bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial and seasonal variations of fine particle water-soluble organic carbon (WSOC) over the Southeastern United States: implications for secondary organic aerosol formation
Authors: Zhang X. , Liu Z. , Hecobian A. , Zheng M. , Frank N. H. , Edgerton E. S. , Weber R. J.
Published: April 2012

Abstract. Secondary organic aerosol (SOA) in the Southeastern US is investigated by analyzing the spatial-temporal distribution of water-soluble organic carbon (WSOC) and other PM2.5 components from 900 archived 24 h Teflon filters collected at 15 urban or rural EPA Federal Reference Method (FRM) network sites throughout 2007. Online measurements of WSOC at an urban/rural-paired site in Georgia in the summer of 2008 are contrasted to the filter data. Based on FRM filters, excluding biomass-burning events (levoglucosan < 50 ng m−3), WSOC and sulfate were highly correlated with PM2.5 mass and both comprised a large mass fraction of PM2.5 (13% and 35%, respectively). Sulfate and WSOC both tracked ambient temperature throughout the year, suggesting the temperature effects were mainly on the photochemical processes that lead to secondary formation. FRM WSOC, and to a lesser extent sulfate, were spatially homogeneous throughout the region, yet WSOC was moderately enhanced (27%) in locations of greater predicted isoprene emissions in summer. A Positive Matrix Factorization (PMF) analysis identified two major source types for the summer WSOC; 22% of the WSOC were associated with ammonium sulfate, and 56% of the WSOC was associated with brown carbon and oxalate. A small urban excess of FRM WSOC (10%) was observed in the summer of 2007, however, comparisons of online WSOC measurements at one urban/rural pair (Atlanta/Yorkville) in August 2008 showed substantially greater difference in WSOC (31%) relative to the FRM data, suggesting a low bias for urban filters. The measured Atlanta urban excess, combined with the estimated boundary layer heights, gave an estimated Atlanta daily WSOC production rate in August of 0.55 mg C m−2 h−1 between mid-morning and mid-afternoon. This study characterizes the regional nature of fine particles in the Southeastern US, confirming the importance of secondary organic aerosol and the roles of both biogenic and anthropogenic emissions.
Temporal variability of live (stained) benthic foraminiferal faunas in a river-dominated shelf – Faunal response to rapid changes of the river influence (Rhône prodelta, NW Mediterranean)
Authors: Goineau A. , Fontanier C. , Jorissen F. , Buscail R. , Kerhervé P. , Cathalot C. , Pruski A. M. , Lantoine F. , Bourgeois S. , Metzger E. , Legrand E. , Rabouille C.
Published: April 2012

Abstract. In the context of the French research project CHACCRA (Climate and Human-induced Alterations in Carbon Cycling at the River-seA connection), living (rose Bengal-stained) benthic foraminifera were investigated at two stations (24 and 67 m depth) in the Rhône prodelta (NW Mediterranean, Gulf of Lions). The aim of this study was to precise the response of benthic foraminiferal faunas to temporal changes of the Rhône River inputs (e.g. organic and terrigeneous material). Each site was sampled in April 2007, September 2007, May 2008 and December 2008, permitting to observe foraminiferal faunas of the 63–150 and >150 μm size fractions under a wide range of environmental conditions. Obvious variations in foraminiferal faunal composition were observed during the four investigated periods at the shallowest Station A located in the close vicinity of the Rhône River mouth. After major Rhône River flood events, different colonisation stages were observed with foraminiferal faunas responding with an opportunistic strategy few days to weeks after the creation of a peculiar sedimentary environment (Leptohalysis scottii, May 2008) or high organic matter supplies (Ammonia tepida, December 2008). Under more stable conditions, relatively diverse and equilibrated faunas grew in the sediments. Species benefited from noticeable input of riverine phytodetritus to the sediment during spring bloom conditions (April 2007; e.g. Bolivina dilatata, Nonionella stella, Stainforthia fusiformis), or high amounts of still bio-available organic matter under more oligotrophic conditions (September 2007; e.g. Ammonia tepida, Psammosphaera fusca). The reduced influence of the Rhône River input at the farther Station N led to less contrasted environmental conditions during the four sampling periods, and so to less obvious variations in foraminiferal faunal composition. During reduced riverine influence (i.e. low Rhône discharge), species able to feed on fresh phytodetritus (e.g. Clavulina cylindrica, Hopkinsina atlantica, Nonionella iridea and Nonionella turgida) benefited from eutrophic conditions of the spring bloom (April 2007, May 2008). Conversely, the occurrence of Nouria polymorphinoides under oligotrophic conditions (September 2007, December 2008) was indicative of a benthic environment potentially disturbed by bottom currents. This study put into evidence the extremely rapid response of benthic foraminiferal faunas to strong variations in environmental conditions mostly induced by the Rhône dynamics.
Photoproduction of ammonium in the Southeastern Beaufort Sea and its biogeochemical implications
Authors: Xie H. , Bélanger S. , Song G. , Benner R. , Taalba A. , Blais M. , Lefouest V. , Tremblay J.-É. , Babin M.
Published: April 2012

Abstract. Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH4+). During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH4+ photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin. The photoammonification efficiency decreased with increasing wavelength across the ultraviolet and visible regimes and was higher in offshore waters than in shelf and estuarine waters. The efficiency was positively correlated with the molar nitrogen : carbon ratio of DOM and negatively correlated with the absorption coefficient of chromophoric DOM (CDOM). Combined with collateral measurements of CO2 and CO photoproduction, this study revealed a stoichiometry of DOM photochemistry with a CO2:CO:NH4+ molar ratio of 165:11:1 in the estuary, 60:3:1 on the shelf, and 18:2:1 in the Canada Basin. The NH4+ efficiency spectra, along with solar photon fluxes, CDOM absorption coefficients and sea ice concentrations, were used to model the monthly surface and depth-integrated photoammonification rates in 2009. The summertime (June–August) rates at the surface reached 6.6 nmol l−1 d−1 on the Mackenzie Shelf and 3.7 nmol l−1 d−1 further offshore; the depth-integrated rates were correspondingly 8.8 μmol m−2 d−1 and 11.3 μmol m−2 d−1. The offshore depth-integrated rate in August (8.0 μmol m−2 d−1) was comparable to the missing dissolved inorganic nitrogen (DIN) source required to support the observed primary production in the upper 10-m layer of that area. The yearly NH4+ photoproduction in the entire study area was estimated to be 1.4 × 108 moles, with 85 % of it being generated in summer when riverine DIN input is low. Photoammonification could mineralize 4 % of the annual dissolved organic nitrogen (DON) exported from the Mackenzie River and provide a~DIN source corresponding to 7 % of the riverine DIN discharge and 1400 times the riverine NH4+ flux. Under a climate warming-induced ice-free scenario, these quantities would increase correspondingly to 6 %, 11 %, and 2100 times. Photoammonification is thus a significant nitrogen cycling term and may fuel previously unrecognized autotrophic and heterotrophic production pathways in the surface SE Beaufort Sea.
Extreme pointer years in tree-ring records of Central Spain as evidence of climatic events and the eruption of the Huaynaputina Volcano (Peru, 1600 AD)
Authors: Génova M.
Published: April 2012

Abstract. The study of pointer years of numerous tree-ring chronologies of the central Iberian Peninsula (Sierra de Guadarrama) could provide complementary information about climate variability over the last 405 yr. In total, 64 pointer years have been identified: 30 negative (representing minimum growths) and 34 positive (representing maximum growths), the most significant of these being 1601, 1963 and 1996 for the negative ones, and 1734 and 1737 for the positive ones. Given that summer precipitation was found to be the most limiting factor for the growth of Pinus in the Sierra de Guadarrama in the second half of the 20th century, it is also an explanatory factor in almost 50% of the extreme growths. Furthermore, these pointer years and intervals are not evenly distributed throughout time. Both in the first half of the 17th and in the second half of 20th, they were more frequent and more extreme and these periods are the most notable for the frequency of negative pointer years in Central Spain. The interval 1600–1602 is of special significance, being one of the most unfavourable for tree growth in the centre of Spain, with 1601 representing the minimum index in the regional chronology. We infer that this special minimum annual increase was the effect of the eruption of Huaynaputina, which occurred in Peru at the beginning of 1600 AD. This is the first time that the effects of this eruption in the tree-ring records of Southern Europe have been demonstrated.
Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a Coarse Resolution Model
Authors: Mengel M. , Levermann A. , Schleussner C.-F. , Born A.
Published: April 2012

Abstract. Direct observations, satellite measurements and paleorecords reveal strong variability in the Atlantic subpolar gyre on various time scales. Here we show that variations of comparable amplitude can only be simulated in a coupled climate model in the proximity of a dynamical threshold. The threshold and the associated dynamic response is due to a positive feedback involving increased salt transport in the subpolar gyre and enhanced deep convection in its center. A series of sensitivity experiments is performed with a coarse resolution ocean general circulation model coupled to a statistical-dynamical atmosphere model which in itself does not produce atmospheric variability. To simulate the impact of atmospheric variability, the model system is perturbed with freshwater forcing of varying but small amplitude and multidecadal to centennial periodicity, and observational variations in wind stress. While both freshwater and wind-stress-forcing have a small direct effect on the strength of the subpolar gyre, the magnitude of the gyre's response is strongly increased in the vicinity of the threshold. Our results thus indicate that baroclinic self-amplification in the North Atlantic ocean can play an important role in presently observed SPG variability and thereby North Atlantic climate variability on multidecadal scales.
Record extension for short-gauged water quality parameters using a newly proposed robust version of the line of organic correlation technique
Authors: Khalil B. , Adamowski J.
Published: April 2012

Abstract. In many situations the extension of hydrological or water quality time series at short-gauged stations is required. Ordinary least squares regression (OLS) of any hydrological or water quality variable is a traditional and commonly used record extension technique. However, OLS tends to underestimate the variance in the extended records, which leads to underestimation of high percentiles and overestimation of low percentiles, given that the data is normally distributed. The development of the line of organic correlation (LOC) technique is aimed at correcting this bias. On the other hand, the Kendall-Theil robust line (KTRL) method has been proposed as an analogue of OLS with the advantage of being robust in the presence of outliers. Given that water quality data are characterised by the presence of outliers, positive skewness and non-normal distribution of data, a robust record extension technique is more appropriate. In this paper, four record-extension techniques are described, and their properties are explored. These techniques are OLS, LOC, KTRL and a new technique proposed in this paper, the robust line of organic correlation technique (RLOC). RLOC includes the advantage of the LOC in reducing the bias in estimating the variance, but at the same time it is also robust to the presence of outliers. A Monte Carlo study and empirical experiment were conducted to examine the four techniques for the accuracy and precision of the estimate of statistical moments and over the full range of percentiles. Results of the Monte Carlo study showed that the OLS and KTRL techniques have serious deficiencies as record-extension techniques, while the LOC and RLOC techniques are nearly similar. However, RLOC outperforms OLS, KTRL and LOC when using real water quality records.
Engineering of Oriented Myocardium on Three-Dimensional Micropatterned Collagen-Chitosan Hydrogel
Authors: Chiu Loraine L.Y. , Janic Katarina , Radisic Milica
Published: April 2012

Introduction:

Surface topography and electrical field stimulation are important guidance cues that aid the organization and contractility of cardiomyocytes in vivo. We report here on the use of these biomimetic cues in vitro to engineer an implantable contractile cardiac tissue.

Methods:

Photocrosslinkable collagen-chitosan hydrogels with microgrooves of 10 μm, 20 μm and 100 μm in width were fabricated using polydimethylsiloxane (PDMS) molds. The hydrogels were seeded with cardiomyocytes, placed into a bioreactor array with the microgrooves aligned with the electrical field lines, and stimulated with biphasic square pulses at 1 Hz and 2.5 V/cm.

Results:

At Day 6, cardiomyocytes were aligned in the direction of the microgrooves. When cultivated without electrical stimulation, the excitation threshold of engineered cardiac tissues using micropatterned hydrogels was significantly lower than using smooth hydrogels, thus showing the importance of cell alignment to cardiac function. The success rate of achieving beating constructs was higher with the application of electrical stimulation. In addition, formation of dense contractile cardiac organoids was observed in groups with both biomimetic cues. The cultivation of cardiomyocytes on hydrogels with 10 μm grooves yielded 100% beating tissues with or without electrical stimulation, thus suggesting a smaller groove width is necessary for cells to communicate and form proper gap junctions. However, electrical field stimulation further increased cell density and enhanced tissue morphology which may be essential for the integration of the tissue construct to the native heart tissue upon implantation.

Conclusions:

The biodegradability of the hydrogel substrate allows for the rapid translation of the engineered, oriented cardiac tissue to clinical applications.
Development of Artificial Neural Network–Based Algorithms for the Classification of Bileaflet Mechanical Heart Valve Sounds
Authors: Bagno Andrea , Licciardello Claudia , Tarzia Vincenzo , Bottio Tomaso , Pengo Vittorio , Gerosa Gino
Published: April 2012

Objectives:

As is true for all mechanical prostheses, bileaflet heart valves are prone to thrombus formation; reduced hemodynamic performance and embolic events can occur as a result. Prosthetic valve thrombosis affects the power spectra calculated from the phonocardiographic signals corresponding to prosthetic closing events. Artificial neural network–based classifiers are proposed for automatically and noninvasively assessing valve functionality and detecting thrombotic formations. Further studies will be directed toward an enlarging data set, extending the investigated frequency range, and applying the presented approach to other bileaflet mechanical valves.

Methods:

Data were acquired for the normofunctioning St. Jude Regent valve mounted in the aortic position of a Sheffield Pulse Duplicator. Different pulsatile flow conditions were reproduced, changing heart rate and stroke volume. The case of a thrombus completely blocking 1 leaflet was also investigated. Power spectra were calculated from the phonocardiographic signals and used to train artificial neural networks of different topologies; neural networks were then tested with the spectra acquired in vivo from 33 patients, all recipients of the St. Jude Regent valve in the aortic position.

Results:

The proposed classifier showed 100% correct classification in vitro and 97% when applied to in vivo data: 31 spectra were assigned to the right class, 1 received a false positive classification, and 1 was “not classifiable.”

Conclusion:

Early malfunction detection is necessary to prevent thrombotic events in bileaflet mechanical heart valves. Following further clinical validation with an extended patient database, artificial neural network–based classifiers could be embedded in a portable device able to detect valvular thrombosis at early stages of formation: this would help clinicians make valvular dysfunction diagnoses before the appearance of critical symptoms.
TANQUA KAROO, ANCIENT ANALOG FOR FINE-GRAINED SUBMARINE FANS
Authors: BOUMA ARNOLD H. , WICKENS H. DEVILLE
Published: April 2012

The Permian Tanqua subbasin in the southwestern Karoo Basin, South Africa, contains five basin-floor fans and one slope fan. The total outcrop area is about 650 km in size; the individual outcropping fans range in size from about 150 km2 to 450 km2. The arenaceous fans have a high sandstone/shale ratio of about 75-90%, range in individual thickness from 20-60 m, and are separated by 20-75m thick basin shales.

Deposition of each fan is in response to a 4th-order, tectonically controlled relative sea-level lowering within a 3rd order transgressive systems tract.

Two basin-floor fans show mid-fan channel complexes with levee-overbank deposits which change in downdip direction into non-channelized, sheet-like outer fan depositional lobes. Simultaneously, the sandstone/shale ratio increases in the same direction. The other three basin-floor fans contain outer fan depositional lobes.

Four of the basin-floor fans show paleocurrent directions from SSW and S, whereas one was fed from the W-WNW. Absence of folding provides ideal lateral correlation; cliff-type outcrops occur over a distance of 34 km. Three 8-12 km long E-W outcrops with only minor regional tilt complete the major data source. A channel complex, assumed to be deposited at the base-of-slope, is found in the most proximal area. The complex comprises both large and small, rather shallow, channel fills with erosional contacts and remnants of probable thin-bedded levees. The single channels are embedded in thin-bedded turbidite series; some are connected physically to the channel fill. Such levee deposits can be composed of very clean sands with thin shales, and have well-developed cross bedding and climbing ripples. They show a significant issuing angle (25-35°) in paleocurrent direction from the channel.

The sheet sands comprise bundles of 6-8 very flat, often amalgamated, lenticular sandstone beds. The amalgamated contacts change laterally into thin shales. Sheet sand bundles are slightly lenticular which is extremely difficult to discern on cursory examination of photo-mosaics of long outcrops, but can be demonstrated by careful bed tracing.

The long outcrops make it possible to collect field data required to 1) improve our understanding of the overall architecture of fine-grained, “low” sandstone/shale ratio submarine fans, and 2) to carry out detailed reservoir simulation programs.
SHELF PROCESSES AND CANYON/CHANNEL EVOLUTION CONTROLLING TURBIDITE SYSTEMS: EXAMPLES FROM THE SERGIPE-ALAGOAS BASIN, BRAZIL
Authors: Cainelli Cesar
Published: April 2012

An industrial data set (seismic sections, well logs, and cores), extending to a water depth of 3,000 m, provided the opportunity to conduct an integrated stratigraphic analysis among shelf, slope, and basin depositional environments. The study focused on a 3,000-m seaward-thickening prograding wedge, subdivided into four sequences. The high energy shelf, dominated by waves and currents, produced mature sands mixed seaward with carbonates that border the shelf edge. Basinward, a thick section of shales was developed contemporaneously. Canyon systems on the sequence boundaries acted as routes through the shelf carbonate rims in the development of deep-water turbidite systems. The timing for down-slope transport of shelf sands was controlled by the evolution of few canyons from immature to mature. Mature canyons that entrenched deeply onshoreward tapped the sands dammed by shelf-edge carbonates. Sands funneled downcanyon were concentrated into isolated or migrating leveed channels as coarsegrained lags of turbidite systems distributed in time and space into the thick slope apron.
FACIES ARCHITECTURE AND RESERVOIR CHARACTERIZATION OF A SUBMARINE FAN CHANNEL COMPLEX, JACKFORK FORMATION, ARKANSAS
Authors: Cook Timothy W. , Bouma Arnold H. , Chapin Mark A. , Zhu Hua
Published: April 2012

The upper Pennsylvanian Jackfork Formation is exposed at the 900 m (2750 ft) wide by 60 m (200 ft) high wall of Big Rock Quarry, in North Little Rock, Arkansas. At this location, the formation provides a strike section view of a sand-rich submarine fan, comprising laterally imbricated and crosscutting channels. Geological heterogeneity within the nested submarine fan channel complex was described qualitatively to note architectural characteristics not usually observed in outcrops due to limited scale of exposure. Field reconaissance and photographic studies revealed a variety of channel fill types in the overall exposure, with amalgamated massive sandstone fill as the dominant lithology.

Architectural drawings of the quarry, made from enlarged photographic prints, were digitized and analyzed using a Shell software package with the intent of translating outcrop-based observations into useful parameters for subsurface reservoir models. The analysis revealed that 1) the facies distribution calculated during the statistical analysis compares favorably to the facies distribution in a core taken 15 m (50 ft) behind the face of the outcrop; 2) no discrete, recognizable beds are continuous across the 900 m (2750 ft) strike-oriented exposure; 3) maximum well spacing (along strike) for a dual production well scenario is approximately 1.6 km (1 mi); and 3) maximum well spacing for an injection-production (water-flood) well plan is approximately 300 m (1000 ft).
SUBMARINE FANS ON THE NORTHEASTERN GRAND BANKS, OFFSHORE NEWFOUNDLAND
Authors: DESILVA NEIL R.
Published: April 2012

The northeastern Grand Banks of Newfoundland is underlain by the Jeanne d’Arc Basin and the Outer Ridge. To date, twelve significant hydrocarbon accumulations, including the giant Hibernia oil field, have been discovered in the basin and three have been discovered on the Outer Ridge. Some of these discoveries are in submarine fans.

The submarine fans on the northeastern Grand Banks can be grouped into four categories based on their age: 1) Late Jurassic submarine fans, derived from highlands to the south, 2) Early Cretaceous submarine fans, related to progradation of deltas of the Hibernia Formation; 3) Late Cretaceous submarine fans, associated with a major clastic wedge that prograded from the western margin of the basin; 4) Early Tertiary basin floor fans and slope fans related to a major sea level lowstand.

Hydrocarbons have been encountered in all four groups of submarine fans. With only about 10% of the potential recoverable oil in the basin discovered so far (McAlpine 1990), they could provide promising drilling targets.
FACIES ARCHITECTURE AND RESERVOIR QUALITY OF MIOCENE MT. MESSENGER DEEP-WATER DEPOSITS, TARANAKI PENINSULA, NEW ZEALAND
Authors: JORDAN DOUGLAS W. , SCHULTZ DOUGLAS J. , CHERNG J. ALBERT
Published: April 2012

The Mt. Messenger Formation exposed along the coastline of the Taranaki Peninsula contains flat-laminated, very-fine to fine-grained sands inlerbedded with bioturbated silt and silty claystone. These beds are typically over 5 cm thick and are the result of high-velocity turbidity currents which allow for good textural sorting and preservation of excellent reservoir-quality sands. Beds less than this thickness, as well as upper parts of many turbidites, typically contain features suggesting reworking, winnowing, and remolding by bottom currents. This winnowing effect is responsible for the good to excellent reservoir properties of the thin, poorly consolidated, well-sorted, very fine-grained lithic arenites. Mt. Messenger sands were deposited on a depositional slope in lower to upper bathyal water depths which was the site for these transforming bottom currents.

The Mt. Messenger overlies Mohakatino, Ferry, and Tawariki sandstones and siltstones which were the initial deepwater sediments in the basin. These sandstones are lithic-rich and fine to medium-grained. The beds are typically massiveappearing but locally contain dewatering features, typical ‘classic’ turbidites (graded beds, slurry or low-density turbidity current tops), and were deposited as thick sheet-like bodies on the basin floor. Winnowing of the sandstones did not take place on a large scale and hence reservoir quality is invariably poor to moderate.

The mica stilpnomelane in the sands is common; this mineral is restricted areally to low-grade regionally metamorphosed sediments and associated veins, most notably to the schists of western Otago, New Zealand, on the northwestern part of the south island The occurrence of this mineral has important implications as to the source of the Mt. Messenger sediments in the North Taranaki area (transport was from south to north from the South Island).
RESERVOIR CLASSIFICATION FOR TURBIDITE INTERVALS AT THE MARS DISCOVERY, MISSISSIPPI CANYON 807, GULF OF MEXICO
Authors: Mahaffie M.J.
Published: April 2012

A descriptive reservoir classification was used to characterize the turbidite sands encountered at Prospect Mars, a significant Gulf of Mexico deep water oil discovery made under joint partnership with Shell Offshore Incorporated and British Petroleum Incorporated. External reservoir geometries observed from seismic data and internal fill characteristics from wireline logs and whole core form the basis for subdividing turbidite sands into three major categories: 1) thin-bedded channel levee and overbank sediments, 2) channel-fill complexes, and 3) sheet sands. This classification scheme was implemented to link the various scales of investigation obtained from the subsurface with details of reservoir architecture determined from turbidite outcrop studies. In this manner, characteristics of sand continuity and connectivity at the outcrop scale can be incorporated with observations from seismic and well control toward more accurately predicting reservoir performance and field development strategy.

Depositional models were constructed for each significant turbidite sand package using this reservoir classification. The majority of reservoirs are described as sheet sands. Minor portions of the basin fill represent channel-fill complexes. Three depositional models are presented to illustrate the style of deposition at Mars and the utility of this classification scheme. Development drilling is currently underway using these depositional models as a framework for field exploitation.
GEOLOGIC MODELS AND RESERVOIR GEOMETRIES OF AUGER FIELD, DEEPWATER GULF OF MEXICO
Authors: Mcgee D.T. , Bilinski P.W. , Gary P.S. , Pfeiffer D.S. , Sheiman J.L.
Published: April 2012

Located 214 miles southwest of New Orleans in 2862 ft of water, Auger Field has a world-record water depth Tension Leg Platform (TLP). Probable reserves of 220 MMBE exist in four main Plio-Pleistocene turbidite pay horizons. The field contains volatile oil and retrograde gas trapped along a deep paleoridge related to a shallow piercement salt dome and large down-to-the-north and down-to-the-east fault systems. Ten development wells will be completed during 1994. Initial production began April 15, 1994 from the first completed well.

Reservoir styles range from laterally continuous sheet sands (“S” and lower “R” and “Q”) to amalgamated channel sands with overlying levee and overbarik deposits (“N1” and “O”). Over half of the reserves, 120 MMBE, are contained in the lower Pliocene “S” sand which has an average porosity of 24% and permeability of 150 md.

The sheet sand reservoirs with their excellent lateral continuity and expected uniform drainage pattem will be developed with wide and even well spacings. The amalgamated channel reservoirs will be developed with wells placed to optimize drainage patterns around flow barriers such as shingle boundaries and faults. The understanding of reservoir geometries has led to significant project profitability gains due to better development well placements, thus reducing the number of wells required.
GREEN CANYON BLOCK 205 LITHOFACIES, SEISMIC FACIES, AND RESERVOIR ARCHITECTURE
Authors: Rafalowski John W. , Regel Bernard W. , Jordan Douglas L. , Lucidi Douglas O.
Published: April 2012

The Green Canyon Block 205 prospect has five primary reservoirs which range in age from late Pliocene to early Pleistocene. The N1 and N3 sands, which contain 60% of the resource in the prospect, were deposited primarily as turbidites in a middle to lower slope environment within bathyal water depths. Key uncertainties which affect fluid displacement paths and displacement efficiencies were defined during a detailed reservoir characterization. These include 1) facies type and distribution, 2) reservoir architecture, and 3) reservoir continuity. A probabilistic approach allowed for the manipulation of a facies based geologic model to quantify the range of these and other reservoir uncertainties.

Geologic and geophysical data indicate that the N1 and N3 sand lithofacies and associated subenvironments are distinctly different. The N1 sand was deposited as a sand-rich early lowstand fan by aseries of low-density turbidity flows. Facies range from massive sand to thin bedded turbidites, and subenvironments include channel, channel margin, levee, interchannel/overbank, or possibly fan fringe. The N3 sand was deposited as a very sand-rich middle to late lowstand fan by a series of high density turbidity flows. It is composed of a massive sand facies within an amalgamated channel complex.

A lateral offset stacking pattern which became progressively younger to the west is the dominant architectural element for both the N1 and N3 reservoirs. Relative to the N1 sand, the N3 sand exhibits a greater degree of overlap between successive depositional units and therefore has a higher probability of amalgamation.

Drill stem test (DST) type curve analyses indicate the presence of transmissibility restrictions in both sands which correspond to discontinuities seen in the seismic data. In the N1 sand, the analyses indicate that fluid flow may not be inhibited between channel and thin bedded facies but may be restricted between laterally offset depositional units. Seismically defined amalgamation surfaces in the N3 sand do not impede fluid flow within the radius of investigation of the DST.
AN UNCONVENTIONAL MODEL FOR THE DEEP-WATER SANDSTONES OF THE JACKFORK GROUP (PENNSYLVANIAN), OUACHITA MOUNTAINS, ARKANSAS AND OKLAHOMA
Authors: SHANMUGAM G. , MOIOLA R.J.
Published: April 2012

The Pennsylvanian Jackfork Group in the Ouachita Mountains of Arkansas and Oklahoma has conventionally been considered a classic example of a turbidite sequence deposited in a submarine-fan setting. However, the apparent “Bouma turbidite sequences” in these strata, which were used as evidence for single-event turbidity current deposition, were in reality deposited by multiple events, including debris flows and slumps. These were commonly reworked by bottom currents. Normal size grading and Bouma Sequences are essentially absent in these sandstone beds, which appear “massive” (i.e., structureless) in outcrop, but when slabbed reveal diagnostic internal features. Beds exhibit sharp and irregular upper bedding contacts, inverse size grading, floating mudstone clasts, a planar clast fabric, lateral pinch out geometries, moderate to high matrix content (up to 25%), contorted layers, and fluid escape structures. All these features are indicative of sand emplacement by debris flows (mass flows) and slumps. Mud matrix in these sandstones were sufficient to provide cohesive strength to the flow. The dominance of debris-flow and slump deposits (nearly 70% at DeGray Spillway section) and bottom-current reworked deposits (40% at Kiamichi Mountain section), and the lack of turbidites in the Jackfork Group have led us to propose a mass flow dominatewd slope setting. Conventional submarine fan models, designed for turbidite systems, are not applicable to the debris-flow emplaced and bottom-current reworked sandstone beds of the Jackfork Group. This unconventional model has direct implication for sand-body geometry and continuity because deposits of fluidal (suspension) turbidity currents are laterally more continuous than those of plastic (en masse) debris flows.
CHARACTERIZATION AND MODELING OF THIN-BEDDED TURBIDITE DEPOSITS FROM THE GULF OF MEXICO USING DETAILED SUBSURFACE AND ANALOG DATA
Authors: SHEW ROGER D. , ROLLINS DALE R. , TILLER GOTTFRIED M. , HACKBARTH CLAUDIAJ. , WHITE CHRISTOPHER D.
Published: April 2012

Laminated to thinly-bedded turbidite deposits have been penetrated as both primary and secondary objectives throughout the Gulf of Mexico. In the Viosca Knoll area, eastern Gulf of Mexico, several fields and multiple reservoirs are dominated by these types of deposits. Reservoir evaluation is problematic because conventional logs and 3-D seismic cannot resolve the detailed architectural elements and rock properties for reservoir characterization and delineation. Detailed core evaluations, high-resolution logs, analog studies of outcrops and a Pleistocene channel/levee complex, deterministic and probabilistic architectural models, and multiple simulations have all been used to model these reservoirs in order to address reservoir performance and economics.
Outcrop Analysis of a Sand-Rich, Basin-Floor Turbidite System, Permian Bell Canyon Formation, West Texas
Authors: Barton Mark D. , Dutton Shirley P.
Published: April 2012

Outcrops of the Bell Canyon Formation, Delaware Mountain Group, in Culberson County, Texas, were studied to better understand the sandstone depositional processes and determine the dimensions and arrangement of sandstone bodies. The depositional model developed from outcrop can be used to guide reservoir characterization of Delaware sandstone fields. The Bell Canyon Formation is a deep-water siliciclastic unit that accumulated in the Delaware Basin, located in West Texas and southeast New Mexico, during the Late Permian. The Bell Canyon is a sand-rich system that displays a net-to gross of about 70 percent. Grain size is limited to fine sand and coarse silt, and clay-size material is almost entirely lacking.

Stratigraphic relationships indicate that the outcrop sandstones were deposited in a toe-of-slope or basin-floor setting by a system of leveed channels having attached lobes and overbank splays that filled topographically low interchannel areas. Channels are largely filled with massive and cross-stratified sandstones. They are as much as 15 m thick and 100 to 300 m wide. The channels are arranged in a radial pattern that bifurcates and expands down dip. The channels are flanked on both sides by wedges composed of thinly bedded sandstones and siltstones that are interpreted as levees. The levees thin away from the channel, decreasing in thickness from 8 to 1 m over the distance of 1 km. The levees are onlapped by massive sandstones interpreted as interchannel lobes or splays. The lobes, as much as 8 m thick and 10 km wide, display a broad tabular to irregular geometry.

Individual channel-levee and lobe complexes appear to stack in a compensatory fashion and are separated by laterally continuous, meter-thick laminated siltstones. The laminated siltstones are interpreted to have been deposited by the settling of marine organic matter and airborne silt during periods when coarser particles were prevented from entering the basin. The paleogeographic setting, absence of mass-movement features, and high preservation of facies indicate that the outcrop sandstones were deposited in a basin-floor setting.
Application of Outcrop Analogs to Reservoir Characterization of Permian Deep-Water Sandstones, Bell Canyon Formation, Ford Geraldine Unit, West Texas (Delaware Basin)
Authors: Dutton Shirley P. , Barton Mark D.
Published: April 2012

Reservoirs in deep-water sandstones of the Delaware Mountain Group in West Texas and New Mexico have low primary recovery efficiency (<14 percent). Reservoir characterization of a representative Delaware Mountain Group field was performed to identify geologic constraints on producibility. The Ramsey sandstone of the Bell Canyon Formation was investigated in the Ford Geraldine unit, Culberson and Reeves Counties, Texas. Outcrops of the Bell Canyon Formation in Culberson County, Texas, were studied to better interpret the depositional processes that formed the reservoirs at the Ford Geraldine unit and to determine the dimensions of reservoir sandstone bodies.

On the basis of core descriptions, subsurface mapping, and the depositional model developed from outcrop, the 0-to 60-ft-thick (0- to 18-m) Ramsey sandstone interval in the Ford Geraldine unit was interpreted to consist of sheetlike turbidite lobe deposits overlain and incised by channel and levee deposits. Because of the narrow range of grain sizes in Ramsey sandstones and the absence of detrital clay, log patterns are generally not diagnostic of facies. Comparison of sedimentary structures viewed in core to facies identified in outcrop was key to interpreting the reservoir facies. Lobe deposits consist of massive and convoluted sandstones that have load and dewatering structures, suggesting that the sandstones were deposited rapidly from high-density turbidity currents. Channel facies, which are approximately 1,200 ft (370 m) wide and 15 to 35 ft (5 to 10 m) thick, overlie and locally incise the lobe deposits. They consist of massive and crossbedded sandstones interpreted to have been deposited from high-density turbidity currents. Channel margins, characterized by rippled and convoluted sandstones interbedded with siltstones, are interpreted as channel levees formed by overbanking of low-density turbidity currents. The levees are onlapped by massive sandstones interpreted as interchannel lobes or splays. Ramsey sandstones are bounded by laterally continuous, organic-rich siltstones deposited by settling from suspension. Siltstone beds and extensively calcite cemented sandstones are the most important causes of reservoir complexity and reduced sweep efficiency.
3-D Ground-Penetrating Radar Imaging of Turbidite Outcrop Analogs
Authors: Young Roger Adams , Peterson Benjamin E. , Slatt Roger M.
Published: April 2012

High-resolution outcrop stratigraphic analysis is becoming increasingly utilized to build detailed, quantitative reservoir architectural models. With suitably long outcrops, preferably in three dimensions, this analysis can provide the best method of developing reservoir models that include hard data on continuity and connectivity of different bed types. The addition of geophysical logs and cores taken immediately behind outcrop faces provides a valuable means for geological correlation in the plane of the outcrop.

Such outcrop studies, however, do not image the interior structure of a volume. Even if an extensive distribution of boreholes has been drilled to define sedimentary units at an outcrop, the scale of significant sedimentary and structural features may still be smaller than can be captured. This type and scale of information is important because features smaller than the limit of seismic resolution may be extremely significant in determining production.

In this paper, ground-penetrating radar signatures of two very different turbidite analogs are presented. In the first case, Pennsylvanian-age, amalgamated channel sandstones, which are characterized by silica-cementation, show exceptional depth of radar penetration, and displacement of interbedded sandstones and shales extends a fault mapped in outcrop. In the second case, Cretaceous-age, channelized turbidite sandstones clearly show internal complexity within the channel fill and define the nature of the relationship between sandy fill and the adjacent thin beds.
Applications of High-Resolution Sequence Stratigraphy to Reservoir Prediction and Flow Unit Definition in Aggradational Tidal Successions
Authors: McIlroy Duncan , Flint Stephen , Howell John
Published: April 2012

A common element of sequence stratigraphic models for ancient shallow marine systems is the shift from wave-dominated shoreface deposition during highstand to tidal/ estuarine deposition within incised valleys during early base-level rise. In this widely used model, tide-dominated sedimentation is thus restricted to specific base-level positions, which has important implications for prediction of reservoir geometry and quality. However, this model neither adequately explains nor allows reservoir prediction in aggradational tide-dominated reservoir successions. The Lower-Middle Jurassic Lajas Formation of the Neuquén Basin, Argentina, comprises 500 m of well-exposed tidedominated facies deposited within low-frequency unconformity-bounded sequences, which are tide dominated throughout. The maintenance of macrotidal conditions over several complete base-level cycles during the 8 m.y. within which the Lajas was deposited is interpreted as being due to the structural topography inherited from rifting, in which the whole sub-basin behaved as a structurally controlled estuary. Facies associations include prograding tidal deltas, stacked sandy tidal channel fills, extensive lagoonal deposits, and tidal-flat successions, which are locally cut by heterolithic tidal-channel-fill facies. Despite the narrow bathymetric depositional range of the Lajas sediments and the complex facies variability, parasequences can be defined and correlated on a kilometer scale. Unlike simpler fluvial or wave-dominated shallow marine systems, there are two types of parasequence, each with different net:gross sandstone ratios and different vertical/lateral reservoir-quality trends. These parasequences form the building blocks for accurate reservoir modeling in complex tidal reservoirs.
Multi-Scale Characterization and Modeling of Heterolithic Tidal Systems, Offshore Mid-Norway
Authors: Martinius Allard W. , Ringrose Philip S. , Næss Arve , Wen Renjun
Published: April 2012

The Lower Jurassic Tilje Formation on the Halten Terrace, offshore mid-Norway, forms an important reservoir in a number of hydrocarbon fields. A high volume fraction (80 percent) of the formation is heterolithic in nature, showing various styles of sandstone-mudstone intercalated bedding at several scales. The depositional model is based on a general facies classification scheme applicable to all fields. The stratigraphic interval discussed was deposited in a narrow basin during overall rising relative sea level as a tide/wave-dominated, mud-rich delta with well-developed prodelta, delta-front, and estuarine-type distributary-channel facies. The main heterolithic deposits are found in the prodelta, delta-front, and distal parts of the estuarine-type distributary-channel-mouth areas, whereas relatively “clean” facies occur in medial areas of these distributaries.

Lithofacies associations are modeled in 3D using stochastic, object-based methods, and the heterolithic architecture at the lithofacies scale is modeled using a process-based sedimentary architecture tool. Multiple data sources (core, log, and outcrop-analogs) are used to establish a data-rich procedure for estimating the effective reservoir properties within a step-wise upscaling procedure. Our results show the importance of integrating multiscale data with good sedimentary models to accurately estimate reservoir properties in these heterolithic formations. We derive effective property functions (for example kv/kh) for different facies and identify important reservoir flow units using flow simulations of stochastic realizations.
Stratigraphic Correlation Surfaces and 3-D Reservoir Model Construction: Constraints from Walther’s Law Models and Outcrop Analog Data
Authors: Kerans Charles
Published: April 2012

A critical step in 3-D reservoir model construction is interpretation of stratigraphic-framework surfaces that guide data distribution between wells. Application of outcrop-scaled Walther’s Law depositional models that include information on depositional dip and facies-tract width is a basic guide for subsurface correlations. Ramp-crest grainstone complexes from the Permian of the Guadalupe Mountains, southeast New Mexico, and the Cretaceous of the Comanche Shelf, South Texas, form the bases for models with constrained depositional dips and facies-tract widths. Facies partitioning between transgressive and highstand systems tracts (TST and HST) as shown in outcrops of the Comanche Shelf Cretaceous along the Pecos River indicates that Walther’s Law models must be calibrated to the systems tracts level to gain maximum prediction of facies distribution and stratal geometry. Lacking these calibrated Walter’s Law models, correlations tend to produce an overly homogeneous lithostratigraphic correlation scheme, such as that applied to the Permian Seminole San Andres Unit of the Permian Basin.
Integrated Geological, Geophysical, and Computer Approach for Predicting Reef Lithofacies and Reservoirs: Upper Jurassic Smackover Formation, Appleton Field, Alabama
Authors: Mancini Ernest A. , Benson D. Joe , Hart Bruce S. , Chen Hanna , Balch Robert S. , Parcell William C. , Wang Wen-Tai , Panetta Brian J.
Published: April 2012

Reefs have long been known from the Upper Jurassic Smackover Formation in the Gulf Coastal Plain; however, these carbonate lithofacies have unique acoustic properties that make them difficult to define using 3-D seismic reflection technology. In the eastern Gulf Coastal Plain, microbial reef buildups occur on pre-Jurassic paleotopographic basement features on a carbonate ramp margin. Development of these buildups is a result of the interplay among paleotopography, sea-level changes, and carbonate productivity. An integrated approach of geological interpretation, computer modeling, and seismic imaging indicates that Smackover reef development is restricted to the flanks of high-relief structures, whereas on low-relief structures reef development occurred on both the crest and flanks. The combination of geological and computer modeling of parameters affecting reef development associated with pre-Jurassic paleohighs in conjunction with 3-D seismic imaging increases the chances of drilling a successful exploration well and in designing an effective field-scale reservoir management strategy.