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Papers by John Howell

Sedimentology, 2021

Sediments deposited by glacial meltwaters (for example, ice‐contact delta deposits) form permeabl... more Sediments deposited by glacial meltwaters (for example, ice‐contact delta deposits) form permeable packages in the subsurface that can act as reservoirs for both water and hydrocarbons. They are also an important source of aggregate for the construction industry. As reservoirs they are challenging to characterize in terms of their structure, flow and storage properties due to their complex depositional history. In this study, ice‐contact deltas of Salpausselkä I and II end moraines in Southern Finland are studied using a combination of geomorphological mapping, sedimentological studies and near surface geophysical methods. Sedimentary logs from isolated outcrops were correlated to ground penetrating radar (GPR) profiles to unravel the internal structure and depositional history of these ice‐contact deltas. Subsequently, electrical resistivity tomography (ERT) and gravity data were analysed to estimate the depth to bedrock and to model porosity distribution within the sediments. Resu...

Marine Geology, 2019

Marine-based ice streams are responsible for a significant proportion of the ice mass loss from t... more Marine-based ice streams are responsible for a significant proportion of the ice mass loss from the present-day Greenland Ice Sheet, East Antarctic Ice Sheet (EAIS) and West Antarctic Ice Sheet (WAIS) but the processes controlling their initiation, evolution and shutdown remain elusive, hindering our understanding of how existing ice masses will respond to predicted future warming. The exposed beds of palaeo-ice streams offer a unique opportunity to study subglacial processes, which are largely inaccessible in contemporary settings. We use high resolution multibeam swath bathymetry data from the Barents Sea to map the geomorphology of a palaeo-ice stream bed, located in Olgastretet (Olga Trough), approximately 75 km southeast of Kong Karls Land and 200 km east of central Svalbard. This reveals evidence for shut down of a marine-based ice stream, followed by a phase of passive retreat or lift-off of the ice stream facilitating preservation of crevasse-squeeze ridges (CSRs). Subsequently, active retreat of the ice margin was re-established and is marked by recessional moraine ridges located upstream of the CSRs. Previously, CSRs have been mainly associated with surging land-terminating ice margins, however our work adds to recent observations of CSRs on the beds of marine-based ice streams, implying that they may be more common than previously thought. It also indicates that marine-based ice streams may switch on-and off in a surge-like manner which has important implications for our understanding of ice stream life cycles and the modelling of ice sheets.

Science advances, 2018

Geometries of Early Pleistocene [2.58 to 0.78 million years (Ma) ago] ice sheets in northwest Eur... more Geometries of Early Pleistocene [2.58 to 0.78 million years (Ma) ago] ice sheets in northwest Europe are poorly constrained but are required to improve our understanding of past ocean-atmosphere-cryosphere coupling. Ice sheets are believed to have changed in their response to orbital forcing, becoming, from about 1.2 Ma ago, volumetrically larger and longer-lived. We present a multiproxy data set for the North Sea, extending to over a kilometer below the present-day seafloor, which demonstrates spatially extensive glaciation of the basin from the earliest Pleistocene. Ice sheets repeatedly entered the North Sea, south of 60°N, in water depths of up to ~250 m from 2.53 Ma ago and subsequently grounded in the center of the basin, in deeper water, from 1.87 Ma ago. Despite lower global ice volumes, these ice sheets were near comparable in spatial extent to those of the Middle and Late Pleistocene but possibly thinner and moving over slippery (low basal resistance) beds.

Petroleum Geoscience, 2015

Facies models for wave-dominated shorelines include an "offshore transition zone" between shelfal... more Facies models for wave-dominated shorelines include an "offshore transition zone" between shelfal mudstones and nearshore shoreface sandstones. Offshore transition zone deposits are commonly tabular sandstone beds interbedded with continuous mudstone beds. However, observations from the Blackhawk Formation show that the offshore transition zone locally consists of erosive-based sandstone beds with "pinch-and-swell" geometries containing steep-walled gutter-casts, in areas larger than 6 x 2 km along strike and dip. This increases the amount of sand-on-sand-contacts, and leads to improved vertical permeability. Predicting the distribution of erosive offshore transition within the subsurface is therefore desirable. In this study, offshore transition zone deposits have been studied using virtual outcrops. Tabular offshore transition zone deposits have continuous sandstone and mudstone beds much longer than 500 m, and erosive offshore transition zone deposits have discontinuous shales on average 60 m long. Reservoir modelling shows a 10-3 times increase in vertical permeability in erosive compared to tabular offshore transition deposits, the magnitude decreasing with increasing fraction of shale. Erosive offshore transition deposits occur near distributary channels, subaqueous channels and abrupt bathymetric breaks. A regional study shows that erosive offshore transition zone deposits are mainly developed where parasequences prograde into deeper water offshore the platform break of the preceding parasequence, are commonly associated with basinal turbidites, and may be related to erosion by bypassing turbidity currents. Formatted: Numbering: Continuous which will be very low if the beds are tabular (low K v /K h ratio) but higher if there mudstones are eroded, leading to sand-on-sand contacts (higher (K v /K h ratio). This has the potential to dramatically alter the flow properties of such facies in hydrocarbon reservoirs. The objectives of this paper are fivefold: (1) To describe offshore transition deposits with special reference to the OTZe; (2) to document occurrence of OTZe versus OTZt in the study area; (3) to document bed geometries in tabular and erosive offshore transition deposits; (4) to quantify how reservoir properties vary in tabular and erosive offshore transition deposits; and finally (5) to discuss possible mechanisms for formation of erosive offshore transition and propose a predictive model for their occurrence in other systems. Geological background The studied deposits are exposed in the Book Cliffs of central Utah, USA (Fig. 1), and are part of the Campanian Blackhawk Formation (Fig. 2; Young 1955). The formation is part of a clastic wedge which prograded into the retro-arc foreland basin of the Sevier Orogen, a result of subduction on the western side of the North American plate, leading to the accretion of terranes and development of the Sevier mountain chain (Kauffman & Caldwell 1993). This foreland basin was part of the Western Interior Seaway, which developed at a time of very high sea-level during the Cretaceous (Haq et al. 1988). The sediment source was the uplifting Sevier Mountains to the east, and the depositional system comprised an alluvial plain with distributive fluvial systems that fed the wave-dominated Blackhawk shorelines (Howell & Flint 2003; Rittersbacher et al. 2014; Hampson et al. 2013). The stratal architecture of the Blackhawk Formation illustrates large scale progradation under a longterm rise in relative sea-level (Howell & Flint 2003). The shallow-marine part of the Blackhawk Formation has been subdivided into six, mainly progradational, tongues named the Spring Canyon, Aberdeen, Kenilworth, Sunnyside, Grassy and Desert members (Fig. 2; Young 1955), which are separated by regional flooding surfaces and landward facies belt shifts greater than 10 km (Young 1955; Hampson & Howell 2005; Hampson 2010). The members are further divided into parasequences, progradational sandstone tongues deposited under a single shoreline transit, separated by flooding surfaces developed during smaller transgressions on the scale of a few kilometers (Fig. 2; Van Wagoner et al. 1990; Hampson & Howell 2005).

From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin, 2014

Depositional systems to seDimentary successions on the norwegian continental margin other publica... more Depositional systems to seDimentary successions on the norwegian continental margin other publications of the international association of sedimentologists special puBlications 45 linking Diagenesis to sequence stratigraphy Edited by Sadoon Morad, J. Marcelo Ketzer and Luiz F. De Ros 2012, 522 pages, 246 illustrations 44 sediments, morphology and sedimentary processes on continental shelves Advances in Technologies, Research and Applications Edited by Michael Z. Li, Christopher R. Sherwood and Philip R. Hill 2012, 440 pages, 231 illustrations 43 Quaternary carbonate and evaporite sedimentary Facies and their ancient analogues A Tribute to Douglas James Shearman Edited by Christopher G. St. C. Kendall and Abdulrahman S. Alsharhan 2010, 494 pages, 263 illustrations 42 carbonate systems During the olicocene-miocene climatic transition Edited by Maria Mutti, Werner E. Piller and Christian Betzler 2010, 304 pages, 154 illustrations 41 perspectives in carbonate geology

… of Landslides in South East Asia …, 2008

The Peoples' Democratic Republic of Lao is a landlocked country bordered by Vietnam to the east, ... more The Peoples' Democratic Republic of Lao is a landlocked country bordered by Vietnam to the east, Thailand to the south and west and China to the north. It is predominantly hilly or mountainous, and experiences a subtropical climate defined by a distinct rainy season during the summer. Annual rainfall varies in the mountainous regions of the north between 1.5m and 4m per year, most of which falls during the summer months, sometimes in association with typhoons developed in the South China Sea. Forest occupies the majority of slopes that neighbour the road network.

The use of high resolution surveying techniques has increased dramatically in earth science appli... more The use of high resolution surveying techniques has increased dramatically in earth science applications over the last decade. New products, software solutions and an increased attention to "usability" have made terrestrial laser scanning (lidar) and digital photogrammetry popular methods for obtaining more detailed geometric data for many applications. Geology, especially the study of outcrops, is one such application area where the introduction of laser scanning in particular has benefitted, by allowing an increasingly quantitative approach at a variety of scales. Despite this, most of the contribution of modern surveying techniques has been related to the capture of topographic detail - the shape and form of outcrops - while the remote mapping of outcrop lithology has yet to be satisfactorily addressed. Ground-based spectral imaging offers new possibilities for an improved understanding of outcrop composition, by mapping lithology and the distribution of mineralogy with...

Petroleum Geoscience, 2008

Journal of Sedimentary Research, 2003

In the middle Green River Formation of central Nine Mile Canyon, Uinta Basin, Utah, several lacus... more In the middle Green River Formation of central Nine Mile Canyon, Uinta Basin, Utah, several lacustrine-dominated intervals ϳ10 m thick comprise aggradational carbonate parasequence sets and a progradational clastic parasequence. Maximum flooding surfaces are best identified within profundal oil shale that caps some of the clastic parasequences. These lacustrine transgressive systems tracts therefore exhibit parasequence stacking patterns unlike typical marine sequences. Two types of sequence boundary are identified. Type A sequence boundaries display evidence for a basinward shift in facies across a regionally mappable surface that is an angular or, rarely, parallel unconformity, and they typically juxtapose amalgamated braided fluvial channel sandstone (late lowstand systems tract) onto the profundal oil shale. They also bound depositional sequences that show a distinct asymmetry, being dominated by transgressive systems tracts 5-80 m thick. Highstand systems tracts are less than 4 m thick and may be removed completely, by erosion on overlying sequence boundaries. Other surfaces satisfy only some of the standard criteria of sequence boundaries and are termed type B sequence boundaries. Type A sequence boundaries mark pronounced base-level falls following times when the Uinta Lake had merged with a lake in an adjacent basin to form a much deeper lake. Such merging permitted the establishment of a new threshold at higher elevation following lakelevel balancing. Type B sequence boundaries are interpreted as marking base-level falls from a barely merged lake or a lake that had an outflow. Over a 200 m stratigraphic thickness, type A sequence boundaries are more common upsection, indicating that, with time, a pluvial climate became more pronounced or that the adjacent lake was more easily filled. Type A sequence boundaries also become angular rather than parallel unconformities upsection, suggesting increased tilting of the basin margin over time.

Geosphere, 2007

Advances in data capture and computer technology have made possible the collection of three-dimen... more Advances in data capture and computer technology have made possible the collection of three-dimensional, high-resolution, digital geological data from outcrop analogs. This paper presents new methodologies for the acquisition and utilization of three-dimensional information generated by groundbased laser scanning (lidar) of outcrops. A complete workfl ow is documented-from outcrop selection through data collection, processing and building of virtual outcropsto geological interpretation and the building of geocellular models using an industry-standard, reservoir-modeling software. Data sets from the Roda Sandstone in the Spanish Pyrenees and the Grabens region of Canyonlands National Park, Utah, USA, are used to illustrate the application of the workfl ow to sedimentary and structural problems at a reservoir scale. Subsurface reservoir models are limited by available geological data. Outcrop analogs from comparable systems, such as the Roda Sandstone and the Grabens, are commonly used to provide additional input to models of the subsurface. Outcrop geocellular models can be analyzed both statically and dynamically, wherein static examination involves visual inspection and the extraction of quantitative data on body geometry, and dynamic investigation involves the simulation of fl uid fl ow through the analog model. The work presented in this study demonstrates the utility of lidar as a data collection technique for the building of more accurate outcrop-based geocellular models. The aim of this publication is to present the fi rst documentation of a complete workfl ow that extends from outcrop selection to model investigation through the presentation of two worked data sets.

Geological Society, London, Special Publications, 2014

The aerial extent, thickness and internal distribution of grain-size are key, bed-scale controls ... more The aerial extent, thickness and internal distribution of grain-size are key, bed-scale controls on turbidite reservoir performance. Process-based modelling provides a method for predicting both the sandbody thickness and the grain-size distribution within the bed. The goal of the current study is to test such an approach on the Annot Sandstone in the Peïra Cava Sub-basin in SE France, and determine whether the process-based model can reliably recreate the bed characteristics observed in the outcrop. Turbidity currents were modelled using a commercially available software solution called MassFlow3D that is based on computational fluid dynamics. The goal of the current study was to accurately replicate a single bed (termed MU5). To achieve this goal, the base of the basin was structurally restored and then a simplified simulation of the beds below MU5 was generated using four flow events in order to recreate the bathymetry on to which MU5 was simulated. Several versions of MU5 were s...

Geological Society, London, Special Publications, 2007

Relay ramps associated with overlapping faults are commonly regarded as efficient conduits for fl... more Relay ramps associated with overlapping faults are commonly regarded as efficient conduits for fluid flow across potentially sealing intra-reservoir fault zones. The current study demonstrates that structural heterogeneity in the often anomalously wide damage zone of relay ramps may represent potential baffles to intra-ramp fluid flow. A network of ramp-parallel, ramp-diagonal and curved cataclastic deformation bands causes compartmentalization of the ramp studied in Arches National Park, Utah. Harmonic average calculations demonstrate that, although single deformation bands have little or no effect on effective permeability, the presence of even a very small number of low-permeable deformation band clusters could reduce along-ramp effective permeability by more than three orders of magnitude. Thus, although relay zones may maintain large-scale geometric communication, the results of this study demonstrate that caution must be exercised when considering relay ramps as fluid conduits...

Revista geológica de Chile, 2001

A section equivalent to the Pliocene La Portada Formation exposed in the coastal cliff at Hornito... more A section equivalent to the Pliocene La Portada Formation exposed in the coastal cliff at Hornitos, northern Chile, contains a ca. 7-10 m thick conglomerate bed. The bed occurs within a succession of shallow marine sandstones and has an erosional contact with underlying ...

Sedimentology, 2010

Skip to Main Content. Wiley Online Library will be disrupted 3 Sep from 10-12 BST for monthly mai... more Skip to Main Content. Wiley Online Library will be disrupted 3 Sep from 10-12 BST for monthly maintenance. ...

The Photogrammetric Record, 2010

This paper discusses the application of laser scanning and photo-realistic modelling to aid the s... more This paper discusses the application of laser scanning and photo-realistic modelling to aid the study of geological outcrops, using two examples from central and eastern Utah, USA, which are analogues to subsurface hydrocarbon fields. Terrestrial laser scanning point clouds were triangulated to obtain high-resolution surface representations, which were combined with semi-metric imagery to give texture-mapped photo-realistic models of the outcrops. Such models provide the basis for geological interpretation and were used to reconstruct the geometries of layers over the extent of the study area. The digitised geological layers were in turn used to build geocellular volumes that capture the properties of the geology. These models were built in subsurface reservoir modelling software and were used to simulate the flow of fluids through the reservoir analogue. In this way, the spatial information provided significantly more detailed quantitative data and greatly improved the outcrop studies compared to traditional field techniques.

Photogrammetric Engineering & Remote Sensing, 2010

Petroleum Geoscience, 2008

Estimates of recovery from oil fields are often found to be significantly in error, and the multi... more Estimates of recovery from oil fields are often found to be significantly in error, and the multidisciplinary SAIGUP modelling project has focused on the problem by assessing the influence of geological factors on production in a large suite of synthetic shallow-marine reservoir models. Over 400 progradational shallow-marine reservoirs, ranging from comparatively simple, parallel, wavedominated shorelines through to laterally heterogeneous, lobate, river-dominated systems with abundant low-angle clinoforms, were generated as a function of sedimentological input conditioned to natural data. These sedimentological models were combined with structural models sharing a common overall form but consisting of three different fault systems with variable fault density and fault permeability characteristics and a common unfaulted end-member. Different sets of relative permeability functions applied on a facies-by-facies basis were calculated as a function of different lamina-scale properties and upscaling algorithms to establish the uncertainty in production introduced through the upscaling process. Different fault-related upscaling assumptions were also included in some models. A waterflood production mechanism was simulated using up to five different sets of well locations, resulting in simulated production behaviour for over 35 000 full-field reservoir models. The model reservoirs are typical of many North Sea examples, with total production ranging from c. 15 10 6 m 3 to 35 10 6 m 3 , and recovery factors of between 30% and 55%. A variety of analytical methods were applied. Formal statistical methods quantified the relative influences of individual input parameters and parameter combinations on production measures. Various measures of reservoir heterogeneity were tested for their ability to discriminate reservoir performance. This paper gives a summary of the modelling and analyses described in more detail in the remainder of this thematic set of papers.

Sedimentology, 2021

Sediments deposited by glacial meltwaters (for example, ice‐contact delta deposits) form permeabl... more Sediments deposited by glacial meltwaters (for example, ice‐contact delta deposits) form permeable packages in the subsurface that can act as reservoirs for both water and hydrocarbons. They are also an important source of aggregate for the construction industry. As reservoirs they are challenging to characterize in terms of their structure, flow and storage properties due to their complex depositional history. In this study, ice‐contact deltas of Salpausselkä I and II end moraines in Southern Finland are studied using a combination of geomorphological mapping, sedimentological studies and near surface geophysical methods. Sedimentary logs from isolated outcrops were correlated to ground penetrating radar (GPR) profiles to unravel the internal structure and depositional history of these ice‐contact deltas. Subsequently, electrical resistivity tomography (ERT) and gravity data were analysed to estimate the depth to bedrock and to model porosity distribution within the sediments. Resu...

Marine Geology, 2019

Marine-based ice streams are responsible for a significant proportion of the ice mass loss from t... more Marine-based ice streams are responsible for a significant proportion of the ice mass loss from the present-day Greenland Ice Sheet, East Antarctic Ice Sheet (EAIS) and West Antarctic Ice Sheet (WAIS) but the processes controlling their initiation, evolution and shutdown remain elusive, hindering our understanding of how existing ice masses will respond to predicted future warming. The exposed beds of palaeo-ice streams offer a unique opportunity to study subglacial processes, which are largely inaccessible in contemporary settings. We use high resolution multibeam swath bathymetry data from the Barents Sea to map the geomorphology of a palaeo-ice stream bed, located in Olgastretet (Olga Trough), approximately 75 km southeast of Kong Karls Land and 200 km east of central Svalbard. This reveals evidence for shut down of a marine-based ice stream, followed by a phase of passive retreat or lift-off of the ice stream facilitating preservation of crevasse-squeeze ridges (CSRs). Subsequently, active retreat of the ice margin was re-established and is marked by recessional moraine ridges located upstream of the CSRs. Previously, CSRs have been mainly associated with surging land-terminating ice margins, however our work adds to recent observations of CSRs on the beds of marine-based ice streams, implying that they may be more common than previously thought. It also indicates that marine-based ice streams may switch on-and off in a surge-like manner which has important implications for our understanding of ice stream life cycles and the modelling of ice sheets.

Science advances, 2018

Geometries of Early Pleistocene [2.58 to 0.78 million years (Ma) ago] ice sheets in northwest Eur... more Geometries of Early Pleistocene [2.58 to 0.78 million years (Ma) ago] ice sheets in northwest Europe are poorly constrained but are required to improve our understanding of past ocean-atmosphere-cryosphere coupling. Ice sheets are believed to have changed in their response to orbital forcing, becoming, from about 1.2 Ma ago, volumetrically larger and longer-lived. We present a multiproxy data set for the North Sea, extending to over a kilometer below the present-day seafloor, which demonstrates spatially extensive glaciation of the basin from the earliest Pleistocene. Ice sheets repeatedly entered the North Sea, south of 60°N, in water depths of up to ~250 m from 2.53 Ma ago and subsequently grounded in the center of the basin, in deeper water, from 1.87 Ma ago. Despite lower global ice volumes, these ice sheets were near comparable in spatial extent to those of the Middle and Late Pleistocene but possibly thinner and moving over slippery (low basal resistance) beds.

Petroleum Geoscience, 2015

Facies models for wave-dominated shorelines include an "offshore transition zone" between shelfal... more Facies models for wave-dominated shorelines include an "offshore transition zone" between shelfal mudstones and nearshore shoreface sandstones. Offshore transition zone deposits are commonly tabular sandstone beds interbedded with continuous mudstone beds. However, observations from the Blackhawk Formation show that the offshore transition zone locally consists of erosive-based sandstone beds with "pinch-and-swell" geometries containing steep-walled gutter-casts, in areas larger than 6 x 2 km along strike and dip. This increases the amount of sand-on-sand-contacts, and leads to improved vertical permeability. Predicting the distribution of erosive offshore transition within the subsurface is therefore desirable. In this study, offshore transition zone deposits have been studied using virtual outcrops. Tabular offshore transition zone deposits have continuous sandstone and mudstone beds much longer than 500 m, and erosive offshore transition zone deposits have discontinuous shales on average 60 m long. Reservoir modelling shows a 10-3 times increase in vertical permeability in erosive compared to tabular offshore transition deposits, the magnitude decreasing with increasing fraction of shale. Erosive offshore transition deposits occur near distributary channels, subaqueous channels and abrupt bathymetric breaks. A regional study shows that erosive offshore transition zone deposits are mainly developed where parasequences prograde into deeper water offshore the platform break of the preceding parasequence, are commonly associated with basinal turbidites, and may be related to erosion by bypassing turbidity currents. Formatted: Numbering: Continuous which will be very low if the beds are tabular (low K v /K h ratio) but higher if there mudstones are eroded, leading to sand-on-sand contacts (higher (K v /K h ratio). This has the potential to dramatically alter the flow properties of such facies in hydrocarbon reservoirs. The objectives of this paper are fivefold: (1) To describe offshore transition deposits with special reference to the OTZe; (2) to document occurrence of OTZe versus OTZt in the study area; (3) to document bed geometries in tabular and erosive offshore transition deposits; (4) to quantify how reservoir properties vary in tabular and erosive offshore transition deposits; and finally (5) to discuss possible mechanisms for formation of erosive offshore transition and propose a predictive model for their occurrence in other systems. Geological background The studied deposits are exposed in the Book Cliffs of central Utah, USA (Fig. 1), and are part of the Campanian Blackhawk Formation (Fig. 2; Young 1955). The formation is part of a clastic wedge which prograded into the retro-arc foreland basin of the Sevier Orogen, a result of subduction on the western side of the North American plate, leading to the accretion of terranes and development of the Sevier mountain chain (Kauffman & Caldwell 1993). This foreland basin was part of the Western Interior Seaway, which developed at a time of very high sea-level during the Cretaceous (Haq et al. 1988). The sediment source was the uplifting Sevier Mountains to the east, and the depositional system comprised an alluvial plain with distributive fluvial systems that fed the wave-dominated Blackhawk shorelines (Howell & Flint 2003; Rittersbacher et al. 2014; Hampson et al. 2013). The stratal architecture of the Blackhawk Formation illustrates large scale progradation under a longterm rise in relative sea-level (Howell & Flint 2003). The shallow-marine part of the Blackhawk Formation has been subdivided into six, mainly progradational, tongues named the Spring Canyon, Aberdeen, Kenilworth, Sunnyside, Grassy and Desert members (Fig. 2; Young 1955), which are separated by regional flooding surfaces and landward facies belt shifts greater than 10 km (Young 1955; Hampson & Howell 2005; Hampson 2010). The members are further divided into parasequences, progradational sandstone tongues deposited under a single shoreline transit, separated by flooding surfaces developed during smaller transgressions on the scale of a few kilometers (Fig. 2; Van Wagoner et al. 1990; Hampson & Howell 2005).

From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin, 2014

Depositional systems to seDimentary successions on the norwegian continental margin other publica... more Depositional systems to seDimentary successions on the norwegian continental margin other publications of the international association of sedimentologists special puBlications 45 linking Diagenesis to sequence stratigraphy Edited by Sadoon Morad, J. Marcelo Ketzer and Luiz F. De Ros 2012, 522 pages, 246 illustrations 44 sediments, morphology and sedimentary processes on continental shelves Advances in Technologies, Research and Applications Edited by Michael Z. Li, Christopher R. Sherwood and Philip R. Hill 2012, 440 pages, 231 illustrations 43 Quaternary carbonate and evaporite sedimentary Facies and their ancient analogues A Tribute to Douglas James Shearman Edited by Christopher G. St. C. Kendall and Abdulrahman S. Alsharhan 2010, 494 pages, 263 illustrations 42 carbonate systems During the olicocene-miocene climatic transition Edited by Maria Mutti, Werner E. Piller and Christian Betzler 2010, 304 pages, 154 illustrations 41 perspectives in carbonate geology

… of Landslides in South East Asia …, 2008

The Peoples' Democratic Republic of Lao is a landlocked country bordered by Vietnam to the east, ... more The Peoples' Democratic Republic of Lao is a landlocked country bordered by Vietnam to the east, Thailand to the south and west and China to the north. It is predominantly hilly or mountainous, and experiences a subtropical climate defined by a distinct rainy season during the summer. Annual rainfall varies in the mountainous regions of the north between 1.5m and 4m per year, most of which falls during the summer months, sometimes in association with typhoons developed in the South China Sea. Forest occupies the majority of slopes that neighbour the road network.

The use of high resolution surveying techniques has increased dramatically in earth science appli... more The use of high resolution surveying techniques has increased dramatically in earth science applications over the last decade. New products, software solutions and an increased attention to "usability" have made terrestrial laser scanning (lidar) and digital photogrammetry popular methods for obtaining more detailed geometric data for many applications. Geology, especially the study of outcrops, is one such application area where the introduction of laser scanning in particular has benefitted, by allowing an increasingly quantitative approach at a variety of scales. Despite this, most of the contribution of modern surveying techniques has been related to the capture of topographic detail - the shape and form of outcrops - while the remote mapping of outcrop lithology has yet to be satisfactorily addressed. Ground-based spectral imaging offers new possibilities for an improved understanding of outcrop composition, by mapping lithology and the distribution of mineralogy with...

Petroleum Geoscience, 2008

Journal of Sedimentary Research, 2003

In the middle Green River Formation of central Nine Mile Canyon, Uinta Basin, Utah, several lacus... more In the middle Green River Formation of central Nine Mile Canyon, Uinta Basin, Utah, several lacustrine-dominated intervals ϳ10 m thick comprise aggradational carbonate parasequence sets and a progradational clastic parasequence. Maximum flooding surfaces are best identified within profundal oil shale that caps some of the clastic parasequences. These lacustrine transgressive systems tracts therefore exhibit parasequence stacking patterns unlike typical marine sequences. Two types of sequence boundary are identified. Type A sequence boundaries display evidence for a basinward shift in facies across a regionally mappable surface that is an angular or, rarely, parallel unconformity, and they typically juxtapose amalgamated braided fluvial channel sandstone (late lowstand systems tract) onto the profundal oil shale. They also bound depositional sequences that show a distinct asymmetry, being dominated by transgressive systems tracts 5-80 m thick. Highstand systems tracts are less than 4 m thick and may be removed completely, by erosion on overlying sequence boundaries. Other surfaces satisfy only some of the standard criteria of sequence boundaries and are termed type B sequence boundaries. Type A sequence boundaries mark pronounced base-level falls following times when the Uinta Lake had merged with a lake in an adjacent basin to form a much deeper lake. Such merging permitted the establishment of a new threshold at higher elevation following lakelevel balancing. Type B sequence boundaries are interpreted as marking base-level falls from a barely merged lake or a lake that had an outflow. Over a 200 m stratigraphic thickness, type A sequence boundaries are more common upsection, indicating that, with time, a pluvial climate became more pronounced or that the adjacent lake was more easily filled. Type A sequence boundaries also become angular rather than parallel unconformities upsection, suggesting increased tilting of the basin margin over time.

Geosphere, 2007

Advances in data capture and computer technology have made possible the collection of three-dimen... more Advances in data capture and computer technology have made possible the collection of three-dimensional, high-resolution, digital geological data from outcrop analogs. This paper presents new methodologies for the acquisition and utilization of three-dimensional information generated by groundbased laser scanning (lidar) of outcrops. A complete workfl ow is documented-from outcrop selection through data collection, processing and building of virtual outcropsto geological interpretation and the building of geocellular models using an industry-standard, reservoir-modeling software. Data sets from the Roda Sandstone in the Spanish Pyrenees and the Grabens region of Canyonlands National Park, Utah, USA, are used to illustrate the application of the workfl ow to sedimentary and structural problems at a reservoir scale. Subsurface reservoir models are limited by available geological data. Outcrop analogs from comparable systems, such as the Roda Sandstone and the Grabens, are commonly used to provide additional input to models of the subsurface. Outcrop geocellular models can be analyzed both statically and dynamically, wherein static examination involves visual inspection and the extraction of quantitative data on body geometry, and dynamic investigation involves the simulation of fl uid fl ow through the analog model. The work presented in this study demonstrates the utility of lidar as a data collection technique for the building of more accurate outcrop-based geocellular models. The aim of this publication is to present the fi rst documentation of a complete workfl ow that extends from outcrop selection to model investigation through the presentation of two worked data sets.

Geological Society, London, Special Publications, 2014

The aerial extent, thickness and internal distribution of grain-size are key, bed-scale controls ... more The aerial extent, thickness and internal distribution of grain-size are key, bed-scale controls on turbidite reservoir performance. Process-based modelling provides a method for predicting both the sandbody thickness and the grain-size distribution within the bed. The goal of the current study is to test such an approach on the Annot Sandstone in the Peïra Cava Sub-basin in SE France, and determine whether the process-based model can reliably recreate the bed characteristics observed in the outcrop. Turbidity currents were modelled using a commercially available software solution called MassFlow3D that is based on computational fluid dynamics. The goal of the current study was to accurately replicate a single bed (termed MU5). To achieve this goal, the base of the basin was structurally restored and then a simplified simulation of the beds below MU5 was generated using four flow events in order to recreate the bathymetry on to which MU5 was simulated. Several versions of MU5 were s...

Geological Society, London, Special Publications, 2007

Relay ramps associated with overlapping faults are commonly regarded as efficient conduits for fl... more Relay ramps associated with overlapping faults are commonly regarded as efficient conduits for fluid flow across potentially sealing intra-reservoir fault zones. The current study demonstrates that structural heterogeneity in the often anomalously wide damage zone of relay ramps may represent potential baffles to intra-ramp fluid flow. A network of ramp-parallel, ramp-diagonal and curved cataclastic deformation bands causes compartmentalization of the ramp studied in Arches National Park, Utah. Harmonic average calculations demonstrate that, although single deformation bands have little or no effect on effective permeability, the presence of even a very small number of low-permeable deformation band clusters could reduce along-ramp effective permeability by more than three orders of magnitude. Thus, although relay zones may maintain large-scale geometric communication, the results of this study demonstrate that caution must be exercised when considering relay ramps as fluid conduits...

Revista geológica de Chile, 2001

A section equivalent to the Pliocene La Portada Formation exposed in the coastal cliff at Hornito... more A section equivalent to the Pliocene La Portada Formation exposed in the coastal cliff at Hornitos, northern Chile, contains a ca. 7-10 m thick conglomerate bed. The bed occurs within a succession of shallow marine sandstones and has an erosional contact with underlying ...

Sedimentology, 2010

Skip to Main Content. Wiley Online Library will be disrupted 3 Sep from 10-12 BST for monthly mai... more Skip to Main Content. Wiley Online Library will be disrupted 3 Sep from 10-12 BST for monthly maintenance. ...

The Photogrammetric Record, 2010

This paper discusses the application of laser scanning and photo-realistic modelling to aid the s... more This paper discusses the application of laser scanning and photo-realistic modelling to aid the study of geological outcrops, using two examples from central and eastern Utah, USA, which are analogues to subsurface hydrocarbon fields. Terrestrial laser scanning point clouds were triangulated to obtain high-resolution surface representations, which were combined with semi-metric imagery to give texture-mapped photo-realistic models of the outcrops. Such models provide the basis for geological interpretation and were used to reconstruct the geometries of layers over the extent of the study area. The digitised geological layers were in turn used to build geocellular volumes that capture the properties of the geology. These models were built in subsurface reservoir modelling software and were used to simulate the flow of fluids through the reservoir analogue. In this way, the spatial information provided significantly more detailed quantitative data and greatly improved the outcrop studies compared to traditional field techniques.

Photogrammetric Engineering & Remote Sensing, 2010

Petroleum Geoscience, 2008

Estimates of recovery from oil fields are often found to be significantly in error, and the multi... more Estimates of recovery from oil fields are often found to be significantly in error, and the multidisciplinary SAIGUP modelling project has focused on the problem by assessing the influence of geological factors on production in a large suite of synthetic shallow-marine reservoir models. Over 400 progradational shallow-marine reservoirs, ranging from comparatively simple, parallel, wavedominated shorelines through to laterally heterogeneous, lobate, river-dominated systems with abundant low-angle clinoforms, were generated as a function of sedimentological input conditioned to natural data. These sedimentological models were combined with structural models sharing a common overall form but consisting of three different fault systems with variable fault density and fault permeability characteristics and a common unfaulted end-member. Different sets of relative permeability functions applied on a facies-by-facies basis were calculated as a function of different lamina-scale properties and upscaling algorithms to establish the uncertainty in production introduced through the upscaling process. Different fault-related upscaling assumptions were also included in some models. A waterflood production mechanism was simulated using up to five different sets of well locations, resulting in simulated production behaviour for over 35 000 full-field reservoir models. The model reservoirs are typical of many North Sea examples, with total production ranging from c. 15 10 6 m 3 to 35 10 6 m 3 , and recovery factors of between 30% and 55%. A variety of analytical methods were applied. Formal statistical methods quantified the relative influences of individual input parameters and parameter combinations on production measures. Various measures of reservoir heterogeneity were tested for their ability to discriminate reservoir performance. This paper gives a summary of the modelling and analyses described in more detail in the remainder of this thematic set of papers.