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Submarine debris flows are hazards when they threaten the facilities that are built on sea floor to facilitate submarine transportation. The dynamics of submarine debris flow is simple once the debris material gets in the flow motion and that it can be represented using simple physics. A two-dimensional model with two-layer Bingham fluid representations, SDFlow2D, was developed by using an Eulerian frame of reference to predict the consequences of complex submarine debris flows. The model was viscoplastic in nature based on depth-averaged approximation to the Shallow Water Equations (SWE), and it assumes that the flow consists of a non-deforming upper layer riding on a deforming layer. The model was verified by comparing the numerical solution with experimental observations as well as with an analytical solution. The comparison shows a good agreement with analytical solution and an acceptable agreement with experimental observations. The model was found to be capable of simulating real-word submarine debris flows. The consequence of bed material entrainment is worth studying as this process adds antecedent sediment to the debris flow mass that in turn increases the intensity of hazard. The modeling code SDFlow2D was enhanced by using simple physics to include the capability of computing bed material entrainment. It was assumed that no inertial force was involved in the process, and that the entrainment was instantaneous. The modified SDFlow2D was applied to two idealized cases and to a prognostic case. A total variation diminishing (TVD) scheme with flux limiter was applied with MacCormack predictor-corrector scheme to smooth out the spurious solution near the source area of debris flow. While the TVD scheme served that purpose to some extent, it was not helpful to make the model robust as the computational time was 15 times greater than that of using the code without TVD scheme. The Bayesian inverse modeling was implemented to quantify the Bingham parameters uncertainty. The technique helps find not only the most probable pair of Bingham parameters but also the distribution of the parameters by conducting a small number of model simulations. The overall outcome of the study benefits the deep sea explorers as well as the designers and planners in charge of designing the submarine structures. / A Dissertation submitted to the Department of Scientific Computing in partial fulfillment of the Doctor of Philosophy. / Spring Semester 2017. / April 04, 2017. / Bayesian Inversion, Deep Sea Geohazard Modeling, Modeling Bed Sediment Entrainment, Sub-Aerial Debris Flow Modeling, Submarine Debris Flow Modeling, Two Layer Bingham Fluid / Includes bibliographical references. / Ming Ye, Professor Co-Directing Dissertation; Alan W. Niedoroda, Professor Co-Directing Dissertation; Vasubandhu Misra, University Representative; Sachin Shanbhag, Committee Member; Xiaoqiang Wang, Committee Member.

ABSTRACT The purpose of this thesis project work is to build reservoir models (structural, facies and Petrophysical property models) of the different reservoir surfaces using integrated data sets (seismic, wells, fault sticks, eclipse models, horizon surfaces) of the Norne field which is located in blocks 6608/10 and 6508/1 in the southern part of the Nordland II area. Different visualizations techniques, volume rendering and seismic attributes were applied to aid the seismic interpretation and to provide detailed evaluation/integration of the data. 3D seismic interpretation for the whole seismic volume within the reservoir section was done manually with controlled input surfaces/reflectors of the Top horizons of the Not and Åre Formations. Fault and surfaces interpretation of the reservoir were generated as key inputs in the modeling process The structural 3D grid skeleton and models were generated with critical inputs of the manually interpreted faults/horizons, using different qualitative/quantitative templates in Petrel. This was followed by well interpretation and upscaling to provide discrete facies which are needed in populating the structural models of each of the reservoir surfaces. A probabilistic facies model was done to capture the proportion of the spatial dimensions of each discrete facies in the model frame. The initiation of this study involves quantitative data quality controls and management of inputs files into the Petrel window, qualitative control involves transferring geologic licenses/understanding to the various interpretations in the visualization schemes, seismic interpretation and reservoir modeling templates. The combination of different data type and idea (volumes, wells, top surfaces, and fault sticks) types means that the user must have a multivariate understanding (Geologic, Geophysical, Petrophysical, Geostastistic, Geo-Modeling and Reservoir Engineering) in other to integrate the data sets and deliver the models. Eleven wells were used in reference to the Top surface of the Not, Åre Top surfaces and Statoil Reference report of the field, to deliver and control the seismic interpretation. A wedge shape structure was observed in the reservoir section. Typically, minor and major faults were interpreted as forming compartments in the reservoir, which were interpreted across the different lines. The structural framework in the field was largely defined by the Norne Horst and associated faults, with the erosional surface of the BCU with internal sub unconformities observed. The property facies model of the reservoir surfaces (Garn, Ile, Tofte, and TIlje) suggest that the Norne Horst and sub relief structures are mainly sand rich, which provides additional prospect indicators in exploring the field

Seismic interpretation of 13 lines has been conducted in the Hammerfest and Tromsø basin areas in the southwestern Barents Sea. Based on interpretations, a 3D Geomodel comprising 10 layers has been constructed. Depth conversion of the Geomodel was accomplished after building of the herein required velocity model. Paleobathymetric reconstruction was performed for 9 time intervals from Top Oxfordian/Late Jurassic until Intra Sotbakken/Base Pliocene utilizing SINTEF´s basin modeling tool SEMI Paleowater. The restoration method is based on the information about depositional geometries from seismic sequences combined with zero or near zero water depth indicators. The time intervals have been restored using the deep marine infill scenario. The reconstruction showed that the Early Cretaceous paleo-water depth was greatly influenced by the Late Jurassic-Early Cretaceous rifting episode that resulted in the formation of deep marine basins and structural highs. Differential subsidence during the Cretaceous led to more stable areas in the east and rapidly subsiding basins in the west of the study area. Compressional tectonics in the Early Paleogene resulted in the development of the Senja Ridge as a positive structure. From the Oligocene until the Miocene, a period of shallow marine conditions was restored in the Hammerfest and Tromsø basins. The transition to a passive continental margin and resulting thermal subsidence led to a new deepening in the Neogene.

The Statfjord Formation (Rhaetian-Sinemurian) produces from six fields across the North Sea, but no discoveries have yet been made in the 12 exploration wells across the Oseberg South Field. The field has undergone two major periods of rifting in the Permian-Triassic and from the mid-Jurassic to Early Cretaceous. The Statfjord Formation was deposited during the Permian-Triassic post-rift period, but its tectonic influence on the paleogeography of the formation is not well understood. An isopach map produced from seismic interpretation and RMS modelling of the Statfjord Formation showed a westward thickening trend towards the present-day Viking Graben. This study presents results obtained using new, high-quality OBC seismic data that has allowed for faults throughout the field to be mapped in great detail. Supported by stratigraphic correlations and biostratigraphy, the mapping has showed that most faults can be assigned to either of the main rifting phases or their associated post-rift subsidence histories. Large, east-dipping faults are believed to have originated during the Permo-Triassic rifting, with evidence of movement into the Cretaceous. Large thickness increases of the formation over the westward dipping Oseberg and Brage Faults, as well as syn-rift sediments within some grabens in the J structure indicate movements of these faults during deposition. Biostratigraphic data show that the lowermost part of the Statfjord Formation was approximately the same thickness across the field until the Late Triassic, constraining the initiation of the Oseberg and Brage Faults to the Early Jurassic. Interpretations from timelines correlated within the Statfjord Formation suggest that the rate of subsidence along different faults was not consistent through time. Thickness changes along strike of the fault indicate that the movement along the fault was diachronous. This study aims to show that major fault activity influenced the deposition, and possibly preservation potential of sediment in the Statfjord Formation. The second phase of rifting is believed to have initiated many of the faults within the field, as well as reactivated the Oseberg and Brage Faults. Additional NW-SE faults in the Omega structure show no evidence of syn-rift sediments at the Statfjord Formation level, suggesting a mid-Jurassic post-rift origin. Similarly oriented faults were seen in the C structure, however, the presence of syn-rift sediments was difficult to ascertain, and no conclusions about the timing of initiation were made.

The North Sea basin is one of the best-studied areas in the world with respect to thestructural and sedimentary architecture of rift zones. The Base Cretaceous Unconformity,which defines a mappable horizon at the transition from synrift to postrift sequencesassociated with the Jurassic–Cretaceous rift, is well known as a reference marker for bothseismic and well log interpretations and covers most of the basin. This unconformity isinterpreted at the locations of the Øygarden Fault Zone, the Troll Fault Block, the NorthViking Graben, the Tampen Spur, the Snorre Fault Block, the Sogn Graben and the HordaPlatform. The complexities of the unconformity have been established and vary with thestructural and geographical position within the basin. However, as the Base CretaceousUnconformity covers most of the northern North Sea, its structural time map, is used to derivethe picture of post-structural framework of a rift basin and to locate essential structures in thedeeper sections.Three main reflectors (Pre-Jurassic 1, Pre-Jurassic 2 and Top seismic basement)located beneath the Base Cretaceous Unconformity on the Horda Platform, and have beeninterpreted using 2D seismic reflection data. These three reflectors have been studied in orderto investigate in detail the displacement gradients and possible linkage of the early faultsystem under the Horda Platform, and to evaluate their effect on the large-scale sedimentarchitecture. A main reason to work on the structures under the Horda Platform is due to thefact that these structures are believed to have existed already in the early stages of thenorthern North Sea basin development.The extensional normal fault systems of both the Permo-Triassic and the Late Jurassicrifts are considered a key control on the geological structures and sedimentary architecture ofthe region as presently seen. The basin evolution related Permo-Triassic rifting is mostpronounced on the eastern part of the Horda platform where its synrift geometry is obviouslyseen with the huge segment length and largest uplift explainable by a flexural stretchingmodel. The rift axis is transferred to position at base of the Viking graben during the Late-Jurassic rifting with the smaller magnitude of extension than the Permo-Triassic as clearlyseen by the less thickness of the synrift geometry. However, the structural evolution of normalfaults and the basin architecture under the Horda Platform is particularly affected by thecomplex interaction of fault linkage, fault propagation, fault growth, and death of faultthrough times from the early stage to the final stage of the basin development. Apart from theeffects of major tectonic controls, additionally, non-tectonic parameters, such as climate, seaor lake level changes, and differences in amount and type of sediment supply, should be takeninto account to influence the stratigraphic and sedimentation patterns in the basin.

<p>Petroleum is generated from finely grained source rocks rich in organic materials and accumulated and trapped in reservoir rocks with relatively higher permeability and porosity. Expulsion of petroleum through and out of source rocks is called primary migration. Primary migration, as a link between source rocks and carrier rocks, presents a vital challenge to the society of petroleum geosciences and exploration and attracts the research interests of many geologists and geochemists. Despite extensive research the effective mechanisms responsible for primary migration of hydrocarbons are still in intensive debate. </p><p> Conversion of kerogen to oil and/or gas results in appreciable volume increase due to the density difference between the precursor and the products. Overpressure is developed as a natural consequence in well-sealed dense source rocks at great depths. When the overpressure reaches some critical value, bedding-parallel microcracks are initiated owing to laminated structure and strength anisotropy of source rocks. As transformation proceeds, microcracks are driven to grow subcritically by the overpressure. Such microcracks serve as migration conduits for hydrocarbon flow and may connect to other preexisting conductive fractures to form fracture networks or systems, which may facilitate further migration of hydrocarbons. Convincing evidence from observations in nature and laboratory experiments is found to support the idea that microcracks caused mainly by overpressure buildup from hydrocarbon generation functions as effective primary migration pathways. Based on those published findings, the present dissertation adopted an integrated approach consisting of petroleum geochemistry, petrophysics and fracture mechanics to assess the role of self-propagating microfractures as an effective mechanism for primary migration of hydrocarbons. Four models were developed: migration though subcritical propagation and coalescence of collinear oil-filled cracks, migration through subcritical propagation of an oil-filled penny-shaped crack in isotropic source rocks, subcritical growth of a penny-shaped crack filled by hydrocarbon mix in anisotropic source rocks, and a penny-shaped crack driven by overpressure during conversion of oil to gas. To predict the migration time and quantities of oil and natural gas, we use the reaction kinetics taking into account of pressure and temperature histories during continuous burial of sediments. To account for the compressibility of gas at high temperatures and pressures, we adopt an equation of state for methane, the predominant component of natural gas. To address the excess pressure buildup through volume expansion associated with kerogen degradation and initiation of microfractures, we employ linear fracture mechanics. To simulate the propagation of microcracks, hence the migration of hydrocarbons, we use a finite difference approach. The time period for pressure build-up, the overpressure evolution over time, and crack propagation distance and duration are determined using the coupled model where the interaction of hydrocarbon generation and expulsion is included. A detailed systematic parametric study is carried out to investigate the sensitivity of hydrocarbon migration behavior to variations in the input parameters including elastic and fracture properties of source rocks, richness and type of organic matter and burial history. </p><p> Oil retained in the microfractures may be subjected to thermal cracking to form gas when the gas window is reached as the temperature and pressure continue to increase with the progressive burial. Numerical results are presented for the two cases: kerogen conversion to hydrocarbon mix and subsequently oil conversion to gas. The modeling results agree well with published geological observations which suggest that microfractures caused by overpressures mainly due to hydrocarbon generation serve as effective migration pathways for hydrocarbons within well-sealed source rocks under favorable burial conditions. The fully coupled multiphysics modeling allows us to gain some insight on the primary migration of hydrocarbons, which is essential for the exploration of source rocks. </p>

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Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Earle F. McBride. Vita. Includes bibliographical references. Also available from UMI.