Plug Formation Process Research Articles

Czynniki wpływające na proces piaszczenia w odwiertach kierunkowych

Many wells of offshore fields in Azerbaijan are subject to sanding and plugging. This is especially observed in wells at a late stage of development. The process of plug formation in directional wells is known to be characterized by a variety of factors associated with both natural conditions and the parameters of their development and, most importantly, operation. The degree of influence of the factors varies, in addition to the fact that all of them (directly or indirectly) are interconnected. Sand production is often observed during completion (development) and operation of wells, especially when the productive reservoirs are represented by weakly cemented rocks. It is worth noting that in the case of sand plug formation, the permeability of which is 200 times greater than the per-meability of the productive formation, the oil production rate decreases by 34%. This sand contains up to 5% of oil and poses a problem upon its removal, as it results in environmental contamination. In addition, it deposits in pipelines, surface equipment, causing erosion. This kind of complication is almost universal. Sand removal is one of the main reasons for the formation of cavities and collapse of columns. This problem has acquired particular relevance with the development of thermal methods for the extraction of high-viscous oils: the viscosity of oil decreases, and its fluidity increases. In this case, some reservoirs lose their cementing binder - viscous oil. During planned and emergency shutdowns, when the coolant injection stops, the reverse flow of the coolant enters the injection wells and removes mechanical impurities. This also leads to the formation of sand plugs in the wells and prevents the normal injection of the coolant. The existing methods of operating wells affected by sanding can be divided into two groups: 1) operation of wells with the removal of sand from the reservoir; 2) prevention of sand production from the formation.

Flow loop study of a cold and cohesive slurry. Pressure drop and formation of plugs

Slurries of cohesive particles constitute a significant risk during subsea petroleum production due to their potential to plug the flow. This article describes a flow loop study of a slurry consistent with 0.23-mm ice particles in decane. The experiments were conducted for the concentration of particles up to 20.3% vol. and Re < 25000. The cohesion of ice was suggested by controlling the temperature of the slurry. The relative viscosity of the slurry was computed as a function of particle concentration using pressure drop measurements. The relative viscosity was 3.1 for the concentration of 20.3%. The Bingham-fluid model agreed with the empirical calculations within the discrepancy of 15.5%. Increased viscosity of slurry led to a higher pressure drop in the flow loop compared to the single-phase case. Pressure drops for 20.3% slurry flow were 5.2% and 44.4% higher than for pure decane at Reynolds numbers of 24778 and 4956, respectively. The test section of the loop was equipped with an orifice to induce the formation of plugs. The plugs were observed at particle concentrations below 7.0%. The article presents detailed experimental logs depicting the process of plug formation. The observed blocking cases partially agreed with flow maps from the literature. In addition, we note the applicability of the blockage risk evaluation technique from the Colorado School of Mines.

An Efficient No-Shutdown Pipe-Fixing Freezing Design for Water Management System in Hospitals during COVID-19: A Case Study

Ensuring the uninterrupted flow of the complex piped water distribution networks to combat the COVID-19 pandemic in Taiwan’s hospitals has become a priority. The process involved in the no-shutdown pipe fixing freezing method depends on the water supply system design and the conditions of the environment. Before carrying out repair works onsite, two experiments were undertaken to estimate the liquid nitrogen supply rate and make sure of its adequacy in relation to the fixing system’s heat transfer performance. Using an iron exhaust pipe and galvanized steel inlet pipe with jacket for a 50-mm-diameter water pipe, temperature variations and timelapse were recorded and analyzed. The results showed that the frost length on the water pipe surface at either side of the jacket was 1.2–1.8 times of the pipe diameter. The ice length (~45 cm) was longer than the jacket (~34 cm), and the water pressure at the jacket inlet side was 1 kg/cm2 greater than at the exit. Injecting the right amount of liquid nitrogen into the inlet and at a proper speed between 0.7 and 0.8 kg/min will ensure a safe and smooth completion of the ice plug formation process. The design and processes have been used successfully in hospital water supply system fixing works.

A bioinspired microfluidic model of liquid plug-induced mechanical airway injury.

Occlusion of distal airways due to mucus plugs is a key pathological feature common to a wide variety of obstructive pulmonary diseases. Breathing-induced movement of airway mucus plugs along the respiratory tract has been shown to generate abnormally large mechanical stresses, acting as an insult that can incite acute injury to the airway epithelium. Here, we describe a unique microengineering strategy to model this pathophysiological process using a bioinspired microfluidic device. Our system combines an air-liquid interface culture of primary human small airway epithelial cells with a microengineered biomimetic platform to replicate the process of mucus exudation induced by airway constriction that leads to the formation of mucus plugs across the airway lumen. Specifically, we constructed a compartmentalized three-dimensional (3D) microfluidic device in which extracellular matrix hydrogel scaffolds reminiscent of airway stroma were compressed to discharge fluid into the airway compartment and form liquid plugs. We demonstrated that this plug formation process and subsequent movement of liquid plugs through the airway channel can be regulated in a precisely controlled manner. Furthermore, we examined the detrimental effect of plug propagation on the airway epithelium to simulate acute epithelial injury during airway closure. Our system allows for a novel biomimetic approach to modeling a complex and dynamic biophysical microenvironment of diseased human airways and may serve as an enabling platform for mechanistic investigation of key disease processes that drive the progression and exacerbation of obstructive pulmonary diseases.

A continuum model for platelet plug formation and growth

When the wall of a blood vessel is damaged, the immediate response of the body to prevent blood loss is the creation of a platelet plug. The process is both chemical (platelets are chemically activated to adhere to the injured wall) and mechanical (platelets are convected by blood flow, which interacts with the forming plug). A continuum model for platelet plug formation and growth is presented in this work, which allows to study the interaction between platelet plug morphology and local haemodynamics. The numerical framework consists of two parts: a biochemical model combined with a new plug growth model. The biochemical model is a system of convection-diffusion-reaction equations, each of which represents the dynamics of platelets and chemicals involved in the plug formation process. The plug growth model defines the plug interface displacement based on the outcome of the biochemical model, that is, on the number of deposited bounded platelets on the injured part of the vessel wall. Results for different cases are shown, together with a comparison between the sole biochemical model and the complete model that includes plug growth. The framework opens the way to the development of continuum models for full blood clot formation and growth in physiologically relevant configurations.

Evaluation of the plug formation process of silicified microcrystalline cellulose

To investigate the powder plug formation process of silicified microcrystalline cellulose (SMCC) under compression forces consistent with automatic capsule-filling machines, a single-ended saw-tooth wave was used to make powder plugs with different heights (6, 8, 12 mm), at two different punch speeds (1 and 50 mm/s) on a tablet compaction simulator. SMCC was compared to Starch 1500, anhydrous lactose (direct tableting grade), and microcrystalline cellulose. Heckel analysis showed that ‘apparent mean yield pressures’ (AMYP) of all tested materials increased with an increase in the plug height and punch speed. AMYP appeared to depend on the material type and punch speed. Not all materials fit the Shaxby–Evans relationship at such low compression forces (less than 250 N). Only SMCC 90, SMCC HD90 and anhydrous lactose data fit the equation at both punch speeds. Due to poor axial load transmission, the R values of all tested materials decreased with an increase in the plug height. The experimental data fit the Kawakita equation quite well. Overall, Kawakita's b values were inversely related to AMYP values. The maximum breaking force (MBF) of a 12 mm plug formed at a punch speed of 50 mm/s correlated well with the work of compaction, except for SMCC HD90 and SMCC X, which exhibited very high MBF values. This research demonstrated that several grades of SMCC produced plugs having higher MBF than anhydrous lactose and Starch 1500 under similar compression conditions. The apparently higher compactability of these materials at low plug formation forces may be beneficial in developing direct fill formulations for automatic capsule filling machines.

Capsule Filling Machine Simulation. I. Low-Force Powder Compression Physics Relevant to Plug Formation

The objective of this study was to simulate powder plug formation and explore the low-force powder compression physics of the process. A single-ended saw-tooth waveform was used to make powder plugs, representing no. 1 size capsules, at constant punch speeds of 1, 10, and 100 mm/sec on a tablet compaction simulator. Plugs of different heights (4, 8, and 12 mm) were made in a prelubricated die from three materials: Avicel PH 102, anhydrous lactose, and Starch 1500. The compression data were fit to Heckel's pressure–density relationship, Kawakita's pressure–volume relationship, and Shaxby–Evans's exponential relationship. Heckel analysis of this low-pressure range data revealed “apparent yield pressures” of 25–70 MPa, which were dependent upon the material type, machine speed, and plug height. Shaxby–Evans's relationship was found to hold in that the axial load transmission decreased exponentially with increased plug height/diameter ratio. A dramatic decrease in the coefficient of lubrication, R, with increase in plug height was attributed to poor axial load transmission through the length of the plug. Kawakita's pressure–volume relationship fit the plug formation data very well, and it was evident from this model (Kawakita constant, a) that Avicel PH 102 had the largest available volume for reduction. The plug formation process can be simulated using a programmable tablet compaction simulator. Overall, the data analysis demonstrated that the compression models available for tableting that were used in this study can also be applied to the powder plug formation process with appropriate interpretation.

Hydrate plugging problems in undersea natural gas pipelines under shutdown conditions

Undersea oil and gas transportation pipelines in cold regions often have thermodynamically suitable conditions for the formation of gas hydrates. There is a widespread concern in the petroleum industry that the hydrate formation could result in a partial or complete plug. A shutdown offshore pipeline condition is emulated in the laboratory to obtain methane hydrate plug formation data. The experiments were conducted at a temperature of 274 K and at pressures of 4, 5 and 7 MPa. Furthermore, a mathematical model which couples intrinsic hydrate formation kinetics with heat and mass transfer phenomena is presented to describe the overall hydrate plug formation process. The effective diffusivities of methane gas through hydrate are estimated by matching the model predictions with the experimental data. The results indicate that the plugging problem is not severe for an unplanned pipeline shutdown for periods less than 48 h. However, caution in the restarting procedure is recommended.

Growth and ultrastructural differentiation of sporangia in Phytophthora palmivora.

Development of sporangia in Phytophthora palmivora Butler consists of two main stages. The first involves expansion of the sporangial initial to about the size of the mature sporangium, whereas the second is characterized by the differentiation of the expanded vesicle to the mature sporangium. Differentiation includes basal plug formation, secondary sporangial wall thickening, and apical papilla formation.Expansion of the sporangial initial appears to be mainly the result of cytoplasmic inflow from the mycelial mat coupled with surface growth of the vesicle wall. Basal plug formation terminates the phase of expansion. The process of plug formation involves deposition of wall-like material at the base of the expanded vesicle. The depositions, which grow from the periphery towards the center of the sporangiophore, are at first rather irregular in shape but eventually lead to complete occlusion, thus separating the immature sporangium from the sporangiophore. Sporangial wall thickening starts at the basal plug and progresses towards the developing apical papilla. Papilla formation is initiated by an apical bulge of the immature sporangium. The cytoplasm within the bulge is specialized and characterized mainly by populations of small (50–100 nm) and large (about 250 nm) vesicles, which appear to be involved in papilla formation. Papilla deposition resembles hyphal tip growth in the absence of cell expansion.