scholarly journals Modeling of transient flows in viscoelastic pipe network with partial blockage

2021 ◽  
Author(s):  
Parvin Chahardah-Cherik ◽  
Manoochehr Fathi-Moghadam ◽  
Sadegh Haghighipour
Keyword(s):  
Transient Analysis ◽  
Transient Flow ◽  
Pipe Wall ◽  
Pipe Network ◽  
Transient Flows ◽  
Short Period ◽  
Good Consistency ◽  
Free Case ◽  
The Time Domain ◽  
Experimental Pressure

Abstract In this study, transient flow and partial blockage in polyethylene (PE) pipe network are investigated experimentally and numerically using the method of characteristics in the time domain considering pipe-wall viscoelasticity. The experiments were conducted on a PE pipe network with and without partial blockage. The experimental pressure signals were damped during a short period of time in the blockage-free case. The numerical model was calibrated by the inverse transient analysis (ITA). The hydraulic transient solver calibrated with one Kelvin–Voigt element showed good consistency with the experimental results. Partial blockages with different lengths and sizes were examined at different locations of the pipe network. Results reveal an increase in head loss, pressure signal damping, and phase shift with increase in blockage. In addition, the location and characteristics of blockages with different sizes were determined using the ITA in the pipe network.

Estimating Drainage-Area Pressure With Flow-After-Flow Testing

2012 ◽  
Vol 15 (05) ◽  
pp. 571-583 ◽  
Author(s):  
C.S.. S. Kabir ◽  
M.. Elgmati ◽  
Z.. Reza
Keyword(s):  
Transient Analysis ◽  
Transient Flow ◽  
Management Practice ◽  
Time Lapse ◽  
Drainage Area ◽  
Rate Data ◽  
Reservoir Model ◽  
Pragmatic Approach ◽  
Rate Transient Analysis ◽  
Vexing Problem

Summary Estimating the average drainage-area pressure (pav) of individual wells is a cornerstone to any reservoir-management practice. Yet conventional methods do not always offer reliable solutions to this vexing problem. This study shows that transient flow-after-flow (FAF) testing offers an excellent opportunity to establish pav in a time-lapse mode, when conducted following operational shutdowns. Instrumented wells are natural candidates for FAF testing. Real-time surveillance offers the opportunity to perform rate-transient analysis that results in drainage volume and, consequently, pav. However, gathering quality rate data commensurate with pressure over a long producing period is fraught with uncertainty, which raises questions about the validity of the pav so obtained. In addition, continuous changes in drainage-boundary conditions pose modeling challenges with a given reservoir model. Therefore, the independent estimation of pav cannot be overemphasized. This paper presents a theroretical framework for transient FAF testing and also shows a pragmatic approach to handling pressure/rate data incoherence.

Drilling Riser Disconnection Challenges in Ultra-Deep Water

2018 ◽  
Author(s):  
Alexandre Diezel ◽  
Germain Venero ◽  
Victor Gomes ◽  
Leandro Muniz ◽  
Rafael Fachini ◽  
...  
Keyword(s):  
Good Representation ◽  
Regular Wave ◽  
Computational Simulations ◽  
Successful Operation ◽  
Dynamic Positioning System ◽  
Drilling Rig ◽  
Wave Approach ◽  
Short Period ◽  
Drilling Operations ◽  
The Time Domain

With the extension of the offshore drilling operations to water depths of 10,000 ft and beyond, the technical challenges involved also increased considerably. In this context, the management of the riser integrity through the application of computational simulations is capital to a safe and successful operation — particularly in harsh environments. One of the main challenges associated with keeping the system under safe limits is the recoil behavior in case of a disconnection from the well. The risk that an emergency disconnect procedure can take place during the campaign is imminent, either due to failure of the dynamic positioning system or due to extreme weather in such environments. Recent work [1] in the field of drilling riser dynamic analysis has shown that the recoil behavior of the riser after a disconnection from the bottom can be one of the main drivers of the level of top tension applied. Tension fluctuations can be very large as the vessel heaves, especially in ultra-deep waters where the average level of top tension is already very high. In order to be successful, a safe disconnection must ensure that the applied top tension is sufficient for the Lower Marine Riser Package (LMRP) to lift over the Blow-Out Preventer (BOP) with no risk of interference between the two. This tension should also not exceed a range in which the riser will not buckle due to its own recoil, that the telescopic joint will not collapse and transfer undesirable loads onto the drilling rig or that the tensioning lines will not compress. A good representation of such behavior in computational simulations is therefore very relevant to planning of the drilling campaign. A case study is presented herein, in which a recoil analysis was performed for a water depth of 11,483ft (3,500m). Numerical simulations using a finite element based methodology are applied for solving the transient problem of the riser disconnection in the time domain using a regular wave approach. A detailed hydro-pneumatic tensioning system model is incorporated to properly capture the effect of the anti-recoil valve closure and tension variations relevant during the disconnection. A reduction of conservativism is applied for the regular wave approach, where the maximum vessel heave likely to happen in every 50 waves is applied instead of the usual maximum in 1000 waves approach. ISO/TR 13624-2 [4] states that using the most probable maximum heave in 1000 waves is considered very conservative, as the event of the disconnection takes place in a very short period of time. The challenges inherent to such an extreme site are presented and conclusions are drawn on the influence of the overall level of top tension in the recoil behavior.

Design of Water Hammer Protection for FPSO Domestic Water System Based on AFT-Impulse

2020 ◽  
Author(s):  
Zhang Huan ◽  
Zhang Qipeng ◽  
Wang Chao ◽  
Xu Jiangguo ◽  
Kong Weiwen
Keyword(s):  
Working Conditions ◽  
Transient Analysis ◽  
Water System ◽  
Water Hammer ◽  
Network System ◽  
Pipe Network ◽  
Safe Operation ◽  
Domestic Water ◽  
Pipe Length ◽  
Control Factors

Abstract Due to the limitation of cabin space, FPSO domestic water pipe network system has the characteristics of long water delivery distance, more bending of pipeline and frequent opening and closing of valves, etc. The above characteristics are very likely to cause water hammer in the pipeline, resulting in increased risk of safe operation of pipe network system. In this paper, a FPSO domestic water system was taken as the research object. In view of the water hammer problem in the pipe network system, the model of FPSO domestic water system was established by using dynamic fluid analysis software AFT-Impulse, combined with the factors affecting the water hammer phenomenon (such as pipe diameter, velocity of wave, pipe length, pipeline roughness and valve closing time), the steady state analysis and transient analysis of multi-working conditions and multi-scenarios were realized to determine the main control factors. Based on the influence of main control factors, a comparison scheme of water hammer protection in FPSO domestic water system was proposed. Through the transient analysis of AFT-Impulse software under multi-working conditions, the optimal scheme of water hammer protection for FPSO domestic water system was obtained, which provided guarantee for the safe operation of the system.

Transient Analysis of Dam-Reservoir Interaction Based on Dynamic Stiffness of SBFEM

2011 ◽  
Vol 378-379 ◽  
pp. 213-217
Author(s):  
Shang Ming Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Time Domain ◽  
Transient Analysis ◽  
Ground Motions ◽  
Dynamic Stiffness ◽  
Dam Reservoir ◽  
The Time Domain ◽  
Infinite Reservoir ◽  
Element Method

The scaled boundary finite element method (SBFEM) was extended to solve dam-reservoir interaction problems in the time domain and a dynamic stiffness used in the SBFEM of semi-infinite reservoir in the time domain was proposed, which was evaluated by the Bessel function. Based on the dynamic stiffness, transient responses subjected to horizontal ground motions were analyzed through coupling the SBFEM and finite element method (FEM). A dam was modeled by FEM, while the whole fluid in reservoir was modeled by the SBFEM alone or a combination of FEM and SBFEM. Two benchmark examples were considered to check the accuracy of the dynamic stiffness. Results were compared with those from analytical or substructure methods and good agreements were found.

scholarly journals The February 9, 1971 San Fernando earthquake: A study of source finiteness in teleseismic body waves

1978 ◽  
Vol 68 (1) ◽  
pp. 1-29 ◽  
Author(s):  
Charles A. Langston
Keyword(s):  
Near Field ◽  
Dislocation Line ◽  
Strong Motion ◽  
Body Waves ◽  
P Waves ◽  
Long Period ◽  
Short Period ◽  
Wave Forms ◽  
San Fernando ◽  
The Time Domain

abstract Teleseismic P, SV, and SH waves recorded by the WWSS and Canadian networks from the 1971 San Fernando, California earthquake (ML = 6.6) are modeled in the time domain to determine detailed features of the source as a prelude to studying the near and local field strong-motion observations. Synthetic seismograms are computed from the model of a propagating finite dislocation line source embedded in layered elastic media. The effects of source geometry and directivity are shown to be important features of the long-period observations. The most dramatic feature of the model is the requirement that the fault, which initially ruptured at a depth of 13 km as determined from pP-P times, continuously propagated toward the free surface, first on a plane dipping 53°NE, then broke over to a 29°NE dipping fault segment. This effect is clearly shown in the azimuthal variation of both long period P- and SH-wave forms. Although attenuation and interference with radiation from the remainder of the fault are possible complications, comparison of long- and short-period P and short-period pP and P waves suggest that rupture was initially bilateral, or, possibly, strongly unilateral downward, propagating to about 15 km depth. The average rupture velocity of 1.8 km/sec is well constrained from the shape of the long-period wave forms. Total seismic moment is 0.86 × 1026 dyne-cm. Implications for near-field modeling are drawn from these results.

scholarly journals PRELIMINARY POWER TRANSIENT ANALYSIS OF THE SUPER FR WITH AXIALLY HETEROGENEOUS CORE

2021 ◽  
Vol 247 ◽  
pp. 07002
Author(s):  
Tsutomu Okui ◽  
Akifumi Yamaji
Keyword(s):  
Temperature Gradient ◽  
Transient Analysis ◽  
Large Temperature ◽  
Control Rod ◽  
Mox Fuel ◽  
Fuel Layer ◽  
Axial Temperature ◽  
Short Period ◽  
Full Power ◽  
Supercritical Water Cooled Reactor

The Super FR is one of the SuperCritical Water cooled Reactor (SCWR) concepts with once-through direct cycle plant system. Recently, new design concept of axially heterogeneous core has been proposed, which consists of multiple layers of MOX and blanket fuels. To clarify the safety performance during power transient, safety analyses have been conducted for uncontrolled control rod (CR) withdrawal and CR ejection at full power. RELAP/SCDAPSIM code was used for the safety analysis. The results show that the peak cladding surface temperature (PCST) is high in the upper MOX fuel layer. It is also shown that axial temperature gradient of cladding greatly increases in a short period. Suppressing such large temperature gradient may be a design issue for the axially heterogeneous core from the viewpoint of ensuring fuel integrity.

scholarly journals Numerical modeling transient flow in plastic pipes

2019 ◽  
Vol 286 ◽  
pp. 07001
Author(s):  
N. Achak ◽  
B. Bahrar ◽  
K. Gueraoui
Keyword(s):  
Numerical Modeling ◽  
Constitutive Equations ◽  
Method Of Characteristics ◽  
Transient Flow ◽  
Pipe Wall ◽  
Digital Processing ◽  
Numerical Code ◽  
Plastic Pipes ◽  
And Behavior ◽  
Good Agreement

We present a numerical code for calculating transient flow in plastic pipes, especially in the polyethylene pipe, to analysis effect of material viscoelasticity on water hammer phenomena. The set partial differential equations to be solved is obtained using conservation laws and behavior for the fluid and the pipe wall, associated with constitutive equations of the two media, and relationships compatibility of interfaces on velocities and stresses. A global digital processing is achieved using the method of characteristics. The results obtained are in good agreement with those found in the literature.

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