bluuebunny/crossref_metadata_2025_split huggingface dataset:
FORMATION OF MODERN SAND-RICH FACIES BY MARINE CURRENTS ON THE ANTARCTIC CONTINENTAL SHELF
Authors: Anderson John B. , Smith Michael J. 
Published: October 2019

Abstract
Sediments delivered to the seas surrounding Antarctica are not subjected to the fluvial and coastal processes which would otherwise sort them before reaching the continental shelf. For this reason, the Antarctic continental shelf is an ideal environment in which to study the role of marine currents in sediment transport and deposition.
The results of theoretical studies and laboratory flume experiments on sediment transport indicate that moderately strong marine currents are capable of transporting fine-to-very fine sand in suspension. These currents are therefore capable of transporting these sands great distances on the shelf. Modern sand-rich facies, derived from the unsorted glacial debris of the Antarctic continental shelf, provide striking evidence for this.
Four areas of the Antarctic continental shelf were examined in detail, the Ross Sea shelf, George V shelf, Pennell Coast shelf, and the continental shelf of the northwestern corner of the Weddell Sea. All of these areas have extensive sand-rich facies on their outer shelves. These facies are hundreds of kilometers long and tens of kilometers wide. The thickness of these deposits is limited by the availability of sand to the outer shelf.
Physical oceanographic data from the Ross Sea and George V continental shelves indicate that sand-rich facies of these areas occur where the modified derivatives of Circumpolar Deep Water extend onto the shelf. Near-bottom current meter records from the Ross Sea shelf show frequent and sustained currents with speeds capable of suspending very-fine to fine sand. Wind-driven currents appear to be active sediment transporting agents to a depth of nearly 300 m, but most of the Antarctic continental shelf is deeper than this. The sea floor of the inner shelf is mainly blanketed by muds, which implies weak thermohaline circulation at depths below 300 m.
SHELF SANDSTONES OF THE ROBULUS L ZONE, OFFSHORE LOUISIANA
Authors: HART GEORGE F. , FERRELL RAY E. , LOWE DONALD R. , LENOIR ANN E. 
Published: October 2019

Abstract
A detailed palynologic, sedimentologic, and mineralogic investigation of the Robulus L No. 2 and the Robulus L No. 5 sands in cores from Texaco well No. 6 of Vermilion Block 31, offshore Louisiana, confirms that the units were deposited in the middle to outer part of the continental shelf during the early Miocene Epoch. The co-occurrence of the dinocysts, Hystrichosphaeropsis obscura and Lejeunecysta hyalina, further restricts the cored intervals to the Burdigalian Age. Variations in the abundances of Polysphaeridium zoharyi, Lingulodinium machareophorum, Tuberculodinium vancampoae, and terrestrial organic matter indicate the sediments are mixtures of marine and estuarine debris accumulating in the neritic zone.Five lithofacies and seven palynofacies are recognized. Current-structured, medium-grained sandstone containing abundant terrestrial organic matter and shell fragments (lithofacies B) forms the best potential reservoirs. Original high clay content and bioturbation restrict the permeability of other lithofacies and, hence, their producing potential. The Robulus L No. 2 is a better producer because lithofacies B is more abundant. Sandstones of this lithofacies often exhibit porosities between 15-28 percent and permeabilities as high as 2000 md because of their coarser grain size and the dissolution of shell fragments. In the Texaco No. 6 well, there is a clear relationship between original characteristics of the sediments, diagenesis, and hydrocarbon production.
Chemical and Isotopic Evidence of the Origins of Natural Gases in Offshore Gulf of Mexico
Authors: Rice Dudley D. 
Published: October 2019

ABSTRACT
The chemical and isotopic composition of natural gases from 55 fields in the offshore Gulf of Mexico province has been analyzed. The gases display a trend of more positive δ13C1 values (−70 to −35 ‰ (permil)) with increasing depth and age of producing reservoir. The mechanisms responsible for this fractionation are biogenic enrichment of 12C1, thermal cracking, and mixing. Separate trends are present in Texas and Louisiana which suggest a higher geothermal gradient or different type of organic matter in offshore Texas. There is considerable scatter along the general trend because gases generated from deeper, thermally mature source rocks have commonly migrated to shallower immature reservoirs.
The province is primarily a gas-producing region for three reasons. Many gas fields, particularly those of Pleistocene age, are of apparent biogenic origin. This gas is characterized by enrichment of the light isotope 12C in methane (δ13C1 more negative than −55 ‰) and by large amounts of methane (C1/C1-5 &gt; 0.99). Miocene gas accumulations in the western part of the province are either the result of early stages of thermal cracking of liquid hydrocarbons because of a higher geothermal gradient, or a different type of organic matter from which the hydrocarbons were derived. This gas is wetter than biogenic gas (C1/C1-5 &gt; 0.94) and isotopically heavy (δ13C1 more positive than −40 ‰). Many gas fields in reservoirs of all ages are the result of “separation-migration” in which the gas phase was physically segregated from a petroleum accumulation. These gases are similar in composition to gas associated with petroleum.
Preliminary Analysis of the Entire Holocene Valley Fill Sequence As Revealed by the P-I-90 Boring, Terrebonne Parish, Louisiana
Authors: Connor Paul F. , Kuecher Gerry J. , Hazel Joseph E. 
Published: October 2019

ABSTRACT
This paper provides a preliminary analysis of the PI90 boring that penetrated the entire Holocene valley fill sequence in Terrebonne Parish, Louisiana. The PI90 boring was acquired as part of the Louisiana Geological Survey -U.S. Geological Survey cooperative research project concerning wetland subsidence in Louisiana. The borehole site is located near Cocodrie, about 19 km inland of Louisiana's coastal barrier islands. A total depth of 65.0 m was reached and recovered, utilizing a combination of wet-rotary drilling and pushcores, 1.5 m in length and 7.62 cm in diameter. From the top of the coarse-grained Pleistocene Substratum (±62.5 m) to the surface, seven coarsening-upward cycles ranging from 3.0 to 12.0 m in thickness were encountered. These coarsening-upward cycles were interpreted by in-situ cone penetrometer and bore-log descriptions. They are indicative of seven separate delta-building episodes during overall regional Holocene transgression.
The Mississippi Delta Plain’S Levees, Crevasses, and Sediments
Authors: Davis Donald W. 
Published: October 2019

ABSTRACT
From its inception, New Orleans was an “island city” surrounded by water. When it was surveyed in 1720, each block was circled with drainage ditches. These small channels established New Orleans' dependence on a levee/drainage network. Levee construction began as early as 1718. By 1727, a hand-made embankment protected the earliest city–the “Vieux Carre.” With time the initial levee extended along the Mississippi River for a total of 67.6 km. The first artificial levee built to protect New Orleans was in place, but it was neither high enough nor wide enough. By the 1850s, intermittent dikes flanked most of the lower Mississippi River.
After the devastating flood of 1927, the Mississippi River was locked into a conduit framed by artificial levees. The river can no longer inundate its historic flood plain. Sediments are channeled away from the wetlands. Loss of these sediments deprives the coast of the material necessary to build new land at a rate slightly greater than subsidence. There is nothing available that can offset the rapid rate of wetland loss. Consequently, to exist in this dynamic and sometimes inhospitable physiographic province, the population had to develop and utilize innovative engineering techniques, unconventional wisdom, and unique cultural occupancy patterns.
Geomorphic History, Geologic Framework, and Hard Mineral Resources of the Petit Bois Pass Area, Mississippi-Alabama
Authors: McBride Randolph A. , Byrnes Mark R. , Penland Shea , Pope David L. , Kindinger Jack L. 
Published: October 2019

ABSTRACT
Approximately 200 line-km of high-resolution seismic reflection data, 24 vibracores, historical maps, and aerial photography were used to delineate the geomorphic history, geologic framework, and potential hard mineral resources of the Petit Bois Pass area. Petit Bois Pass is a natural tidal inlet system located between Petit Bois and Dauphin islands at the Mississippi-Alabama state line. Since its opening, the inlet has migrated to the west at rates exceeding 50 m/yr. However, the main channel of Petit Bois Pass has remained relatively stable since 1917, occupying an antecedent topographic depression cut into underlying pre-Holocene deposits. Pre-Holocene deposits form the eastern core of Dauphin Island, where they are subaerially exposed. The pre-Holocene surface dips to the west, providing a platform for the narrow, elongated Holocene spit of Dauphin Island. The pre-Holocene surface crops out on the shoreface at the western end of Dauphin Island 8 to 9 m below mean low water (MLW). Farther to the west, vibracores from the main inlet channel of eastern Petit Bois Pass contain only Holocene sediment, suggesting that the pre-Holocene surface is &gt;11 m below MLW. West of the main tidal channel, the undulating pre-Holocene surface shallows in the central portion of the pass before dipping down to &gt;11 m under Petit Bois Island. It appears that tidal channels associated with Petit Bois Pass occupy pre-Holocene fluvial channels cut by either the Pascagoula, Escatawpa, or Fowl rivers during lower sea level. In the study area, the primary hard mineral resource targets include Holocene tidal inlet channels, ebbtidal deltas, and shoreface sand ridges, while abandoned pre-Holocene fluvial channels are considered secondary.
RATES OF RELATIVE SEA LEVEL CHANGE IN THE NORTHERN GULF OF MEXICO
Authors: Ramsey Karen E. 
Published: October 2019

ABSTRACT
Over the last 65 years, relative sea-level has averaged 0.23 cm/yr in the Gulf of Mexico, and as much as 1.5 cm/yr in the Mississippi River delta plain of Louisiana, ranking the second highest after Japan by global region. Under the conditions of rapid sea-level rise and subsidence, thousands of acres of productive coastal wetlands have been converted to open water each year. Between 1956 and 1978, Texas and Mississippi lost 11,400 ha and 2490 ha of wetlands respectively. Louisiana lost 18,755 ha of wetlands.
Relative sea-level rise (RSL), which is the combined effects of eustatic change and subsidence, ranges from 0.15 cm/yr to 0.23 cm/yr in Mississippi and Florida and 0.63 cm/yr to 1.5 cm/yr in Texas and Louisiana, respectively. The Environmental Protection Agency (EPA), National Resource Council (NRC), and the Intergovernmental Panel on Climate Change (IPCC) predict eustatic sea level to increase over the next century due to global climate change. With predicted change, areas currently influenced by subsidence will experience a dramatic increase in rates of land loss. Other areas in the northern Gulf of Mexico may begin to experience the coastal land loss conditions currently observed in Louisiana if the predictions are accurate.
LITHOSTRATIGRAPHY, BIOSTRATIGRAPHY, AND ISOTOPIC INVESTIGATION OF A BORING IN MAIN PASS AREA, BLOCK 303: A CALIBRATION OF HIGH RESOLUTION SEISMIC STRATIGRAPHY
Authors: ROBERTS HARRY H. , FILLON RICHARD H. , KOHL BARRY , BOUMA ARNOLD H. , SYDOW JOHAN 
Published: October 2019

ABSTRACT
A 300 ft (92 m) continuous boring collected in the Main Pass lease area, Block 303, provides excellent data for a better understanding of shelf margin deltaic deposition and facies architecture in relation to glacio-eustatic cycles.
The boring penetrated a complete late Pleistocene deltaic progradational wedge characterized by sand-rich sediments that are represented as well-developed clinoforms on high-resolution seismic records. A thin shell-rich transgressive sand overlies the delta and its superimposed gravel to sand-filled channel. Below the delta, a shale and calcareous shale section occurs that represents prodelta and distal shelf deposits. It comprises about half the boring and accounts for most of the time represented by the sedimentary column sampled. Sediments of the boring span six oxygen isotope stages or three sea level cycles. Lithologically, the boring reveals an upward succession of shale to carbonate-rich shale to silty-shale and thin sandy laminae to sands (fine to medium grain size) of the delta to a thin organic shale to a massive/cross laminated channel fill to a carbonate-rich silty shale. Biostratigraphic data indicate that this upward lithologic succession reflects water depths of inner shelf to outer neritic to marginal marine and back to outer neritic.
Restoration of Wetlands Using Pipeline Transported Sediments
Authors: Suhayda Joseph N. , Kemp G. Paul , Jones Robert S. , Peckham Jeanene 
Published: October 2019

ABSTRACT
A joint federal-state effort has been initiated in Louisiana to reduce current 6,000 hectare annual coastal wetland losses and restore wetland building in the Mississippi River delta. At $50 to $60 million annually, this initiative ranks with efforts in Florida and California as among the most ambitious habitat restorations yet undertaken. It is proposed that slurry pipelines be considered as modern surrogates for natural distributary channels in a subsiding delta tightly managed for navigation, flood control, fisheries and energy development. A twenty year scenario is proposed as one example of how funds available today might be used to stabilize wetland loss by building, saving and maintaining wetlands using a pipeline-based infrastructure to transport sediments. This model predicts that stabilization, or “no net loss” of coastal wetlands, could be achieved after 16 years.
INFLUENCE OF SUBMARINE CANYON EROSION AND SEDIMENTATION ON ALLOCHTHONOUS SALT BODY GEOMETRY: THE PATHWAY OF BRYANT CANYON IN GARDEN BANKS
Authors: FIDUK JOSEPH C. 
Published: October 2019

ABSTRACT
The path of Bryant Canyon was identified during the structural and sequence stratigraphic mapping of reprocessed, migrated, 72-fold seismic data in the Garden Banks OCS area. The canyon pathway winds around and through salt structures in Garden Banks and continues to the south where it eventually overrides the allochthonous salt sheet that extends to the Sigsbee Escarpment. Stratigraphic evidence suggests that Bryant Canyon may be 0.2-0.3 Ma in age. It is now almost entirely infilled with shelf-derived (probably deltaic) sediments near the shelf/slope break and with turbidite and/or slump deposits farther down slope. Erosional features and reentrants in paleoshelf margins suggest that earlier canyons may also have occupied this pathway. The path of Bryant Canyon may be a primary and long standing conduit for shelf-derived coarse clastic sediments being transported into deep water.
Sediments and sedimentation associated with Bryant Canyon have affected salt body geometries observed within the Garden Banks area in three ways. First, updip and lateral differential loading by sediments infilling Bryant Canyon helped drive salt migration. Variations in size and location of these differential loads influence the direction and rate of salt flow. Second, sediment transported down Bryant Canyon has physically eroded and incised certain salt structures. Although rare, deep water erosion and dissection of salt structures directly affects their observed geometries. Third, erosion has removed the sediment covering some shallowly buried salt structures thus exposing them to sea water. Geometries of the exposed structures are affected by both the disruption of isostatic equilibrium and by the effects of salt water dissolution.
Nearest the shelf margin the effect of differential sediment loading is most advanced. There, sedimentation has dissected the allochthonous salt into closely spaced salt stocks. Farther down slope the dissection process is less complete. Bryant Canyon intersects and parallels a dip-oriented salt ridge. In southernmost Garden Banks, the effects of differential sediment loading are least advanced. Sediment transported down Bryant Canyon has created a series of dip-oriented salt-free fensters within the continuous allochthonous salt sheet.
MODELLING THE EFFECTS OF SALT-INDUCED TOPOGRAPHY ON DEPOSITION FROM TURBIDITY CURRENTS
Authors: KNELLER BEN , McCAFFREY BILL 
Published: October 2019

Abstract
Prediction of turbidite sandstone reservoirs in topographically variable systems is approached through a combination of physical and conceptual modelling; scaled physical analogues help to constrain geometries, while physically based genetic facies models predict the distribution of lithotypes. Data are presented for experimental gravity flows interacting with obstacles simulating salt-induced topography. Interactions between the flow and topographic features are dependent upon the shape and orientation of the obstacle, and upon its size relative to the height of the flow. Deposition of sediment from turbidity currents is as dependent on flow non-uniformity as it is upon unsteadiness; the nature and magnitude of flow nonuniformity are functions of down-flow changes in gradient or confinement, and it is therefore a function of the topography over which the flow is moving. This can be combined with the effects of flow unsteadiness to create a powerful, physically based facies model that predicts the relations between turbidite facies and the topographic elements of turbidite systems.
STRATIGRAPHIC ANATOMY OF SHELFAL MIOCENE RESERVOIRS: WESTERN MATURÍN BASIN, VENEZUELA
Authors: PORTA RODOLFO , GALEAZZI SEBASTIÁN , SADLER PETER , RISI DANIEL , ULIANA MIGUEL , LEGARRETA LEONARDO , MITCHUM ROBERT M. 
Published: October 2019

ABSTRACT
The Maturin basin is a supercharged hydrocarbon setting that hosts the world’s largest individual oil accumulation: the Orinoco Belt, in situ 1.2 TBO. Miocene strata represent the most prolific reservoirs in the Maturin and in several of the Eastern Venezuela-Trinidad oil districts. Production in this region is in excess of 10 BBO. In spite of protracted and intense exploration and production activity by the oil industry, detailed stratigraphic knowledge on the oil-bearing Miocene successions has received only limited consideration in the public domain literature. As part of a field reactivation project undertaken on behalf of Corpoven S.A., rightholder of the Quiamare-La Ceiba unit (Fig. 1), the Lower-Middle Miocene succession in NE Anzoátegui was analyzed from a sequence-stratigraphic and reservoir-characterization perspective. The study follows a four-fold approach: the first part outlines the geodynamic context and describes the key elements of the basin-scale Miocene stratigraphy and paleogeography; the second part discusses the sequence stratigraphy of the 4,000 m (12,000 ft) thick Miocene series over the SW fringe of the Maturin fold-thrust belt, as well as the implications of the regional stratal patterns and facies architecture for trapping potential; the third part examines the anatomy of individual reservoirs at the parasequence scale, describes the effects of fourth-order sequences on trapping, and analyzes internal reservoir facies heterogeneities; the last part focuses on the potential of seismic inversion for pre-drill reservoir prediction and efficient development planning.
Figure 1.Location map of the area of this study and the Eastern Venezuela Basin.
SHELL’S EXPLORATION STRATEGIES AND LEARNINGS IN THE MATURE GULF OF MEXICO SHELF
Authors: SHEPARD J.L. , FOSTER R.A. , GODO T.J. 
Published: October 2019

ABSTRACT
Exploration strategies and tactics are dynamic, reacting and evolving in response to drilling success and failure, evolving technology, economic factors, infrastructure availability, and the type and perceived abundance of remaining opportunities. This paper addresses the transformation of one company’s approach to exploration in a mature province. In late 1992, Shell Offshore Incorporated implemented a new Gulf of Mexico shelf exploration strategy. The new “drill any profitable prospect” strategy replaced a strategy that emphasized finding the “big one.” One outcome of the new strategy is a larger drillsite portfolio that is more balanced with regard to risk and reward.
Two prospects offer insights into potential complications and challenges in the discovery appraisal process and the value of reservoir architecture models to successful appraisal. While the example prospects are illustrative of a slope depositional environment, the strategies and learnings themselves are independent of depositional environment and have business relevance to deltaic and non-marine exploration and development activities in diverse settings.
FACIES ANALYSIS OF THE UPPER EOCENE LA PAZ FORMATION, PROVINCIA FIELD, NORTHERN MIDDLE MAGDALENA VALLEY BASIN, COLOMBIA
Authors: SUAREZ MARIO , WEIMER PAUL , KRAUS MARY J. , PULHAM ANDREW J. 
Published: October 2019

ABSTRACT
The upper Eocene La Paz Formation is the primary petroleum reservoir in the Provincia Field, located in the eastern foothills of the northern Middle Magdalena Valley Basin, Colombia. The average thickness of the La Paz reservoir is 800 feet in the Provincia field. A facies analysis of this unit was conducted using 332 feet of core, which were calibrated with well logs, core petrophysical data, and used for well log facies associations predictions in six wells. Four facies associations are recognized and represent deposition in braided trunk channel, minor channel (distributary or crevasse), crevasse splay and floodplain subenvironments. The minor channel and crevasse splay deposits comprise avulsion deposits. The avulsion deposits are volumetrically important and comprise nearly half of the reservoir (49.1%). Recognition of significant avulsion deposits in this study suggests that channel avulsion and preservation of thick avulsion sequences may be common in braided stream settings and are not exclusively characteristic of meandering systems.
The best reservoir facies in the La Paz Formation are subarkosic sandstones (porosity 16.7%, permeability 409.2 md), deposited in braided trunk channels and comprise 30.6% of the total reservoir thickness. Sandstone facies in the avulsion deposits have poor reservoir quality (porosity 12.9%, permeability 29 md) and act as fluid flow retardants (or lateral plugs). Floodplain deposits comprising 20.3% of the reservoir are impermeable and are the main vertical barriers.
Based on the depositional model, a 2-D reservoir zonation was constructed for the La Paz reservoir. Six flow units were defined, ranging from 50 to 140 feet in thickness, each separated by floodplain deposits. Within the flow units, interbedded avulsion deposits and trunk channel deposits produce high reservoir heterogeneity. Understanding all of the depositional elements in this type of fluvial system has helped to create realistic reservoir characterization that could be applied to reservoir simulation models.