Dry well analysis of well 6407/10-5 at 793 area, Norwegian Sea.

Master's thesis in Petroleum Geosciences Engineering.The region of investigation is located in the Norwegian Sea, which is an area of high hydrocarbon activity. Many reservoirs have been successfully identified, drilled, and now they are producing in large oil & gas fields. However, the Norwegian Sea has a complex geology as it resulted from Permian to Late Jurassic crustal extension, which created rift basins and several horst and graben structures. Most of the important hydrocarbon reservoirs in the Norwegian Sea are Jurassic. Because of the complex geology, identifying these reservoirs and successfully positioning wells is challenging. The research for this project is conducted on a dry well, 6407/10-5 in area 793 that was drilled along the western fault bounded Frøya High in the Norwegian Sea. The Frøya High is a Triassic paleo-uplift: a NNE-SSW trending horst bounded by the Vingleia and Klakk fault complexes on the eastern side and a major fault on the western side, which separates it from the Froan Basin. A Jurassic rollover anticline developed along the western margin of the Frøya High where the well is located. Since 2015, many fields such as Pil, Bue and Snilehorn, have been discovered in the same geological trend. However, in the study area, the two wells 6407/10-1 and 6407/10-2, drilled in the 1980s, only contain hydrocarbon shows, and the newly drilled well 6407/10-5 is dry. This study focuses on identifying the failure reason of the dry well 6407/10-5. Newly acquired 3D seismic data covering the study area, well reports, log data and geochemical reports of the wells 6407/10-1 and 6407/10-2 are used for the project. This research provides an understanding of the geological elements of the petroleum system of the study area i.e., seal, reservoir, source and trap, which lead to debate the reasons for failure of the well. A set of methodologies are defined to test each element. Here, local source is not functional and top seal of the reservoir is heavily faulted. Trap failure is the main reason for dry well as fault besides the trap has high potential of leaking

Marine geophysical investigation of the Hatton bank volcanic passive continental margin

The Durham/Cambridge/Birmingham Universities two-ship marine geophysical cruise to the Hatton Bank continental margin took place in May/June 1985, during which single- and two-ship seismic reflection/refraction data, together with under way gravity and magnetic anomaly, and bathymetric data were collected within a 200 km by 150 km area straddling the continent-ocean transition. The processing, modelling and interpretation of four two-ship synthetic aperture profiles (SAP) and the gravity and magnetic anomaly data is presented. Gravity models show that a density model based on the crustal velocity structure defined by synthetic seismogram modelling of the two-ship expanding spread profiles is insufficient to reproduce the observed gravity profile across the margin. This requires additional contributions in the form of density gradients in the underlying sub-crustal part of the lithosphere and asthenosphere, and this is investigated by thermal modelling. Analysis of the magnetic anomaly data shows that oceanic magnetic anomalies 21 and 22 are developed in the north-west of the 1985 survey area. Anomalies 23 and 24 cannot be recognised due to post-rift igneous activity and/or subaerial seafloor spreading. The positions of anomalies 23 and 24B are reconstructed within the survey area, and the theoretical anomaly 24B position is used to determine the position of the continent-ocean boundary. Analysis of the anomalies recorded on the upper continental slope shows that the acoustic basement in this area is volcanic. Interpretation of the SAP profiles shows that the margin can be described in terms of three distinct volcanic sequences. The continental sequence is composed of lavas extruded onto continental crust during a period of continental volcanism which occurred before the onset of seafloor spreading just prior to anomaly 24B.The sequence thickens to the north-west, to form a set of seaward-dipping reflectors. The oceanic sequence comprises oceanic crust within which structurally different seaward-dipping dipping reflectors are developed. This sequence is associated with the reconstructed positions of anomalies 23 and 24B, and is interpreted as having formed during a period of subaerial seafloor spreading. The late sequence separates, and in part overlies the continental and oceanic sequences. Magnetic anomalies associated with the late sequence are arcuate, and have high amplitudes, implying an origin other than simple seafloor spreading. The late sequence is interpreted as originating from post-rift igneous activity in the Eocene

3-D seismic investigation of the diagenesis and deformation of Cenozoic siliceous sediments on the Eastern Atlantic Margin

Three-dimensional seismic data from the East Atlantic Margin are used to investigate the diagenesis and deformation of siliceous sediments. Three themes were tackled. At the Gjallar Ridge, offshore Norway, seismic and well data indicate that diagenesis of siliceous sediments occurs across a zone ~300 m thick. At the top of the zone circular regions, with relief of ~200 m, are interpreted as regions of preferential diagenesis. Below these, regions with a similar size and distribution are attributed to the same cause. The chemistry of formation water expelled transiently through polygonal faults may play a role in their formation. This is the first recognition from seismic data that silica diagenetic transformation zones can be hundreds of metres thick and heterogeneous, as observed at outcrop previously. On the Mauritanian continental margin layer-bound fault systems deform a probable siliceous succession. Where this succession mantles canyons the majority of faults strike perpendicular to the canyon axes due to increased bedding dip and most are antithetic to bedding dip. Where the bedding dip is greater than ~1°, synthetic faults dip more steeply than antithetic faults, which is the exact opposite that would be expected on a dipping margin. It is hypothesised that the layer hosting the faults has been subjected to simple shear of ~20° or more, rotating the fault planes. Lastly at the Vema Dome, offshore Norway four submarine slides are identified in siliceous sediments. Each covers an area of ~30 km2, is up to 600 m thick, with an upper surface topography consisting of a series of arcuate ridges perpendicular to the dip of the slope. The slides are dominated by fold-and-thrust structures, have short transport distances, and unusually low ratios of length to thickness. These characteristics are attributed to deep detachments and the shear strength of siliceous sediments at shallow burial depths

Tectono-stratigraphic evolution of the West Orkney Basin: implications for hydrocarbon exploration

The West Orkney Basin is situated in a frontier hydrocarbon region of the United Kingdom Continental Shelf. This study presents a reappraisal of the tectono-stratigraphic development and petroleum potential of the basin, and is based on a recent compilation and partial reprocessing of all the available 2D reflection seismic for the area. Evidence for the presence of Devonian lacustrine source-rocks in the basin is demonstrated by the recognition of a syn-rift sequence overlying basement, which comprises two packages of contrasting seismic facies characteristics, which are correlateable to onshore Devonian source-rock and reservoir facies. The syn-rift sequence is truncated at unconformity; that is related to Late Carboniferous inversion of the Great Glen-Walls Boundary Fault system. A second major phase of rifting within the basin, with formation of new faults and reactivation of pre-existing Devonian faults, is interpreted to have initiated in the Late Permian and dwindled into the Early Jurassic. Subsequent extensive exhumation events occurred in the Mid-Jurassic to Early Cretaceous and Cenozoic, with removal of about 2.5 km of Upper Triassic to Lower Jurassic sediments and perhaps 0.5 to 1 km of Upper Cretaceous rocks. Timing of hydrocarbon generation from Devonian source-rocks was modelled using Genesis 1D basin-modelling software from Zetaware, and the results from this indicate that it most probable that the majority of hydrocarbon generation in the basin preceded the end of the second phase of rifting in the basin (Late Permian to Early Jurassic). Therefore, the major risks with play-concepts based on a Devonian source-rock are considered to be seal integrity during multiple and prolonged uplift events

The Volcanic Development and Petroleum System Evolution of the Faroe-Shetland Basin.

The large volume of intrusive igneous material associated with volcanic rift margins introduces significant uncertainty to both hydrocarbon exploration and subsequent prospectivity. Understanding the habit, emplacement and distribution of such material in the context of rift evolution is essential to understanding the evolution of volcanic rift margins. The recent availability of high-quality 3D seismic data from the rift basins of the NE Atlantic Margin has enhanced our understanding of the 3D geometry and emplacement mechanisms of sill intrusions. Although how these intrusions fit within the wider margin context is often overlooked. The West of Shetland area provides an insight into the process of volcanic rift interaction in a petroleum prospective area. Using multi-client 2D and 3D seismic data this study places reservoir scale observations of sill morphology, distribution and sill-fault interactions within a wider basin context. The study demonstrates that the style and volume of sill intrusion is heavily influenced by the large scale basin structure, the position along the volcanic margin and small scale structural heterogeneities. Given the variations in sill size and frequency there are also implications for the bulk intrusive magma distribution across the margin. Predicting hydrocarbon prospectivity in frontier, or under-explored basins, is inherently uncertain. In order to reduce this uncertainty, sensitivity analysis is performed on key modeling input parameters to define a best practice workflow for undertaking basin modeling in the Faroe-Shetland Basin and similar passive continental margin settings. As the emplacement of igneous intrusions into sedimentary successions has been shown to locally elevate heat flow, the sill complex is incorporated into the regional 2D modeling to investigate the effect sill emplacement has on hydrocarbon prospectivity. The results highlight the importance of determining the timing of emplacement and the volume of igneous material when assessing the potential impact on maturation and generation of hydrocarbons. The modelling suggests that through an appraisal of sensitivity in areas of poor, limited or even absent data, such as frontier basins we can derive a more constrained basin modeling approach that reduces exploration uncertainty

Assessment of mining activities with respect to the environmental protection

This paper deals with the impact of mining on the environment. Coal mining is still among the most widespread and most intense mining activity, which disturbs the landscape around us bringing regional environmental, economic and aesthetic problems. However, for many countries in the world, including the Czech Republic, deposits of raw materials play an important role, especially for purposes of producing electricity and thermal energy. At the same time, growing emphasis laid on the environmental protection can be observed worldwide. To meet the increasing ecological demands, it is reasonable to consider the most significant aspects of mining activities from the environmental point of view, as well as to consider the possibilities of the abandoned mines utilization as possible waste dumps. Parts of this problem consist in: the monitoring, environmental impacts assessment of exploration and mining activities and waste disposal mining, which may significantly contribute to the environmental protection in the future. Several parameters that can significantly affect the usability of the waste disposal mining, such as geological structure, hydro-geological conditions, material composition and physical and mechanical properties of rocks are discussed in detail in this work. The article also includes a practical example of Environmental Impact Assessment process for the particular activity of OKD stock company, which is the only producer of hard coal (bituminous coal) in the Czech Republic. Its coal is mined in the southern part of the Upper Silesian Coal Basin - in the Ostrava-Karvina coal district. KeywordsWeb of Science221937

CONTROLS ON FACIES DISTRIBUTION AND PROPERTIES IN THE NORTHWEST BORNEO DEEP WATER FOLD-AND-THRUST BELT

The deep-water fold-and-thrust belt of NW Borneo contains a structurally complex region of active folds. The opening of the South China Sea during Oligocene to Middle Miocene times led to a Southeastward rifting of the continental crust of the Dangerous Grounds. Subduction of oceanic crust to the Southeast took place under the NW Borneo continental margin, with oceanic subduction ending at ~16 Ma. Collision between the Dangerous Grounds and the NW Borneo margin resulted in uplift and erosion of the Crocker Ranges, and shed large volumes of sediment Northwest into the adjacent sedimentary basins. The resultant fold-and-thrust belt hosts up to 8 km thickness of Mid-Miocene to Recent turbidites and submarine fan sediments, closely associated with fold growth. This study provides new interpretations of regional, three-dimensional (3-D), multichannel seismic-reflection profiles, and utilises data from 25 exploration and appraisal wells. The target of the wells is the fan system, located at the crestal part of the thrusted hanging walls of growth anticlines. This research studies the geometry and structural vergence of the folds, sequence stratigraphy, and burial history. Collectively, these are the controlling factors affecting the facies distribution and properties in the study area. Approaches include seismic analysis, well log analysis, petrology, and basin modelling. Fold-and-thrust belt evolution and syn-tectonic deposition were influenced by subduction and gravitational tectonic events, the proximity and variety of sediment provenance, and seabed topography during deposition. There was an important effect of overpressure generated by disequilibrium compaction, which preserved the porosity in the deeper formations. This study identified the individual fold growth magnitude, sediment provenances, depositional settings of the deep-water slope water environment, and accommodation space for the facies compartmentalisation seen in the wells, and models the depositional settings and the submarine channel pathways, with possible high quality reservoir distributions

Seismic Stratigraphy and Geomorphology of Palaeocene Volcanic Rocks, Faroe-Shetland Basin

2D and 3D seismic reflection data in the Faroe-Shetland Basin have been used to remotely study buried, large-scale Palaeocene volcanic structures emplaced during continental flood basalt volcanism in the Faroe-Shetland Basin. The flood basalts were emplaced as thick and extensive pāhoehoe lava flows from multiple sources, including fissure systems close to the Faroese shelf and from volcanic centres within the basin. This thesis has investigated the distribution and internal structure of the flood basalts based on the hypothesis that volcanic eruptions produce volcanic depositional successions that record the temporal and spatial variations of the basin into which they are emplaced. Multiple eruptions will produce cycles of volcanic deposition that are delineated by hiatal surfaces. These successions can be recognised in seismic reflection data by applying seismic stratigraphic concepts in order to gain insights into the evolution of volcanic basin-fill. The Faroe-Shetland Basin contains a variety of depositional environments, including a deepening marine basin where continental flood basalts reached a palaeo-shoreline and constructed an extensive lava-fed delta system >1000 m thick. The delta is composed of 13 seismic reflection units whose stacking architecture primarily records variations in lava supply and accommodation. Modification of the delta front was by erosion and debris avalanches. The second environment is subaerial to shallow marine where the continental flood basalts emplaced multiple lava flows 10 - 60 m thick which coalesced to form extensive and overlapping lava flow fields. Four seismic reflection units have been recognised and record variations in source and supply of the lava flows. During reoccurring periods of volcanic quiescence, fluvial channels 350 – 500 m wide incised across the lava flow fields, constrained by flow field topography. The volcanic depositional successions used to reconstruct the volcanic basin-fill history of the Faroe-Shetland Basin indicate that eruptive styles and volcanic structures varying significantly over relatively small areas (tens of km2). Many of the seismic observations have been compared to outcrop analogues, are scale-independent and are indicative of emplacement environment. Analysis has also led to the development of a volcanic seismic stratigraphic model as depositional patterns produced during volcanic activity are primarily driven by volcanic supply. The results presented in this thesis have many important implications for stratigraphy, hydrocarbon exploration and basin modelling in the Faroe-Shetland Basin and therefore can be applied beyond the fields of volcanology or seismic interpretation