Plug Removal Research Articles

Effect of soil plug removal on the load-carrying capacity of symmetric and non-symmetric pile groups

ABSTRACT This study comprises experimental tests that consist of 138 tests that are divided as follows: 36 tests for single pile, 36 tests for pile group (2 × 1), 36 tests for pile group (2 × 2) and 30 tests for pile group (2 × 3). All tubular piles are tested in poorly graded sand. Different parameters are considered such as the method of installation, relative density, removal of soil plug with respect to length of plug and pile length-to-diameter ratio. Strain gauges are used to separate skin friction with two components of shear resistance and end bearing. It was concluded that the removal of soil plug from piles (single or group) will cause a reduction in single and group capacities due to the elimination of two components, internal friction and the confining in end-bearing zone. The maximum reduction occurs in the dense state of soil with 61.5% and 83% for single and group of piles, respectively.

Comparison of the use of d-enantiomeric and l-enantiomeric antimicrobial peptides incorporated in a calcium-chelating irrigant against Enterococcus faecalis root canal wall biofilms

ObjectivesTo compare the anti-biofilm efficacy of two antimicrobial peptides (AMPs), 1018 and DJK-5, in disrupting canal wall biofilms in the isthmus, canal and dentinal tubules of single-rooted maxillary premolars. MethodsEnterococcus faecalis single-species biofilms were formed in-situ in the root canal system of the premolars (n = 91). Confocal laser scanning microscopy, bacterial sampling, colony-forming unit counting, XTT assay, lactate dehydrogenase assay and phenol-sulphuric acid method were used to identify the anti-biofilm efficacy of both AMPs and their influence on bacterial metabolic activity. ResultsBoth AMPs disrupted in-situ E. faecalis biofilms and altered their metabolic activity. At 20 μg/mL, the d-enantiomeric AMP DJK-5 killed 55.5 %, 57.3 % and 55.8 % of biofilm bacteria in the isthmus, canal and dentinal tubules, respectively, in 1 min. In contrast, the l-enantiomeric AMP 1018 only eradicated 25.6 %, 25.5 % and 27.5 % of biofilm bacteria in the isthmus, canal and dentinal tubules, respectively, within the same time. Anti-biofilm efficacy of the root canal irrigants tested were in the order: 6 % NaOCl > 20 μg/mL DJK-5 > 10 μg/mL DJK-5 > 20 μg/mL 1018 > 10 μg/mL 1018 > 0.9 % NaCl. ConclusionsThe present results are confirmatory of previous studies, in that d-enantiomeric AMPs exhibit more potent antibacterial properties than l-enantiomeric AMPs against E. faecalis biofilms within the canal space. Nevertheless, the potency of both AMPs are concentration-dependent. Incorporation of these agents into EDTA, a non-antibacterial calcium-chelating irrigant for removal of the inorganic component of the canal space debris, does not reduce the efficacy of either AMP. Clinical SignificanceThe present study provides the proof of concept that incorporation of an antimicrobial peptide into a calcium-chelating root canal irrigant enhances the disinfection of intratubular single-species biofilms during smear layer and smear plug removal.

Improved kinetic Equations for a NaNO2/NH4Cl Heat Generating System and their Implications in Oil Production

A NaNO2/NH4Cl heat generating system has been widely applied in oil production process in China, for paraffin plug removal, in-situ fracturing, etc. Establishing an accurate kinetic equation for the NaNO2/NH4Cl system is important for field operation applications. In this study, based on a strictly controlled group of experiments, the kinetic equation for the NaNO2/NH4Cl heat generating system is established and regressed by the method of undetermined coefficients, on condition that the heat loss of the reaction is relatively small and could be neglected. It is obvious that in many field applications the heat loss is considerably high and cannot be neglected; hence the equation is improved by taking into consideration the heat loss input. The improved equation shows a better correlation with experimental data, particularly for long reaction times. The established equation reveals the relationship between the reaction rate and the concentrations of the reactants and catalyst This study has practical significance for calculating the temperature field near the well bore and can be used for parameter optimization of the NaNO2/NH4Cl heat generating system.

Shape of male palpal hook affects female sexual cannibalism in Leucauge mariana (Araneae: Tetragnathidae)

In the Colombian orb-web spider Leucauge mariana (Taczanowski, 1881) (Tetragnathidae), both sexes contribute to mating plug formation. Males of this species show a conductor hook that could be involved in providing stability to the mating pair and used for mating plug removal. The aim of the study was to assess the relationship between the shape of the conductor hook in L. mariana and mating duration, the amount of sperm stored, and the occurrence of sexual cannibalism. We used geometric morphometric tools for studying the conductor hook shape. The width of the base of the conductor hook was negatively correlated with the probability of sexual cannibalism by females (PC2 = 0.017), but we did not find a significant relation with mating duration and the amount of sperm transferred. Female choice on male hook shape, or on the stability provided by the hook during the mating position, could be occurring in this species.

Experimental and Computational Investigation of Particle Filtration Mechanisms in Partially Damaged DPFs

<div class="section abstract"><div class="htmlview paragraph">Understanding the filtration mechanisms in partially damaged Diesel Particulate Filters is very important for the design of exhaust systems with efficient On-Board Diagnosis functionality, especially as new threshold limits have been recently applied for particulate mass leakage. Two common types of DPF failure are included in this study, namely rear plug removal and internal failure due to uncontrolled regeneration with excessive deposit loading. Initially, the two respective filters were loaded on the engine bench with particle measurement upstream and downstream, and then they were disassembled and sectioned to study the deposit distribution. The analysis of the second filter revealed several modes of failure that should be expected under real-life conditions such as material accumulation in the inlet channels, substrate melting, and crosswise and diagonal crack development. Moreover, a computational model with the necessary adjustments is used to simulate the loading experiments and interpret the underlying filtration mechanisms. The processed results reveal small effects of temperature and mass flow rate on the filtration efficiency and a comparatively stronger impact of the total deposit loading. The local deposit loading is uniform in the intact segments, while it is non-uniform with a minimum value at the failure location in the unplugged and internally damaged segments. This finding is consistent with the wall flow predicted by the model, whereas some discrepancies of the model can be attributed to a secondary collection mechanism.</div></div>

Proposal and Experimental Trials on an Autonomous Robot for Rigless Well Intervention

Summary Well interventions, especially in offshore wells, are costly and usually very time-consuming to conduct. This is related mainly to the need for a rig or a similar unit to perform these operations. In this paper we propose the development of an autonomous robot for rigless well interventions. The robot will be inserted through the tree using a special tool. This proposal will result in significant cost reduction by eliminating the rig when performing light–workover operations in offshore locations. This reduces intervention time because a simpler unit might be used to deploy the robot. Examples of operations that could be performed by the robot are production logging, gas–lift valve replacement, sliding–sleeve opening and closing, and plug insertion or removal. To evaluate this proposal, a conceptual robot was designed. The feasibility of this conceptual robot was evaluated theoretically. After that, a simplified test robot was constructed to test critical aspects experimentally, in laboratories, and in a test well. The traction system, energy storage, and a positioning algorithm were evaluated. In this paper we will outline the intervention strategy proposed, perform a theoretical evaluation of this proposal on the basis of the conceptual robot, and present experimental results obtained with the simplified test robot.

Experimental and numerical study on direct electrical heating for plug removal of subsea waxy crude pipelines

Subsea pipeline of waxy crude oil may face a high risk of the wax plug during shut down or pigging. Direct Electrical Heating (DEH) technology is expected to be an efficient and convenient way to melt the wax plug in the subsea pipeline. An industrial-scale experimental facility with a test tube of 10-in. diameter and a power supply of 0–1350 A is set up, and then several sets of experiments are carried out. Simultaneously, the melting process of the wax plug is simulated by FLUENT software. The numerical model is validated from the aspects of liquid fraction and solid patterns. The melting rate and temperature of the wax plug with different wax content and current are analyzed, and the temperature of the pipe wall is considered for the sake of pipeline integrity. Furthermore, to avoid secondary solidification, the recooling process of the wax plug and pipe wall is also discussed. Finally, the effects of the “Maximum Allowable Temperature”, “Maximum Safe Power”, “Effective Liquid Fraction” and “Applicable Heating Time” on economic evaluation are investigated, and the correlations are developed between the above factors and common pipe diameters (6–32-in.), which shows heating with maximum safe power is also the most economical method in engineering.

Composite Plugging Removal Technology and Application in Low Permeability Oilfield

In an oilfield factory, the blocking and jam in Chang 2 reservoir is very serious. In recentyears, according to analysizing different plugging mechanism and optimizing acidizing formula, theoptimal plugging removal technology was formed suitable for the solution for the Chang 2 reservoirof oilfield factory. This plugging removal formula increases the efficiency radius, and increases thedosage of additives to protect the pipe, rod and pump from the precipitation such as Ca2+and Mg2+,which causes new pollution. Reasonable multiple technologies were designed, and low displacementmethod was used in the injection process, aiming at the characteristics of Chang 2 reservoir. Thismethod extends the time of plugging removal fluid staying around the well bore, which can eliminateplugging near well bore area effectively, and improve the permeability. DQ-1 composite pluggingremoval and other kinds of plugging removal methods have been used more than 50 times, and theeffect is remarkable, which made a positive contribution to stable production of the oilfield.

A Comparison of Friction Measurements of Intact Articular Cartilage in Contact with Cartilage, Glass, and Metal

The goal of this study was to develop a method of friction testing utilizing cartilage counter surfaces with a complete subchondral bone plate and compare the results to the cartilage on glass and metal (steel) counter surfaces. Articular cartilage surfaces with the underlying subchondral bone intact were not isolated through plug removal. Friction testing was completed using a tribometer (n=16). The coefficient of friction (COF) was measured between the proximal articular surfaces of the second carpal bone when brought into contact with the articular surface of the distal radial facet. The COF of the distal radial facet was obtained with glass and metal counter surfaces. Cartilage-cartilage interfaces yielded the lowest COF when a normal force of 5N and 10N was applied. No statistically significant increase in COF was noted for any combination when an increased normal force was applied (10N), although an increase was observed when glass and metal was in contact with cartilage. COF significantly increased when comparing the cartilage counter surface to metal under an applied load of 5N (p=0.0002). When a 10N load was applied, a significant increase in the COF was observed when comparing the cartilage counter surface to both the glass and metal counter surfaces (p=0.0123 and p < 0.0001 respectively). Results have shown that the described methodology was accurate, repeatable, and emulates physiologic conditions when determining the friction coefficient. The determined COF of cartilage against cartilage is significantly lower than cartilage against metal or glass.

Application of Acidizing and Plugging Removal Technology in Chang 2 Reservoir of CH Oilfield

In view of the serious scale and blockage in Chang 2 reservoir of a certain oil production plant, in recent years, based on the scientific and technological project “Acidification technology test of Chang 2 reservoir in XX-YY District” completed in 2013, a series of blockage removal workers suited to different blockage characteristics in this area have been formed by studying and analyzing a large number of indoor data, optimizing the acidification formula. The dosage of additives is increased, thus protecting oil pipes, rods and pumps, and preventing new pollution caused by precipitation of Ca2+, Mg2+. In view of the specific situation of reservoir blockage, 222 wells have been carried out with various blockage removal measures, such as compound acidification, blockage removal and so on. The cumulative oil increase is 7894.8 tons, with an average of 38.7 tons per well, which has made a positive contribution to the stable production of oil production plants

Influence of energy characteristics of vibropercussion source on efficiency of soil plug removal from casing pipes

This article describes the method of virbopercussion ramming of an open-ended steel pipe in soil. The study focuses on interaction between the pipe and internal soil plug by the law of dry friction. The test bench for the effect exerted by impact impulses on displacement of soil plug is presented. The reduction in the friction force under the simultaneous static influence on the soil plug and vibropercussion load on the pipe is evaluated. The influence of energy characteristics of vibropercussion source on the efficiency of soil plug removal from the pipe is determined.

Analytical and Experimental Analysis of Static Friction Forces of Moving Cables Inside Curved Pipes

In-pipe robots are a powerful tool for hydrate plug removal inside ultradeepwater pipes. Most of these robots operate with the energy supplied by umbilical cables. The present work focuses on the development of a general strategy for computing the required forces for pulling such cables confined in ducts of generic length and geometry. Based on classical mathematical models applied in cable friction evaluation, a new equation set was developed and implemented in a computational algorithm designed to evaluate the static friction force related to the cumulative effects along the arbitrary set of curves present in a generic pipe. Therefore, the proposed computational routine can calculate the static friction forces associated with a cable inside a given pipe, whose coordinates are fed by the user. To evaluate the simulation performance, the achieved results were compared with the data obtained through experimental tests performed using a cable with polymeric coating positioned inside ducts. Different geometries, loads, and lubricating conditions were tested, and the analytical model could suitably estimate the required force to move an umbilical cable inside pipes.

Study on removing calcium carbonate plug from near wellbore by high-power ultrasonic treatment.

In this paper, the effects of ultrasonic wave on the removal of inorganic scaling and plugging in cores and the influence of the key wave field parameters, process parameters and core physical parameters on the plugging removal efficiency are systematically studied. The main dynamic mechanism of ultrasonic plugging removal is also systematically analyzed. Results show that the transducer frequency, transducer power, ultrasonic treatment time and initial permeability of core have great influence on the effect of ultrasonic scale removal. When the cumulative treatment time of ultrasonic wave exceeds 60 min, the recovery rate of core permeability tends to be stable. Best effect can be achieved when processing for 80-120 min cumulatively; the plugging removal effect is improved with the increase of ultrasonic transducer power and ultrasonic frequency, but the effect of plugging removal is not obvious with the further increasing of them. In addition, it is proved that the effect of removing calcium carbonate plug from near wellbore by hydrochloric acid solution is slightly better than that by ultrasonic treatment alone. Finally, the micro dynamic mechanism of removing inorganic scale plug by high-power ultrasonic treatment is discussed in view of ultrasonic inorganic scale body crushing, ultrasonic cavitation, ultrasonic friction, ultrasonic peristaltic transport operation and ultrasonic fracture-making and permeability-increasing effect.

CONCERNING TO REMOVAL METHODS HYDRATE FORMATION (ON EXAMPLE OF URENGOY FIELD)

Background At present, the development of gas fields is in most cases complicated by the increase in moisture content in natural gas. The main reason for this phenomenon is a decrease in pressure, gas temperature and, as a result, this leads to the appearance of water vapor that has condensed and accumulated in wells and gas pipelines. Further saturation of natural gas at an elevated pressure and positive temperature can lead to the formation of solid physicochemical compounds - hydrates. The occurrence of such crystalline substances can lead to the blockage of wells, gas pipelines, separators, disruption of the work of stabilizing and gauging devices, and as a result to a decrease in the level of oil production. Often, pressure regulators and fittings fail, gas is throttled, accompanied by a sharp decrease in temperature, and the disruption of the normal operation of the oil and gas production equipment. Aims and Objectives Determination of factors affecting the intensity of hydrate formation, and the study of methods to combat the formation of gas hydrates on the example of the Urengoy field. Results The factors that directly affect the intensity of hydrate formation are determined: moisture content, temperature, pressure, component composition of the gas. The possible places for gas hydrates formation are given: at fittings, in piping of pipes, in separators, in loops, on diafragms of metering sections. The main methods of preventing the hydrate formation and removal of hydrate plugs are present: increasing the gas temperature, reducing the gas pressure, removing moisture from the gas using absorbents and adsorbents, inhibitors. Methods for the control of hydrate formation, using in Urengoi field, are presented. A thermal calculation of the plume was performed, which allows determining the temperature change along the gas pipelines and determining the possible place of hydrate formation.

Repair of cartilage defects with devitalized osteochondral tissue: A pilot animal study.

Devitalization using high hydrostatic pressure (HHP) treatment inactivates cells while matrix structure and biomechanical properties are maintained. Because of strong chondroinductive potential of HHP-devitalized cartilage matrix, it may be used as scaffold for reconstruction of (osteo-)chondral lesions. In this pilot study, we evaluated the feasibility of HHP-devitalized osteochondral tissue to repair osteochondral defects in a rabbit model. Removal and reimplantation of osteochondral plugs were performed in 12 female New Zealand White rabbits. From the knee joint of each animal, osteochondral plugs (diameter = 4 mm; depth = 2.5 mm) were harvested and devitalized by HHP (452 MPa for 10 min). Afterward, the plugs were reimplanted into the respective cavity, from where they were taken. Animals were sacrificed 12 weeks postoperatively and the integration of osteochondral plugs was examined using μ-CT, MRI, and histological staining. Furthermore, revitalization of HHP-treated osteochondral plugs was characterized by gene expression analyses. Macroscopic evaluation of tissue repair at implantation sites of HHP-treated osteochondral plugs showed an adequate defect filling 12 weeks after implantation. Plug margins were hardly detectable indicating successful tissue integration. Additionally, gene expression analyses demonstrated initial revitalization of the HHP-treated tissue 12 weeks postoperatively. Our preliminary data revealed that HHP-treated osteochondral plugs could be used to refill osteochondral defects in the knee joint and promote cell migration into defect site. Data indicated that HHP-treated tissue has the potential to act as functional scaffolds for reconstruction of cartilage defects. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2354-2364, 2019.

Laboratory Experiments on the Removal of Soil Plugs During Soil Piping and Internal Erosion

Abstract. Plugging of soil pipes can be detrimental to hillslope stability. A soil pipe commonly becomes plugged through internal erosion when the pipe wall collapses. When a pipe becomes plugged, a pressure buildup occurs upslope from the plug. This pressure may be enough to remove the plug, or the pressure may continue to build in the soil matrix, which may lead to hillslope failures. Based on field observations, it is known that both processes occur, but limited data exist to understand if and when plug removal or pressure buildup occurs or how to model these processes. This study involved well-controlled laboratory experiments to determine instantaneous pressure buildup behind soil plugs and conditions for which an idealized plug in a soil pipe will be removed. Laboratory experiments were conducted with a smooth or roughened 100 cm long clear polyvinyl chloride (PVC) pipe. A pipe plug (3 or 6 cm) was established 90 cm along the pipe length. Triplicate experiments were conducted with two pipe diameters, two soil types (sand and sandy loam), two plug lengths, three pipe roughness values, various packing densities, and with both dynamic and constant pressure heads. Digital pressure gauges were installed to monitor pressures in the pipe both before and after the plug. The upslope pressure and the length of time that the plug withstood the pressure before removal were recorded. Regardless of pressurized time, all plugs were initially mobilized as intact plugs and then in many cases quickly disaggregated. Some sandy loam plugs withstood pressures of 100 cm; more cohesive plugs could withstand much higher pressures. In addition, pressurized times exceeded 1000 s for some plug conditions even with short (3 to 6 cm) plugs. Therefore, hillslopes upslope of a plugged soil pipe may experience considerable pressure buildup for extended periods of time. Plug physical characteristics are important; for example, the plug’s bulk density had a positive exponential relationship with the pressurized time. Soil water dynamics inside the plug will need to be considered, as well as the hydraulic boundary providing inflow to the soil pipe. These experiments provided insight into the dynamics of plugged soil pipes with the eventual goal of assisting in being able to better predict internal erosion and hillslope failure. Future experiments are needed across a wider range of soil types. Keywords: Hillslope, Internal erosion, Macropore, Pipe clogging, Pipeflow, Pressure buildup, Sediment transport, Soil plug.

Oxygen Alkaline Dental's Cleaners from Tooth Plaque, Food Debris, Stains of Blood, and Pus: A Narrative Review of the History of Inventions.

Objective:This review shows the history of inventions of devices, hygiene products, and methods of dissolution and removal of pus, sulfur plugs, blood crusts, and plaque.Material and Methods:The search for inventions was carried out in the databases, such as Google Patent, Google Scholar, Scopus, and PubMed. The key words used in this search were as follows: toothbrushes, toothpicks, toothpastes, plaque, cleaning products for teeth and dentures, teeth whiteners and dentures, bleach bruises and blood stains, pus, sulfur plugs, and pus solvents. A total of 24 inventions were evaluated for review.Results:In recent years, hygiene products that quickly dissolve and bleach pus, sulfur plugs, blood stains, and plaque because of alkaline saponification of protein–lipid complexes and cold boiling inside the biological masses have been invented. Such an action has a heated above 37°C supersaturated sodium bicarbonate solutions containing hydrogen peroxide in moderate concentrations and gaseous oxygen under excessive pressure. Cold boiling inside the dense biological masses occurs under the action of catalase and/or due to the normalization of internal pressure in the solution.Conclusion:Alkalinity, hyperthermia, and hyperoxygenation of solutions with high internal pressure optimize whitening of teeth and dentures because of alkaline saponification and cold boiling.

Analysis of ethanol as plug removal agent in near borehole zones for coal bed methane

As coal bed methane (CBM) gas production can be reduced by reservoir pollution within near borehole zones, the feasibility of the use of ethanol as a plug removal agent and its impact on gas production are discussed in this paper. Four representative samples of Yima, Datong, Shaqu, and Yangquan coals were selected across a range of different ranks and were soaked with ethanol for experiments, and their change characteristics before and after treatment were compared using optical microscopy, mercury intrusion, and isothermal adsorption techniques. The results of this analysis revealed that the pore volume and porosity of coal samples increased following ethanol treatment, while the affinity for methane was significantly reduced. The use of ethanol was also advantageous because it reduced water lock and damage. This research showed that the use of ethanol as a plug removal agent in CBM near borehole zones has significant potential engineering applications.

Reversible deafferentation of the zebrafish olfactory bulb with wax plug insertion

BackgroundDeafferentation of the zebrafish olfactory bulb allows investigation of neuroplasticity in a particularly dynamic brain region of a popular model animal known for its regenerative abilities. Current methods to remove sensory input to the zebrafish olfactory bulb differ in the extent of deafferentation and potential for recovery. New methodWe present a novel method of olfactory bulb deafferentation using continuous wax plug insertions into the nasal cavity of zebrafish. Wax plugs were placed in the nasal cavity and replaced if needed over 1wk or 3wk survival periods. Wax plugs were removed from fish after 1wk of occlusion to analyze the potential recovery of the olfactory organ and bulb. ResultsWax plug insertions caused a dramatic reduction in olfactory organ size and structure and significantly reduced afferent input to the olfactory bulb after 1wk and 3wk. Removal of the wax plugs after 1wk allowed for recovery of the olfactory organ and subsequent reinnervation of the olfactory bulb. Comparisons with existing methodsChemical ablation with detergent causes partial, temporary deafferentation of the olfactory bulb. Cautery ablation causes complete, permanent deafferentation of the olfactory bulb. Wax plug insertions cause nearly complete, temporary deafferentation, allowing both significant deafferentation and the potential for reinnervation of the olfactory bulb. ConclusionsThe wax plug insertion method of deafferentation described here is unique in that it destroys almost completely the structure of the olfactory organ and removes almost completely sensory input to the olfactory bulb, yet the organ returns to its typical morphology and afferent innervation returns.

Using cupriethylenediamine (CED) solution to decrease cellulose fibre network strength for removal of pulp fibre plugs

AbstractThe pulp and paper industry is the largest industrial sector that converts wood‐based materials into fibre‐related products. It is common for pulp fibre plugs to develop within pipelines and equipment causing operational downtime, which ultimately requires the use of costly procedures for plug removal. In this study, a laboratory‐scale set‐up was developed to measure the breakup pressure of pre‐formed plugs to indicate the plug (fibre network) strength. A cupriethylenediamine (CED) solution was investigated with regards to its ability to decrease the plug strength. When the concentration of the CED solution is 0.1 M or lower, the plug breakup pressure increases due to fibre swelling. Conversely, when the CED concentration is 0.2 M or greater, the plug breakup pressure decreases significantly due to partial fibre dissolution.