Pipe Blockage Research Articles

Experimental study on the diagnosis of operation state of gas extraction pipeline based on pressure gradient method

ABSTRACT The working state of the gas drainage pipe network is the key to the safe drainage of underground mine gas. In order to quickly and accurately determine whether the pipe network is working normally, the flow law of the gas in the pipeline is studied. A diagnosis method of gas extraction pipeline by pressure gradient method is established. A gas drainage pipe network experimental platform is constructed. And the blockage and leakage of single pipe are carried out. The influence of air leakage of main pipe on negative pressure of branch pipe is studied, as well as the influence of negative pressure change of temporary pumping station on parallel pipe is explored. The method of image photography is proposed to calculate the pipeline flow, and the error is 2.7% compared with the orifice flowmeter. The results show that when the abnormalities exist in the extraction pipeline, the slope of the pressure curve corresponding to the abnormalities increases rapidly, the slope of the downstream curve is slightly larger than the slope of the upstream curve when the pipeline is leaking, and the slope of the downstream curve returns to the same as the slope of the upstream curve when the pipeline is blocked. The closer the location of the vacuum pump is to the air leakage, the faster the negative pressure of the vacuum pump decreases, and the less it affects the negative pressure of the branch circuit. When the downhole temporary pumping station extraction system is connected in series with the permanent pumping station extraction system on the ground, the temporary pumping station’s negative pressure value needs to be set reasonably, seriously affecting the extraction effect of the adjacent extraction pipeline. Finally, monitoring the gas drainage pipeline in Yuwu mine by pressure gradient method, it is found that the pressure drop slope at measuring points 6–7 is abnormal (−3 × 104), and the pressure drop slope of measuring points 7–8 returned to normal (−7 × 105), so it is judged that the drainage pipeline is blocked at 1300–1500 m away from the pump station.

Identification of inlet pipe blockage level in centrifugal pump over a range of speeds by deep learning algorithm using multi-source data

This paper focusses on the identification of the blockage fault in the inlet pipe of centrifugal pump over a range of speed using data obtained from different types of sensors. Acceleration, pressure and motor line current signatures taken using accelerometer, pressure transducer and current probe, respectively, and are used for identification of the pipe blockage level. Methodology is given for the blockage detection based on the multiclass classification using the deep learning algorithm at different blockage levels and speed of rotation of the pump. Importance of the multi-source data collection is emphasized based on the obtained results. Effect of the motor speed is also discussed when considered as an input feature to the classifier. It is observed that the use of combinations of different types of sensors help to identify the blockage level with better accuracy (close to 100% for many combinations). Blockage level prediction at each speed separately, is also given, which can be used for the fault diagnosis of single speed pumps. Finally, the performance of the classifier is tested using some unknown data (different from the data at training speed) to check the blockage prediction accuracy of the classifier.

Application of coal seam grouting to prevent and extinguish fire technology in Fusheng Coal Mine

Spontaneous combustion of coal not only releases toxic and harmful gases, but also may cause gas and coal dust explosions to endanger the lives of miners. The No.15 coal seam of Fusheng Coal Mine in Shanxi has a short period of spontaneous combustion and is prone to spontaneous combustion. In order to prevent spontaneous combustion of coal seams, it is proposed to use grouting to prevent fire extinguishing technology, mainly through the design of grouting system, the selection of grouting materials, the calculation of grouting parameters, the optimization of grouting technology and the selection of grouting equipment, etc. And it establishes methods for monitoring the effects of grouting zone temperature and gas composition, fire-fighting grouting accounts, etc. A series of grouting safety technical supporting measures such as grouting work system, prevention of pipe blockage, prevention of slurry running, setting of filter slurry sealing and drainage channels, etc. are proposed.

Fault Simulation and Experimental Study on High-Thrust LOX/LH2 Rocket Engine

In order to locate the fault in a test of a high-thrust LOX/LH2 engine, the dynamic characteristic simulation model library of liquid rocket engine is established, and the dynamic characteristic simulation model of the high-thrust LOX/LH2 engine is built. The accuracy of the simulation model is verified by comparing the model with the experimental parameters. According to the possible faults of the engine, the simulation calculation is carried out in turn, and the results are compared with the measured parameters. Through the comparison, it is found that the most likely failure mode is the blockage of the exhaust pipe of the oxygen turbine. The simulation results verified by experiments were in good agreement, which not only proves the accuracy of fault location, but also proves the feasibility of fault location of high-thrust oxyhydrogen engine by dynamic simulation, laying a foundation for further development of fault monitoring and location technology for high-thrust LOX/LH2 rocket engine in the future.

Anti-Blocking Mechanism of Flocking Drainage Pipes in Tunnels Based on Mathematical Modeling Theory

Crystalline pipe plugging in tunnel drainage systems is one of the causes of tunnel lining cracking and water leakage. Therefore, effective prevention of crystalline pipe blockage in tunnel drainage systems is very important to ensure the safety and stability of the lining structure during tunnel operation. Combined with the theories of fluid mechanics, structural mechanics and basic physics, the flocking and anti-blocking mechanism of drainage pipe was comprehensively analyzed by using the method of mathematical modeling, including: (1) the calculation expression of average velocity of the flocked section of a flocked drainage pipe v = Q/(C1 − C2(r + r′)) and the calculation formula of flowing water pressure under the action of groundwater Fw = KAγQ2/(2g(C1 − C2(r + r′))2); (2) the flow velocity v0 in the flocked drainage pipe shall meet v2 < 4gπrlτ1/γKA, crystals will be attached to the fluff and the crystals will maintain dynamic balance; (3) the flow velocity v0 in the flocked drainage pipe shall meet v2 ≥ 4gπrlτ1/γKA, crystals will not adhere to the fluff and the flocked drainage pipe will remain unobstructed. The research on the mechanism of preventing blockage of flocking drainage pipes fills the gap in research theory in this regard, contributes to the popularization and application of blocking prevention technology of flocking drainage pipes, reduces the maintenance cost during operation of tunnel drainage systems and ensures the safe and normal operation of tunnels.

Correlating Antiagglomerant Performance with Gas Hydrate Cohesion.

Although inhibiting hydrate formation in hydrocarbon-water systems is paramount in preventing pipe blockage in hydrocarbon transport systems, the molecular mechanisms responsible for antiagglomerant (AA) performance are not completely understood. To better understand why macroscopic performance is affected by apparently small changes in the AA molecular structure, we perform molecular dynamics simulations. We quantify the cohesion energy between two gas hydrate nanoparticles dispersed in liquid hydrocarbons in the presence of different AAs, and we achieve excellent agreement against experimental data obtained at high pressure using the micromechanical force apparatus. This suggests that the proposed simulation approach could provide a screening method for predicting, in silico, the performance of new molecules designed to manage hydrates in flow assurance. Our results suggest that entropy and free energy of solvation of AAs, combined in some cases with the molecular orientation at hydrate-oil interfaces, are descriptors that could be used to predict performance, should the results presented here be reproduced for other systems as well. These insights could help speed up the design of new AAs and guide future experiments.

A Coupled Hydrate and Compositional Wellbore Simulator: Understanding Hydrate Inhibition from Associated Brines in Oil and Gas Production

Summary Hydrates are ice-like solids composed of a water-based lattice “encaging” gas molecules. They form under conditions of high pressure and low temperature. In the oil and gas industry, where these conditions are easily met, hydrate formation may cause pipe blockages and severe financial implications, making its prevention (and remediation) one of the main flow-assurance concerns. Desired hydrate inhibition may come from electrolytes naturally dissolved in the water that is produced in conjunction with the hydrocarbon stream, or alcohols can be deliberately injected for such a purpose. When trying to predict hydrate conditions in real-world production systems, computer simulation should ideally integrate hydrate and multiphase-flow calculations. Failing to do so [by performing a decoupled analysis with a flow simulator and a separate pressure/volume/temperature (PVT) package for example] may generate misleading results under certain flow conditions. This paper presents an integrated wellbore simulator to deal with this issue. A hydrate model is added to verify hydrate formation for specific pressure, temperature, and composition of each gridblock. Integration with a geochemical package allows consideration of electrolyte inhibition coming from the associated brine. After successfully comparing results with the available simulators and the experimental data, it is demonstrated that when flowing gas/water ratios (GWRs) exceed 105 scf/STB, water condensation throughout the flow may dilute the beneficial effect arising from the brine composition, thus reducing electrolyte inhibition. Conversely, mineral precipitation along the flow path has shown a nearly negligible impact on this effect.

Study on the relationship between slurry film thickness and rheology of fillers based on film theory

The key problem of paste filling technology lies in whether paste can meet the requirements of stope structural parameters on cementing strength, pipe transportation and mining methods on filling performance. The separated paste will cause serious wear and even pipe blockage in the pipeline transportation process. If the paste is separated in the stope, the strength of the filling body will be uneven, and accidents such as delamination and stacking will occur. The occurrence of these situations is extremely unfavorable to the filling operation. Just as the material determines the performance, in order to ensure the paste has excellent filling performance, it is necessary to systematically study the internal relationship between paste filling materials and filling performance. Paste is a complex suspension system composed of aggregate, water, cementing materials and additives. Compared with traditional low-concentration classified tailings slurry, it has the characteristics of wide particle size distribution, high solid content, strong chemical action on particle surface, etc. Under the interaction of these factors, paste presents macroscopic characteristics such as plasticity and stability. These macroscopic characteristics are embodied in rheology, that is, rheological characteristics of paste. The research shows that the rheological properties of paste are affected by the gradation, concentration and cementing material of filling material, and the change of gradation of filling material has the most significant effect on the rheological properties of paste. The change of the micro-level composition causes the change of the rheological properties of the paste on the macro level, thus causing the change of the paste filling performance. In the final analysis, the gradation of the traceable filling material is an important factor that determines the paste filling performance.

Optimization Study of Fluffy Materials Flocking Drainage Pipes to Resist Blockage Based on MD Binding Energy

Drainage pipe blockage resulting from crystals is one of the causes for cracking and leakage of tunnel lining. Therefore, effective prevention from drainage pipe blockage caused by crystals is crucial to ensure the safety and stability of lining structures during the operation of tunnel drainage system. Based on a large number of indoor model tests and numerical simulation analyses, binding energy between four materials and the calcium carbonate aqueous solution (“solid + liquid” system) and that between the four materials and the two typical growth crystals of calcium carbonate (“solid + solid” system) were studied. The research results indicated that: (1) The four materials all had an adsorption effect on the calcium carbonate aqueous solution system, and the PA6 had the greatest adsorption effect while the PP had the smallest adsorption effect; (2) There was spontaneous adsorption between the PVC or PA6 and the two typical growth crystals of calcium carbonate and no adsorption between the PP or SiC and the two typical growth crystals of calcium carbonate unless external energy was in place; (3) The PP and SiC can be used as the materials for drainage pipe flocking, but it shall be ensured that the fluffy material has a good geometrical property. The prevention technology for crystallization that causes drainage pipe blockage fills the gap in the research of drainage pipe blockage caused by crystals, which can reduce the maintenance cost for the operation of the tunnel drainage system and ensure safe and normal operation of the tunnel.

Investigation of CO2 hydrate slurry flow characteristics with particle dissociation for carbon storage and transportation

CO2 capture and storage technology is an effective method to mitigate the greenhouse effect and hydrate slurry is a high-efficiency way of CO2 transportation. In this study, in order to further reduce the cost and improve the transportability, a new CO2 hydrate slurry transport mode which allows a small part of hydrate particles to dissociate during flow process is proposed. To investigate the CO2 hydrate slurry flow characteristics and particle micro behaviors, a multiphase flow model coupled with hydrate dissociation kinetic model and population balance model is established. Experimental results are used to verify this integrated model. Furthermore, the effects of hydrate dissociation on CO2 transportability are also analyzed. The results indicate that the dissociation rate of hydrate during flow process can be divided into rapid dissociation stage and weakened dissociation rate stage. The agglomeration of hydrate particle can reduce the total surface area, further resisting the dissociation rate. The hydrate particle size experiences a process of growing to dynamic balance. The hydrate dissociation can decrease the mean viscosity of CO2 hydrate slurry flow, which can reduce the pressure drop and energy loss compared with the flow without hydrate dissociation. The generated bubbles can accelerate the CO2 hydrate slurry flow, increasing the transportability and reducing the risk of hydrate blockage in pipe induced by agglomeration.

Neural network identification of water pipe blockage from smart embedded passive acoustic measurements

AbstractThis study presents a new neural network approach to identify the presence and type of obstruction in pipes from measurements of passive acoustic emissions. Inserts were used in a fluid re‐circulation loop to simulate different types of blockage at various flow rates within the turbulent regime, generating patterns of acoustic emissions. The data were pre‐processed using Fourier analysis, and two candidate sets of statistical descriptors were extracted for each measurement. The first set used average and spread of the Fourier transform amplitudes, the second used data binning to obtain a concise representation of the spectrum of amplitudes. Experimental evidence showed the second set of descriptors was the most suitable to train the neural network to recognize with accuracy the presence and type of blockage. The obtained results compare favourably with the literature, indicating that the approach provides a tool to enhance process monitoring in water supply systems, in particular early detection of upstream blockages.

A new highly stable methane hydrate from the synergic mixture of common promoters: Experimental and modeling surveys

One of the main issues in flow assurance in offshore operations, specially at high pressure conditions as in deep pipelines is the formation of hydrates in the corners of pipelines that causes notable problems like pipe blockage followed by an explosion. Hydrate or gas hydrate is a bright solution for gas storage and transportation. Tetrabutylphosphonium bromide (TBPB) and tetrabutylammonium bromide (TBAB) are salts capable of tackling the thermodynamic and kinetic limitations of hydrate formation/dissociation conditions. In the present work, the effect of TBAB, TBPB and TBAB + TBPB mixture on CH4 hydrate dissociation condition was studied. All experiments were performed by pursuing a constant-volume pressure search technique with the step heating approach to study the effects of additive mixtures with different compositions. A mass fraction of 5%, 10% TBAB/TBPB was used. The experiments were conducted at 280–290.05 K and 1–5.5 MPa. In all the conducted experiments, the mixture had a promoting effect. After generating the accurate data of TBAB-TBPB-CH4 hydrate in water system, a thermodynamic prediction model was developed to investigate efficient hydrate-based applications. The hydrate phase was predicted on the basis of Chen and Guo's approach. Soave−Redlich−Kwong equation of state was applied to predict the required methane properties in the gas phase. The TBAB-TBPB activity coefficient and water activity in the electrolyte phase were obtained through the Bromley equations. The results of the proposed thermodynamic model showed that there is a satisfactory accordance between the experimental phase equilibrium data and the predicted data with an acceptable AARD % of 0.95%.

Treatment Technology of Closed Tunnel Filled with Water

During the construction of No.3 connection gallery between huyong station and lvdaohu station of first phase project of Line 2 Foshan Rail Transit, water and sand kicks caused the large-scale settlement of tunnel segments. After comparison and selection of schemes, the rehabilitation scheme of abandoning the existing right line tunnel, shield machine starting from huyong station and heading to Lvdaohu Station by changing the line, is finally adopted. In order to prevent secondary disasters caused by the collapse of abandoned tunnels, the ground boreholes are used to fill the abandoned tunnels. During the construction, a series of key construction technologies have been formed, such as sectional backfill of abandoned tunnel, alternate backfill of underwater concrete and mortar, and prevention of pipe blockage. The results of core-drilling test and subsequent construction procedures show that the treatment scheme of abandoned tunnel is reliable and feasible, which can provide reference for similar projects.

Effect of Monitoring Points on Detection Accuracy of Incomplete Blockage in CO2 Pipeline

Based on the transient pressure wave method, this paper uses OLGA simulation software to detect CO2 incomplete pipe blockage, sets different monitoring points in the pipeline, uses its pressure response data for the calculation of blocking position, blocking length and strength, and determines the best monitoring point by analyzing the relative error of specific blocking parameters. For blockage length, when the monitoring point is close to the blockage position, it has the highest measurement accuracy and a relative error of less than 0.535%. Therefore, the monitoring point should be set up separately at the pipe entrance and near the front of the blocking position, so that the internal blockage of the pipe can be detected more accurately and effectively.

Analysis of Construction Quality Problems of Indoor Drainage Installation

If the indoor drainage pipe is blocked and the drainage is not smooth, sewage and pollutants will enter the room and endanger human health. If the pipeline is blocked as a result, a certain intensity of water pressure may be brought, which may cause pipeline leakage. In this article, we will analyze and explain the quality problems that often occur during the construction process due to the blockage of the internal drainage pipe, and propose appropriate methods and solutions to improve the quality of the project.

Electrical resistivity method to appraise static segregation of gangue-cemented paste backfill in the pipeline

For effective prevention of pipe blockage caused by segregation, a real-time electrical resistivity monitoring method is proposed. The cross-sectional horizontal electrical resistivity (HER) at different depths and diametrical electrical resistivity (DER) with different orientations of gangue-cemented paste backfill (GCPB) under different mass concentrations in pipe were investigated. The results show that HER can capture the real-time segregation characteristics. Under the action of segregation, the HER decline rate in the upper region is greater than that in the lower region at the early stage, and the derived segregation index (SI) gradually decreases. The HER difference in the stable HER change stage between layers decreases with an increase in the mass concentration. DER is less sensitive than HER, and can only distinguish the difference of the static stability between the GCPBs with lower mass concentrations (78% and 79%). Finally, the relationship between ER and aggregate distribution determined by image analysis was established.

Assessment of the Acoustic Reflectometry Technique to Detect Pipe Blockages

Abstract Flow assurance is an important aspect of deepwater pipeline design and operation since one of the critical issues is the eventual initiation and growth of hydrate or paraffin blockages under certain conditions. Another relevant problem is the incidence of inorganic scale deposition in oil well production tubes during operation. Offshore operators can obtain enormous benefits if information regarding the position and extent of an eventual blockage is available since mitigation measures can be optimized. This work deals with experimental and numerical simulations of an acoustic system to identify and measure blockages. The technique uses a short duration acoustic pulse that is injected into the pipe. When the pulse encounters an impedance discontinuity, a portion is reflected toward the acoustic source. The analysis of the measured signal reflections can provide valuable data related to the location and size of the blockages. An experimental setup with a steel pipe of 4 in. internal diameter and length of 100 m was developed to evaluate the suitability of the technique for gas pipelines. In parallel, finite element analyses were performed using the commercial software abaqus to simulate the same physical parameters. The experiments were numerically reproduced with good correlation proving the potential of the technique. Subsequently, a parametric study was carried out to examine the acoustic detection capability using different blockage types. Finally, a prototype of the acoustic reflectometry detection system was developed and tested in a full-scale onshore water-filled pipeline to show the feasibility of the method for detecting blockages.

A review of key tools for oil pipe blockage operation in gas wells under pressure

Blockage in tubing is an important guarantee for gas wells under pressure. The internal blockage is to close the channel inside the tubing through a sealing device, the pipe string can be lifted and lowered under pressure. In order to prevent natural gas from leaking through the tubing channel during well completion and string lifting operations, a plugging tool in the tubing is required to block the tubing channel, and the blockage is removed after the operation is completed to effectively control the pressure in the well. This article starts with the key tools related to internal plugging operations in Snubbing operation, introduces the basic principles of setting the internal plugging barriers when running the tubing string in completion operations, and introduces the key tools for internal plugging when the tubing runs in completion operations. The internal plugging method of the pipe string under pressure is introduced. The key tools (bridge plugs) and setting methods that have been matured or formed at home and abroad when the pipe string is lifted in workover are introduced. Well technology and key tool selection provide reference. Finally, we analyze and think about the domestically developed self-developed internal plugging tools for pressurized operations in my country. It is believed that internal clogging is not an isolated process of oil, gas, and water plugging, but is usually a process of multi-system construction processes working together. The key domestic tools and equipment also need to further improve their autonomous capabilities in terms of overall performance and stability, as well as intelligence.

Spatial heterogeneity assessment of factors affecting sewer pipe blockages and predictions

Efficient management of sewer blockages requires increased preventive maintenance planning. Conventional approaches to the management of blockages in sewer pipe networks constitute largely unplanned maintenance stemming from a lack of adequate information and diagnosis of blockage causative mechanisms. This study mainly investigated a spatial statistical approach to determine the influence of explanatory factors on increased blockage propensity in sewers based on spatial heterogeneity. The approach consisted of the network K-function analysis, which provided an understanding of the significance of the spatial variation of blockages. A geographically-weighted Poisson regression then showed the degree of influence that explanatory factors had on increased blockage propensity in differentiated segments of the sewer pipe network. Lastly, blockage recurrence predictions were carried out with Random Forest ensembles. This approach was applied to three municipalities. Explanatory factors such as material type, number of service connections, self-cleaning velocity, sagging pipes, root intrusion risk, closed-circuit television inspection grade and distance to restaurants showed significant spatial heterogeneity and varying impacts on blockage propensity. The Random Forest ensemble predicted blockage recurrence with 60–80% accuracy for data from two municipalities and below 50% for the last. This approach provides knowledge that supports proactive maintenance planning in the management of blockages in sewer pipe networks.

Flow correlations and transport behaviour of turbulent slurries in partially filled pipes

Transportation of fluids in partially filled pipes is common to many areas of industry (e.g. sewerage, mining, and nuclear), yet many aspects remain under-developed, particularly for multiphase and non-Newtonian flows. In this paper a simple framework to enable the accurate prediction of the bulk flow behaviour and settling characteristics of slurries in open conduits is developed and validated experimentally. The experiments involve measurements of flow rate, flow depth and the settling regime for two different solids concentrations of two types of non-colloidal suspensions across a broad range of channel slopes, Reynolds numbers, and Froude numbers. A method is presented that can be used to make a priori predictions of critical sedimentation velocities, which can inform future pipeline designs and operations to minimise the environmental and commercial costs of slurry transfers, including reducing the risk of pipe blockages. Only one parameter required for this technique is not related to the measurable physical properties of the pipeline or fluid. However, it is empirically shown to be well represented by a single, dimensionless constant for all fluids and pipelines tested.