scholarly journals Supplemental Material: Autogenic translation and counter point bar deposition in meandering rivers

2021 ◽  
Author(s):  
Z. Sylvester ◽  
et al.
Keyword(s):  
Meandering Rivers ◽  
Point Bar ◽  
Forward Models ◽  
Point Bars

Animations illustrating the evolution of counter point bars in the study area and in forward models.

scholarly journals Supplemental Material: Autogenic translation and counter point bar deposition in meandering rivers

2021 ◽  
Author(s):  
Z. Sylvester ◽  
et al.
Keyword(s):  
Meandering Rivers ◽  
Point Bar ◽  
Forward Models ◽  
Point Bars

Animations illustrating the evolution of counter point bars in the study area and in forward models.

scholarly journals Autogenic translation and counter point bar deposition in meandering rivers

2021 ◽  
Author(s):  
Z. Sylvester ◽  
P.R. Durkin ◽  
S.M. Hubbard ◽  
D. Mohrig
Keyword(s):  
Satellite Imagery ◽  
Riparian Vegetation ◽  
Kinematic Model ◽  
Time Lapse ◽  
Sediment Deposition ◽  
Lateral Migration ◽  
Meandering Rivers ◽  
Point Bar ◽  
Point Bars ◽  
Meander Bends

Although it has long been recognized that deposition along meandering rivers is not restricted to convex banks (i.e., point bars), the consensus is that sediment deposition on concave banks of channel bends mostly occurs when meander bends translate downstream because erosion-resistant barriers inhibit their lateral migration. Using a kinematic model of channel meandering and time lapse satellite imagery from the Mamoré River in Bolivia, we show that downstream translation and associated concave bank deposition are essential, autogenic parts of the meandering process, and resulting counter point bars are expected to be present whenever perturbations such as bend cutoffs and channel reoccupations create short bends with high curvatures. The implication is that zones of concave bank deposition with lower topography, finer-grained sediment, slack water, and riparian vegetation that differs from point bars are more common than previously considered.

Small-scale experiments on ice-jam initiation in a curved channel

1994 ◽  
Vol 21 (5) ◽  
pp. 719-727 ◽  
Author(s):  
Gilberto E. Urroz ◽  
Robert Ettema
Keyword(s):  
Froude Number ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Small Scale ◽  
Curved Channel ◽  
Point Bar ◽  
Ice Jams ◽  
Ice Jam ◽  
Point Bars ◽  
River Bends

Two principal ice-jam initiation mechanisms, namely, lodgement and gorging, were identified through ice conveyance experiments in a small-scale, curved flume of rectangular cross section. Polyethylene blocks and beads were used to simulate ice fragments. Lodgement occurred for ice fragments that were large relative to channel width, while gorging took place when ice pieces were relatively small and were transported through the channel in multilayer. Channel roughness was found to have a significant effect in helping the arching mechanism that produces lodging. Maximum ice-floe concentration before jamming was found to increase linearly with Froude number, F, when gorging was dominant, but showed little dependence on F for ice jams initiated by lodging. Experiments conducted with point bars placed at the bends indicated that ice jams were initiated mainly by beaching of floes on the point bar. Maximum ice-floe concentration also increased linearly with Froude number for the point-bar experiments. Key words: ice-covered rivers, river bends.

VISUALISATION OF A FLUVIAL CHANNEL RESERVOIR ANALOGUE FROM THE BIRKHEAD FORMATION, MERRIMELIA, MERANJI AND PELICAN FIELDS, EROMANGA BASIN

2003 ◽  
Vol 43 (1) ◽  
pp. 453 ◽  
Author(s):  
T. Nakanishi ◽  
S.C. Lang ◽  
A.B. Mitchell
Keyword(s):  
Seismic Data ◽  
Sedimentary Facies ◽  
Mean Value ◽  
3D Seismic ◽  
Point Bar ◽  
Channel Belt ◽  
Point Bars ◽  
Seismic Amplitudes ◽  
3D Seismic Data ◽  
Eromanga Basin

The effective production of hydrocarbons from the Birkhead Formation, Eromanga Basin, relies heavily on understanding the complex distribution of reservoir and seal rocks deposited in a fluvial environment. To visualise this complexity, sequence stratigraphic concepts applied to non-marine basins were combined with 3D seismic data visualisation in a study of the Birkhead interval over the Merrimelia, Meranji and Pelican fields.Fluvial channel, crevasse splay channel, floodplaincrevasse splay complex and floodplain facies were recognised from the well log motifs in the Birkhead Formation. The interval is interpreted as an alluvial transgressive systems tract bounded by flooding surfaces consisting of shaly or coaly intervals. Lateral discontinuity of the fluvial system can be demonstrated between these surfaces. Seismic amplitude distributions in the 3D seismic data in the upper part of this transgressive systems tract illustrate well developed meandering fluvial channels. Combining the spatial distributions of sedimentary facies from the well logs and the seismic amplitudes results in the interpretation of a fluvial meandering channel belt that includes point bars and abandoned channels.The point bar sandstones in the channel belt should make good reservoirs and the juxtaposition of the point bar and abandoned channel facies can result in a stratigraphic trap component to the reservoir rocks within the channel belt. Although the point bars are known to be wet in the study area, it is still useful to consider their capacity as oil reservoirs, since they may serve as analogues for similar untested point bars elsewhere. Multiple realisations of the distribution of sandstone thickness of the point bars were generated by conditional simulation, using seismic amplitudes to control extrapolation of the well data. This gave a potential reserves distribution with a mean value of 18.8 million bbl in place. The complexity of the fluvial channel systems in the Birkhead Formation described in this paper should aid understanding of the reservoir and seal distribution and help optimise production from this interval in other fields.

The Point Bar Environment in the Mackenzie River Delta

1972 ◽  
Vol 9 (11) ◽  
pp. 1382-1393 ◽  
Author(s):  
Don Gill
Keyword(s):  
Fine Fraction ◽  
River Delta ◽  
Plant Colonization ◽  
Populus Balsamifera ◽  
Point Bar ◽  
Balsam Poplar ◽  
Sediment Sorting ◽  
Point Bars ◽  
Lower Water Content ◽  
Mackenzie River

Helicoidal flow and sediment sorting along the convex portion of shifting channels in the Mackenzie River Delta cause point bars to be composed of the coarsest material available to plant colonization. Sorting by aeolian action further reduces the fine fraction in point bar soils. Coarse-textured deposits maintain a lower water content and a higher soil temperature than other deltaic surfaces, thus nearly every point bar is colonized by a discrete plant association. This ecosystem is dominated by balsam poplar (Populus balsamifera), and the distribution of well developed poplar stands is restricted to point bars. The successional ecology of this ecosystem is discussed in relation to the point bar environment.

Lateral accretion of modern unvegetated rivers: remotely sensed fluvial–aeolian morphodynamics and perspectives on the Precambrian rock record

2016 ◽  
Vol 154 (3) ◽  
pp. 609-624 ◽  
Author(s):  
ALESSANDRO IELPI
Keyword(s):  
Remotely Sensed ◽  
Windward Side ◽  
Precambrian Rock ◽  
Meandering Rivers ◽  
Fluvial Deposits ◽  
Rio Negro ◽  
Aeolian Dunes ◽  
Point Bars ◽  
Aeolian Systems ◽  
Bank Collapse

AbstractModern unvegetated rivers flowing through aeolian-dune fields demonstrate potential as analogues for pre-vegetation fluvial landscapes. A prominent example is contained in the Lençóis Maranhenses of Brazil, a coastal aeolian system hosting the semi-perennial Rio Negro. Remotely sensed images covering c. 45 years display the rhythmic expansion and wind-driven shift of single-threaded and sinuous fluvial trunks alternating with wider braided plains. Sinuous tracts feature mid-channel and bank-attached bars, including expansional point bars with subdued relief. The morphology, accretion and sediment transport of unvegetated point bars in the Rio Negro are compared to the morphodynamics of vegetated meandering rivers. Unvegetated point bars are composed of large coalescent unit bars, lack apparent scroll topography and are preferentially attached to channel banks located on the windward side of the river course. Unvegetated meanders have expansional behaviour related to downwind channel trailing. Point bars maintain an expansional planform despite spatial confinement induced by aeolian dunes. Channel-flow impingement onto cohesion-less banks favours scouring of deep pools along the bar tails, which host bank-collapse deposits subsequently reworked into new bars. Analogies to Precambrian rivers suggest that ancient unvegetated fluvial landscapes were not unequivocally featured by low sinuosity, especially if characterized by a low gradient and stable discharge. This inference is supported by ongoing studies on Proterozoic fluvial–aeolian systems in the Canadian Shield. Lack of scroll topography introduces overlap with low-sinuosity fluvial facies models, underscoring the value of observing ancient fluvial deposits in planform, or along 3D sections where the palaeodrainage of channel bodies and attached bars can be compared.

scholarly journals Lateral accretion features ( epsilon cross-bedding) and point bars in the weichselian Køge Esker, East­Sjælland, Denmark

1988 ◽  
Vol 37 ◽  
pp. 11-19
Author(s):  
Jens Peter Jensen
Keyword(s):  
Point Bar ◽  
Flow Discharge ◽  
Cross Bedding ◽  
Complex Point ◽  
Point Bars

In the Køge Esker, Spanager lateral accretion features ( epsilon cross-bedding) were produced by complex point bar growth. The point bar genesis is based upon the presence of epsilon cross-bedding, the channel side attached nature of the bar (inner accretionary bank) and the paleoflow pattern. The Spanager sequence is divided into three flow discharge cycles ("megavarvic" sedimentation units).

Architectural Structure of Channel Sand Bodies in Meandering River and Remaining Oil Tapping Study-as on PI2a of South-Two Area in Sanan Field

2011 ◽  
Vol 361-363 ◽  
pp. 8-14
Author(s):  
Zong Bao Liu ◽  
He Bi
Keyword(s):  
Quantitative Research ◽  
Single Point ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Point Bar ◽  
Verification Methods ◽  
Remaining Oil ◽  
Point Bars ◽  
And Performance ◽  
Sand Bodies

According to the theory of reservoir architectural structure and sedimentology, applied the hierarchy analysis, pattern guidance and performance verification methods, taking the South-Two area for example, with the cores, logs and performance, we have done some quantitative research on the parameters of composite channel sand bodies, single point bar sand bodies and the lateral accretion bodies on point bars in South two area, built Three-dimensional model of point bars. Study shows that the point bar sand bodies in PI2a unit are meandering point bar sand bodies formed by the lateral accretion of distributary channels in coastal delta distributary plain. The space combination model of lateral accretion bodies is horizontal-obique type. The width of lateral accretion bodies is 38.5～54m, the average dip of lateral accretion layer is 9.5°, and separation of lateral accretion layer is about 15m. The features above shows the spatial distribution of the lateral accretion body on point bars. With the changes of seepage field and gravity, the influence to remaining oil of lateral accretion layer has been analyzed. Numerical simulation and performance showed that the main concentration of remaining oil is in the upper of the point bar lateral accretion body, proposed the principles and methods of horizontal wells in the point bar sand bodies to tapping potential remaining oil, which provide a theoretical guidance to domestic similar fine reservoir description and the remaining oil tapping.

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