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Collaborating Authors
Lecomte, Isabelle
Paleokarst reservoirs: Efficient and flexible characterization using point-spread-function-based convolution modeling
Jensen, Kristian (University of Bergen) | Johansen, Martin Kyrkjebø (University of Bergen) | Lecomte, Isabelle (University of Bergen) | Janson, Xavier (The University of Texas at Austin) | Tveranger, Jan (NORCE Norwegian Research Centre AS) | Kaschwich, Tina (NORSAR)
Abstract Paleokarst originates from the collapse, degradation, and infill of karstified rock, and it typically features spatially heterogeneous elements such as breakdown products, sediment infills, and preserved open cavities on all scales. Paleokarst may further contain aquifer or hydrocarbon reservoirs and may pose a drilling hazard during exploration. Seismic characterization of paleokarst reservoirs therefore remains a challenging and important task. We have determined how the application of 2D (3D) spatial convolution operators, referred to as point-spread functions (PSFs), allows for seismic modeling of complex and heterogeneous paleokarst geology at a cost equivalent to conventional repeated 1D convolution. Unlike the latter, which only considers vertical resolution effects, PSF-based convolution modeling yields simulated prestack depth-migrated images accounting for 3D resolution effects vertically and laterally caused by acquisition geometries, frequency-band limitations, and propagation effects in the overburden. We confirm the validity of the approach by a comparison of modeled results to results obtained from a published physical modeling experiment. Finally, we present four additional separate case studies to highlight the usability and flexibility of the approach by assessing different issues and challenges pertaining to characterizing and interpreting seismic features of paleokarst. Through PSF-based convolution modeling, geoscientists working with paleokarst seismic data may be better able to understand how various acquisition and modeling parameters affect seismic images of paleokarst geology.
- North America > United States > Texas (1.00)
- Europe (1.00)
- Phanerozoic > Cenozoic (0.67)
- Phanerozoic > Paleozoic > Permian (0.46)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.69)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.66)
- Geophysics > Seismic Surveying > Seismic Modeling (1.00)
- Geophysics > Seismic Surveying > Seismic Interpretation (1.00)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition (0.93)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (0.87)
- South America > Argentina > Patagonia > Neuquén > Neuquen Basin (0.99)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- (25 more...)
We investigate the correlation between rock properties and seismic expression in sand-injectite complex within shallow depositional systems. We first upscale 1D microstructural observations to a 3D geological-scale model, and then perform 3D seismic forward modeling. Using an existing theoretical rock-physics investigation in brine- and gas-saturated poorly-consolidated sands as well as illite-dominated shales, we consider the influence of frequency-related behavior as a fundamental part in the upscaling process of sand and shale elastic properties. The 3D synthetic modeling assumes that sands microstructural features are isotropic while shales are vertical transverse isotropic, and is heterogeneous at the field-scale, i.e., shales are finely layered while sands have complex geometry. The seismic modeling results show that the sand intrusions are difficult to detect in the seismic sections because of the small acoustic impedance contrast with the surrounding shales but also due to the irregular features of top and bottom sands, and the complex connectivity between the parent sands with the sand intrusions. Their visibility is further compromised with the effect of complex wave propagation and the interferences of backscatter seismic energy (constructive and destructive) as a result of 3D heterogeneities in shale and sand petrophysical and elastic properties. Therefore, even in the most optimal survey illumination, a careful interpretation of the reflectivity response is still required to predict most sand boundaries. Presentation Date: Wednesday, October 14, 2020 Session Start Time: 8:30 AM Presentation Time: 11:25 AM Location: 360A Presentation Type: Oral
- Europe > Norway > North Sea > Northern North Sea > South Viking Graben > PL 150 > Block 24/9 > Volund Field > Hermod Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > South Viking Graben > PL 150 > Block 24/9 > Volund Field > Balder Formation (0.99)
- Europe > Norway > Barents Sea > Hammerfest Basin > PL 229 > Block 7122/8 > Goliat Field > Kapp Toscana Group > Realgrunnen Subgroup > Kapp Toscana Group > Realgrunnen Subgroup > Snadd Formation > Realgrunnen Subgroup > Tubåen Formation > Sassendalen Group > Kobbe Formation (0.99)
- (63 more...)
Efficient and flexible characterization of paleokarst seismic signatures using point-spread function-based convolution modeling
Jensen, Kristian (University of Bergen) | Lecomte, Isabelle (University of Bergen) | Janson, Xavier (University of Texas at Austin) | Tveranger, Jan (NORCE Norwegian Research Centre AS)
Paleokarst reservoirs originate from collapse, degradation and infill of karstified rock, and typically feature spatially heterogeneous elements such as breakdown products, sediment infills and preserved open cavities on all scales. Seismic characterization of paleokarst reservoirs therefore remains a challenging task. Through the application of 2(3)D spatial convolution operators, referred to as point-spread functions, efficient and flexible seismic modeling of prestack depth migrated paleokarst signatures may be obtained at a low computational cost. The present paper investigates the application of this method on paleokarst-type reservoirs by performing a qualitative comparison of seismic signatures generated using this approach and signatures obtained from a physical modeling experiment. We further illustrate the suitability/utility of the method by analyzing modeled prestack depth-migrated images of a selected target area in a 3D geocellular model of the Devil’s Sinkhole in Texas. Presentation Date: Wednesday, October 14, 2020 Session Start Time: 9:20 AM Presentation Time: 10:10 AM Location: Poster Station 9 Presentation Type: Poster
ABSTRACT Fluid escape pipes and blow out structures represent important seal bypass system (SBS) affecting the overburden. Most of those structures have been proven major fluid conduits that may reveal important hints on the fluid migration and fine-tuning our understanding on the main process controlling their genesis can be crucial in elucidating subsea hazard aspects during exploration stage. However, due to the lack of direct geological evidence and clear geophysical imaging, there are still uncertainties concerning they main architecture (root, conduit and seal). In order to contribute to the seismic interpretation of those subsurface structures, we propose a forward seismic modeling aiming at exploring the nature of certain seismic structure responses and architectures observed across the Loyal field (Shetland basin) and using different petrophysics properties. We first build a geological model with essential rock profiles and well logging data constrained. Then, we employ three approaches, i.e., forward modeling, ray-tracing analysis and time-to-depth conversion, to unravel and explore some of the main internal structures observed within the interpreted fluid pipe seal by-pass structures present in the Loyal field. The results allow us to put some constrains on the origin and nature of some specific seismic features observed in the seal bypass structures: (i)Â the absorption effects in the conduit result in the lacking resolution in the internal-pipe and root structures, (ii)Â the upward deflections are almost formed by the real upward dragging intrusive material and (iii)Â the internal pipes are affected by low velocities related to fluid-rich solid material. Presentation Date: Wednesday, September 18, 2019 Session Start Time: 1:50 PM Presentation Time: 2:15 PM Location: Poster Station 4 Presentation Type: Poster
- Europe > United Kingdom > Atlantic Margin > West of Shetland (0.85)
- Europe > Norway > North Sea (0.51)
- Europe > United Kingdom > Atlantic Margin > West of Shetland > Faroe-Shetland Basin > Judd Basin > Block 204/20 > Greater Schiehallion Field > Loyal Field (0.99)
- Europe > Norway > North Sea > Central North Sea > Shetland Group > Lista Formation (0.99)
ABSTRACT A common problem encountered when migrating seismic data is the blurring and partial retrieval of the stratigraphic model of interest due to limited survey illumination, propagation effect functions of the overburden velocity, frequency-band limited wavelets, and more. Through the application of ray-generated 2(3)D spatial convolution operators, referred to as , these blurring effects and partial illumination may be analyzed in more detail, which enhances our understanding of seismic image quality, prior or after acquisition and processing. To illustrate our purpose, we apply the method on the synthetic Sigsbee2A model at selected target areas, and study how, e.g., amplitude effects and aperture width affect the migrated image. A ray approach allows indeed for efficient sensitivity studies on various parameters, thus explaining differences in seismic image quality, while possibly helping fine-tuning imaging parameters. Presentation Date: Tuesday, October 16, 2018 Start Time: 8:30:00 AM Location: 205A (Anaheim Convention Center) Presentation Type: Oral
Prestack inversion and multiattribute analysis for porosity, shale volume, and sand probability in the Havert Formation of the Goliat field, southwest Barents Sea
Yenwongfai, Honore Dzekamelive (Statoil ASA, University of Oslo) | Mondol, Nazmul Haque (University of Oslo, Norwegian Geotechnical Institute (NGI)) | Faleide, Jan Inge (University of Oslo) | Lecomte, Isabelle (University of Bergen, University of Oslo) | Leutscher, Johan (Eni Norge)
Abstract An integrated innovative multidisciplinary approach has been used to estimate effective porosity (PHIE), shale volume (), and sand probability from prestack angle gathers and petrophysical well logs within the Lower Triassic Havert Formation in the Goliat field, Southwest Barents Sea. A rock-physics feasibility study revealed the optimum petrofacies discriminating ability of extended elastic impedance (EEI) tuned for PHIE and . We then combined model-based prestack inversion outputs from a simultaneous inversion and an EEI inversion into a multilinear attribute regression analysis to estimate absolute and PHIE seismic attributes. The quality of the and PHIE prediction is shown to increase by integrating the EEI inversion in the workflow. Probability distribution functions and a priori petrofacies proportions extracted from the well data are then applied to the and PHIE volumes to obtain clean and shaly sand probabilities. A tectonic-controlled point-source depositional model for the Havert Formation sands is then inferred from the extracted sand bodies and the seismic geomorphological character of the different attributes.
- Europe > Norway > Barents Sea (1.00)
- Asia (1.00)
- Phanerozoic > Paleozoic > Permian (1.00)
- Phanerozoic > Mesozoic > Triassic > Lower Triassic (0.48)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geology > Structural Geology > Tectonics > Compressional Tectonics > Fold and Thrust Belt (0.67)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (1.00)
- Geophysics > Seismic Surveying > Seismic Interpretation (1.00)
- South America > Colombia > Huila Department > Neiva Basin > Balcon Field (0.99)
- Europe > Norway > Barents Sea > PL 535 > Havert Formation (0.99)
- Europe > Norway > Barents Sea > Hammerfest Basin > PL 229 > Block 7122/8 > Goliat Field > Kapp Toscana Group > Realgrunnen Subgroup > Kapp Toscana Group > Realgrunnen Subgroup > Snadd Formation > Realgrunnen Subgroup > Tubåen Formation > Sassendalen Group > Kobbe Formation (0.99)
- (65 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic modeling (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
3D structure and formation of hydrothermal vent complexes at the Paleocene-Eocene transition, the Møre Basin, mid-Norwegian margin
Kjoberg, Sigurd (The University of Oslo) | Schmiedel, Tobias (The University of Oslo) | Planke, Sverre (The University of Oslo, Volcanic Basin Petroleum Research (VBPR)) | Svensen, Henrik H. (The University of Oslo) | Millett, John M. (Volcanic Basin Petroleum Research (VBPR), The University of Aberdeen) | Jerram, Dougal A. (The University of Oslo, DougalEarth) | Galland, Olivier (The University of Oslo) | Lecomte, Isabelle (NORSAR, The University of Bergen) | Schofield, Nick (The University of Aberdeen) | Haug, Øystein T. (The University of Oslo) | Helsem, Andreas (Statoil)
Abstract The mid-Norwegian margin is regarded as an example of a volcanic-rifted margin formed prior to and during the Paleogene breakup of the northeast Atlantic. The area is characterized by the presence of voluminous basaltic complexes such as extrusive lava and lava delta sequences, intrusive sills and dikes, and hydrothermal vent complexes. We have developed a detailed 3D seismic analysis of fluid- and gas-induced hydrothermal vent complexes in a area in the Møre Basin, offshore Norway. We find that formation of hydrothermal vent complexes is accommodated by deformation of the host rock when sills are emplaced. Fluids are generated by metamorphic reactions and pore-fluid expansion around sills and are focused around sill tips due to buoyancy. Hydrothermal vent complexes are associated with doming of the overlying strata, leading to the formation of draping mounds above the vent contemporary surface. The morphological characteristics of the upper part and the underlying feeder structure (conduit zone) are imaged and studied in 3D seismic data. Well data indicate that the complexes formed during the early Eocene, linking their formation to the time of the Paleocene-Eocene thermal maximum at c. 56 Ma. The well data further suggest that the hydrothermal vent complexes were active for a considerable time period, corresponding to a c. 100 m thick transition zone unit with primary Apectodinium augustum and redeposited very mature Cretaceous and Jurassic palynomorphs. The newly derived understanding of age, structure, and formation of hydrothermal vent complexes in the Møre Basin contributes to the general understanding of the igneous plumbing system in volcanic basins and their implications for the paleoclimate and petroleum systems.
- Phanerozoic > Cenozoic > Paleogene > Paleocene (1.00)
- Phanerozoic > Cenozoic > Paleogene > Eocene > Ypresian (0.48)
- Geology > Geological Subdiscipline > Volcanology (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.66)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.47)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition (1.00)
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Interpretation (1.00)
- South America > Argentina > Patagonia > Neuquén > Neuquen Basin (0.99)
- Europe > United Kingdom > Atlantic Margin > West of Shetland > Rockall Basin (0.99)
- Europe > Norway > Norwegian Sea > Møre Basin > PL 208 > Springar Formation (0.99)
- (5 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- (2 more...)
Prestack simultaneous inversion to predict lithology and pore fluid in the Realgrunnen Subgroup of the Goliat Field, southwestern Barents Sea
Yenwongfai, Honore Dzekamelive (Statoil ASA, University of Oslo) | Mondol, Nazmul Haque (University of Oslo, Norwegian Geotechnical Institute (NGI)) | Faleide, Jan Inge (University of Oslo) | Lecomte, Isabelle (University of Oslo, University of Bergen)
Abstract An integrated multidisciplinary workflow has been implemented for quantitative lithology and fluid predictions from prestack angle gathers and well-log data within the Realgrunnen Subgroup in the Goliat Field, southwestern Barents Sea. We have first performed a qualitative amplitude-variation-with-angle (AVA) attribute analysis to assess the spatial distribution of lithology and fluid anomalies from the seismic data. A simultaneous prestack elastic inversion was then carried out for quantitative estimates of the P-impedance and ratio. Probability density functions, a priori lithology, and fluid class proportions extracted from well-log training data are further applied to the inverted P-impedance and seismic volumes. The AVA qualitative analysis indicates a class IV response for the top of the reservoir, whereas anomalies from the AVA attribute maps agree largely with the clean sand probabilities predicted from the Bayesian facies classification. The largest misclassification in the lithology classification occurs between shaly sands and shales. A mixed lithology and fluid classification indicates a smaller degree of overlap and allows for the discrimination of hydrocarbon sands. Integration of a qualitative AVA analysis and a quantitative Bayesian probability approach helps in constraining the depositional facies variability within the Realgrunnen Subgroup. Finally, a possible influence of tectonic activity during the deposition of the Realgrunnen reservoir is inferred based on the facies distribution maps.
- Phanerozoic > Paleozoic (1.00)
- Phanerozoic > Mesozoic > Jurassic (0.93)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.70)
- Geology > Structural Geology > Tectonics > Compressional Tectonics > Fold and Thrust Belt (0.68)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.66)
- North America > Canada > Nunavut > Sverdrup Basin (0.99)
- Europe > Norway > Barents Sea > Kobbe Formation (0.99)
- Europe > Norway > Barents Sea > Hammerfest Basin > PL 229 > Block 7122/8 > Goliat Field > Kapp Toscana Group > Realgrunnen Subgroup > Kapp Toscana Group > Realgrunnen Subgroup > Snadd Formation > Realgrunnen Subgroup > Tubåen Formation > Sassendalen Group > Kobbe Formation (0.99)
- (99 more...)
ABSTRACT This study implements a multidisciplinary approach to porosity (PHIE), shale volume (Vsh) and sand probability estimation from prestack angle gathers and petrophysical well logs. A rock physics feasibility study revealed the optimum petrofacies discriminating ability of extended elastic impedance (EEI) and PHIE. Multilinear regression analysis is then applied to the output of the simultaneous inversion of seismic data to estimate Vsh and PHIE. Probability distribution functions (PDFs) and facies extracted from the well data are then applied to the Vsh and PHIE volumes to obtain a sand probability cube for the Lower Triassic Havert Formation in the Goliat field, SW Barents Sea. Presentation Date: Monday, October 17, 2016 Start Time: 1:50:00 PM Location: 155 Presentation Type: ORAL
- Europe > Norway > Barents Sea > PL 535 > Havert Formation (0.99)
- Europe > Norway > Barents Sea > Kobbe Formation (0.99)
- Europe > Norway > Barents Sea > Hammerfest Basin > PL 229 > Block 7122/8 > Goliat Field > Kapp Toscana Group > Realgrunnen Subgroup > Kapp Toscana Group > Realgrunnen Subgroup > Snadd Formation > Realgrunnen Subgroup > Tubåen Formation > Sassendalen Group > Kobbe Formation (0.99)
- (96 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic modeling (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Ray-based seismic modeling of geologic models: Understanding and analyzing seismic images efficiently
Lecomte, Isabelle (NORSAR, University of Oslo) | Lavadera, Paul Lubrano (NORSAR) | Anell, Ingrid (University of Oslo) | Buckley, Simon J. (Uni Research) | Schmid, Daniel W. (University of Oslo) | Heeremans, Michael (University of Oslo)
Abstract Often, interpreters only have access to seismic sections and, at times, well data, when making an interpretation of structures and depositional features in the subsurface. The validity of the final interpretation is based on how well the seismic data are able to reproduce the actual geology, and seismic modeling can help constrain that. Ideally, modeling should create complete seismograms, which is often best achieved by finite-difference modeling with postprocessing to produce synthetic seismic sections for comparison purposes. Such extensive modeling is, however, not routinely affordable. A far more efficient option, using the simpler 1D convolution model with reflectivity logs extracted along verticals in velocity models, generates poor modeling results when lateral velocity variations are expected. A third and intermediate option is to use the various ray-based approaches available, which are efficient and flexible. However, standard ray methods, such as the normal-incidence point for unmigrated poststack sections or image rays for simulating time-migrated poststack results, cannot deal with complex and detailed targets, and will not reproduce the realistic (3D) resolution effects of seismic imaging. Nevertheless, ray methods can also be used to estimate 3D spatial prestack convolution operators, so-called point-spread functions. These are functions of the survey, velocity model, and wavelet, among others, and therefore they include 3D angle-dependent illumination and resolution effects. Prestack depth migration images are thus rapidly simulated by spatial convolution with detailed 3D reflectivity models, which goes far beyond the limits of 1D convolution modeling. This 3D convolution modeling should allow geologists to better assess their interpretations and draw more definitive conclusions.
- Geology > Structural Geology (1.00)
- Geology > Geological Subdiscipline > Geomechanics (0.93)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.93)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
- Europe > United Kingdom (0.89)
- Europe > Netherlands (0.89)