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77th EAGE Conference and Exhibition - Workshops
- Conference date: June 1-4, 2015
- Location: Madrid, Spain
- Published: 01 June 2015
21 - 40 of 128 results
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Construction of Synthetic Shale Based on Physical Simulation Method
More LessSummaryIn this paper, a construction method of synthetic shale sample is proposed. Fine particles (3000–5000 mesh), brittle mineral, clay, carbonate, organic carbon and cement powder are mixed together in different amounts and then cold-pressed the mixture to obtain solid synthetic samples. And basic measurements of the finished samples are conducted in the laboratory to verify whether they are able to meet the requirements of relevant studies by simulating natural shale. The final sample similar to real shale cores in aspects of mineral composition, pore structure, seismic characteristics, etc. is constructed. The biggest characteristic of synthetic shale samples can be simply summarized as controllability, i.e., their mineral composition, diagenetic pressure, cementation degree, porosity, permeability, etc. can all be set according to experiment requirements, and an arbitrary combination of different factors is possible to meet multiple research needs.
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Decline Curve Analysis for Low Permeability Gas Condensate Reservoirs - Effect of Fluid Richness, Inertia and Coupling
Authors C. Johnson and M. JamiolahmadySummaryDecline curve analysis has been proposed as an efficient approach for estimating reservoir and well parameters especially in unconventional gas reservoirs where the use of conventional pressure-transient analysis is often technically and economically challenging. This study investigates the applicability of the widely accepted Fetkovich type curves to low permeability gas-condensate reservoirs under various operating conditions. A synthetic reservoir model based on one of the Fetkovich et al. (1987) case histories was first constructed and validated. Then the impacts of condensate gas richness, different rock types, relative permeability (kr) including coupling or capillary number (increase in kr as flow velocity increases and/or interfacial tension decreases) and inertia (decrease in kr as flow velocity increases) on estimated parameters were examined. The results show that the quality of match (and parameter estimates) between the generated decline curve and type curves is dependent on the condensate saturation level around the wellbore and the nature of the kr curves. In those cases where non-Darcy effects are strong enough to affect the results, use of Fetkovich type curves in the presence of inertia (coupling) results in pessimistic (optimistic) estimates of permeability, and higher (lower) skin estimates than the non-rate-dependent values input into the simulations.
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Towards a Joint Programming on Geological Disposal – The Joprad Project
More LessSummaryThe goal of The JOPRAD project is to prepare the setting up of a “Joint Programming on Radioactive Waste Disposal” that would be established to coordinate at the European level, national research programmes and the associated research and development (R&D) activities on geological disposal for high activity long lived radioactive waste. This action includes reviewing of all strategic aspects linked to a stepwise move towards a Joint Programming in this field. This project will involve organisations that are active in the safety, management and disposal of radioactive waste and research entities. The first step of this project will be to engage in discussion with Member States representatives in order to clarify the organisation of their national R&D consistent with the implementation of the Council Directive. The second step will be to identify existing research programmes that could contribute to the identification of common scientific objectives and activities as well as specific aspects that the organisations would like to develop in the Joint Programme. The third step will be to draft the joint “Programme Document” that should be the technical background of the Joint Programming. This action will lead to the further integration of the interested research community and hence help to maintain and develop the EU leadership in knowledge and expertise for innovative radioactive waste management solutions that effectively matches public expectations. Moreover, it will further reinforce and make the interaction at EU level between WMOs, TSOs, industry, policy makers and the research community more effective.
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How Rift-related/Plate-forming Processes Control Structure and Shortening in Fold-thrust Belts
More LessSummaryFold-thrust belts (FTBs) are archetypical tectonic features adjacent to collisional orogens, where structural traps account for 14% of discovered oil reserves. After decades of field and seismic surveys, detailed geological interpretations have emphasized their high degree of structural complexities. This has dampened academic research interest and impetus towards the understanding of larger scale geodynamic processes related to their development.
FTBs express processes by which plate convergence in collisional orogenic belts is accommodated by accretion within the continental lithosphere. Two dominant tectonic modes are observed in FTBs, thin-skinned and thick-skinned. Thin-skinned style characterized regions dominated by underthrusting, suggesting simple-shear subduction of the underlying crust. A recently discovered relationship between structure of FTBs and plate forming processes ( Mouthereau et al., 2013 ) shows that styles of tectonic deformation at the front of orogenic belts are controlled by age-dependent, deep-seated, properties of the crust and sub-continental mantle. More generally, the role of inherited thermo-tectonic properties of the lithosphere and the architecture of former continental margins is increasingly being shown to be a major driver in the evolution of mountain belts. This research should stimulate novel R&D integrated efforts on both rifted margin and thrust belt.
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Integrated Workflow for Risk Assessment in Fold-and-thrust Belts
By F. RoureSummaryOur understanding of sedimentary basins and thrust belts has greatly benefited from recent improvement of imagery techniques, accounting for a renewed interest for hydrocarbon exploration in fold-and-thrust belts.
This paper describes, using various case studies worldwide, the integrated workflow developed at IFP-EN to reconstruct the kinematic and thermal evolution of fold-and-thrust belts (foothills) and adjacent forelands, and the way numerical modelling and analytical work can improve our predictions in terms of energy resources, hydrocarbon potential and reservoir risk assessment.
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Coupling Tectonics and Surface Processes in Fold and Thrust Belts - Insights from 30 Years of Analog Modeling
More LessSummaryThrough a rapid overview of 30 years of analog modeling studies, we outline the role of the primary mechanisms and processes that exert a strong control on fold and thrust belts evolution. Following this general approach, we address major open questions regarding the global and local responses (i.e., at orogenic scale and at the scale of faults or ridges) of a fold and thrust belt under the impact of tectonic or climatic forcing at different time scales. Insights from analog models are used to: a) characterize the behavior of wedges subject to different geometric, kinematic and rheologic boundary conditions and b) show how the interactions between surface and tectonic processes influence the structures, kinematics of deformation, exhumation mechanisms, and long-term evolution. Impact of first order parameters such as the initial tectonic setting, material transfer in the wedge, structural inheritance (OCT and inherited extensional structures), and their role on the tectonic evolution of fold and thrust belts will be successively reviewed. Several case studies of active or fossil orogens (Taiwan, the western Alps and the Variscan belt) representative of first order tectonic processes are presented in the light of field observation and analog experiments comparison.
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What are the Limits of Balanced Sections in Fold and Thrust Belts
By J. VergesSummaryIn this paper the limits of the geological cross-sections are explored as well as their validity depending on the used datasets and multidisciplinary approaches. Selected cross-sections from different orogenic belts are discussed and framed within plate tectonic reconstructions. The Pyrenees formed during convergence between Iberia and Europe producing the inversion of the relatively narrow basin system between the two plates. Contrarily, the Zagros fold belt is a more complicated orogenic chain produced by an initial obduction phase and a later collision between Eurasia and Arabia. The uncertainties and variability of published balanced cross-sections through these orogenic systems need further constrain to solve problems that cannot be interpreted only with existing structural information.The integration of multidisciplinary studies at different scales of work might help constraining the evolution of the orogenic events and might provide solutions for regions that cannot be addressed solely by the construction of the balanced cross-section using structural information.
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Apatite (U-Th)/He Thermochronology Data Interpretation in Fold and Thrust Belt - New Insights from Physical Point of View
Authors C.G. Gautheron, D. Mbongo-Djimbi, C. Gerin, J. Roques, C. Bachelet, E. Oliviero and L. Tassan-GotSummaryThe apatite (U–Th)/He (AHe) system has rapidly become a very popular thermochronometer to constrain burial and exhumation phases in a variety of geological contexts, including fold and thrust belt. In this particular case, detrital apatite crystals come from different sources and are characterized by different pre-deposit ages and grain chemistry. However the actual He diffusion models are not well constrained and do not fully explain the mechanism of He retention. This is particularly true for detrital apatite crystals and AHe age interpretation can be tricky. In order to have a deeper insight on this issue, multidisciplinary studies on apatite combining physical studies were performed. We propose new He diffusion coefficient, so closure temperature and a physical He diffusion model. We will propose a new way of interpreting AHe datasets on fold and thrust belt samples more particularly, because of their own apatite characteristics. Two examples from Peruvian Subandean zone and south Pyrenean foreland will be given. We will show how a better interpretation of He diffusivity will improve significantly AHe data and thermal histories obtained by data inversion.
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Balanced Cross-sections, Thermochronology and Unexplored Plays - The Peru Case Study
Authors P. Baby, Y. Calderon, C. Hurtado, N. Espurt, M. Louterbach, A. Eude, S. Brusset, M. Roddaz, S. Brichau and R. BolanosSummaryIn the Peruvian Subandean fold and thrust belt, the construction of 4 serial balanced cross-sections from a good set of structural data and an extensive knowledge of the stratigraphy and geodynamic evolution allow a more refined definition of the unexplored plays, as sub-thrusts, duplexes or pre-Cretaceous structures. Sequential restorations are proposed by coupling thermochronologic analyses with growth strata studies. The results show significant north-south variations in the geometry, the timing and the rate of the deformation. This latitudinal variation is related to the pre-Andean basins inheritance, but also to the Andean slab geometry. Thermochronologic ages correspond to the most recent tectonic uplifts and cannot be disassociated from the study of growth strata that might have recorded oldest events. North of the Peruvian Subandean zone, the thrusts propagation seems continuous since the Late Cretaceous. In the south, two stages of Cenozoic deformation are clearly indentified.
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From Andes to Zagros - Variations in Structural Styles and Seismic Data from Two Processors’ Perspectives
Authors R.W. Vestrum and J.M. GittinsSummaryAn overview of data examples from a variety of settings illustrates the similarities and differences in structural style, velocity structure, and acquisition conditions. We have observed that younger rocks typically show lower velocities and the lower compressibility of these strata results in velocities more sensitive to depth of burial. Velocity gradients need more testing in younger basins with lower velocity rocks. Another observation is that more topsoil with wetter surface conditions appear to offer better coupling for seismic sources and receivers, which could explain why we see better signal-to-noise ratios on seismic data from rainforest versus desert environments. Desert outcrops may read like a geology textbook, but visual clarity at the surface comes at a cost of clarity in the subsurface.
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Broadband Seismic Imaging of Thrust Belt along the Outer Banda Arc in Indonesia
Authors M. Fujimoto, Y. Sasaki, Y. Guo and M. OharaSummary3D broadband seismic technique and appropriate PrSDM imaging technique provided us significant improvements in seismic imaging for both thrust complex and sub-thrust structures. Broadband 3D seismic imaging contributed better recovery of seismic energy from deep sections where conventional seismic imaging could not reveal any reflections. Pre-migration deghosting technology provided us the stable phase of wavelets and desired broadband frequency spectrum in the seismic image. The velocity model constructed from the combination of Kirchhoff PrSDM and Controlled Beam Migration provided better resolution and continuity of seismic images under thrust complexes and large fault surfaces by overcoming the poor illumination issue. These technologies contributed to revealing subtle fault displacements, reducing depth structure uncertainty below thrust complex and increasing the understanding of petroleum systems and risk elements of exploration target in a frontier region.
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Fast-track 2D Seismic Processing While Drilling to Ameliorate Foothills Exploration and Optimize Side-track Trajectory
Authors F. Sapin, H. Allouche, G. Sterbecq, B. Chevallier, G. Guerin, B. Eriksen and P. RochatSummaryThe petroleum exploration in foothills domains remains challenging in terms of positioning a well in an optimal manner to target different objectives in places where there are several mechanical discontinuities in the stratigraphy separating them and inducing often shifted structural tops. In consequence, seismic imaging, as well as a good geological knowledge, is mandatory to predict a well trajectory suited for all the targeted objectives. In Kurdistan Region of Iraq, the mechanical stratigraphy is rather simple but the tightening of the structures often leads to the activation of internal mechanical discontinuities and a shift of the main objectives tops. In consequence, and as in any foothills environment, side-tracked wells have to be carefully planned.
After drilling the first leg of a well, and finding out that we were clearly out of our predictions in terms of structural positioning and in the evidence that the deepest objective cannot be drilled with the first leg, the decision to drill a side-track came quickly. Meanwhile, we performed a fast-track processing on the closest 2D line in order to image the high dips of the drilled formations. The output allowed us to help optimizing the side track trajectory and to ahead with better constraints.
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Inversion, Detachment Folds, and Out-of-sequence Thrusts in the Papua New Guinea Fold Belt
Authors K.C. Hill and R. WightmanSummaryAnalysis of structural profiles through oil- and gas-fields of the Papuan Fold Belt indicates that the preexisting configuration of basement played a significant role in the compressional deformation. The Moran-Paua structures overlie upthrust basement and comprise small asymmetric detachment folds subsequently decapitated by out-of-sequence thrusts, causing shearing of the forelimb. Interpretation of reflection seismic data in the Agogo area suggests a 10° regional dip in basement and a thick syn-rift sequence in which a large detachment fold was formed, probably associated with early basement thrusting at Moran. The forelimb of the fold was then cut through by low-angle thrust faults creating oilfields in both the gentle hangingwall and steep footwall-forelimb. Along strike at Usano, in contrast, seismic interpretation suggests that the basement is shallower dipping and rift sediments appear to be thinner. There, the detachment folds were not developed and early basement thrusting/inversion resulted in a shear zone. Subsequent thrusting along Jurassic and Upper Cretaceous décollements created duplexes and cut through the shear zone such that it was oversteepened creating the Usano oilfield in the hangingwall. Understanding these relationships is important in defining new hydrocarbon plays.
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Plio-pleistocene Thrusting in the Eastern Amazonian Orogenic Wedge (South Peru)
Authors M. Louterbach, M. Roddaz, P. Baby, S. Brichau, J. Bailleul and Y. CalderónSummaryQuantifying interactions between uplift, climate, deformation and exhumation processes remains difficult, mainly due to a paucity of data relevant to all processes. Central Andes are a prime example to study the respective role of climate forcing and tectonic activity on mountain building. In this study we propose new data (thermochronology, biostratigraphy, field observations and seismic interpretations) focused on the Eastern Cordillera (EC) and the Sub-Andean Zone (SAZ) of southern Peru between 12ºS and 14ºS, in order to i) constrain the timing of deformation, and to ii) demonstrate that contrary to recent studies, our new data outline that the Plio-Peistocene uplift and erosion of the Andes are more likely related to thrust induced exhumation than to a climate forcing. Low temperature thermochronological results obtained for the EC and the SAZ, as well as the growth strata documented in seismic and on the field allow to determine two main deformation periods: i) from the Oligocene to Middle Miocene (~25-14 Ma), and ii) from the Late Miocene to Pleistocene (~10-2.8 Ma). The Plio-Pleiostocene cooling induced by the erosion of the EC in southern Peru is not controlled by climatic change, but better by the development of duplex in the Andean front.
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New Exploration Concepts in Zagros Fold Thrust Belt and Persian Gulf, Iran
Authors S. Jahani, I. Abdollahie Fard and S. SherkatiSummaryAfter more than 100 years hydrocarbon exploration, The Zagros Fold-Thrust Belt (ZFAB) is still remained as one of the most talented regions for future hydrocarbon discovery. Three main hydrocarbon structures originated from the Neogene folding, inherited deep-seated faults and buried salt diapirs. Remained many complex and small structures with potential prospect in the ZFTB which has not completely studied yet. They could be categorized in: (1) Fault related structures as subtle traps, which formed in response to intermediate detachments during Zagros folding or formed below the thrust faults, (2) Long time halokinesis prepared suitable small traps around the diapirs or under the salt sheets, (3) Inherited deep-seated fault movement and see-level changing formed stratigraphic-structural traps towards the palaeohighs, (4) Results of few drilled wells in pre-Permian sediments (Faraghan Formation) proved new gas reserves (5) and oil rings developed in some of onshore folded anticlinal. Consequently for future oil and gas exploration has to take two strategies. For oil exploration focuses more on the complex and small structures including subtle traps, stratigraphic-structural traps around salt diapirs and Palaeohighs. Whereas, for gas exploration remained many huge anticlines to the eastern part of ZFTB which has not been investigated in details.
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Analogue Modelling of the Papua New Guinea Fold and Thrust Belt
Authors R. Darnault, K.C Hill, J.M Mengus, J.M Daniel, J.P Callot and J.C RingenbachSummaryIn the PNG Fold Belt the jungle-covered mountains limit data acquisition so that the internal geometry and evolution of the large anticlines are poorly understood. It is postulated that the anticlines formed above old normal faults in basement, which has been tested by analogue modelling and 3D computerized X-ray tomographic scanning. Layers of corundum, sand, silicone and sand/silicone mixes were used to represent the PNG stratigraphy of 2 km of molasse, 1 km of carbonate, 1 km of mudstone, 500m of sandstone and shale reservoirs and 0.5-3 km of syn-rift clastics. The thicknesses, strengths and velocities of deformation were all scaled appropriately and erosion/deposition was modelled by adding or removing ‘molasse’. It was found that the carbonate deformation was often detached from that of the underlying reservoirs and that the structural style was critically dependent upon the strength of the intervening mudstone and of the basal detachment. Structural style was also strongly correlated to deformation rate, in that slower convergence rates yielded a single large fold, whereas optimum rates yielded more realistic detachment folds. It was observed that the development of an overturned detachment fold was greatly enhanced when the basement fault was first partially inverted.
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Development of Detachment Folds on Syn-orogenic Sequences Including Salt Layers
Authors O. Pla, J.A Muñoz, O. Ferrer, E. Roca and O. GratacósSummaryThe southern Pyrenean foreland basin is formed by a thick syn-orogenic sequence that includes several evaporitic layers with salt that are involved in the fold-and-thrust belt. The Oliola anticline is a detachment fold probably developed at the southern pinch-out of the syn-orogenic Cardona salt unit that also involves younger syn-contractional evaporitc unit (Barbastro Fm.).
Based on this natural analogue and using an experimental approach (sandbox models) we propose a new kinematic model for the development of detachment folds with multilayered evaporites in the Ebro basin. Analogue modelling of detachment folds suggests a new scenario for diapirs formation in compressional tectonic settings.
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Genesis and Tectono-thermal Evolution of the Altiplano (Central Andes), from the Basin to the Orogen
Authors A.M.M. Robert, P. Baby and M. RoddazSummaryWe would like to present our project that aims to investigate the tectono-thermal evolution of the Altiplano in the Central Andes from the basin to the orogenic scale and to study the interplay between Earth's deep and surface processes in convergent context.
We aim to unravel the sedimentologic, structural and thermal evolution of the hinterland basins of the Altiplano in order to provide critical evidences for the history and style of the deformation in that region. In fact, these basins remain attractive frontier basins for petroleum exploration.
At the orogenic scale, this study projects to compare regional cross-sections at different latitudes. According to the available seismic and seismologic data, we propose to produce 2 regional lithospheric-scale cross-sections mainly based on detailed balanced cross-sections and geophysical modeling.
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Algorithmic Aspects of Extended Waveform Inversion
By W. SymesSummaryExtended waveform inversion uses inference of an extended model, depending on non-physical parameters, to extract velocity information directly from waveform data. It has been observed that fitting data at all stages of velocity updates, a possibility offered by model extension, appears to be important to assure reliability of algorithms of this type. An analysis of the modeling operator derivative provides an explanation for this observation, and reveals the link between extended waveform inversion and traveltime tomography.
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Inversion Velocity Analysis - The Importance of Regularisation
Authors H. Chauris, C.A. Lameloise and E. CocherSummaryInversion Velocity Analysis has been recently proposed as an alternative to Migration Velocity Analysis. Under the Born approximation, it consists of first determining the optimal reflectivity model such that the synthetic data set nicely fits with the observed data set. Then, a standard velocity analysis is applied to the inverted reflectivity. The main differences with respect to the classical approach is the use of iterative migration versus standard migration. We propose here an alternative way to compute the gradient of the objective function and demonstrate the importance of the regularisation term introduced to determine the optimal reflectivity model.
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