.
AAPG‐ER Newsletter – December 2008
EXPLORATION COUNTRY FOCUS
Large fields are not found anymore, which is also a
result of the present low risk drilling strategy of the
companies. In the future the development of the
smaller fields will only be economically viable when
the present day infrastructure is maintained. This will
require conditions such as high energy prices, a
favorable mining policy and synergy between
different possible users of the infrastructure.
Among the interesting new play concepts are the
indications for Early Carboniferous reefs and
recovery of shallow gas. Recently Chevron has
successfully started the development of a shallow
Plio‐Pleistocene gas field in the Northern Dutch
offshore. This success shows that also this shallow
gas can be produced.
Furthermore, there is increased awareness of the fact
that the assets can be of economic importance even
after the production of hydrocarbons has ended. E.g.
the potential for the use of depleted gas fields for the
storage of natural gas or CO2 draws attention from
policy makers and industry alike.
Overall the proven reserves are still substantial and
new exploration and production activities will play an important role in The
Netherlands for at least the next twenty years. █
Corresponding author: douwe.vanlevernik@tno.nl
REFERENCES
BP Statistical Review of World Energy 2008, www.bp.com
Doornenbal, J.C. et al, 2009. Petroleum Geological Atlas of the Southern
Permian Basin Area. EAGE Publications b.v.
Oil and Gas in The Netherlands Annual review Exploration and Production 2007
A review of oil and gas exploration and production activities during 2007and a
prognosis of the production for the period 2008‐2033. www.nlog.nl
Wong, T., Batjes, D.A.J., de Jager, J., 2007. Geology of the Netherlands
Figure 4: Creaming curve for the gasfields in the Rotliegend reservoirs, representing the bulk of the
Dutch gasfields. (www.nlog.nl)
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