An inventory of the available surficial data on active faults in Italy has been compiled by gathering all the available information on peninsular Italy (project by CNR, National Group for the Defense against Earthquakes), the central-eastern Alps and the Po Plain (EC ‘PALEOSIS’ project). Such information has been summarised in maps (reporting surficial expressions of faults with length L≥11 km) and in a table where fault parameters relevant for seismic hazard assessment (e.g. slip rates, recurrence intervals for surface faulting events, etc..) have been reported. Based on the geological characteristics of the Italian territory, a fault has been considered as active if it shows evidence of Late Pleistocene-Holocene displacements. Active faults in Italy are distributed throughout the entire Apennine chain, in the Sicilian and Calabrian regions and in some Alpine sectors, but knowledge is not homogeneously distributed through the territory. The largest amount of data is related to the central Apennines. In contrast, fault geometries and parameters are less well defined in the southern Apennines, Sicily and Calabria, where investigations have started more recently. Knowledge is sparse in the northern Apeninnes, where data necessary to define fault parameters are lacking and also the chronology of the activity has to be considered cautiously. Abundant blind faulting in the Po Plain hinders the detection of active faults by means of the classical surficial investigations and therefore the present knowledge is limited to the Mantova fault. Blind faults and the peculiar recent geological history of the Alpine areas, which is strongly conditioned by the erosional and depositional activity during and after the last glacial maximum, also hinder the identification of active faults in the central-eastern Alps. Some faults in this Alpine sector are believed to be active, but data on their segmentation are still missing. Available information indicates that Italian active faults are usually characterised by slip rates lower than 1 mm/yr. Recurrence intervals for surface faulting events are longer than 1,000 years in the central and southern Apennines. This review on the Italian active faults represents the first step to produce a map of the major seismic sources in Italy, which in turn will result from the merge of surficial data with seismological and geological subsurficial data. The available knowledge gathered in this paper indicates those areas where data are presently sparse. It should be, therefore, possible to better plan future geomorphological and paleoseismological investigations.

For the first time this project attempts to directly correlate magnetotelluric and geochemical data with the aim of creating a model on the regional distribution of potential pre-Westphalian source rocks deposited in marine environments in the North German basin.

Analysis of the magnetotelluric data shows, that there is a deep good conductor at the north-eastern fringe of the North German basin around the islands of Rügen and Usedom and on the mainland north east of the Anklam Fault. Through integration with seismic data and the offshore well G14 the conductor can be correlated with the Cambro-Ordovician Scandinavian Alum shales. To the south an adjoining area approximately corresponding to the depo-centre of the Rotliegend basin lacks a deep good conductor. Therefore it can be assumed that a regional distribution of comparable source rocks is unlikely. Another excellent and important conductor starts to the south west of the Lower Elbe Line extending along the Dutch-German border into the North Sea, and into the Münsterland. Its place in the local stratigraphy has not been adequately established. It is most likely that this good conductor corresponds to the black shales of the Early Namurian and the Dinantian, which is the case in the boreholes Münsterland 1 and Pröttlin 1 for example. In this paper they are collectively called Rhenohercynian Alum shales. On the Dutch-German border a transition into the “Bowland Shale” facies or equivalents is to be expected. It cannot be ruled out that even stratigraphically older black shales, possibly from the Cambro-Ordovician could contribute to the high integrated conductivity of the deep good conductor.

The evidence of highly conductive layers in the deep subsurface poses the question whether these layers could be potential source rocks for the gases in the north German gas fields. This question can be answered with a clear yes. Gas and isotope geochemical studies on gases from producing Rotliegend deposits have shown that Rhenohercynian Alum shales have been a significant source for these fields. This will be illustrated in detail using the gas fields from the production province “Ems Estuary” as an example.

The Broad Fourteens Basin is a NW-SE trending Mesozoic structural element that was affected by inversion movements during the Late Cretaceous (Subhercynian Phase) and Early Tertiary (Laramide Phase). Since the overlying Tertiary section of this area is relatively little studied, a multi-disciplinary investigation was initiated using both seismic and well data. The present study is the first phase of that project and deals exclusively with the stratigraphical framework and sedimentary development based on well logs from approximately forty wells.

The Tertiary sedimentary section in this area (maximum thickness up to approximately 800 m) consists of siliciclastic rocks that generally correlate well with the established lithostratigraphical framework of the Netherlands. However, the highly variable thickness of these lithological units, illustrated by isopach maps for all units, reflect the intricate pattern of sea level movements, differential vertical movements and the ensuing erosion, that took place in this tectonically active area.

Well P06-02, one of the most complete sections in the center of the area, was selected for detailed biostratigraphical analysis to support further stratigraphical subdivision and correlation. This yielded information on both the distribution pattern of various lithological units and the influence of large, partly global, events during basin development. It is concluded that application of detailed sequence stratigraphy in the study area is very problematic and only 2nd and some 3rd order cycles could be recognized.

This paper presents observations of recent faulting activity in the karstic network of the Rochefort Cave (Namur Province, Belgium, Europe). The principal recent tectonic features are bedding planes reactivated as normal faults, neo-formatted normal faults in calcite flowstone, fresh scaling, extensional features, fallen blocks and displacement of karstic tube. The seismo-tectonic aspect is expanded by the presence of fallen blocks where normally the cavity must be very stable and in equilibrium. Three main N 070° fault planes and a minor one affect, at a decimetre scale, the karst features and morphology. The faults are still active because recent fresh scaling and fallen blocks are observable. The breaking of Holocene soda straw stalactites and displacements of artificial features observed since the beginning of the tourist activity, in the last century, also suggest very recent reactivation of these faults. This recent faulting can be correlated to present-day tectonic activity, already evidenced by earthquakes in the neighbouring area. Therefore, karstic caves are favourable sites for the observation and the quantification of recent tectonic activity because they constitute a 3-D framework, protected from erosion. Fault planes with this recent faulting present slickensides. Thus a quantitative analysis in term of stress inversion, with the help of striated faults, has permitted to reconstruct the stress tensor responsible for the brittle deformation. The principal NW-SE extension (σ3 horizontal) is nearly perpendicular to that of the present regional stress as illustrated by the analysis of the last strong regional earthquake (Roermond, The Netherlands) in 1992. During the Meso-Cenozoic, the main stress tectonics recorded in this part of the European platform is similar to the present one with a NE-SW direction of extension.

The discrepancy between the regional stress field and the local stress in the Rochefort cave can be the result of the inversion of the σ2 and σ3 axes of the stress ellipsoid due to its symmetry or of a local modification at the ground surface of the crustal stress field as it has been already observed in active zones.

Seismic hazard in low seismicity areas of Europe has traditionally been considered insignificant. However, in the light of the recently conducted paleoseismic studies along the Rhine Graben, a revision is required. Previously applied standard probabilistic seismic hazard assessment (PSHA) methods, using Poissonian approach for the earthquake occurrence, can now be substituted by renewal models where fault parameters such as the maximum magnitude, recurrence interval and the elapsed time since the last occurrence of a large earthquake, can be utilized. In this study, the application and the influence of the available paleoseismic data in the Lower Rhine Graben to seismic hazard analysis is demonstrated. The resulting hazard maps, when compared to the standard PSHA using Poissonian approach, indicate a more precise geographical distribution of the estimated seismic hazard levels. The influence of the paleoseismic data seem to be less important for return periods less than a 1000 years. Among the different input models, the highest values reach to 170 cm/sec2 for a 1000 year return period using a combination of Poissonian and renewal models.

In contrast to oil field development, gas field development requires tight integration of subsurface, surface and economic issues due to the difficulty of storing surplus produced gas and the large effect of the back-pressures in a surface network on the individual well performance. As a major gas supplier the Shell Group, and in particular NAM, has extensive experience in this field.

The gas production from onshore fields in the North Friesland area is a recent NAM development. A 10 million cubic meter per day LTS gas treatment installation located near the village of Anjum came on stream in 1997. Production initially started from 3 wells in 2 fields to deliver gas to the Gasunie grid at Grijpskerk. The total area comprises 10 fields and 4 remaining prospects and is planned to be fully developed by the year 2001, using wet gas pipelines to route the production to either the Anjum LTS installation or the Grijpskerk SilicaGel installation.

The Rotliegend reservoirs in this part of the Netherlands are very heterogeneous and require a more detailed subsurface simulation than feasible with the standard NAM tool for gas field development (GENREM). In addition, the area is close to the Waddenzee and based on extensive ecological research, NAM uses a stringent, self-imposed ecological constraint, whilst evaluating the development plans for this area. Detailed subsidence studies have been run using subsidence-modeling tools, which run under a software user-interface called FrontEnd, an in-house development by the Shell Group. Also running under this interface is an application for gas field development called Gas Field Planning Tool (GFPT). GFPT combines a detailed subsurface simulator with a surface simulator using a development planning module, which handles economic and operational aspects of the integrated model. Lastly, the interface gives access to a powerful command language and a mathematical toolbox, which can be used to define almost any missing functionality.

Making use of the flexibility offered by the FrontEnd interface and with help from available expertise in RTS (Shell Rijswijk), an integrated GFPT model was built, which not only incorporates operational and economic constraints, but also does optimization and subsidence analysis. The model is used to evaluate all development options and scenarios for this area in a consistent manner. Therefore, all proposed development plans are optimized within all applied constraints whether they are related to surface, subsurface, economic, or environmental aspects.

Production history and well performance are very close to those predicted by these detailed models, which will allow accurate prediction of future field performance and subsidence.

To provide quantitative information on the ground acceleration necessary to break speleothems, laboratory measurements on samples of stalagmite have been performed to study their failure in bending. Due to their high natural frequencies, speleothems can be considered as rigid bodies to seismic strong ground motion. Using this simple hypothesis and the determined mechanical properties (a minimum value of 0.4 MPa for the tensile failure stress has been considered), modelling indicates that horizontal acceleration ranging from 0.3 m/s2 to 100 m/s2 (0.03 to 10g) are necessary to break 35 broken speleothems of the Hotton cave for which the geometrical parameters have been determined. Thus, at the present time, a strong discrepancy exists between the peak accelerations observed during earthquakes and most of the calculated values necessary to break speleothems. One of the future research efforts will be to understand the reasons of the defined behaviour. It appears fundamental to perform measurements on in situ speleothems.

Gas Field Planning Tool (GFPT) was developed in 1990 by the Shell Group of Companies to fill the need for a tool for gas field planning and development using deterministic subsurface and surface models. Main initiators were Shell Canada, NAM (the Netherlands), Shell Expro (UK) and BSP (Shell Brunei), as these companies are major gas producers.

Shell Companies now have several years experience with using the GFPT. Application ranges from simple single field models to corporate-level models with a large number of gas reservoirs and wells. Shell companies now using GFPT models are Shell Expro (UK), BSP (Brunei), SSB (Malaysia), Shell Canada, SPDC (Nigeria), SDA (Australia), Woodside (Australia), PDO (Oman), NAM (the Netherlands), New Business Development (e.g. Lunar Project) and in future also Shell Egypt.

NAM currently has a GFPT model for the Anjum field in Friesland and for the Ten Arlo field in the north of Holland.

GFPT is currently being migrated to an HFPT (Hydrocarbon Field Planning Tool), which can also be used for planning of condensate, oil and water developments and for control of hydrocarbon compositions in the network using PVT de-lumping at the well head (e.g. for LNG plants) and optimisation techniques (linear, non-linear or based on bean-back lists).

In some karstic caves, the observation of numerous broken stalagmites may provide potential secondary evidence for intense palaeoearthquakes during recent past times. We have named these morpho-sedimentologic features seismothems. A methodology has been developed to discriminate broken speleothems due to earthquake-induced effects or caused by other mechanisms. A study has been carried out in the Belgian karst areas. In the Vesdre Valley, it seems difficult to find evidence of the well-known Verviers earthquake, probably the most destructive historical earthquake known in Belgium which occurred in 1692 AD. The most important concentration of broken stalagmites was discovered in the caves between Hotton and Han-sur-Lesse. The observations in the cave of Hotton suggest a seismic origin, the other origins can not be the cause of the speleothem break. This result implies a strong earthquake situated close to the cave. A preliminary AMS 14C age suggests a minimum age of 10100 ±1200 cal 14C yr BR for one stalagmite rupture in the Hotton cave.

Value Analysis is a powerful tool to increase the value of a capital investment project and to capture cost saving opportunities. It is a method conceived during WorldWar II and frequently used on infrastructure projects, especially in the USA.

The Value Analysis process typically consists of a well prepared 3 to 5 day workshop with focus on generating ideas to improve the current engineering concept. Emphasis is on screening all proposals in order to identify the most promising ideas. The workshop results in a number of proposals to modify the existing engineering concept.

Stork Engineers & Contractors have used the Value Analysis method on several projects as well as in proposals for Engineering, Procurement and Construction (EPC) projects in the Exploration and Production (EP) industry.

Typical results of Value Analysis led to a decrease of Total Cost of Ownership by some 10 to 30%. A well facilitated Value Analysis workshop also leads to mutual trust and understanding between the parties involved.

A key element in a Value Analysis is (re)definition of the proposed functionality of a project. This is done through challenging the existing technical concept by increasing this functionality or by meeting this functionality at a lower cost.

The discovery in 1959 of natural gas in a well drilled by the Nederlandse Aardolie Maatschappij (NAM) near Hoogezand, Gemeente Slochteren, a town in the Province of Groningen, led to the development and establishment of major natural gas production in the Netherlands. This important industrial development could not have started and the necessary investments would not have been made by the industry, if not in accordance with the then applicable Napoleonic Mining Law of 1810 a concession had been applied for and granted allowing to exploit this discovery. From this point of view, admittedly a lawyer’s view, the award of the concession, which was named Groningen, should be considered to be the actual starting point for the aforesaid development.

On 1 July 1961 NAM submitted its application for a concession based on its Slochteren discovery and with this submission the negotiations started between the Netherlands government on the one side and NAM and its two shareholders, viz. Shell and Exxon, on the other side, on the terms and conditions to be incorporated in the applied for concession. On the government’s side attention was focused on two aspects: how to integrate the natural gas discovered into the economy of the country and how to involve the State in the production and disposal thereof. From the outset the government intended, that the State’s interests should be represented by the Staatsmijnen in Limburg (State Mines) in order to give this coal mining enterprise a future outside and independent from its ailing coal mining business in the Province of Limburg. To this end the government arranged for State Mines to enter into a maatschap (partnership) with NAM. In this partnership State Mines would get a 40% participating interest, leaving 60% for NAM. The concession would be granted to NAM, but the latter would be obliged to produce the natural gas reserves contained within the concession for the account and responsibility of the partnership. The partnership would be managed by State Mines with a 50% voting right and by NAM’s two shareholders each with a 25% voting right.

In the deed of concession, which was granted on 30 May 1963, it is stipulated, that any natural gas not needed by the concessionaire for its own operations should be sold to a corporation to be designated by the Minister and the articles of association of which would require the latter’s approval. This corporation, named the NV Nederlandse Gasunie (the Gasunie), was established on 6 April 1963. Its shareholders were (and still are) State Mines (now Energie Beheer Nederland (EBN)) with a 40% shareholding interest, the two shareholders of NAM, each with a 25% interest, and the State itself with a 10% interest. The Gasunie is allowed to realise from its business of buying, transporting and selling natural gas an after tax profit of NGL 80 million per year. Any surplus revenues are transferred to NAM (the transfer sum) in payment of the gas delivered by NAM.

The concession area comprises about 2,970 square km, covering the territory of the Province of Groningen and the territorial waters adjacent to the Province. The concession area includes part of the Waddenzee, an area in respect of which special environmental/zoning rules and regulations are in force. As a matter of fact any exploitation of the gas reserves situated in that area is ruled out, at least for the foreseeable future.

The concession area also includes an area described as the Common Area in the Supplementary Eems I Dollard Agreement of 14 May 1962. Under the terms of this Agreement natural gas produced from the gas reserves situated in the Common Area had to be shared with German concessionaires. NAM was appointed the operator for implementing the provisions of the Agreement.

A certain varying amount of subsidence is experienced throughout the concession area. In this matter the partnership agreed to compensate, up to a certain financial limit, third parties which incurred costs or suffered damage in connection with said subsidence.

The province of Groningen is flat and level, lying at an elevation close to sea level. The area is intensely cultivated and water table levels are a matter of concern. When the size of the Groningen gasfield was recognized in the sixties, it was realized, that substantial subsidence might occur at the surface affecting a large area.

Intensive studies were performed over time to predict future subsidence. These studies are supported by theoretical and experimental research in Shell since the 1950’s concerning reservoir compaction and related surface subsidence. To monitor reservoir compaction and surface subsidence on a regular basis, an extensive monitoring program was set up by NAM. The program comprises leveling surveys, GPS measurements, measurements of shallow formation compaction and in-situ reservoir compaction.

In Groningen weak earthquakes have occurred since 1991 at irregular intervals. A multidisciplinary study from 1991–1993 on the relationship between gas production and earthquakes in the northern part of the Netherlands, combined with further studies concluded, that under certain circumstances these earthquakes may result from gas production. Monitoring is carried out through a seismic observation network with borehole sensors and locally installed accelerometers.

Because of the expected impact of subsidence induced by gas production on surface water management, an Agreement was concluded between the Province of Groningen and NAM.

In line with the 1983 Agreement the ‘Commissie Bodemdaling’ was founded, in which both NAM and the Province of Groningen are represented. On the basis of NAM predictions and actual measurements this Committee determines, what measures are to be taken to prevent, minimize or to correct for effects of gas production induced surface subsidence.

This paper deals with production and pricing policies for the Groningen gasfield. It will provide an evaluation of the past and a view to its future in a liberalized European gas market. The lifelong production potential and high productivity of the Groningen gasfield is unique. The extremely low-cost field is also unique in the sub-optimal manner in which it has been exploited over the whole of its forty year life to date. Its initial monopolistic situation in the West European energy economy created an opportunity for its development to be limited to production levels, whereby super-normal profits were generated on high value sales at the cost of consumers’ welfare.

The breach in the monopoly, through competition from Soviet gas, readily able to undercut Groningen prices, posed a serious threat both to unit values and market expansion. Fortunately, the fortuitous 1973/4 international oil supplies and pricing crisis restored Groningen’s fortunes. Following the upward price adjustments for foreign sales, the stage was set for achieving high company profits and massive government revenues. Dutch society in a broader sense benefited only indirectly through government tax expenditures. Again, energy consumers’ welfare gains were ignored.

This remains the essence of the situation, pending agreement on the introduction of the liberalized market to meet EU directives. Currently the Dutch gas regime and policy objectives are being adjusted to the requirements of operating in a liberalized market. These changes recognize: first, the invalidity of the government’s long-held fears for gas scarcity in such a way, that the earlier steps to restrict both foreign and national sales have been abandoned, and second, the need to reinstate Gasunie as an active, rather than a passive, player in the European gas market, in which other participants have subverted Gasunie’s earlier dominance.

The second part of the paper will examine, whether and how these changes can be reconciled with the core elements of the Dutch gas policy, i.e. state and private revenues, co-ordination of supply and production, the ‘small fields policy’ and the balancing role of the Groningen field. The liberalization of the European gas market, together with changes in the pattern of supply and demand and stated Dutch policy objectives of energy policy may give rise to conflicts between the interests of the Dutch State, the owners of the field and, again, the consumers.