scholarly journals Transient simulation of vapor-liquid eruption and overpressure in the drainage terminal of an inclined pipeline during pigging process after water pressure test

2020 ◽  
Author(s):  
Tao Deng ◽  
Jun Zhou ◽  
Xuan Zhou ◽  
Tian Meng ◽  
Guangchuan Liang ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Water Pressure ◽  
Mass Conservation ◽  
Oil And Gas Industry ◽  
Stable Operation ◽  
Transient Model ◽  
Water Pressure Test ◽  
Pressure Test ◽  
The Status ◽  
Vapor Liquid

Abstract Pigging technology is widely used in the oil and gas industry. During the course of pigging, after a water pressure test, the instability of the pig caused by terrain fluctuation can affect the stable operation of the pipeline and even cause burst accidents. This paper describes the four stages of pig movement in an inclined pipeline, with vapor-liquid eruption occuring in the last stage. A hydraulic transient model of the pigging operation after a water pressure test is established based on mass conservation and motion equations, the dynamic equation of the pig, and the vapor-liquid eruption model. The model can simulate the status of fluid flow in the pipeline, track the movement of the pig, and predict the pressure pulses. The simulation results are consistent with the data of two burst accidents, which verifies the correctness of the established model and the reliability of the calculated results. It can therefore provide a reliable and effective theoretical basis for developing a pigging plan on site.

Experiment and Dynamic Simulation of PIG Motion during Pigging Operation in a Slope Pipeline

2018 ◽  
Vol 16 (9) ◽  
Author(s):  
Jun Zhou ◽  
Tao Deng ◽  
Guangchuan Liang ◽  
Jinghong Peng ◽  
Tian Meng ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Water Pressure ◽  
Oil And Gas Industry ◽  
Unsteady Motion ◽  
Stable Operation ◽  
Two Phase ◽  
Transient Model ◽  
Water Pressure Test ◽  
Pressure Test ◽  
Hydraulic Pulse

Abstract Pigging techniques are widely used in the oil and gas industry. The unsteady motion of the PIG in an undulating pipe section during the pigging process after a water pressure test affects the stable operation of the pipeline and also causes a pipe rupture accident in serious cases. First, an experimental study was conducted to investigate the pigging process of air–water two phase pipe flows, and the PIG reverse movement and hydraulic pulse phenomenon were observed. Subsequently, a hydraulic transient model of the pigging process after a water pressure test was established in a dual-grid system. The model combined mass and motion equations of gas and liquid and PIG dynamic equations, considered three types of PIG motion states, namely positive movement, reverse movement and still, and used the method of characteristics to solve the equations. The model exhibits the ability for PIG tracing and hydraulic pulse prediction. It can be used to obtain the position and speed of the PIG. Finally, the field data and simulation results were compared, and the results indicated that they are essentially identical. This verified the accuracy of the model that is established in this study and the reliability of computed results and provided a reliable and effective theoretical basis for the development of field pigging plans.

scholarly journals A Method and Equipment for Continuously Testing the Permeability Coefficient of Rock and Soil Layers

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Wei Chen ◽  
Datian Cui ◽  
Meng Xu ◽  
Rongchao Xu
Keyword(s):  
Flow Rate ◽  
Test Section ◽  
Permeability Coefficient ◽  
Water Pressure ◽  
Pumping Test ◽  
Testing Method ◽  
Water Pressure Test ◽  
Pressure Test ◽  
Test Hole ◽  
Rock And Soil

The water pressure test and steady-flow pumping test are still commonly used for measuring the permeability coefficient of rock and soil strata. Limited by the fact that the average value of the permeability coefficient could be obtained only by this testing method, the accuracy of the experimental results of the permeability coefficient for special rock and soil strata is not good. Therefore, a new on-site testing method and equipment for continuously measuring the permeability coefficient of rock and soil strata is studied in this paper. The method is suitable for water pressure testing in borehole and the steady-flow pumping test. The technical proposal is when the pumping test or water pressure test is carried out, the final water penetration will tend to be a stable value, and then, the high-precision current meter probe will be placed at the bottom of the pumping test hole or water pressure test hole. For the pumping test, the current meter will be lifted uniformly from the bottom of the borehole testing section to the stable water level. Meanwhile, the flow rate of a differential zone of the tested section is continuously detected. For the water pressure test, the current meter will be lifted uniformly from the bottom of the borehole test section to the top of the borehole test section, and the flow rate of the differential section will be continuously detected. Through data analysis and processing, not only the average permeability coefficient of the detected sections can be obtained but also the permeability coefficient of the differential section of the rock and soil stratum can be calculated, respectively. Furthermore, the corresponding relationship between the permeability coefficient and the detected location can be obtained. In view of the abovementioned reasons, the leaking point, the specific position, and the leakage quantity of the detected section could be found out accurately, which will improve the accuracy of the testing results obviously.

scholarly journals Comparative Study of CFD and LedaFlow Models for Riser-Induced Slug Flow

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3733
Author(s):  
Rasmus Thy Jørgensen ◽  
Gunvor Rossen Tonnesen ◽  
Matthias Mandø ◽  
Simon Pedersen
Keyword(s):  
Slug Flow ◽  
Oil And Gas ◽  
Cfd Simulation ◽  
Numerical Models ◽  
Oil And Gas Industry ◽  
Test Facility ◽  
Cfd Model ◽  
Two Phase ◽  
Transient Model ◽  
Vof Model

The goal of this study is to compare mainstream Computational Fluid Dynamics (CFD) with the widely used 1D transient model LedaFlow in their ability to predict riser induced slug flow and to determine if it is relevant for the offshore oil and gas industry to consider making the switch from LedaFlow to CFD. Presently, the industry use relatively simple 1D-models, such as LedaFlow, to predict flow patterns in pipelines. The reduction in cost of computational power in recent years have made it relevant to compare the performance of these codes with high fidelity CFD simulations. A laboratory test facility was used to obtain data for pressure and mass flow rates for the two-phase flow of air and water. A benchmark case of slug flow served for evaluation of the numerical models. A 3D unsteady CFD simulation was performed based on Reynolds-Averaged Navier-Stokes (RANS) formulation and the Volume of Fluid (VOF) model using the open-source CFD code OpenFOAM. Unsteady simulations using the commercial 1D LedaFlow solver were performed using the same boundary conditions and fluid properties as the CFD simulation. Both the CFD and LedaFlow model underpredicted the experimentally determined slug frequency by 22% and 16% respectively. Both models predicted a classical blowout, in which the riser is completely evacuated of water, while only a partial evacuation of the riser was observed experimentally. The CFD model had a runtime of 57 h while the LedaFlow model had a runtime of 13 min. It can be concluded that the prediction capabilities of the CFD and LedaFlow models are similar for riser-induced slug flow while the CFD model is much more computational intensive.

Impact Analysis of High-Pressure Test Pit Concrete Wall

2016 ◽  
Author(s):  
Kumarswamy Karpanan ◽  
Jereme Monson ◽  
Arun Suryanarayanan
Keyword(s):  
High Pressure ◽  
Wall Thickness ◽  
Impact Analysis ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Analytical Prediction ◽  
Concrete Wall ◽  
Safety Issues ◽  
Pressure Test ◽  
Cfd Analyses

High-pressure assemblies used in the oil and gas industry are usually pressure tested in hydro and gas pits. Pressure testing is critical in qualifying new components. Test pressures can be as high as 30 ksi or more. The high pressure water or gas used in testing can store large amounts of energy. Any component or part subjected to this pressure will experience high stresses. If any part of the assembly fails during the testing process, the stored energy of the high-pressure test media in the system can cause the failed part to be ejected at a very high velocity, leading to potential safety issues. Therefore it is crucial to design the reinforced concrete wall of the test pit appropriately to contain the ejected part and prevent or minimize associated damage. This report presents methods to determine the concrete perforation thickness and subsequently, calculate the required test pit wall thickness for stopping a projectile. Since the projectile velocity is a function of test pressure, volume of the pressurized vessel (tested equipment), projectile plug geometry, vessel material, and the pressurized fluid, analyses will include all of these parameters. The test assembly and the ejected part will be simplified into a vessel and a plug in order to make quantitative assessments of the concrete pit wall penetration. Results from the analyses are expected to provide guidance on the concrete wall thickness for designing a safe, high-pressure test pit. The projectile velocities predicted analytically will be compared with those predicted by CFD analyses. Additionally, the analytical prediction of concrete perforation will be verified by running an explicit FE analysis of the concrete impact using LS-DYNA.

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