Development and validation of a three-dimensional morphological model

A method is presented which enables the computation of the suspended load as the depth-integration of the product of the local concentration and flow velocity. The method is based on the computation of the reference concentration from the bed-load transport. Measured concentration profiles have been used for calibration. New relationships are proposed to represent the size gradation of the bed material and the damping of the turbulence by the sediment particles. A verification analysis using about 800 data shows that about 76% of the predicted values are within 0.5 and 2 times the measured values.

Sediment Transport, Part II: Suspended Load Transport

Many currently producing shale-gas reservoirs are overmature oil-prone source rocks. Through burial and heating these reservoirs evolve from organic-matter-rich mud deposited in marine, lacustrine, or swamp environments. Key characterization parameters are: total organic carbon (TOC), maturity level (vitrinite reflectance), mineralogy, thickness, and organic matter type. Hydrogento-carbon (HI) and oxygen-to-carbon (OI) ratios are used to classify organic matter that ranges from oil-prone algal and herbaceous to gas-prone woody/coaly material. Although organic-matter-rich intervals can be hundreds of meters thick, vertical variability in TOC is high ( 50% of the total porosity, and these pores may be hydrocarbon wet, at least during most of the thermal maturation process. A full understanding of the relation of porosity and gas content will result in development of optimized processes for hydrocarbon recovery in shale-gas reservoirs.

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From Oil-Prone Source Rock to Gas-Producing Shale Reservoir - Geologic and Petrophysical Characterization of Unconventional Shale Gas Reservoirs

Development of a three-dimensional, regional, coupled wave, current, and sediment-transport model

A method is presented that makes the classification of bed forms, the prediction of the bed‐form dimensions and the effective hydraulic roughness of the bed forms feasible. The proposed relationships are based on the analysis of reliable flume and field data. A verification analysis using about 1,500 (alternative) reliable flume and field data shows good results in predicting the hydraulic roughness (friction factor). For field conditions, the proposed method yields considerably better results than previously proposed methods, which are reviewed here. The proposed method has also been used to predict the flow depth and the total bed‐material load.

Sediment Transport, Part III: Bed Forms and Alluvial Roughness

Principles of sediment transport in rivers, estuaries and coastal seas

Attention is given to the properties of sediment beds over the full range of conditions (silts to gravel), in particular the effect of fine silt on the bed composition and on initiation of motion (critical conditions) is discussed. High-quality bed-load transport data sets are identified and analyzed, showing that the bed-load transport in the sand range is related to velocity to power 2.5. The bed-load transport is not much affected by particle size. The prediction of bed roughness is addressed and the prediction of bed-load transport in steady river flow is extended to coastal flow applying an intrawave approach. Simplified bed-load transport formulas are presented, which can be used to obtain a quick estimate of bed-load transport in river and coastal flows. It is shown that the sediment transport of fine silts to coarse sand can be described in a unified model framework using fairly simple expressions. The proposed model is fully predictive in the sense that only the basic hydrodynamic parameters (dep...

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Unified view of sediment transport by currents and waves. I: Initiation of motion, bed roughness, and bed-load transport

The problem of suspended sediment transport in river and coastal flows is addressed. High-quality field data of river and coastal flows have been selected and clustered into four particle size classes 60-100, 100-200, 200-400, and 400-600 m. The suspended sand transport is found to be strongly dependent on particle size and on current velocity. The suspended sand transport in the coastal zone is found to be strongly dependent on the relative wave height Hs/h, particularly for current velocities in the range 0.2-0.5 m/s. The time-averaged over the wave period advection-diffusion equation is applied to compute the time-averaged sand concentration profile for combined current and wave conditions. Flocculation, hindered settling, and stratification effects are included by fairly simple expressions. The bed-shear stress is based on a new bed roughness predictor. The reference concentration function has been recalibrated using laboratory and field data for combined steady and oscillatory flow. The computed transport rates show reasonably good agreement within a factor of 2 with measured values for velocities in the range of 0.6-1.8 m/s and sediments in the range of 60-600 m. The proposed method underpredicts in the low-velocity range 0.6 m/s. A new simplified transport formula is presented, which can be used to obtain a quick estimate of suspended transport. The modeling of wash load transport in river flow based on the energy concept of Bagnold shows that an extremely large amount of very fine sediment clay and very fine silt can be transported by the flow.

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Unified View of Sediment Transport by Currents and Waves. II: Suspended Transport

A two-dimensional vertical mathematical model for suspended sediment is presented. The model is based on the width-integrated convection-diffusion equation for the sediment particles including settling effects. The local fluid velocities and mixing coefficients are described by a new so-called Profile model, which is based on the application of flexible profiles to represent the vertical distribution of the basic variables. Measured and computed velocities of strongly nonuniform flows were used for calibration of the Profile model. A stochastic approach is introduced to represent the sediment input at the bed. A bed concentration or an upward sediment flux can be specified (optional). The convection-diffusion equation is solved by a finite-element method, which proved to be better than a finite-difference method. An extensive sensitivity analysis is presented to show the influence of the main controlling parameters of the model. Finally, a verification analysis is presented using flume and field data of dredged trenches.

Leo C. van Rijn

Papers

Principles of sediment transport in rivers, estuaries and coastal seas

Sediment Transport, Part II: Suspended Load Transport

Unified view of sediment transport by currents and waves. I: Initiation of motion, bed roughness, and bed-load transport

Unified View of Sediment Transport by Currents and Waves. II: Suspended Transport

Mathematical Modeling of Suspended Sediment in NonUniform Flows