Publications
139 results found
Zhang Z, Geiger S, Rood M, et al., 2017, A Tracing Algorithm for Flow Diagnostics on Fully Unstructured Grids With Multipoint Flux Approximation, SPE Journal, Vol: 22, Pages: 1946-1962, ISSN: 1930-0220
Flow diagnostics is a common way to rank and cluster ensembles of reservoir models depending on their approximate dynamic behavior before beginning full-physics reservoir simulation. Traditionally, they have been performed on corner-point grids inherent to geocellular models. The rapid-reservoir-modeling (RRM) concept aims at fast and intuitive prototyping of geologically realistic reservoir models. In RRM, complex reservoir heterogeneities are modeled as discrete volumes bounded by surfaces that are sketched in real time. The resulting reservoir models are discretized by use of fully unstructured tetrahedral meshes where the grid conforms to the reservoir geometry, hence preserving the original geological structures that have been modeled.This paper presents a computationally efficient work flow for flow diagnostics on fully unstructured grids. The control-volume finite-element method (CVFEM) is used to solve the elliptic pressure equation. The flux field is a multipoint flux approximation (MPFA). A new tracing algorithm is developed on a reduced monotone acyclic graph for the hyperbolic transport equations of time of flight (TOF) and tracer distributions. An optimal reordering technique is used to deal with each control volume locally such that the hyperbolic equations can be computed in an efficient node-by-node manner. This reordering algorithm scales linearly with the number of unknowns.The results of these computations allow us to estimate swept-reservoir volumes, injector/producer pairs, well-allocation factors, flow capacity, storage capacity, and dynamic Lorenz coefficients, which all help approximate the dynamic reservoir behavior. The total central-processing-unit (CPU) time, including grid generation and flow diagnostics, is typically a few seconds for meshes with O (100,000) unknowns. Such fast calculations provide, for the first time, real-time feedback in the dynamic reservoir behavior while models are prototyped.
Hampson GJ, Premwichein K, 2017, Sedimentologic character of ancient muddy subaqueous-deltaic clinoforms: Down Cliff Clay Member, Bridport Sand Formation, Wessex Basin, UK, Journal of Sedimentary Research, Vol: 87, Pages: 951-966, ISSN: 1527-1404
Muddy subaqueous clinoforms are a common feature of many modern deltas, particularly those developed in basins with strong waves, tides, or oceanographic currents. Ancient examples have only rarely been reported, implying that they are under-recognized. Herein, the sedimentological characteristics of muddy subaqueous-deltaic clinoforms from the Lower Jurassic Down Cliff Clay Member of the Bridport Sand Formation, Wessex Basin, UK, are described and interpreted, as a reference to re-evaluate other ancient shallow-marine mudstone successions.Deposits below the Down Cliff Clay clinoforms consist of erosionally based, bioclastic sandy limestone beds intercalated with upward-thickening fossiliferous claystones and siltstones (facies association A), which record upward-increasing water depth under conditions of minor input of clastic sediment and reworking by storm waves. These deposits are downlapped by foreset-to-toeset deposits of the subaqueous-deltaic clinoforms, which comprise claystones and siltstones that contain calcareous nodules and are variably bioturbated by a low-diversity trace-fossil assemblages dominated by Chondrites (facies association B). These foreset-to-toeset deposits record slow deposition (undecompacted sediment accumulation rate of c. 4.4 m/Myr) from suspension fall-out and distal sediment gravity flows under conditions of intermittent and/or poor oxygenation of bottom waters. Clinoform foreset deposits dip paleoseaward at 2°, and consist of siltstones and sandy siltstones that are moderately to completely bioturbated by a high-diversity trace-fossil assemblage (facies association C). Thin (< 1 cm), erosionally based, parallel-laminated and current-ripple cross-laminated siltstone and very fine-grained sandstone beds in the foreset deposits record episodic sediment gravity flows and tractional currents. Foreset deposits record relatively rapid deposition (undecompacted sediment accumulation rate of c. 194 m/Myr) above effective storm wave
Debbabi Y, Jackson MD, Hampson GJ, et al., 2017, Capillary Heterogeneity Trapping and Crossflow in Layered Porous Media, Transport in Porous Media, Vol: 120, Pages: 183-206, ISSN: 0169-3913
We examine the effect of capillary and viscous forces on the displacement of one fluid by a second, immiscible fluid across and along parallel layers of contrasting porosity, and relative permeability, as well as previously explored contrasts in absolute permeability and capillary pressure. We consider displacements with wetting, intermediate-wetting and non-wetting injected phases. Flow is characterized using six independent dimensionless numbers and a dimensionless storage efficiency, which is numerically equivalent to the recovery efficiency. Results are directly applicable to geologic carbon storage and hydrocarbon production. We predict how the capillary–viscous force balance influences storage efficiency as a function of a small number of key dimensionless parameters, and provide a framework to support mechanistic interpretations of complex field or experimental data, and numerical model predictions, through the use of simple dimensionless models. When flow is directed across layers, we find that capillary heterogeneity traps the non-wetting phase, regardless of whether it is the injected or displaced phase. However, minimal trapping occurs when the injected phase is intermediate-wetting or when high-permeability layers contain a smaller moveable volume of fluid than low-permeability layers. A dimensionless capillary-to-viscous number defined using the layer thickness rather than the more commonly used system length is most relevant to predict capillary heterogeneity trapping. When flow is directed along layers, we show that, regardless of wettability, increasing capillary crossflow reduces the distance between the leading edges of the injected phase in each layer and increases storage efficiency. This may be counter-intuitive when the injected phase is non-wetting. Crossflow has a significant impact on storage efficiency only when high-permeability layers contain a smaller moveable volume of fluid than low-permeability layers. In that case, capillary he
Flood YS, Hampson GJ, 2017, Analysis of floodplain sedimentation, avulsion style and channelised fluvial sandbody distribution in an upper coastal plain reservoir: Middle Jurassic Ness Formation, Brent Field, UK North Sea, Sedimentology of Paralic Reservoirs: Recent Advances, Editors: Hampson, Reynolds, Kostic, Wells, Publisher: Geological Society of London, Pages: 109-140
Numerical models and recent outcrop case studies of alluvial-to-coastal-plain strata suggest that autogenic avulsion can control the stacking density and architecture of channelized fluvial sandbodies. The application of these models to subsurface well data was tested by the analysis of upper coastal plain deposits of the late Bajocian Ness Formation in the Brent Field reservoir, UK North Sea. These coastal plain deposits accumulated during the progradation and retrogradation of the wave-dominated ‘Brent Delta’. Sedimentological facies analysis and palaeosol characterization in cores were used to interpret the styles of palaeochannel avulsion. These results were then compared with the dimensions and distributions of channelized fluvial sandbodies that had been quantified by spatial statistical tools (lacunarity, Besag’s L function) applied to interpretative correlation panels between closely spaced wells. The results indicate that the distributions of channelized sandbodies may plausibly have been generated by avulsions and that they influence sandbody connectivity and pressure depletion patterns. Intervals of upper coastal plain strata with relatively wide sandbodies that display some clustering in their stratigraphic architecture are associated with a high proportion of avulsions by incision and annexation in core samples. Such intervals display relatively good vertical pressure communication and relatively slow, uniform pressure depletion.
Hampson GJ, Reynolds AD, Kostic B, et al., 2017, Introduction to the sedimentology of paralic reservoirs: recent advances, Sedimentology of Paralic Reservoirs: Recent Advances, Editors: Hampson, Reynolds, Kostic, Wells, Publisher: Geological Society of London, Pages: 1-6, ISBN: 9781786202741
Paralic reservoirs reflect a range of clastic depositional environments developed along or near coastlines, including deltas, shoreline–shelf systems and estuaries. Such reservoirs provide the backbone of production in many mature basins around the world, and contribute significantly to global conventional hydrocarbon production. Strata that host these reservoirs are shaped by a wide variety of depositional processes and controls which reflect the upstream supply of sediment and water, the characteristics of the receiving basin, relative sea level, tectonic setting, and the internal dynamics of depositional systems. Consequently, they exhibit much variability in their stratigraphic architecture and sedimentological heterogeneity, which translates into complex patterns of reservoir distribution and reservoir performances that are challenging to predict, optimize and manage. This Special Publication presents new research and developments in established approaches to exploration and production of paralic reservoirs. It arises from the conference and associated core workshop titled ‘Sedimentology of Paralic Reservoirs: Recent Advances and their Applications’, which was organized by the Petroleum Group of the Geological Society of London and held in London from 18 to 21 May 2015.
Hampson GJ, Howell JA, 2017, Sedimentologic and sequence-stratigraphic characteristics of wave-dominated deltas, AAPG Bulletin, Vol: 101, Pages: 441-451, ISSN: 0149-1423
Wave-dominated deltaic strata form prolific hydrocarbon plays in many mature basins across theworld. Examples include the Jurassic Brent Group play in the North Sea, offshore UK and Norway(e.g., Husmo et al., 2003), Eocene Jackson Group and Oligocene Frio Formation plays, Texas, onshoreUSA (e.g., Fisher et al., 1970; Galloway and Morton, 1989), and Tertiary plays in the Niger Deltaprovince, offshore Nigeria (e.g., Evamy et al., 1978), the Baram Delta province, offshore Brunei (e.g.,Rijks, 1981), and the Columbus Basin, offshore Trinidad and Tobago (e.g., Sydow et al., 2003). Wavedominateddeltas also form key exploration targets in frontier basins (e.g., Triassic Snadd Formation,Barents Sea, offshore Norway; Klausen et al., 2014, 2016).The overall architecture of many wave-dominated deltaic reservoirs is determined by their sequencestratigraphic framework, together with their structural configuration. Sequence stratigraphicframeworks contain elements such as shoreface-shelf parasequences bounded by flooding surfaces,and fluvio-estuarine complexes that fill incised coastal valleys developed at sequence boundaries. Theinternal facies distributions and stacking patterns of such elements are ordered, which aids predictionof reservoir character and behavior. Outcrop analogues of wave-dominated deltaic reservoirs displayaspects of ordered stratigraphic architecture across a range of spatial scales that are equivalent tothose observed in core, well-log and seismic data, and can therefore be used to support interpretationof their subsurface counterparts.
Le Blevec T, Dubrule O, john CM, et al., 2017, Modelling asymmetrical facies successions using pluri-Gaussian simulations, Geostatistics Valencia 2016, Editors: Cassiraga, Vargas-Guzmán, Publisher: Springer, Pages: 59-75, ISBN: 978-3-319-46818-1
An approach to model spatial asymmetrical relations between indicators is presented in a pluri-Gaussian framework. The underlying gaussian random functions are modelled using the linear model of co-regionalization, and a spatial shift is applied to them. Analytical relationships between the two underlying gaussian variograms and the indicator covariances are developed for a truncation rule with three facies and cut-off at 0. The application of this truncation rule demonstrates that the spatial shift on the underlying gaussian functions produces asymmetries in the modelled 1D facies sequences. For a general truncation rule, the indicator covariances can be computed numerically, and a sensitivity study shows that the spatial shift and the correlation coefficient between the gaussian functions provide flexibility to model the asymmetry between facies. Finally, a case study is presented of a Triassic vertical facies succession in the Latemar carbonate platform (Dolomites, Northern Italy) composed of shallowing-upward cycles. The model is flexible enough to capture the different transition probabilities between the environments of deposition and to generate realistic facies successions.
Debbabi Y, Jackson MD, Hampson GJ, et al., 2017, Viscous Crossflow in Layered Porous Media, Transport in Porous Media, Vol: 117, Pages: 281-309, ISSN: 0169-3913
van Cappelle M, Ravnas R, Hampson GJ, et al., 2017, Depositional evolution of a progradational to aggradational, mixed-influenced deltaic succession: Jurassic Tofte and Ile formations, southern Halten Terrace, offshore Norway, MARINE AND PETROLEUM GEOLOGY, Vol: 80, Pages: 1-22, ISSN: 0264-8172
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Zhang Z, Geiger S, Rood M, et al., 2017, Flow Diagnostics on Fully Unstructured Grids, Pages: 772-787
Flow-diagnostics are a common way to rank and cluster ensembles of reservoir models based on their approximate dynamic behaviour prior to commencing full-physics reservoir simulation. Traditionally, flow diagnostics are carried out on corner-point grids inherent to geocellular models. The novel "Rapid Reservoir Modelling" (RRM) concept enables fast and intuitive prototyping and updating of reservoir models. In RRM, complex reservoir heterogeneities are modelled as discrete volumes bounded by surfaces that can be modified using simple sketching operations in real time. The resulting reservoir models are discretized using fully unstructured 3D meshes where the grid conforms to the reservoir geometry. This paper presents a new and computationally efficient numerical scheme that enables flow diagnostic calculations on fully unstructured grids. Time-of-flight and steady-state tracer distributions are computed directly on the grid. The results of these computations allows us to estimate swept reservoir volumes, injector-producer pairs, well-allocation factors, flow capacity, storage capacity and dynamic Lorenz coefficients which all help approximate the dynamic reservoir behaviour. We use the Control Volume Finite Element Method (CVFEM) to solve the elliptic pressure equation. A scalable matrix solver (SAMG) is used to invert the linear system. A new edge-based CVFEM is developed to solve hyperbolic transport equations for time-of-flight and tracer distributions. An optimal reordering technique is employed to deal with each control volume locally such that the hyperbolic equations can be computed in an efficient node-by-node manner. This reordering algorithm scales linearly with the number of unknowns. The total CPU time, including grid generation and flow diagnostics, is typically below 3 seconds for grids with 50k unknowns. Such fast calculations provide, for the first time, real-time feedback on changes in the dynamic reservoir behaviour while the reservoir m
jordan OD, Gupta S, Hampson GJ, et al., 2016, Preserved stratigraphic architecture and evolution of a net-transgressive mixed wave- and tide-influenced coastal system: Cliff House Sandstone, northwestern New Mexico, USA, Journal of Sedimentary Research, Vol: 86, Pages: 1399-1424, ISSN: 1527-1404
The Cretaceous Cliff House Sandstone comprises a thick (400 m) net-transgressive succession representing a mixed wave- and tide-influenced shallow-marine system that migrated episodically landwards. This study examines the youngest part (middle Campanian) of the Cliff House Sandstone, exposed in Chaco Cultural Natural Historical Park, northwest New Mexico, U.S.A. Detailed mapping of facies architecture between a three-dimensional network of measured sections has allowed the character, geometry, and distribution of key stratigraphic surfaces and stratal units to be reconstructed. Upward-shallowing facies successions (parasequences) are separated by laterally extensive transgressive erosion (ravinement) surfaces cut by both wave and tide processes. Preservation of facies tracts in each parasequence is controlled by the depth of erosion and migration trajectory of the overlying ravinement surfaces. In most parasequences, there is no preservation of the proximal wave-dominated facies tracts (foreshore, upper-shoreface), resulting in thin (4–7 m) top-truncated packages. Four distinct shallow marine tongues (parasequence sets) have been identified, consisting of ten parasequences with a total stratigraphic thickness of ~ 100 m. Each tongue records an episode of complex shoreline migration history (multiple regressive–transgressive phases) in an overall net-transgressive system. The ravinement surfaces provide a stratigraphic framework in which to understand partitioning of tide- and wave-dominated deposits in a net-transgressive system, and a model is presented to account for the sediment distribution and stratigraphic architecture observed in each parasequence. Despite a complex internal architecture, parasequences exhibit a predictable pattern which can be related to the regressive and transgressive phases of deposition. Preservation of wave-dominated facies tracts is associated with shoreline regression, while tide-dominated facies tracts are interpreted to
Blévec TL, Dubrule O, John CM, et al., 2016, Building More Realistic 3-D Facies Indicator Models, International Petroleum Technology Conference, Publisher: IPTC
<jats:title>Abstract</jats:title><jats:p>We present a generalization of Pluri-Gaussian Simulation (PGS) of facies that is constrained by facies transiograms instead of variograms. The main benefit is that the transiogram can be different in opposite directions whereas the variogram is symmetric. This is important as geology shows vertical (e.g. shoaling upward successions) and lateral (e.g. proximal-to-distal trends, preferential facies pinch-outs) asymmetries in facies transitions that cannot be quantified by variograms. Mathematically, the modelling approach is based on the incorporation of a spatial shift between the underlying gaussian random functions ("shifted PGS"). The matching with the transiograms is achieved by numerical computation of a multi-gaussian integral. Consequently, the modelled heterogeneities can account for a spatial polarity that may be vertical (upwards/downwards), lateral (proximal/distal), or oriented in any other direction. The method is illustrated using outcrop data from a reservoir analog deposited in a carbonate shoal environment over a lateral distance of about 2 km, i.e. equivalent to inter-well spacing in a typical hydrocarbon reservoir. A comparative study is performed between classical PGS and shifted PGS methods. The shifted PGS method successfully models the spatial ordering/asymmetry between high-permeability shoal and low-permeability backshoal facies. This new method widens the possibilities of facies modelling in complex geological environments, and produces more realistic predictive geological models.</jats:p>
Armitage JJ, Burgess PM, Hampson GJ, et al., 2016, Deciphering the origin of cyclical gravel front and shoreline progradation and retrogradation in the stratigraphic record, Basin Research, Vol: 30, Pages: 15-35, ISSN: 1365-2117
Nearly all successions of the near-shore strata exhibit cyclical movements of the shoreline, which have commonly been attributed to cyclical oscillations in relative sea level (combining eustasy and subsidence) or, more rarely, to cyclical variations in sediment supply. It has become accepted that cyclical change in sediment delivery from source catchments may lead to cyclical movement of boundaries such as the gravel front, particularly in the proximal segments of sediment-routing systems. In order to quantitatively assess how variations in sediment transport as a consequence of change in relative sea-level and surface run-off control stratigraphic architecture, we develop a simple numerical model of sediment transport and explore the sensitivity of moving boundaries within the sediment-routing system to change in upstream (sediment flux, precipitation rate) and downstream (sea level) controls. We find that downstream controls impact the shoreline and sand front, while the upstream controls can impact the whole system depending on the amplitude of change in sediment flux and precipitation rate. The model implies that under certain conditions, the relative movement of the gravel front and shoreline is a diagnostic marker of whether the sediment-routing system experienced oscillations in sea level or climatic conditions. The model is then used to assess the controls on stratigraphic architecture in a well-documented palaeo-sediment-routing system in the Late Cretaceous Western Interior Seaway of North America. Model results suggest that significant movement of the gravel front is forced by pronounced (±50%) oscillations in precipitation rate. The absence of such movement in gravel front position in the studied strata implies that time-equivalent movement of the shoreline was driven by relative sea-level change. We suggest that tracking the relative trajectories of internal boundaries such as the gravel front and shoreline is a powerful tool in constraining the
Massart BYG, Jackson MD, Hampson GJ, et al., 2016, Effective flow properties of heterolithic, cross-bedded tidal sandstones: Part 1. Surface-based modeling, AAPG Bulletin, Vol: 100, Pages: 697-721, ISSN: 0149-1423
Tidal heterolithic sandstones are commonly characterized by millimeter- to centimeter-scale intercalations of mudstone and sandstone. Consequently, their effective flow properties are poorly predicted by (1) data that do not sample a representative volume or (2) models that fail to capture the complex three-dimensional architecture of sandstone and mudstone layers. We present a modeling approach in which surfaces are used to represent all geologic heterogeneities that control the spatial distribution of reservoir rock properties (surface-based modeling). The workflow uses template surfaces to represent heterogeneities classified by geometry instead of length scale. The topology of the template surfaces is described mathematically by a small number of geometric input parameters, and models are constructed stochastically. The methodology has been applied to generate generic, three-dimensional minimodels (9 m3 volume) of cross-bedded heterolithic sandstones representing trough and tabular cross-bedding with differing proportions of sandstone and mudstone, using conditioning data from two outcrop analogs from a tide-dominated deltaic deposit. The minimodels capture the cross-stratified architectures observed in outcrop and are suitable for flow simulation, allowing computation of effective permeability values for use in larger-scale models. We show that mudstone drapes in cross-bedded heterolithic sandstones significantly reduce effective permeability and also impart permeability anisotropy in the horizontal as well as vertical flow directions. The workflow can be used with subsurface data, supplemented by outcrop analog observations, to generate effective permeability values to be derived for use in larger-scale reservoir models. The methodology could be applied to the characterization and modeling of heterogeneities in other types of sandstone reservoirs.
van Cappelle M, Stukins S, Hampson GJ, et al., 2016, Fluvial to tidal transition in proximal, mixed tide-influenced and wave-influenced deltaic deposits: Cretaceous lower Sego Sandstone, Utah, USA, Sedimentology, Vol: 63, Pages: 1333-1361, ISSN: 0037-0746
Facies models for regressive, tide-influenced deltaic systems are under-represented in the literature compared with their fluvial-dominated and wave-dominated counterparts. Here, a facies model is presented of the mixed, tide-influenced and wave-influenced deltaic strata of the Sego Sandstone, which was deposited in the Western Interior Seaway of North America during the Late Cretaceous. Previous work on the Sego Sandstone has focused on the medial to distal parts of the outcrop belt where tides and waves interact. This study focuses on the proximal outcrop belt, in which fluvial and tidal processes interact. Five facies associations are recognized. Bioturbated mudstones (Facies Association 1) were deposited in an offshore environment and are gradationally overlain by hummocky cross-stratified sandstones (Facies Association 2) deposited in a wave-dominated lower shoreface environment. These facies associations are erosionally overlain by tide-dominated cross-bedded sandstones (Facies Association 4) interbedded with ripple cross-laminated heterolithic sandstones (Facies Association 3) and channelized mudstones (Facies Association 5). Palaeocurrent directions derived from cross-bedding indicate bidirectional currents which are flood-dominated in the lower part of the studied interval and become increasingly ebb-directed/fluvial-directed upward. At the top of the succession, ebb-dominated/fluvial-dominated, high relief, narrow channel forms are present, which are interpreted as distributary channels. When distributary channels are abandoned they effectively become estuaries with landward sediment transport and fining trends. These estuaries have sandstones of Facies Association 4 at their mouth and fine landward through heterolithic sandstones of Facies Association 3 to channelized mudstones of Facies Association 5. Therefore, the complex distribution of relatively mud-rich and sand-rich deposits in the tide-dominated part of the lower Sego Sandstone is attributed to t
Mannie AS, Jackson CA-L, Hampson GJ, et al., 2016, Tectonic controls on the spatial distribution and stratigraphic architecture of a net-transgressive shallow-marine syn-rift succession in a salt-influenced rift basin: Middle-to-Upper Jurassic, Norwegian Central North Sea, Journal of the Geological Society, Vol: 173, Pages: 901-915, ISSN: 0016-7649
Syn-depositional deformation in salt-influenced rift basins is complex, being driven by a combination of normal faulting and the growth of salt structures such as diapirs. Due to a lack of data with which to simultaneously constrain basin structure and syn-rift stratigraphic architecture, we have a poor understanding of how these processes control shallow marine deposition in such settings. To improve our understanding we here use seismic reflection and borehole data from the Norwegian Central North Sea to investigate the role that syn-depositional fault growth and salt movement played in controlling the sub-regional stratigraphic architecture of a net-transgressive shallow-marine syn-rift succession (Middle-to-Late Jurassic). The rift-related structural framework, which is usually dominated by normal fault-bound horst and graben, is strongly modified where an Upper Permian salt layer (Zechstein Supergroup) is sufficiently thick and mobile to act as an intra-stratal detachment, giving rise to decoupled rift-related basement and cover structural styles. Furthermore, cover extension allows the salt to rise diapirically, resulting in the formation of large salt diapirs and supra-salt normal faults formed due to late-stage salt withdrawal and diapir collapse. Rift-related normal faulting and the growth of salt structures had a dual control on the depositional thickness and facies distribution within the net-transgressive, predominantly shallow-marine, Middle-to-Upper Jurassic syn-rift succession. The resulting facies architecture reflects a delicate balance between fault- and salt flow-driven accommodation creation and intra- and extra-basinal sediment supply. Where sediment supply and accumulation rate exceeded accommodation, little or no change in facies is observed across syn-depositional structures. In contrast, where accommodation outpaced sediment supply and accumulation rate, footwall-attached shorelines locally developed adjacent to large, thick-skinned normal f
Hampson GJ, 2016, Towards a sequence stratigraphic solution set for autogenic processes and allogenic controls: Upper Cretaceous strata, Book Cliffs, Utah, USA, Journal of the Geological Society, Vol: 173, Pages: 817-836, ISSN: 0016-7649
Upper Cretaceous strata exposed in the Book Cliffs of east–central Utah are widely used as an archetype for the sequence stratigraphy of marginal-marine and shallow-marine deposits. Their stratal architectures are classically interpreted in terms of accommodation controls that were external to the sediment routing system (allogenic), and that forced the formation of flooding surfaces, sequence boundaries, and parasequence and parasequence-set stacking patterns. Processes internal to the sediment routing system (autogenic) and allogenic sediment supply controls provide alternatives that can plausibly explain aspects of the stratal architecture, including the following: (1) switching of wave-dominated delta lobes, expressed by the internal architecture of parasequences; (2) river avulsion, expressed by the internal architecture of multistorey fluvial sandbodies and related deposits; (3) avulsion-generated clustering of fluvial sandbodies in delta plain strata; (4) ‘autoretreat’ owing to increasing sediment storage on the delta plain as it lengthened during progradation, expressed by progradational-to-aggradational stacking of parasequences; (5) sediment supply control on the stacking of, and sediment grain-size fractionation within, parasequence sets. The various potential allogenic controls and autogenic processes are combined to form a sequence stratigraphic solution set. This approach avoids anchoring of sequence stratigraphic interpretations on a specific control and acknowledges the non-unique origin of stratal architectures.
Massart BYG, Jackson MD, Hampson GJ, et al., 2016, Effective flow properties of heterolithic, cross-bedded tidal sandstones: Part 2. Flow simulation, AAPG Bulletin, Vol: 100, Pages: 723-742, ISSN: 0149-1423
Tidal heterolithic sandstone reservoirs are heterogeneous at the sub-meter scale, due to the ubiquitous presence of intercalated sandstone and mudstone laminae. Core-plug permeability measurements fail to sample a representative volume of this heterogeneity. Here we investigate the impact of mudstone drape distribution on the effective permeability of heterolithic, cross-bedded tidal sandstones using three-dimensional (3D) surface-based “mini-models” that capture the geometry of cross-beds at an appropriate scale. The impact of seven geometric parameters has been determined: (1) mudstone fraction, (2) sandstone laminae thickness, (3) mudstone drape continuity, (4) toeset dip, (5) climb angle of foreset-toeset surfaces, (6) proportion of foresets to toesets, and (7) trough or tabular geometry of the cross-beds.We begin by identifying a representative elementary volume (REV) of 1 m3, confirming that the model volume of 9 m3 yields representative permeability values. Effective permeability decreases as the mudstone fraction increases, and is highly anisotropic: vertical permeability falls to c. 0.5% of the sandstone permeability at a mudstone fraction of 25%, while the horizontal permeability falls to c. 5% and c. 50% of the sandstone value in the dip (across mudstone drapes) and strike (parallel to mudstone drapes) directions, respectively. There is considerable spread around these values, because each parameter investigated can significantly impact effective permeability, with the impact depending upon the flow direction and mudstone fraction. The results yield improved estimates of effective permeability in heterolithic, cross-bedded sandstones, which can be used to populate reservoir-scale model grid blocks using estimates of mudstone fraction and geometrical parameters obtained from core and outcrop-analog data.
Sahoo H, Gani MR, Hampson GJ, et al., 2016, Facies-to sandbody-scale heterogeneity in a tight-gas fluvial reservoir analog: Blackhawk Formation, Wasatch Plateau, Utah, USA, Marine and Petroleum Geology, Vol: 78, Pages: 48-69, ISSN: 0264-8172
Using photomosaics and measured sections, this outcrop study characterizes facies-to sandbody-scale heterogeneity in the fluvial and coastal-plain deposits of the Blackhawk Formation of the Wasatch Plateau, Utah, USA, as an outcrop analog for the fluvial tight-gas reservoirs of the adjacent greater western Rocky Mountain basins as well as for conventional fluvial reservoirs elsewhere. Analysis on eight contiguous, vertical cliff-faces comprising both depositional-dip- and -strike-oriented segments provides field-validation and calibration of entire range of fluvial heterogeneity, where: 1) large-scale heterogeneity (10’s of m vertically and 100’s of m laterally) is associated with stacking of channelized fluvial sandbodies encased within coastal-plain fines, 2) intermediate-scale heterogeneity (1’s of m vertically and 10’s of m laterally) is related to type and distribution of architectural elements like bar-accretion and crevasse-splay units within individual sandbodies, and 3) small-scale heterogeneity (10’s of cm vertically and 1’s of m laterally) is attributed to facies spatial variability within individual architectural elements.At a reservoir-scale (∼6 km strike-transect), impact of these heterogeneities has resulted in potential stratigraphic compartmentalization in varied patterns and scales within and among three zones, which have similar lateral extents. Distinct vertical or lateral compartmentalization, contrasting net-to-gross pattern, width-constraint by either large- or intermediate-scale heterogeneity, disparity in communication between principal reservoir compartments by intermediate-scale heterogeneity, and reservoir-quality segregation to barrier styles rendered by small-scale heterogeneity are documented in an array of trends. These intriguing trends are challenging to correlate across the reservoir-scale dataset, contributing to multiple, analogous exploration and production uncertainties. For improved tigh
Armitage JJ, Allen PA, Burgess PM, et al., 2015, Sediment transport model for the Eocene Escanilla sediment-routing system: Implications for the uniqueness of sequence stratigraphic architectures., Journal of Sedimentary Research, Vol: 85, Pages: 1510-1524, ISSN: 1527-1404
Holgate NE, Jackson CA-L, Hampson GJ, et al., 2015, Seismic stratigraphic analysis of the Middle Jurassic Krossfjord and Fensfjord formations, Troll oil and gas field, northern North Sea, Marine and Petroleum Geology, Vol: 68, Pages: 352-380, ISSN: 0264-8172
Villamizar CA, Hampson GJ, Flood YS, et al., 2015, Object-based modelling of avulsion-generated sandbody distributions and connectivity in a fluvial reservoir analogue of low to moderate net-to-gross ratio, Petroleum Geoscience, Vol: 21, Pages: 249-270, ISSN: 1354-0793
Patruno S, Hampson GJ, Jackson CA, et al., 2015, Quantitative progradation dynamics and stratigraphic architecture of ancient shallow‐marine clinoform sets: a new method and its application to the <scp>U</scp>pper <scp>J</scp>urassic <scp>S</scp>ognefjord <scp>F</scp>ormation, <scp>T</scp>roll <scp>F</scp>ield, offshore <scp>N</scp>orway, Basin Research, Vol: 27, Pages: 412-452, ISSN: 0950-091X
<jats:title>Abstract</jats:title><jats:p>This article presents a new numerical inversion method to estimate progradation rates in ancient shallow‐marine clinoform sets, which is then used to refine the tectono‐stratigraphic and depositional model for the Upper Jurassic Sognefjord Formation reservoir in the super‐giant Troll Field, offshore Norway. The Sognefjord Formation is a 10–200‐m thick, coarse‐grained clastic wedge, that was deposited in <jats:italic>ca</jats:italic>. 6 Myr by a fully marine, westward‐prograding, subaqueous delta system sourced from the Norwegian mainland. The formation comprises four, 10–60‐m thick, westerly dipping, regressive clinoform sets, which are mapped for several tens of kilometres along strike. Near‐horizontal trajectories are observed in each clinoform set, and the sets are stacked vertically. Clinoform age and progradation rates are constrained by: (i) regionally correlatable bioevents, tied to seismically mapped clinoforms and clinoform set boundaries that intersect wells, (ii) exponential age–depth interpolations between bioevent‐dated surfaces and a distinctive foreset‐to‐bottomset facies transition within each well, and (iii) distances between wells along seismic transects that are oriented perpendicular to the clinoform strike and tied to well‐based stratigraphic correlations. Our results indicate a fall in progradation rate (from 170–500 to 10–65 km Myr<jats:sup>−1</jats:sup>) and net sediment flux (from 6–14 to ≤1 km<jats:sup>2</jats:sup> Myr<jats:sup>−1</jats:sup>) westwards towards the basin, which is synchronous with an overall rise in sediment accumulation rate (from 7–16 to 26–102 m Myr<jats:sup>−1</jats:sup>). These variations are attributed to progradation of the subaqueous delta into progressively deeper waters, and a concomitant increas
Forzoni A, Hampson G, Storms J, 2015, ALONG-STRIKE VARIATIONS IN STRATIGRAPHIC ARCHITECTURE OF SHALLOW-MARINE RESERVOIR ANALOGUES: UPPER CRETACEOUS PANTHER TONGUE DELTA AND COEVAL SHOREFACE, STAR POINT SANDSTONE, WASATCH PLATEAU, CENTRAL UTAH, USA, JOURNAL OF SEDIMENTARY RESEARCH, Vol: 85, Pages: 968-989, ISSN: 1527-1404
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Gani MR, Ranson A, Cross DB, et al., 2015, Along-strike sequence stratigraphy across the Cretaceous shallow marine to coastal-plain transition, Wasatch Plateau, Utah, U.S.A., Sedimentary Geology, Vol: 325, Pages: 59-70, ISSN: 0037-0738
Graham GH, Jackson MD, Hampson GJ, 2015, Three-dimensional modeling of clinoforms in shallow-marine reservoirs: Part 2. Impact on fluid flow and hydrocarbon recovery in fluvial-dominated deltaic reservoirs, AAPG Bulletin, Vol: 99, Pages: 1049-1080, ISSN: 0149-1423
Permeability contrasts associated with clinoforms have been identified as an important control on fluid flow and hydrocarbon recovery in fluvial-dominated deltaic parasequences. However, they are typically neglected in subsurface reservoir models or considered in isolation in reservoir simulation experiments because clinoforms are difficult to capture using current modeling tools. A suite of three-dimensional reservoir models constructed with a novel, stochastic, surface-based clinoform-modeling algorithm and outcrop analog data (Upper Cretaceous Ferron Sandstone Member, Utah) have been used here to quantify the impact of clinoforms on fluid flow in the context of (1) uncertainties in reservoir characterization, such as the presence of channelized fluvial sandbodies and the impact of bed-scale heterogeneity on vertical permeability, and (2) reservoir engineering decisions, including oil production rate. The proportion and distribution of barriers to flow along clinoforms exert the greatest influence on hydrocarbon recovery; equivalent models that neglect these barriers overpredict recovery by up to 35%. Continuity of channelized sandbodies that cut across clinoform tops and vertical permeability within distal delta-front facies influence sweep within clinothems bounded by barriers. Sweep efficiency is reduced when producing at higher rates over shorter periods, because oil is bypassed at the toe of each clinothem. Clinoforms are difficult to detect using production data, but our results indicate that they significantly influence hydrocarbon recovery and their impact is typically larger than that of other geologic heterogeneities regardless of reservoir engineering decisions. Clinoforms should therefore be included in models of fluvial-dominated deltaic reservoirs to accurately predict hydrocarbon recovery and drainage patterns.
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Graham GH, Jackson MD, Hampson GJ, 2015, Three-dimensional modeling of clinoforms in shallow-marine reservoirs: Part 1. Concepts and application, AAPG Bulletin, Vol: 99, Pages: 1013-1047, ISSN: 0149-1423
Clinoform surfaces control aspects of facies architecture within shallow-marine parasequences and can also act as barriers or baffles to flow where they are lined by low-permeability lithologies, such as cements or mudstones. Current reservoir modeling techniques are not well suited to capturing clinoforms, particularly if they are numerous, below seismic resolution, and/or difficult to correlate between wells. At present, there are no modeling tools available to automate the generation of multiple three-dimensional clinoform surfaces using a small number of input parameters. Consequently, clinoforms are rarely incorporated in models of shallow-marine reservoirs, even when their potential impact on fluid flow is recognized. A numerical algorithm that generates multiple clinoforms within a volume defined by two bounding surfaces, such as a delta-lobe deposit or shoreface parasequence, is developed. A geometric approach is taken to construct the shape of a clinoform, combining its height relative to the bounding surfaces with a mathematical function that describes clinoform geometry. The method is flexible, allowing the user to define the progradation direction and the parameters that control the geometry and distribution of individual clinoforms. The algorithm is validated via construction of surface-based three-dimensional reservoir models of (1) fluvial-dominated delta-lobe deposits exposed at the outcrop (Cretaceous Ferron Sandstone Member, Utah), and (2) a sparse subsurface data set from a deltaic reservoir (Jurassic Sognefjord Formation, Troll Field, Norwegian North Sea). Resulting flow simulation results demonstrate the value of including algorithm-generated clinoforms in reservoir models, because they may significantly impact hydrocarbon recovery when associated with areally extensive barriers to flow.
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Flood YS, Hampson GJ, 2015, Quantitative Analysis of the Dimensions and Distribution of Channelized Fluvial Sandbodies Within A Large Outcrop Dataset: Upper Cretaceous Blackhawk Formation, Wasatch Plateau, Central Utah, U.S.A, Journal of Sedimentary Research, Vol: 85, Pages: 315-336, ISSN: 1527-1404
Patruno S, Hampson GJ, Jackson CA-L, 2015, Quantitative characterisation of deltaic and subaqueous clinoforms, Earth-Science Reviews, Vol: 142, Pages: 79-119, ISSN: 0012-8252
Jackson MD, Hampson GJ, Rood D, et al., 2015, Rapid reservoir modeling: Prototyping of reservoir models, well trajectories and development options using an intuitive, sketch-based interface, Pages: 829-845
Constructing or refining complex reservoir models at the appraisal, development, or production stage is a challenging and time-consuming task that entails a high degree of uncertainty. The challenge is significantly increased by the lack of modeling, simulation and visualization tools that allow prototyping of reservoir models and development concepts, and which are simple and intuitive to use. Conventional modeling workflows, facilitated by commercially available software packages, have remained essentially unchanged for the past decade. However, these are slow, often requiring many months from initial model concepts to flow simulation or other outputs; moreover, many model concepts, such as large scale reservoir architecture, become fixed early in the process and are difficult to retrospectively change. Such workflows are poorly suited to rapid prototyping of a range of reservoir model concepts, well trajectories and development options, and testing of how these might impact on reservoir behavior. We present a new reservoir modeling and simulation approach termed Rapid Reservoir Modeling (RRM) that allows such prototyping and complements existing workflows. In RRM, reservoir geometries that describe geologic heterogeneities (e.g. faults, stratigraphic, sedimentologic and/or diagenetic features) are modelled as discrete volumes bounded by surfaces, without reference to a predefined grid. These surfaces, and also well trajectories, are created and modified using intuitive, interactive techniques from computer visualization, such as Sketch Based Interfaces and Modeling (SBIM). Input data can be sourced from seismic, geocellular or flow simulation models, outcrop analogues, conceptual model libraries or blank screen. RRM outputs can be exported to conventional workflows at any stage. Gridding or meshing of the models within the RRM framework allows rapid calculation of key reservoir properties and dynamic behaviors linked with well trajectories and development plans.
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