PGK - Petroleum Geologische Kring

Electromagnetic (EM) methods have been used in exploration for a long time, even before seismic. In the early days of exploration Magneto-Telluric (MT) methods have been employed in remote areas as in the field only receivers were required. The source used was either the EM fields generated by the sun or in the ionosphere. In well logging EM is used in induction tools. Recently Controlled Source EM (CSEM) is seen as a way of obtaining independent information on the reservoir fluid. With the receivers the electrical resistivity of thin layers in the subsurface can be obtained. Hence, in addition to seismic information to delineate the geological structure the EM based methods provide the pore-fluid information.

Whereas seismic is based on wave propagation, EM is based on diffusion, or can it also be seen as wave propagation? Just as light can be described by wave propagation along rays as well as by wave-fronts, whatever is most appropriate and convenient, so can EM in the Earth also be described by diffusion as well as propagating "waves", be-it severely attenuated.

In MT often Transverse Electric (TE) and Transverse Magnetic (TM) data are mentioned. The origin of that terminology is related to MT acquisition along seismic lines, which can be acquired in dip direction (to be preferred) or strike direction. MT is often associated with investigating conductivity and CSEM is mainly used for mapping resistivity. It will be shown that combining inductive MT and galvanic CSEM data provide the best resistivity subsurface model and certainly in combination with seismic data for structural information.

However, these various kinds of independent data sets need to be combined. This can be done by sequential inversion but the best way is by joint inversion whereby each data set can be weighted by its estimated accuracy. Results of recent inversions, also including gravity information will be shown.

Late Eocene sea retreat from the Tarim Basin (west China) and concomitant Asian paleoenvironmental change
Roderic Bosboom (Utrecht University)

The Paleogene sediments of the Tarim Basin in western China include the remnants of the easternmost extent of a large epicontinental sea, which extended across the Eurasian continent before it retreated westward and eventually separated as the Paratethys Sea. Climate modeling results suggest that this sea retreat is an important forcing mechanism in the aridification of the Asian continental interior. However, the age and paleogeography of the retreat are poorly constrained, hindering understanding of its cause and impacts. Our research reports litho- and biostratigraphic results from various sections recording the last major regression out of the Tarim Basin. Rich micro- and macrofossil assemblages (including benthic foraminifera, ostracods, bivalves, calcareous nannofossils and dinoflagellate cysts) indicate a shallow, proximal and marine environment and date the last marine sediments as latest Bartonian to earliest Priabonian in age (~37 Ma), time-equivalent to the sea level lowstand at the Bartonian–Priabonian boundary but pre-dating both the Oligocene–Miocene regional uplift of the Pamir and Kunlun Shan and the
major eustatic sea-level falls of the Eocene–Oligocene Transition (~34 Ma) and mid-Oligocene (~30 Ma), which are usually held responsible for the sea retreat. Furthermore, a concomitant and significant aridification step at ~36.6 Ma recorded in the Xining Basin along the northeastern Tibetan Plateau suggests that the Tarim Sea served as a significant moisture contributor for the Asian interior.

Relating Petroleum System- & Play Development to Basin Evolution
Suzanne E. Beglinger, Maarten P. Corver, Harry Doust & Sierd Cloetingh (VU Amsterdam)

Most oil and gas provinces are becoming increasingly mature with respect to exploration. Therefore, our understanding of petroleum prospectivity of less well explored basins becomes more important. In such areas, the use of mature basins as analogues can contribute to the identification of new hydrocarbon discoveries. We anticipate that the use of analogues will become increasingly valuable in exploration. The objective of this research is to increase the knowledge of interpreting basin data in order to facilitate prospectivity prediction in new venture exploration through the recognition of patterns of petroleum system- and play development in basin (cycle)s with similar  tectonostratigraphic characteristics.
We demonstrate a newly developed method, allowing for more efficient comparisons between basins with a similar geological background, i.e. basins which could act as analogues for exploration purposes. We apply the concept that sedimentary basins can be classified according to their structural genesis and evolutionary history. The classification is based on breaking the basins down into their tectonostratigraphic cycles. Common elements of petroleum systems and plays are linked to these natural cycles in order to improve the prediction of potential petroleum systems and plays occurring in under-explored basins.

Full elastic seismic data modeling of an outcrop-based high-resolution geological and petrophysical model, Book Cliffs (Utah, USA)
Daria Tetyukhina, Stefan M. Luthi and Dries Gisolf ( Delft University of Technology)

Outcrop observations are often used to develop predictive models and provide quantitative parameters describing the architecture and facies distribution of shallow-marine deposits at a sub-seismic scale to aid the development of exploration and production strategy. The focus of this project is to create a high-resolution depositional model that provides realistic geological and petrophysical reservoir information. As a basis for our geological and petrophysical modeling the analog data from the Book Cliffs (Utah) was used. The model is populated with shear velocity properties using regressions based on empirical data and laboratory experiment. The resulting realistic high-resolution geological model was used to create a seismic synthetic full elastic data-set that bridges the gap between seismic and analog data. The predicted seismic response allows to asses the appearance of small scale stratigraphic features on the seismic data. The ’Kennett invariant embedding method’ was employed for a forward modeling. The method is exact and calculates all internal multiple reflections and transmission effects, as well as all mode-conversions from P to S and vice-versa. Another potential application of the resulting seismic synthetic full elastic data-set is that the full wave form seismic (linear and non-linear) elastic inversion techniques can be applied/ tested. This inversion can provide insights into understanding and interpreting which geological features can/cannot be resolved from seismic data.

Romania arguably has the largest onshore petroleum basin in Europe and has been producing oil and gas ever since the late 19th Century. More than 60,000 exploration & production wells have been drilled over the last century resulting in almost 300 producing fields. When described in these terms one may expect that petroleum provinces in Romania ought to be very mature and all plays creamed off in terms of exploration potential. However, these facts do not reflect the true level of opportunity that remains in the country as a consequence of a number of factors, such as the low level of modern 3D seismic data coverage, the relatively late application of modern geophysical technology, and the opening up of new acreage offshore into deep water frontiers.

Romania has received much attention recently by oil and gas companies interested in lightly explored conventional and, as yet unexplored, unconventional resources. Exploration joint ventures are also becoming more common in a country where, in the past, the largest Romanian state companies, Petrom and Romgaz, dominated the industry
landscape. In 2005 Petrom was partially privatized and the Austrian integrated oil company, OMV became the controlling shareholder. Since this time, significant efforts have been made to modernize exploration practices and probe the frontier areas of the onshore and offshore basins. Opportunities are also being recognised through the
application of industry-standard Data Management techniques to the enormous legacy well and seismic database.

OMV Petrom is actively exploring “Frontier” areas in Romania, two if which are the deep onshore Thrust Belt plays and the offshore Deep Water in the Western Black Sea. Modern exploration techniques have been employed to identify opportunities in the East Carpathians and in the Deep Water Black Sea. Techniques of particular value are Quantitative Structural Geology and 3D Seismic techniques including specialist processing, 3D volume visualization, seismic facies analysis and seismic attribute extraction.

Exploration in Romania is relatively active despite the Global Crisis. Numerous operators are present in the country ranging from supermajors to very small independents. Romania offers relatively favourable fiscal terms and stable government, therefore it is expected the level of investment in the country will remain at significant levels for the foreseeable future.

Over the last 25 years exploration and production in deepwater (in waterdepth in excess of 500 m) has increased greatly to the point that a considerable amount of today´s industry budget is spent on these activities. Whereas initially little was known about the geological setting of deepwater systems (and few people believed in the presence of sandstone reservoirs beyond the continental shelf edge), we now know that downdip of several Neogene delta´s, major turbidite systems occur with appreciable reserves of oil and gas.
Oil accumulations in turbidite sandstones are not new, in fact production from these reservoirs has been going on in the Mio-Pliocene Los Angeles and San Joaquin pull-apart basins in California before Kuenen coined the term in 1957. Similarly, sizeable accumulations have been found in Upper Jurassic, Lower Cretaceous and Lower Tertiary turbidite sequences in the North Sea in a rift-sag setting.
In the mid-eighties exploration moved into deeper water and driven by successes in the Gulf of Mexico, further efforts focused on the Lower Congo Basin, Campos Basin and offshore Nigeria. A common characteristic of these four basins is that the turbidite depocentres overlie a mobile substrate of salt or overpressured shale which provide a high density of traps with a similar and predictable structural/stratigraphic evolution, stacked reservoir/seal pairs, and an easy access to mature source rocks.
A regional comparison of these basins suggests that in a general sense four structural play types can be defined:
-Immediately downdip from the major deltaic expanders, an area of Inner Folds with large trap
closures postdating the emplacement of channelized turbidite reservoirs.
-An area of Mini-Basins where structuration and sedimentation are more or less coeval leading to the emplacement of stacked confined turbidite sheetsands.
-In areas of salt withdrawal, inversion of minibasins with turbidite sheet sands leads to the formation of Turtles.
-An oceanward area of very large Outer Folds which are structurally coupled to deltaic extension updip and where amalgamated unconfined turbidite channels and sheets occur predating trap formation.
Exploration efforts in turbidite basins without a mobile substrate have so far been more limited and concentrated on the Atlantic margins of the United Kingdom and Norway. Typically the density of structural closures is low but individual structures can be very large in areal extent, quite often with a stratigraphic component. Recently, major discoveries in Equatorial Africa have spurred the industry to take a closer look at Cretaceous turbidite systems on both sides of the African continent in what is a very lightly explored play setting.
The objectives of the presentation will be to illustrate with seismic and well data the analogies and differences between the different deepwater basins, as well as to draw some high level conclusions on risks and uncertainties in turbidite exploration at a play level.

The Macondo well problem, causing loss of live and a massive oil spill in the Golf of Mexico has drawn the attention of senior oilfield experts around the world. Also in the Netherlands a small group of independent experts analyzed the problem and provided these analysis together with proposed solutions to BP and the US government and the government manager of the recovery effort, general Ted Allen. The group of the Dutch experts became  known to the public as the Dutch Hurricane Solutions Team. It's primary focus was to enable continuation of the recovery efforts even when a hurricane would enter the area of the accident. The team provided a solution whereby a tie-in to a nearby pipeline would divert the oil from the Macondo well into this pipeline. As soon as the well was capped, therewith preventing further oil spillage to focus of the team was re-directed to the safe and secure abandonment of the Macondo well. The presentation given by one of the team members will provide an insight in the challenges, solutions and decissions taken throughout the recovery operation.

See also this movie on YouTube.

In the 1990’s, the Dutch government launched an extensive liberalisation and privatisation program. Among others, the power, gas, telecom, postal and rail industries were liberalised.

Some 15 years onwards, the results of liberalisation are still under debate. Most recently, the functioning of the postal and rail industries was heavily criticised. At the same time, gas market reform is still ongoing with a fresh set of changes to the gas law approved by parliament on November 30th. In his presentation, Menno van Benthem will provide an overview of the reforms the Dutch gas market has been subjected to. He will also critically assess the successes and failures of gas market liberalisation from both an academic and a commercial perspective. Menno van Benthem received a PhD from the University of Groningen in January 2010 for his research into gas market liberalisation and currently works for E.ON Benelux as portfolio manager gas.

The Netherlands is a gas country, and since the discovery of the Groningen gas field, the Netherlands has developed into the main gas “hub” of western Europe. The gas resources have brought the Dutch State significant income. Although most explorers will agree that exploration in the Netherlands has become very mature, new reserves continue to be added. How long can we expect this to continue?

Elsewhere, in particular in the USA but also in other countries, unconventional gas has resulted in a sharp increase in gas reserves. Some even speak of a “gas supply revolution”. Recently, in 2009, enormous potential unconventional gas volumes have also been quoted for the Netherlands. Numbers so large that even our Groningen field seemed by comparison rather insignificant. Do we indeed have potential for unconventional gas resources in the Netherlands, and are those quoted numbers realistic?

Unconventional gas occurs in gas-prone basins in tight rocks outside conventional structural or stratigraphic traps. It has a (sub)regional extent and does not have well-defined gas-water contacts, and is normally found below water-bearing reservoirs.

In this talk, we will address the possibilities for the different categories of unconventional gas in the Netherlands, both in-place and recoverable, and the impact of its potential on the future Dutch gas reserves. The technical likelihood of these unconventional gas resources being present, their volume potential as well as the do-ability and societal impact of an unconventional gas development in our densely populated country will be addressed.