scholarly journals Structural analysis of superposed fault systems of the Bornholm horst block, Tornquist Zone, Denmark.

2009 ◽  
Vol 57 ◽  
pp. 25-49 ◽  
Author(s):  
Ole Graversen

The Bornholm horst block is composed of Precambrian crystalline basement overlain by Palaeozoic and Mesozoic cover rocks. The cover intervals are separated by an angular unconformity and a hiatus spanning the Devonian through Middle Triassic interval. Late Palaeozoic faulting of the Early Palaeozoic Baltica platform is correlated with early-middle Carboniferous deformation in the Variscan foreland and with faulting associated with dolerite dyke injection in Skåne in the Late Carboniferous – Early Permian. The Palaeozoic fault systems are striking NW-SE and WNW-ESE and the platform series are dipping towards the SE and ESE respectively. The Mesozoic faulting was associated with the development of a horst-graben framework in the Bornholm-Skåne segment of the Sorgenfrei-Tornquist Zone. Mesozoic fault subsidence started in the Rønne Graben in the Triassic. In the Jurassic the Arnager-Sose block became active, cut off from the Bornholm block; in addition the Læså Graben (new) and the Øle Å fault block complex (new) were cut into the central Bornholm block from the south. In the Late Cretaceous the central Bornholm block was perforated by isolated fault blocks, i.e. the Nyker block, the Bøsthøj block and the Lobbæk block (new) along with subsidence of the Holsterhus block and renewed subsidence of the Arnager-Sose block. The Mesozoic series are dipping towards the southwest. The Palaeozoic fault systems were associated with two-dimensional plane strain during ENE-WSW and NNE-SSW extension. By contrast the Jurassic and Cretaceous fault systems were associated with three-dimensional strain with maximum extension striking NE-SW and secondary extension striking NW-SE. The Mesozoic palaeostress fields were associated with the break down of the Pangea supercontinent.

2020 ◽  
Vol 12 (1) ◽  
pp. 851-865
Author(s):  
Sukonmeth Jitmahantakul ◽  
Piyaphong Chenrai ◽  
Pitsanupong Kanjanapayont ◽  
Waruntorn Kanitpanyacharoen

AbstractA well-developed multi-tier polygonal fault system is located in the Great South Basin offshore New Zealand’s South Island. The system has been characterised using a high-quality three-dimensional seismic survey tied to available exploration boreholes using regional two-dimensional seismic data. In this study area, two polygonal fault intervals are identified and analysed, Tier 1 and Tier 2. Tier 1 coincides with the Tucker Cove Formation (Late Eocene) with small polygonal faults. Tier 2 is restricted to the Paleocene-to-Late Eocene interval with a great number of large faults. In map view, polygonal fault cells are outlined by a series of conjugate pairs of normal faults. The polygonal faults are demonstrated to be controlled by depositional facies, specifically offshore bathyal deposits characterised by fine-grained clays, marls and muds. Fault throw analysis is used to understand the propagation history of the polygonal faults in this area. Tier 1 and Tier 2 initiate at about Late Eocene and Early Eocene, respectively, based on their maximum fault throws. A set of three-dimensional fault throw images within Tier 2 shows that maximum fault throws of the inner polygonal fault cell occurs at the same age, while the outer polygonal fault cell exhibits maximum fault throws at shallower levels of different ages. The polygonal fault systems are believed to be related to the dewatering of sedimentary formation during the diagenesis process. Interpretation of the polygonal fault in this area is useful in assessing the migration pathway and seal ability of the Eocene mudstone sequence in the Great South Basin.


2021 ◽  
pp. M57-2021-15
Author(s):  
E. V. Deev ◽  
G. G. Shemin ◽  
V. A. Vernikovsky ◽  
O. I. Bostrikov ◽  
P. A. Glazyrin ◽  
...  

AbstractThe Yenisei-Khatanga Composite Tectono-Sedimentary Element (YKh CTSE) is located between the Siberian Craton and the Taimyr-Severnaya Zemlya fold-and-thrust belt. The total thickness of the Mesoproterozoic-Cenozoic sediments of YKh CTSE reaches 20 to 25 km. They are divided into four tectono-sedimentary elements (TSE): (i) Mesoproterozoic-early Carboniferous Siberian Craton continental margin, (ii) middle Carboniferous-Middle Triassic syn-orogenic Taimyr foreland basin, (iii) late Permian-Early Triassic syn-rift, and (iv) Triassic-Early Paleocene post-rift. The last one is the most important in terms of its petroleum potential and is the most drilled part of the CTSE. Its thickness accounts for half of the total thickness of YKh CTSE. The margins of the post-rift TSE and the inner system of inversion swells and adjacent troughs and depressions were shaped by three tectonic events: (i) middle Carboniferous-Middle Triassic Taimyr orogeny, (ii) Late Jurassic-Early Cretaceous Verkhoyansk orogeny, (iii) Late Cenozoic uplift. These processes led to more intense migration of hydrocarbons, the trap formation and their infill with hydrocarbons. Triassic, Jurassic, and Lower Cretaceous source rocks are mostly gas-prone, and among 20 discovered fields in Jurassic and Cretaceous plays, 17 are gas or mixed-type fields.


Author(s):  
Jan Zalasiewicz ◽  
Mark Williams

There is a celebrated Flemish painting by Pieter Bruegel the Elder in the Kunsthistorisches Museum in Vienna. It depicts the age-old battle between Carnival and Lent. Carnival—a time of high spirits, led in this vision by a fat man on a beer-barrel, carousing and brandishing a pig’s head on a spit—is opposed by Lent, deflating the happy excitement and bringing in a time of sobriety and abstinence. Bruegel’s understanding of these opposed rhythms of rural life in the sixteenth-century Netherlands was acute: he was nicknamed ‘Peasant Bruegel’ for his habit of dressing like the local people, to mingle unnoticed with the crowds, all the better to observe their lives and activities. Bruegel’s vision of the age-old rhythm of life, in the form of an eternal oscillation between two opposing modes, may be taken to a wider stage. From the late Archaean to the end of the Proterozoic, the Earth has alternated between two climate modes. Long episodes of what may be regarded as rather dull stability, best exemplified by what some scientists refer to as the ‘boring billion’ of the mid-Proterozoic, are punctuated by the briefer, though more satisfyingly dramatic, glacial events. This alternation of Earth states persisted into the last half-billion years of this planet’s history—that is, into the current eon, the Phanerozoic. If anything, the pattern became more pronounced, as if it had become an integral part of the Earth’s slowly moving clockwork. There were three main Phanerozoic glaciations—or more precisely, there were three intervals of time when the world possessed large amounts of ice—though in each of these, the ice waxed and waned in a rather complex fashion, and none came close to a Snowball-like state. Thus, these intervals often now tend to be called ‘icehouse states’ rather than glaciations per se. Between these, there were rather longer intervals—greenhouse states—in which the world was considerably warmer; though again, this warmth was variable, and at times modest amounts of polar ice could form. Of the Earth’s Phanerozoic icehouse states, two are in the Palaeozoic Era: one, now termed the ‘Early Palaeozoic Icehouse’ centred on the boundary between the Ordovician and Silurian periods, peaking some 440 million years ago; and a later one centred on the Carboniferous and early Permian periods, 325 to 280 million years ago.


1991 ◽  
Vol 14 (1) ◽  
pp. 503-508 ◽  
Author(s):  
Robert A. Lambert

AbstractThe Victor gas field lies in the Southern North Sea Gas Province on the eastern flank of the Sole Pit Basin. The field straddles Blocks 49/17 and 49/22, and is situated approximately 140 km off the Lincolnshire coast. Victor was discovered in April 1972 and is operated by Conoco (UK) Ltd on behalf of BP, Mobil and Statoil. The structure is an elongated tilted fault block, trending NW-SE. The reservoir sands are contained in the Leman Sandstone Formation (Rotliegendes Group) of Early Permian age, and consist mainly of stacked aeolian and fluvial sands with a gross thickness of 400-450 ft across the field. Porosities vary from 16-20%, with permeabilities ranging from 10 md to 1000 md in the producing zones. Initial gas in place is estimated at about 1.1 TCF with recoverable reserves of the order of 900 BCF. The field was brought on-stream in October 1984, and the five producing wells deliver, on average, 200 MMSCFD through the Viking Field 'B Complex' to the Conoco/BP terminal at Theddlethorpe in Lincolnshire


2014 ◽  
Vol 511-512 ◽  
pp. 779-782 ◽  
Author(s):  
Jiang Tao Yu ◽  
Jin Liang Zhang ◽  
Shuang Yan Chen

Three dimensional geologic modeling is a powerful tool for reservoir development stages of geological study, it can solves many traditional problems existing in geological research through the establishment of precise three dimensional geologic modeling and represents an important direction for the further development of oilfield geological research. Low permeability and thin interbed reservoir of complex fault block have the characteristics of severe heterogeneity, complex relations of oil-water distribution, poor development effect, it is necessary to built high precision three dimensional geologic modeling in the process of oilfield exploration and to fine reservoir description and prediction on this basis, finally reach the purpose of reduce the risk of development and improve the economic benefit. This paper makes geological modeling research and builds structural models sedimentary micro-facies models and phased property model for Zhuzhuang block of Jiangsu oilfield by utilizing three dimensional geologic modeling technique and petrel geology modeling software on the basis of integrated using of geology, logging, oil production test, production of dynamic information, thus it provide a solid basis for reservoir's development and adjustment.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Semyon Isaev

The article discusses the issues of the railway embankment operation crossing faults with upland movements at different angles. Examples of the engineering structures operation are given in this article: tunnels, bridges, roadbed, pipelines in conditions of tectonic activity. Existing regulatory documents recommend choosing a route with a bypass of the places where tectonic faults reach the ground’s surface. However, taking into account the existing fault-block structure of the ground’s crust, it is practically impossible to bypass the tectonic fault zones. The existing network of railways for the most part was laid without taking into account modern requirements norms. Therefore, it seems relevant to study the operation of both the operated and the projected railway track in the tectonic disturbances zones with upland movements. In this article, using the software and computing complex Midas GTS, designed for geotechnical calculations, a study of the railway embankment operation crossing at different angles in the horizontal plane faults with conditional upland movements of the fault block has been carried out. For this, a three-dimensional finite element model was created. The calculations used the Coulomb-Mohr elastoplastic soil work model. As a result, the deformations of the embankment’s main area were analyzed. The deformations components and their contribution to the overall value are considered in detail. Conclusions are made about the change in the longitudinal slope of the axis and the skew of the transverse profile of the main site. For the most deformed sections, normal and tangential stresses diagrams. The research results analysis made it possible to establish a number of characteristic regularities in the change in the embankment’s stress-strain state, depending on the angle between the track and the fault axes. The article is part of the author’s dissertation research


1987 ◽  
Vol 27 (1) ◽  
pp. 245
Author(s):  
J.L. Cosgrove

Natural gas has been discovered in 22 fields in the Central Eromanga and Cooper Basins of southwestern Queensland in the area comprised by ATP 259P. Proved, probable and possible reserves in excess of 36 × 109 m3 (1.27 TCF) are located in four discrete structural provinces. Fluvial sandstones of the Early Permian Patchawarra Formation and Late Permian Toolachee Formation contain the majority of the reserves. Minor amounts of gas are reservoired in the Early Permian Epsilon Formation, the Early-Middle Triassic Nappamerri Formation and the Early Jurassic Hutton Sandstone and Birkhead Formation. Considerable gas-liquids reserves are also found in these reservoirs.Existing reserves are located primarily in structural traps although lithofacies variations are widely recognised, particularly in the Patchawarra Formation, indicating both new play opportunities and difficulties in assessing the undiscovered gas potential of the permit. Additional gas potential is identified in flank areas of the more prominent structural axes such as the Jackson-Wackett-Innamincka Trend in fault-bounded, pinchout and sub-unconformity trapping configurations.More than 200 prospects and leads are identified with the potential to entrap approximately 51 × 109 m3 (1.80 TCF) of gas on an unrisked basis. When combined with reserves from established fields, the ultimate potential of the ATP is assessed as 87 × 109 m3 (8.10 TCF).Despite the very high success rate of previous exploration and appraisal programs, the ultimate gas potential of the Queensland portion of both the Cooper and Eromanga Basins has been only partially addressed. Exploration and appraisal programs providing future additions to proved and probable reserves are considered low risk and are dependent upon an agreement with the Queensland government that would enable the ATP holders to produce and sell gas interstate.


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