Mud Erosion Research Articles

Practical 2DV Modeling of Deposition and Erosion of Sand and Mud in Dredged Channels due to Currents and Waves

Practical 2DV Modeling of Deposition and Erosion of Sand and Mud in Dredged Channels due to Currents and Waves

Preparation of Cemented Carbide and Study of Copper-Accelerated Salt Spray Corrosion and Erosion Behavior.

(1) Mud pulser carbide rotors, as a core component of ground communication in crude oil exploration, are often subjected to mud erosion and acid corrosion, resulting in pitting pits on the surface, which affects the accuracy. The purpose of this study was to investigate the acid corrosion and erosion behavior of cemented carbide materials and provide a reference for the wider application of cemented carbide materials in the petrochemical industry. (2) Experimental samples of tungsten–cobalt carbide were sintered at a low pressure by powder metallurgy. The petrochemical application environment was simulated by accelerated salt spray corrosion and solid slurry erosion with the aid of acidic copper, and the experimental phenomena were analyzed by SEM (scanning electron microscope), EDS (Energy Dispersive Spectroscopy), and XRD (X-ray diffraction). (3) The experimental results show that the coercivity of the pitted cobalt-cemented tungsten carbide prepared in this study was 17.89 KA/m, and the magnetic saturation strength was 14.42 G·cm3/g. The corrosion rate was the fastest during the acidic copper acceleration experiments from 4 h to 16 h, and the corrosion products of WCo3 and Co3O4 were generated on the corrosion surface. The maximum erosion rate of 0.00104 in the erosion experiment corresponds to a corrosion sample with a corrosion time of 36 h. (4) Therefore, the coercive magnetic force and magnetic saturation strength could be derived from the prepared carbide hard phase grains and carbon content in the appropriate range. The corrosion product in the corrosion process slowed the corrosion rate, and a large amount of cobalt and a small amount of tungsten was lost by oxidation during the corrosion process. The corrosion time had the greatest effect on the erosion performance of the carbide, and the long corrosion time led to surface sparseness, which reduced the erosion resistance.

Index of environmental pollution and adaptation of Avicennia marina around the ex-bauxite mining area in Bintan Island

Bintan Island has high bauxite resource potential. However, its utilization is not balanced with efforts to restore ex-mining land. Physical damage includes erosion and sedimentation of red mud along the coast and the surrounding mangrove forest. This study aims to determine environmental pollution based on the accumulation of lead (Pb) and chromium (Cr) in redmud found in mangrove forests around the bauxite ex-mining area and the adaptation of Avicennia marina to heavy metals. This research was conducted from April to December 2020. Research survey and laboratory analysis using Atomic Absorban Spectrophotometry. The results showed that Pb in the sediments and organs of A. marina was higher than Cr. The results showed that the mangrove forest around the bauxite ex-mining area of Bintan Island was contaminated with low levels of Pb and Cr metals (CF<1, PLI<1) and the environment is lightly polluted (0<Igeo<1). Adaptation of A. marina showed that the metal uptake mechanism was rhizofiltration (BCF<1, TF<1, BCF<TF) and the physical condition was slightly damaged. There was no significant effect between Pb and Cr metals in the sediments and organs of A. marina on the stem diameter and tree height (Sig.> 0.05).

Critical Shear Stress for Erosion of Sand-Mud Mixtures and Pure Mud

The erosion threshold of sand-mud mixtures is investigated by analyzing the momentum balance of a sand particle or a mud parcel in the mixture bed surface, and a formula for the critical shear stress of sand-mud mixtures is developed, which also applies for pure sand and mud. The developed formula suggests that the variation of the critical shear stress of sand-mud mixtures over mud content is mainly caused by the varying dry bulk density of the mud component in the mixture. The developed formula reproduces well the variation of the critical shear stress of sand-mud mixtures over mud content and can predict the critical shear stress of both sand-mud mixtures and pure mud in the process of consolidation. The developed formula promises to be convenient for application by relating the critical shear stress to mud content and the dry bulk density of sediment.

Erosion wear characteristics of cemented carbide for mud pulser rotor

Mud pulser is the most commonly used Measurement While Drilling(MWD) instrument for downhole data transmission to the surface. The rotor of the key component of the mud pulser is made of cemented carbide material. Under the action of high speed mud erosion containing solid phase, the rotor will produce erosion wear and reduce the quality of signal transmission. To explore the erosion wear mechanism of rotor carbide in mud containing solid phase particles, the influences of different erosion angles and different erosion abrasive sizes on the erosion wear properties of cemented carbides were studied by taking quartz sand as erosion abrasive. By means of surface profilometer, scanning electron microscope (SEM) and energy spectrum analysis (EDS), the erosion wear mechanism of cemented carbide was revealed. The experimental results show that the erosion wear rate increases gradually with the increase of erosion angle. When the erosion angle is 90°, the maximum average erosion rate of WC-5Co, WC-6Co and WC-10Co cemented carbides is 2.39%, 2.42% and 3.22%, respectively. With the increase of the abrasive particle size, the erosion wear rate of the material increases first and then decreases. When 100–200 um, the maximum average erosion rates of WC-5Co, WC-6Co and WC-10Co are 1.84%, 1.98% and 2.48%, showing a significant “particle size effect”. At low erosion angle, the wear mechanism is furrow and cutting mark, while at high erosion angle, the wear mechanism is pit. The erosion wear mechanism of small particle size abrasives is that a large area of surface layer falls off in the erosion area. The erosion wear mechanism of large particle size abrasive is the material loss in the erosion pit in the erosion area.

What Came First, Mud or Biostabilizers? Elucidating Interacting Effects in a Coupled Model of Mud, Saltmarsh, Microphytobenthos, and Estuarine Morphology

AbstractMud accretion and establishment of biostabilizers, such as microphytobenthos and saltmarsh vegetation, govern the development of estuarine morphology. Mud facilitates saltmarsh survival and microphytobenthos growth, which in turn promotes sedimentation and reduces mud erosion. Consequently, an increasing extent and thickness of mud cover might lead to a stabilization of large‐scale estuarine morphology. To disentangle the interactions between saltmarsh establishment, microphytobenthos colonization, and mud layer formation, we use our novel eco‐morphodynamic model applied to the Western Scheldt estuary. Our model shows that presence of dynamic saltmarsh vegetation and microphytobenthos enhances predictions of mud location in the computations compared to field data. Saltmarsh establishment is partly determined by the antecedent mud content in the bed, resulting in varying emerging vegetation coverage between model experiments of a generic saltmarsh and a saltmarsh species that requires prior mud for establishment. In contrast to microphytobenthos enhancing seasonal mud accretion during their growth period, saltmarshes promote largest accretion when lower biomass and high water levels are present. Interestingly, thick long‐term mud is enhanced despite the biostabilizers seasonal growth. The combination of saltmarsh and microphytobenthos leads to expanding saltmarsh cover and mud area. Generally, mud layer thickness is governed by the ratio of hydroperiod and maximum flow velocity that is mediated by the biostabilizers. On estuary scale, the presence of intertidal vegetation leads to increased mud volumes in the intertidal. Mud layers are enhanced in extent by a mud‐dependent species and in thickness by a generic species. Thus, local biostabilization alters large‐scale morphology controlling long‐term estuarine development.

Case Study of College Veng Road Section Landslide, Aizawl, Mizoram, India

Landslide is a very common feature along highways, roads and inhabited areas, in and around Mizoram. It is one of the most problematic hazards in the region. The present case of landslide, is in the ‘College Veng’ road section. It lies in the south eastern parts of the Aizawl town. This section is situated along the Sikulpuikawn-Bethlehem Veng road. The Coordinates of the “College Veng” slide are between 23°43՛28.56՛՛/92°43՛28.28՛՛ to 23°43՛28.56՛՛/92°43՛28.34՛՛. The slide took place on 17th September, 2017, at mid night. The section had a relatively high amount of dip (48°-50°), and has a lithology comprising of Shale and Sandstone intercalation. The total length of the slide section along the road was 75 feet, with a height of 25 feet. After the critical observation of the incidence, the major aggravating factors were found to be that the heavy rainfall induced the top most shale bed to move down the dip slope. Improper sewage and subsequent mud erosion at the bottom of the shale layer, further accelerated the down slope movement of the slided block.

Age and depositional environment of the Xiaheyan insect fauna, embedded in marine black shales (Early Pennsylvanian, China)

The Early Pennsylvanian Xiaheyan entomofauna (Ningxia, China) is among the earliest assemblages of winged insects known so far, and therefore provides an essential input on deciphering the early diversification of this group. Despite its evolutionary significance, both the age and depositional environment remained poorly constrained. Here, we present high-resolution documentation of litho- and biofacies, biostratigraphy and geochronology of the up to 100 m thick type section. Accordingly, the insect-bearing strata are of latest Bashkirian (latest Duckmantian) to middle Moscovian (Bolsovian) age. The sediments, lithostratigraphically assigned to the Yanghugou Fm., represent a regressional marine sequence formed at the southern margin of the Qilian Inland Sea. Intercalations of crevasse channels and splays that laterally interlock with marine black shales and bioclastic limestones point to deposition in an interdelta bay. Ground-touching waves provoked the erosion of muds at shallow depths leading to mass mortalities among mollusc communities due to rising anoxia, turbidity and water turbulence. In addition, bottom currents transported mud intraclasts towards the basin, where sinking insects that reached the bay via winds and surface currents were buried sub-contemporaneously with bivalves below the storm wave base. Observed differences in insect preservation and assemblage composition across the sequence are found to correlate with lithology and are best explained by distance from land, and the action of events inducing insect carcasses to sink, such as storms. The proposed taphonomic model represents a new fossilization pathway from land to sea and provides new directions for prospecting Paleozoic deposits in the search for insects.

Experimental study on the physical modeling of loess tunnel-erosion rate

Loess tunnel erosion is a distinctive soil erosion pattern that commonly occurs in collapsible loess areas. The resulting soil erosion is a serious and complex problem. At present, most of the research methods on loess tunnel erosion are based on field investigation, and the knowledge obtained is, therefore, mostly qualitative. Erosion characteristics and erosion rates of loess tunnels are rarely revealed quantitatively by laboratory physical modeling or field investigation. In this paper, we report the results of a small model test based on three types of archetypal geological structures that are recognized by field investigation, i.e., vertical fractures, horizontal fractures, and round holes, These results reveal the effect of different initial flow cross sections on the erosion characteristics of loess tunnels. We found that, where water crosses an area of loess, waterfalls dominate initial erosion. We also studied the mud erosion rate to quantitatively reveal tunnel-erosion rates and their variation with time and found that tunnel erosion occurs in three stages: a rapid-erosion stage, an erosion slow-down stage, and a slow uniform-erosion stage. Using a model test to undertake quantitative studies into the relationship between the erosion rate of a loess tunnel and both initial dry density and initial water content, we demonstrated a significant linear negative correlation between these parameters. Through physical simulations combined with field investigation and analysis of survey results, we found that the erosion of loess tunnels occurs with a certain periodicity and that the tunnel-erosion base level plays a decisive role in the erosional features and final morphology of loess tunnels. By increasing our understanding of the internal mechanisms of loess tunnel erosion, our work will contribute to the prevention of cave erosion and reduction in the risks of associated disasters in the Loess Plateau of the Yellow River in China and in other loess-containing areas around the world. Our studies also provide a theoretical basis for carrying out soil and water conservation work in similar areas.

Unified Formula for Critical Shear Stress for Erosion of Sand, Mud, and Sand–Mud Mixtures

AbstractResearch on erosion behavior of sediments usually treats sand and mud separately. However, natural soil often occurs as a sand–mud mixture. An expression for cohesive forces in sand–mud mix...

Modeling of shear stress distribution on mud surface in the subsea sand-mud alternate layer

This study aims at showing that the shear stress distribution on a flat surface in the porous media can be expressed by just one probability density function. It is known that methane hydrate exists in the sand layers off Kii Peninsula in Japan within the turbidite sand-mud alternate strata. One of the concerns about gas production from methane hydrate is mud erosion and consequent reservoir clog caused by skin formation. The erosion rate of mud particles depends on the shear stress distribution on the surface of the mud layer in the alternates. The distribution of shear stress should depend on the flow and reservoir properties. Being able to predict the total mass of the eroded mud in advance would definitely be convenient. The objective of this paper is to propose a mathematical model of shear stress distribution on a flat interface between sand and mud layers, because it is believed that the maximum mud-erosion rate is given at the very beginning of the gas production when the mud surface is almost flat. To obtain the shear stress distribution on a flat surface, we conducted pore-scale numerical simulations using computational domains including numerically generated sand-mud beds. Interestingly, we found that the histograms of the shear stresses fit just one curve by means of proper non-dimensionalization. These consistent histograms of the non-dimensional shear stress were then matched with a Gamma distribution function, to develop a mathematical model. This new finding may make possible to predict the maximum rate of mud erosion if we know water flow velocity and reservoir properties, such as porosity and permeability.

Modelling Fine Sediment Dynamics: Towards a Common Erosion Law for Fine Sand, Mud and Mixtures

This study describes the building of a common erosion law for fine sand and mud, mixed or not, in the case of a typical continental shelf environment, the Bay of Biscay shelf, characterized by slightly energetic conditions and a seabed mainly composed of fine sand and muddy sediments. A 3D realistic hydro-sedimentary model was used to assess the influence of the erosion law setting on sediment dynamics (turbidity, seabed evolution). A pure sand erosion law was applied when the mud fraction in the surficial sediment was lower than a first critical value, and a pure mud erosion law above a second critical value. Both sand and mud erosion laws are formulated similarly, with different parameters (erodibility parameter, critical shear stress and power of the excess shear stress). Several transition trends (linear or exponential) describing variations in these erosion-related parameters between the two critical mud fractions were tested. Suspended sediment concentrations obtained from simulations were compared to measurements taken on the Bay of Biscay shelf with an acoustic profiler over the entire water column. On the one hand, results show that defining an abrupt exponential transition improves model results regarding measurements. On the other hand, they underline the need to define a first critical mud fraction of 10 to 20%, corresponding to a critical clay content of 3–6%, below which pure sand erosion should be prescribed. Both conclusions agree with results of experimental studies reported in the literature mentioning a drastic change in erosion mode above a critical clay content of 2–10% in the mixture. Results also provide evidence for the importance of considering advection in this kind of validation with in situ observations, which is likely to considerably influence both water column and seabed sediment dynamics.

2-2-4 砂泥互層内における泥層浸食の時間変化に関する研究

2-2-4 砂泥互層内における泥層浸食の時間変化に関する研究

Pore-scale numerical simulation of mud erosion in the subsea sand–mud alternate layer using lattice Boltzmann method

Commercial-scale extraction of methane gas from subsea methane hydrate is difficult. A major challenge is mud erosion at the interfaces of sand–mud alternate layers in the subsea strata. Without a clear understanding of the various parameters associated with mud erosion, there may be complications in developing methane hydrate deposits, such as reservoir clogging due to mud particles. This study aims to develop a numerical simulation method to predict mud erosion caused by water flow in pore-scale computational domain. Microscopic sand beds were generated numerically in the computational domain while the water flow through the pores of various-shaped sand grains was numerically simulated using the lattice Boltzmann method. Mud was treated as a continuum and eroded at its surface via the shear stress of water flow using the critical shear stress and erosion rate constant, which were estimated by fitting calculated erosion rates with those of a laboratory-scale experiment. Using this numerical model, simulations of long-term mud erosion were conducted. The simulation showed that when the average velocity of water in the pore space is larger than the critical value and smaller than ten times that value, the erosion rate is almost zero after about 10 days.

Experimental study of mud erosion at the interface of an artificial sand-mud alternate layer

Methane hydrates exist in the sand-mud alternate layers of Japan's offshore turbidite sediments. For gas production from a methane hydrate reservoir, depressurization has been considered as a promising method. When intergranular methane hydrates are dissociated, the flow of produced gas and water may cause mud erosion of turbidite sediments. The eroded mud may plug the pores near the wellbore. This research presents an experimental study for the evaluation of mud erosion at the interface between the sand and mud layers. Artificial cores consisting of sand and mud layers were made and the mass of fine particles eroded by water flow was measured. We, then, adopted a mud erosion model, which represents a linear relationship between the erosion rate of fine particles and average flow velocity in the pore, and obtained a critical flow velocity and a coefficient of the erosion rate of fines in the sand-mud alternate layer.

Experimental study of the density influence on the incipient motion and erosion modes of muds in unidirectional flows: the case of Huangmaohai Estuary

The incipient motion and erosion behavior of bottom muds in coastal areas have wide applications in coastal engineering, water environment management, and also the protection of marine benthic communities. Due to the strong inter-particle cohesion of fine sediments and the diversity in its physical properties, the mechanism of the coastal mud erosion is not well understood and the determination of the threshold for the incipient motion remains a challenge. In order to investigate the influence of the mud density on the incipient motion of fully disturbed coastal mud, experiments were carried out using a 22-m-long laboratory flume and mud samples from Huangmaohai Estuary, South China Sea. Muds with densities ranging from 1100 to 1550 kg/m3 were tested under unidirectional open channel flows, which yielded threshold velocities ranging from 0.11 to 1.67 m/s, corresponding to bed shear stresses ranging from 0.029 to 4.191 N/m2. Based on the experimental results, an empirical formula for the threshold velocity at the incipient motion of coastal muds with different densities is presented. The computed results together with the proposed formula were also compared with other theories. Besides, four different erosion patterns of coastal muds at incipient motion were identified according to experimental observations, namely erosion in the pattern of fluid muds, strips, pieces, and blocks. The physical mechanisms for different erosion patterns were also analyzed and interpreted. The presented experimental achievements well enrich our knowledge of coastal mud behavior and lead to a deeper understanding of the mechanisms of the incipient motion of bottom muds.

More gaps than shale: erosion of mud and its effect on preserved geochemical and palaeobiological signals

Abstract Ths wht th fn-grnd mrine sdmtry rcrd rlly lks like.

Failure Analysis and Troubleshooting for Certain Tracked Artillery Deviation

If a certain type of tracked artillery to keep driving straight, it’s mobile devices must make the lef and the right speed equal to two tracks winding movement. But in the actual moving process, due to the poor working conditions,such as mud and water erosion, sand grinding, undulating slopes, etc, in the case of uneven wear on both sides of the track, tracked artillery in use for some time, and sometimes there will be automatic deviation phenomenon. For this failure phenomenon, the use of the vehicle and steering theory, from the track wear inconsistent, inconsistent tightness, old and new with inconsistencies and change on both sides of the road wheel locating inconsistencies four aspects of a certain type of tracked artillery deviation phenomenon analyzed, by analyzing the proposed treatment measures.

Observation and modeling of the storm-induced fluid mud dynamics in a muddy-estuarine navigational channel

Observations of storm-induced fluid mud dynamics have been conducted at the North Passage deepwater navigational channel (DNC) of the Yangtze Estuary in October to December 2010, during the occurrence of a cold-air front. The measurement data reveal that just after the critical wind wave event, a large amount of fine sediment was trapped in a state of fluid mud along the channel. The observed thickness of the fluid mud was up to about 1–5m, which caused some significant economic and safety problems for shipping traffic in the Yangtze Delta area. The mechanisms and transport processes of the storm-induced fluid mud are analyzed and presented from the angles of both process-oriented and engineering-oriented methods. With the help of hydrodynamics and wave modeling, it could be inferred that the behavior of the storm-induced fluid mud event mainly depends on the overall hydrodynamic regimes and the exchanges of sediment, which is released by storm-wave agitation from adjacent tidal flats. These sediments are accumulated as fluid mud, and subsequently oscillate and persist at those locations with weaker longitudinal residuals in the river- and tide-dominated estuary. In addition, the downslope transport of fluid mud is also thought to have stimulated and worsened the fluid mud event observed in this study. Our modeling results and observations demonstrate that: (1) the transport of fluid mud is an advective phenomenon determining the central position of fluid mud layer along the channel, and it's also a tidal energy influenced phenomenon controlling the erosion and accumulation of fluid mud; and (2) both suspended particulate matter availability and local residual flow regime are of critical importance in determining the trapping probability of sediment and the occurrence of fluid mud.

Simulation on Stress Distribution of Drill Pipe’s Surface Initial Crack

Abstract: In drilling process, drill pipes’ out surface always have lots of pits and scratches due to the corrosive and erosion of mud or wear of well wall in work environment. Through establishing drill pipe’s working model and constitutive equations with Finite Element Analysis Software, the paper have simulated stress distribution on drill pipe body under two different condition that without mechanical damage and with initial crack. Analysis results show that the maximum stress increases with the increasing of initial crack depth, and the maximum stress position turns to crack circumferential root from the crack radial root with the increasing of initial crack’s depth. The analysis result is completely consistent with the actual morphology of crack propagation, as a result, the simulation analysis provides a effective new methods and reference for remaining life assessment and failure analysis of drill pipe.