>Magister Scientiae - MSc / The Orange Basin provides exceptional 3-D structures of folds and faults generated during soft-sediment slumping and deformation which is progressive in nature. 3-D seismic and structural evaluation techniques have been used to understand the geometric architecture of the gravity collapse structures. The location of the seismic surveyed area is approximately 370 km northwest of the Port of Saldanha. The interpretation of gravitational tectonics indicate significant amount of deformation that is not accounted for in the imaged thrust belt structure. The Study area covers 8200 square kilometre (km²) of the total 130 000 km² area of the Orange Basin offshore South Africa. The south parts of the Study area are largely featureless towards the shelf area. The north has chaotic seismic facies as the result of an increase in thrust faults in seismic facies 2. Episodic gravitational collapse system of the Orange Basin margin characterizes the late Cretaceous post-rift evolution. This Study area shows that implications of stress field and thrust faulting to the thickness change by gravity collapse systems are not only the result of geological processes such as rapid sedimentation, margin uplift and subsidence, but also could have occurred as the result of the possible meteorite impact. These processes caused gravitational potential energy contrast and created gravity collapse features that are observed between 3000-4500ms TWT intervals in the seismic data. / Shell Exploration & Production Company

Hydrate Ridge is a peanut shape bathymetric high located about 80 km west of Newport, Oregon on the Pacific continental margin, within the Cascadia subduction zone’s accretionary wedge. The ridge's two topographic highs (S. and N. Hydrate Ridge) are characterized by gas vents and seeps that were observed with previous ODP initiatives. In 2008, we acquired a 3D seismic reflection data set using the P-Cable acquisition system to characterize the subsurface fluid migration pathways that feed the seafloor vent at S. Hydrate Ridge. The new high-resolution data reveal a complex 3D structure of localized faulting within the gas hydrate stability zone (GHSZ). We interpret two groups of fault-related migration pathways. The first group is defined by regularly- and widely-spaced (100-150 m) faults that extend greater than 300ms TWT (~ 250 m) below seafloor and coincide with the regional thrust fault orientations of the Oregon margin. The deep extent of these faults makes them potential conduits for deeply sourced methane and may include thermogenic methane, which was found with shallow drilling during ODP Leg 204. As a fluid pathway these faults may complement the previously identified sand-rich, gas-filled stratigraphic horizon, Horizon A, which is a major gas migration pathway to the summit of S. Hydrate Ridge. The second group of faults is characterized by irregularly but closely spaced (~ 50 m), shallow fractures (extending < 160ms TWT below seafloor, ~ 115 m) found almost exclusively in the GHSZ directly beneath the seafloor vent at the summit of S. Hydrate Ridge. These faults form a closely-spaced network of fractures that provide multiple migration pathways for free gas entering the GHSZ to migrate vertically to the seafloor. We speculate that the faults are the product of hydraulic fracturing due to near-lithostatic gas pressures at the base of the GHSZ. These fractures may fill with hydrate and develop a lower permeability, which will lead to a buildup of gas pressures below the GHSZ. This may lead to a vertical propagation of new fractures to release the overpressure, which results in the high concentration of shallow fractures within the GHSZ seen in the 2008 data. / text

Hundreds of pockmarks and mounds, which seismic reflection sections show to be underlain by chimney-like structures, exist in southeast part of the Vøring plateau, Norwegian continental margin. These chimneys may be representative of a class of feature of global importance for the escape of methane from beneath continental margins and for the provision of a habitat for the communities of chemosynthetic biota. Thinning of the time intervals between reflectors in the flanks of chimneys, observed on several high-resolution seismic sections, could be caused by the presence of higher velocity material such as hydrate or authigenic carbonate, which is abundant at the seabed in pockmarks in this area. Evidence for the presence of hydrate was obtained from cores at five locations visited by the Professor Logachev during TTR Cruise 16, Leg 3 in 2006. Two of these pockmarks, each about 300-m wide with active seeps within them, were the sites of high-resolution seismic experiments employing arrays of 4-component OBS (Ocean-Bottom Seismic recorders) with approximately 100-m separation to investigate the 3D variation in their structure and properties. Shot lines at 50-m spacing, run with mini-GI guns fired at 8-m intervals, provided dense seismic coverage of the sub-seabed structure. These were supplemented by MAK deep-tow 5-kHz profiles to provide very high-resolution detail of features within the top 1-40 m sub-seabed. Travel-time tomography has been used to detail the variation in Vp and Vs within and around the chimneys. Locally high-amplitude reflectors of negative polarity in the flanks of chimneys and scattering and attenuation within the interiors of the chimneys may be caused by the presence of free gas within the hydrate stability field. A large zone of free gas beneath the hydrate stability field, apparently feeding several pockmarks, is indicated by attenuation and velocity pull-down of reflectors.

Over the last decade pockmarks have proven to be important seabed features that provide information about fluid flow on continental margins. Their formation and dynamics are still poorly constrained due to the lack of proper three dimensional imaging of their internal structure. Numerous fluid escape features provide evidence for an active fluid-flow system on the Norwegian margin, specifically in the Nyegga region. In June-July 2006 a high-resolution seismic experiment using Ocean Bottom Seismometers (OBS) was carried out to investigate the detailed 3D structure of a pockmark named G11 in the region. An array of 14 OBS was deployed across the pockmark with 1 m location accuracy. Shots fired from surface towed mini GI guns were also recorded on a near surface hydrophone streamer. Several reflectors of high amplitude and reverse polarity are observed on the profiles indicating the presence of gas. Gas hydrates were recovered with gravity cores from less than a meter below the seafloor during the cruise. Indications of gas at shallow depths in the hydrate stability field show that methane is able to escape through the water-saturated sediments in the chimney without being entirely converted into gas hydrate. An initial 2D raytraced forward model of some of the P wave data along a line running NE-SW across the G11 pockmark shows, a gradual increase in velocity between the seafloor and a gas charged zone lying at ~300 m depth below the seabed. The traveltime fit is improved if the pockmark is underlain by velocities higher than in the surrounding layer corresponding to a pipe which ascends from the gas zone, to where it terminates in the pockmark as seen in the reflection profiles. This could be due to the presence of hydrates or carbonates within the sediments.

Master of Science / Department of Geology / Abdelmoneam Raef / Seismic reservoir characterization and prospect evaluation based 3D seismic attributes analysis in Kansas has been successful in contributing to the tasks of building static and dynamic reservoir models and in identifying commercial hydrocarbon prospects. In some areas, reservoir heterogeneities introduce challenges, resulting in some wells with poor economics. Analysis of seismic attributes gives insight into hydrocarbon presence, fluid movement (in time lapse mode), porosity, and other factors used in evaluating reservoir potential. This study evaluates a producing lease using seismic attributes analysis of an area covered by a 2010 3D seismic survey in the Morrison Northeast field and Morrison field of Clark County, KS. The target horizon is the Viola Limestone, which continues to produce from seven of twelve wells completed within the survey area. In order to understand reservoir heterogeneities, hydrocarbon entrapment settings and the implications for future development plans, a seismic attributes extraction and analysis, guided with geophysical well-logs, was conducted with emphasis on instantaneous attributes and amplitude anomalies. Investigations into tuning effects were conducted in light of amplitude anomalies to gain insight into what seismic results led to the completion of the twelve wells in the area drilled based on the seismic survey results. Further analysis was conducted to determine if the unsuccessful wells completed could have been avoided. Finally the study attempts to present a set of 3D seismic attributes associated with the successful wells, which will assist in placing new wells in other locations within the two fields, as well as promote a consistent understanding of entrapment controls in this field.

Submitted by RICARDO OTTO ROZZA SCHMIDT null (rottoschmidt@gmail.com) on 2016-06-20T16:57:36Z No. of bitstreams: 1 Mestrado Dissertação Final_Dig.pdf: 14191761 bytes, checksum: dbea65724bee20d777cf130e21a9ab56 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-06-23T14:12:58Z (GMT) No. of bitstreams: 1 schmidt_ror_me_rcla.pdf: 14191761 bytes, checksum: dbea65724bee20d777cf130e21a9ab56 (MD5) / Made available in DSpace on 2016-06-23T14:12:58Z (GMT). No. of bitstreams: 1 schmidt_ror_me_rcla.pdf: 14191761 bytes, checksum: dbea65724bee20d777cf130e21a9ab56 (MD5) Previous issue date: 2016-05-03 / Os arenitos de água profunda, designados genericamente como turbiditos, têm enorme relevância energética e econômica para o Brasil. Na Bacia de Campos, a maior parte dos campos produtores contêm níveis turbidíticos da Formação Carapebus (Eoceno), focalizados neste estudo. É o caso dos campos de Enchova e Bonito. Nesta dissertação propõe-se a caracterização geológica-petrofísica dos reservatórios turbidíticos (Eoceno) nestes campos, que mesmo descobertos há 30 anos detém poucas informações publicadas no que se refere à sua disposição espacial litológica e petrofísica. A integração de metodologias e ferramentas possibilita a melhor compreensão dos reservatórios e de suas heterogeneidades. Neste trabalho foram integrados dados oriundos de testemunhos, perfis de poços, sísmica 3-D (40 km²) por meio dos métodos geoestatísticos Krigagem Indicativa e Krigagem Ordinária, de forma a contribuir com o entendimento da distribuição das principais unidades do reservatório. A análise litológica teve como enfoque os métodos qualitativos, apoiada na descrição de testemunhos apresentadas na pasta de poço, e quantitativo, baseado nas análises dos perfis geofísicos de 20 poços. Com base nesta correlação rocha-perfil, os litotipos arenito, carbonato e folhelho foram definidos e extrapolados para os intervalos não testemunhados. A interpretação e correlação dos perfis geofísicos identificaram dois níveis arenosos principais, o inferior com 10 a 15 m e superior com 70 a100 m, separados por uma camada de folhelho de 5 a 20 m. Salienta-se o controle deposicional de uma feição erosiva de idade Maastrichiano-Eoceno Médio, a qual concentra as maiores espessuras de areia a oeste dos campos. A caracterização estrutural do reservatório, definida por três feições dômicas alinhadas a NE, foi definida pela interpretação sísmica 3-D. A análise de atributos sísmicos de amplitude, realizada no intervalo definido entre os horizontes topo e base do reservatório, revelou geometrias associadas a complexos de canais discretos, em Enchova, e lobos canalizados, em Bonito. O modelo litológico do reservatório obtido pela aplicação da Krigagem indicativa representou satisfatoriamente os níveis turbidíticos quando comparados aos dados de poços e mapas atributos sísmicos, que indica as maiores espessuras dos turbiditos a oeste das áreas. O modelo da porosidade obtido pela Krigagem Ordinária (Krigagem Indicativa) indicou melhores condições porosas na porção oeste dos campos, correlacionando-se com o modelo litológico carbonatos fechados e folhelhos no modelo litológico. Ambos, os mapas de atributos sísmicos e modelos obtidos apresentam uma área com potencial exploratório a sul de Bonito, ainda não perfurada segundo a ANP. / Deep-water sandstones, known as turbidites, play an important role in Brazil's energy and economic scenario. In the Campos Basin, Carapebus Formation´s Eocene turbidites produce in most oil fields of the basin. Enchova and Bonito oil fields, focused in this study, represent Eocene sandstone production areas. Discovered 30 years ago, Eocene reservoirs have a lack of information regarding its lithological and petrophysical distribution. This master thesis proposes a geological-getrophysical reservoir characterization of Eocene turbidites on Enchova and Bonito fields. The integration of methodologies and tools enables a better understanding of the reservoir geometry and heterogeneity. This work integrates core descriptions from well reports, well logs and 3-D seismic through Indicator Kriging (lithology) and Ordinary Kriging (porosity) resulting in 3-D solid models. The models possibly a better understand of lithologic and petrophysical reservoir distribution. The lithological analysis is supported by qualitative methods, supported by the 70m core description provided with well log data, and quantitative, based on the analysis of 20 well logs. Based on this correlation between logs and rocks, the lithology classes, sandstone, carbonate and shale, were defined. The well-logs interpretation and correlation identified two main turbidite intervals, the lower 5 to 15 m and upper 70 to 100 m, separated by a shale layer 5 to 20 m. These intervals were depositionally controlled by an erosive feature associated with Maastrichtian-Middle Eocene unconformity, defining the distribution pattern of turbidites sands concentrated on the western portion of the fields. The reservoir structural characterization, performed trough 3-D seismic interpretation, is defined by three domal features separated by normal faults aligned to NE-SW. Seismic amplitude attributes calculated under the reservoir interval revealed channelized geometries on Enchova field and lobate architecture on Bonito field. The reservoir lithological model obtained through Indicator Kriging demonstrate coherence when compared to well data distribution and seismic attributes maps that indicate turbidite greatest thicknesses in western areas. The model of porosity obtained by Ordinary Kriging revealed best porosity conditions in the western portion of the fields, corresponding to the seismic attributes responses and lithological model. Both geostatistical models and seismic attributes maps revealed an interesting non drilled area located on south of Bonito field.

This thesis examines the interaction of pre-existing and evolving salt-related topography on the temporal and spatial evolution of depositional systems in deepwater. To achieve this, the thesis integrates stratigraphic and structural analysis of 3D seismic data from the Miocene record of the salt-influenced Lower Congo Basin, Offshore Angola. Observations at multiple scales ranging from the semi-regional (&gt; 50 km) to local, kilometre-scale and covering timescales ranging from the entire Miocene (~ 18 Myr) to &gt; 2 Myr are presented. At the semi-regional scale, results from this study shows that the progressive along-strike linkage of short (&lt;10 km) fault segments and salt diapirs into through-going large scale (&gt; 30 km) faults and elongated saltwalls results in long lived diversion and/or confinement of depositional system fairways. Axial confinement of fairways occurs where structural strike is parallel to sediment input, contrasting with ponding or diversion of deposits oriented at a high angle to structural strike. The orientation of the structures remains relatively static, which in combination with the fixed sediment entry points of the fairways results in recurrence of the major styles of interaction, and long term pinning of fairways throughout the Miocene. The development of large (10's of km) "sediment shadow" zones devoid of coarse clastics downdip of diverted and or confined sediment gravity flows is also observed through the Miocene. At the intraslope basin (10's of km) and sub-basin scale ( < 10 km), the role of confinement by salt-related structures on the temporal evolution and dip-and-strike variability of Late Miocene channelised-lobe complexes in an elongate intraslope basin was also investigated. At both of these scales, the morphology of the recieving basin geometry significantly influences the dimensions, planform morphology and vertical stacking patterns of channelised-lobe complexes. A transition from thick, radial shaped lobe-complexes which are aggradationally stacked and deposited via 'fill-and-spill' of sub-basins within an intraslope basin to thinner, elongate, laterally offset and compensationally stacked channelised-lobe complexes in the intraslope basin is observed. This transition occurs as the salt-related structural template evolves and confinement changes from the sub-basin scale to the intraslope basin scale. At the depositional element scale ( < 5 km), results from this study further shed light on the critical and hitherto neglected role of salt-related topography in controlling the location of channel to lobe transition zones in deepwater depositional systems. The location of the transition zones are documented from four case studies, with the transitions spatially controlled by salt-related reduction in gradient e.g. a break in slope downflow of monoclinal structures, and/or a reduction in lateral confinement of depositional fairways downflow of segment boundaries. Overall, the result of this thesis show the significant influence which evolving saltrelated topography exerts on the stratigraphic development, geometry and sediment routing patterns on salt-influenced continental margins. In particular the study highlights how variable the interaction between evolving salt-related topography and deepwater sedimentation is at a range of temporal and spatial scales.

Several off-shore volcano-plutonic complexes are imaged in detail in the Parihaka 3D seismic survey in the Taranaki Basin of New Zealand. Three intrusions were analyzed for this study. Part of the Mohakatino Volcanic Centre (15 to 1.6 Ma), these intrusions have steep sides, no resolvable base reflectors, no internal stratification or structure, and they exhibit doming and faulting in the sedimentary strata above the intrusions. Deformation along the sides is dominated by highly attenuated, dipping strata with dips of 45° or higher that decrease rapidly away from the intrusions. Doming extends several hundred meters from the margins and produced many high-angle normal faults and thinned strata. The intrusions lie near normal faults with the Northern Intrusion lying directly adjacent to a segment of the Parihaka Fault. The Central Intrusion has localized normal faults cutting a graben in the area directly above the intrusion and extending in a NE-SW direction away from it. The Western Intrusion is near the western edge of the Parihaka 3D dataset and is not situated directly adjacent to extensional faults.Two distinct zones of intrusion-related faults developed around both the Northern and Central Intrusions representing two different stress regimes present during emplacement, a local stress field created by the intrusions during emplacement and the regional stress field. The deeper zones contain short radial faults that extend away from the intrusion in all directions, representing a local stress field. The shallower faults have a radial pattern above the apex of each intrusion, but farther from it, they follow the regional stress field and trend NE. Using our techniques to interpret radial faulting above both intrusions and the principal of cross-cutting relations, timing of emplacement for these intrusions are 3.5 Ma for the Northern Intrusion and between 5 and 4 Ma for the Central and Western Intrusions.Observed space-making mechanisms for the Northern and Central Intrusions include doming (~16% and 11%, respectively), thinning and extension of roof strata (~4% for both), and extension within the basin itself (29% and 12%). Stoping and floor subsidence may have occurred, but are not visible in the seismic images. Magmatic extension may have played a significant role in emplacement.Several gas-rich zones are also imaged within the seismic data near the sea-floor. They appear as areas of acoustic impedance reversal compared to surrounding sedimentary strata and have a reversal of amplitude when compared to the sea floor. The gas in these zones is either biogenic or sourced from deeper reservoirs cut by normal faults.

Detailed 3D seismic images of a volcano-plutonic complex offshore northwestern New Zealand indicate the intrusive complex lies in a relay zone between NE-trending en echelon normal faults. A series of high angle normal faults fan out from the margin of the Southern Intrusive Complex and cut the folded strata along the margin. These faults terminate against the margins of the intrusion, extend as much as 1 pluton diameter away from the margin, and then merge with regional faults that are part of the Northern Taranaki Graben. Offset along these faults is on the order of 10s to over 100 meters. Strata on top of the complex are thinned and deformed into a faulted dome with an amplitude of about 0.7 km. Steep dip-slip faults form a semi-radial pattern in the roof rocks, but are strongly controlled by the regional stress field as many of the faults are sub-parallel to those that form the Northern Taranaki Graben. The longest roof faults are about the same length as the diameter of the pluton and cut through approximately 0.7 km of overlying strata. Fault offset gradually diminishes vertically away from the top of the intrusion. The Southern Intrusive Complex is a composite intrusion and formed from multiple steep-sided intrusions as evidenced by the complex margins and multiple apophyses. Small sills are apparent along the margins and near the roof of the Southern complex. Multiple episodes of deformation are also indicated by a series of unconformities in the sedimentary strata around the complex. Two large igneous bodies make up the composite intrusion as evidenced by the GeoAnomaly body detection tool. The Southern Intrusive Complex has a resolvable volume of 277 km3. Room for the complex was made by multiple space-making mechanisms. Roof uplift created ~3% of the space needed. Compaction/porosity loss is estimated to have contributed 20-40% of the space needed. Assimilation may have created ~0-30% space. Extension played a major role in creating the space needed and is estimated to have created a minimum of 33% of the space. Floor subsidence and stoping may have occurred, but are not resolvable in the seismic survey.

This research has been focused on the characterisation and analysis of the deposits of large-scale mass movement events that shaped the North Sea Fan since the Mid-Pleistocene. Located at the mouth of the cross-shelf trough Norwegian Channel, the North Sea Fan is one of the largest through-mouth fans in the glaciated european margin with an area of approximately 142,000 km2. Submarine mass movement processed have occurred intermittenrly throughout the Quarternary history of the North Sea Fan, related to recurrent climate-related episodes of growth and retreat of the ice sheets. These processes can transport large amounts of sediment from the upper shelf up to the abyssal basins, playing an important role on the evolution of continental margins and can also reporesnet major geological hazards. This thesis uses mainly 3D seismic data to investigate the external geometry and internal structure of large-scale mass movement deposits. The high spatial resolution provided by the 3D seismic data has allowed a detailed geomorpholocial analysis of these deposits, This study involved the interpretation of the seismic data and the detailed pickling of key reflectors followed by tge extraction of both horizon and window-based seismic attributes. Digital elevation models of the key reflectors and their seismic attribute maps were then transferred to a geographical information system (GIS) where they were interactively interpreted using spatial analysis tools and the full visualisation potential of the software. The outcomes of this study highlight the importance of detailed horizon pickling and interactice interpretation followed by spatial analysis and visualisation in GIS environment. The identification of acoustic patterns within deposits that are normally described from 2D seismic as chaotic or acoustically transparent emphasizes the potential of detailed analysis of 3D seismic data. It gives an example of how this type of data can provide new insights into the mechanisms and processes associated with mass movements. In particular, amplitude and RMS amplitude maps provide remarkable detailed information of internal deformation structures whereas slope, shaded-relief and thickness maps allowed detailed characterisation of the external geometry. Various types of kinematic indicators can be recognized within the mass movement deposits through combined seismic analysis and detaield morphological mapping.