Response of bedrock channel width to tectonic forcing: Insights from a numerical model, theoretical considerations, and comparison with field data

Slug flow in horizontal pipelines and riser systems in deep sea has been proved as one of the challenging flow assurance issues. Large and fluctuating gas/liquid rates can severely reduce production and, in the worst case, shut down, depressurization or damage topside equipment, such as separator, vessels and compressors. Previous studies are primarily based on experimental investigations of fluid properties with air/water as working media in considerably scaled down model pipes, and the results cannot be simply extrapolated to full scale due to the significant difference in Reynolds number and other fluid conditions. In this paper, the focus is on utilizing practical shape of pipe, working conditions and fluid data for simulation and data analysis. The study aims to investigate the transient multiphase slug flow in subsea oil and gas production based on the field data, using numerical model developed by simulator OLGA and data analysis. As the first step, cases with field data have been modelled using OLGA and validated by comparing with the results obtained using PIPESYS in steady state analysis. Then, a numerical model to predict slugging flow characteristics under transient state in pipeline and riser system was set up using multiphase flow simulator OLGA. One of the highlights of the present study is the new transient model developed by OLGA with an added capacity of newly developed thermal model programmed with MATLAB in order to represent the large variable temperature distribution of the riser in deep water condition. The slug characteristics in pipelines and temperature distribution of riser are analyzed under the different temperature gradients along the water depth. Finally, the depressurization during a shut-down and then restart procedure considering hydrate formation checking is simulated. Furthermore, slug length, pressure drop and liquid hold up in the riser are predicted under the realistic field development scenarios.

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A practical technique for estimating service life of MSW leachate collection systems

Canadian Geotechnical Journal ◽

10.1139/cgj-2012-0257 ◽

2013 ◽

Vol 50 (2) ◽

pp. 165-178 ◽

Cited By ~ 11

Author(s):

R. Kerry Rowe ◽

Yan Yu

Keyword(s):

Numerical Model ◽

Service Life ◽

Field Data ◽

Oxygen Demand ◽

Collection System ◽

Leachate Collection ◽

Design Charts ◽

Leachate Characteristics ◽

Practical Model ◽

Measured Field

The leachate characteristics and clogging of the leachate collection system at the Keele Valley Landfill is examined using the numerical model “BioClog”. The calculated effluent leachate concentrations (e.g., the chemical oxygen demand and calcium concentrations) and calculated calcium fraction in the clog material are in encouraging agreement with measured field data. A new practical model is developed and calibrated against the data from the sophisticated numerical model to estimate the service life of leachate collection systems in typical municipal solid waste (MSW) landfills. The procedures for using the new practical model are provided and illustrated by examples. Design charts are presented that may aid the design of leachate collection systems for typical MSW landfills.

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Bedrock channel adjustment to tectonic forcing: Implications for predicting river incision rates

Geology ◽

10.1130/g23106a.1 ◽

2007 ◽

Vol 35 (2) ◽

pp. 103 ◽

Cited By ~ 172

Author(s):

Alexander C. Whittaker ◽

Patience A. Cowie ◽

Mikaël Attal ◽

Gregory E. Tucker ◽

Gerald P. Roberts

Keyword(s):

Channel Adjustment ◽

Bedrock Channel ◽

River Incision ◽

Tectonic Forcing

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Mass balance, grade, and adjustment timescales in bedrock channels

Earth Surface Dynamics ◽

10.5194/esurf-8-103-2020 ◽

2020 ◽

Vol 8 (1) ◽

pp. 103-122 ◽

Cited By ~ 2

Author(s):

Jens Martin Turowski

Keyword(s):

Steady State ◽

Mass Balance ◽

Mechanistic Model ◽

Channel Width ◽

Bedrock Rivers ◽

Channel Incision ◽

Bedrock Channel ◽

Lateral Incision ◽

Lateral Erosion ◽

Bedrock Channels

Abstract. Rivers are dynamical systems that are thought to evolve towards a steady-state configuration. Then, geomorphic parameters, such as channel width and slope, are constant over time. In the mathematical description of the system, the steady state corresponds to a fixed point in the dynamic equations in which all time derivatives are equal to zero. In alluvial rivers, steady state is characterized by grade. This can be expressed as a so-called order principle: an alluvial river evolves to achieve a state in which sediment transport is constant along the river channel and is equal to transport capacity everywhere. In bedrock rivers, steady state is thought to be achieved with a balance between channel incision and uplift. The corresponding order principle is the following: a bedrock river evolves to achieve a vertical bedrock incision rate that is equal to the uplift rate or base-level lowering rate. In the present work, considerations of process physics and of the mass balance of a bedrock channel are used to argue that bedrock rivers evolve to achieve both grade and a balance between channel incision and uplift. As such, bedrock channels are governed by two order principles. As a consequence, the recognition of a steady state with respect to one of them does not necessarily imply an overall steady state. For further discussion of the bedrock channel evolution towards a steady state, expressions for adjustment timescales are sought. For this, a mechanistic model for lateral erosion of bedrock channels is developed, which allows one to obtain analytical solutions for the adjustment timescales for the morphological variables of channel width, channel bed slope, and alluvial bed cover. The adjustment timescale to achieve steady cover is of the order of minutes to days, while the adjustment timescales for width and slope are of the order of thousands of years. Thus, cover is adjusted quickly in response to a change in boundary conditions to achieve a graded state. The resulting change in vertical and lateral incision rates triggers a slow adjustment of width and slope, which in turn affects bed cover. As a result of these feedbacks, it can be expected that a bedrock channel is close to a graded state most of the time, even when it is transiently adjusting its bedrock channel morphology.

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FLOW COMPUTATIONS NEARBY A STORM SURGE BARRIER UNDER CONSTRUCTION WITH TWO-DIMENSIONAL NUMERICAL MODELS

Coastal Engineering Proceedings ◽

10.9753/icce.v20.143 ◽

1986 ◽

Vol 1 (20) ◽

pp. 143

Author(s):

H.E. Klatter ◽

J.M.C. Dijkzeul ◽

G. Hartsuiker ◽

L. Bijlsma

Keyword(s):

Numerical Model ◽

Storm Surge ◽

Field Data ◽

Numerical Models ◽

Flow Patterns ◽

Scale Model ◽

Energy Losses ◽

Local Energy ◽

Two Dimensional ◽

Physical Scale

This paper discusses the application of two-dimensional tidal models to the hydraulic research for the storm surge barrier in the Eastern Scheldt in the Netherlands. At the site of the barrier local energy losses dominate the flow. Three methods are discussed for dealing with these energy losses in a numerical model based on the long wave equations. The construction of the storm surge barrier provided extensive field data for various phases of the construction of the barrier and these field data are used as a test case for the computation at methods developed. One method is preferred since it gives good agreement between computations and field data. The two-dimensional flow patterns, the discharge and the head-difference agree well,, The results of scale model tests were also available for comparison. This comparison demonstrated that depth-averaged velocities, computed by a two-dimensional numerical model, are as accurate as values obtained from a large physical scale model. Even compicated flow patterns with local energy losses and sharp velocity gradients compared well.

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SWASH OSCILLATION AND RESULTING SEDIMENT MOVEMENT

Coastal Engineering Proceedings ◽

10.9753/icce.v21.87 ◽

1988 ◽

Vol 1 (21) ◽

pp. 87 ◽

Cited By ~ 1

Author(s):

Nobuhisha Kobayashi ◽

Michael S. Strzelecki ◽

Andojo Wurjanto

Keyword(s):

Numerical Model ◽

Field Data ◽

Wave Setup ◽

Sediment Movement

A numerical model for predicting the swash oscillation on a beach is described and compared with field data on wave setup and swash statistics on a moderately steep beach with a nearshore bar.

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A Double-Bridge Channel Shape of a Membraneless Microfluidic Fuel Cell

Energies ◽

10.3390/en14216973 ◽

2021 ◽

Vol 14 (21) ◽

pp. 6973

Author(s):

Ji-Hyun Oh ◽

Muhammad Tanveer ◽

Kwang-Yong Kim

Keyword(s):

Fuel Cell ◽

Numerical Model ◽

Power Density ◽

Flow Channel ◽

Channel Width ◽

Channel Height ◽

Cross Sectional ◽

Channel Shape ◽

Microfluidic Fuel Cell ◽

Inner Channel

A double-bridge shape is proposed as a novel flow channel cross-sectional shape of a membraneless microfluidic fuel cell, and its electrochemical performance was analyzed with a numerical model. A membraneless microfluidic fuel cell (MMFC) is a micro/nano-scale fuel cell with better economic and commercial viability with the elimination of the polymer electrolyte membrane. The numerical model involves the Navier–Stokes, Butler–Volmer, and mass transport equations. The results from the numerical model were validated with the experimental results for a single-bridge channel. The proposed MMFC with double-bridge flow channel shape performed better in comparison to the single-bridge channel shape. A parametric study for the double-bridge channel was performed using three sub-channel widths with the fixed total channel width and the bridge height. The performance of the MMFC varied most significantly with the variation in the width of the inner channel among the sub-channel widths, and the power density increased with this channel width because of the reduced width of the mixing layer in the inner channel. The bridge height significantly affected the performance, and at a bridge height at 90% of the channel height, a higher peak power density of 171%was achieved compared to the reference channel.

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Crustal Fault Zones (CFZ) as Geothermal Power Systems: A Preliminary 3D THM Model Constrained by a Multidisciplinary Approach

Geofluids ◽

10.1155/2021/8855632 ◽

2021 ◽

Vol 2021 ◽

pp. 1-24

Author(s):

Hugo Duwiquet ◽

Laurent Guillou-Frottier ◽

Laurent Arbaret ◽

Mathieu Bellanger ◽

Théophile Guillon ◽

...

Keyword(s):

High Temperature ◽

Numerical Model ◽

Power Systems ◽

Fault Zone ◽

Field Data ◽

Large Scale ◽

Numerical Models ◽

Massif Central ◽

Temperature Anomalies ◽

Stress Direction

The Pontgibaud crustal fault zone (CFZ) in the French Massif Central provides an opportunity to evaluate the high-temperature geothermal potential of these naturally permeable zones. Previous 2D modeling of heat and mass transfer in a fault zone highlighted that a subvertical CFZ concentrates the highest temperature anomalies at shallow depths. By comparing the results of these large-scale 2D numerical models with field data, the depth of the 150°C isotherm was estimated to be at a depth of 2.5 km. However, these results did not consider 3D effects and interactions between fluids, deformation, and temperature. Here, field measurements are used to control the 3D geometry of the geological structures. New 2D (thin-section) and 3D (X-ray microtomography) observations point to a well-defined spatial propagation of fractures and voids, exhibiting the same fracture architecture at different scales (2.5 μm to 2 mm). Moreover, new measurements on porosity and permeability confirm that the highly fractured and altered samples are characterized by large permeability values, one of them reaching 10-12 m2. Based on a thermoporoelastic hypothesis, a preliminary 3D THM numerical model is presented. A first parametric study highlights the role of permeability, stress direction, and intensity on fluid flow. In particular, three different convective patterns have been identified (finger-like, blob-like, and double-like convective patterns). The results suggest that vertical deformation zones oriented at 30 and 70° with respect to the maximum horizontal stress direction would correspond to the potential target for high-temperature anomalies. Finally, a large-scale 3D numerical model of the Pontgibaud CFZ, based on THM coupling and the comparison with field data (temperature, heat flux, and electrical resistivity), allows us to explore the spatial geometry of the 150°C isotherm. Although simplified hypotheses have been used, 3D field data have been reproduced.

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Numerical Study on the Effects of Imbibition on Gas Production and Shut-In Time Optimization in Woodford Shale Formation

Energies ◽

10.3390/en13123222 ◽

2020 ◽

Vol 13 (12) ◽

pp. 3222 ◽

Cited By ~ 1

Author(s):

Zhou Zhou ◽

Shiming Wei ◽

Rong Lu ◽

Xiaopeng Li

Keyword(s):

Numerical Model ◽

Hydraulic Fracturing ◽

Field Data ◽

Gas Production ◽

Model Parameters ◽

Water Recovery ◽

Woodford Shale ◽

Capillary Suction ◽

Shale Formation ◽

The Relationship

In shale gas formations, imbibition is significant since the tight pore structure causes a strong capillary suction pressure. After hydraulic fracturing, imbibition during the period of shut-in affects the water recovery of flowback. Although there have been many studies investigating imbibition in shale formations, few papers have studied the relationship between gas production and shut-in time under the influence of imbibition. This paper developed a numerical model to investigate the effect of imbibition on gas production to optimize the shut-in time after hydraulic fracturing. This numerical model is a 2-D two-phase (gas and water) imbibition model for simulating an imbibed fluid flow and its effect on permeability, flowback, and water recovery. The experimental and field data from the Woodford shale formation were matched by the model to properly configure and calibrate the model parameters. The experimental data consisted of the relationship between the imbibed fluid volume and permeability change, the relative permeability, and the capillary pressure for the Woodford shale samples. The Woodford field data included the gas production and flowback volume. The modeling results indicate that imbibition can be a beneficial factor for gas production, since it can increase rock permeability. However, the gas production would be reduced when excessive fluid is imbibed by the shale matrix. Therefore, the shut-in time after hydraulic fracturing, when the imbibition happens in shale, could be optimized to maximize the gas production.

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