Abstract
Underwater pipelines are vital to the oil industry. Extending the service life of these pipelines is a key issue in improving the sustainability of oil transportation. A geotextile mattress with floating plate (GMFP) is a novel and sustainable countermeasure for scour and erosion control and is herein introduced to protect a partially buried pipeline from local scour in steady currents. A series of experiments was designed to verify the protection capabilities of the GMFP and investigate its parametric effects on protection. The average seepage hydraulic gradient under the pipeline was adopted to depict the protection effects of the GMFP, and was calculated with the pore pressure readings under the pipeline. The test results show that the GMFP is capable of protecting a pipeline from the onset of local scour in a unidirectional current. The average seepage hydraulic gradient below the pipeline decreases remarkably after a GMFP is installed. The average hydraulic gradient shows a descending trend with increased sloping angle α when 0.64 < sinα < 0.77. The hydraulic gradient hits a nadir at sinα = 0.77 and climbs with the increasing sloping angle when sinα > 0.82. The hydraulic gradient ascends when the bottom opening ratio δ increases from 0.167 to 0.231, due to the decreased intensity of the bottom vortex. The hydraulic gradient drops with a rising plate height, except for a fluctuation at Hp = 0.12 m. An approximate negative correlation is found between the obstruction height of the floating plate and the average hydraulic gradient under the pipeline. This could be partially attributed to the extension and amplification of the bottom vortex on the leeside of the pipeline due to the increased plate obstruction height.
Highlights
Underwater pipelines are vital to the oil industry
The onset of scour was reported to start on the downstream side of the pipeline [2,34] and numerical simulations on the seepage field under the pipeline showed that the upward seepage hydraulic gradient reaches the maximum value at the intersection of the pipeline surface and the downstream bed [3,35]
We demonstrate that the geotextile mattress with floating plate (GMFP) is capable of protecting a pipeline from scour in steady currents
Summary
Underwater pipelines are vital to the oil industry. Oil and gas can be transported safely and sustainably between offshore platforms and oil refineries. It should be noted that the GMFP is different from the geotextile mattress with sloping curtain studied in Xie et al [26,31] Such differences include the structure of the sand-pass openings, and the flexibility of the floating plate (curtain), to name a few. Which is capable The sampling ra6toef of o14f the pressure sensors was 100 Hz. The onset of scour was reported to start on the downstream side of the pipeline [2,34] and numerical simulations on the seepage field under the pipeline showed that the upward seepage hydraulic gradient reaches the maximum value at the intersection of the pipeline surface and the downstream bed [3,35]. The averaged seepage hydraulic gradient between points A and B ∂(p/γ)/∂s was calculated by (Figure 6): TThhee pprreessssuurreemmeeaassuureremmenentstswFFweiiggreeuurrreseetas66∂tr∂..atsPPero dtoerrγebdpeepp bfrroeee=rsfseossupurtheγrrAeeet A−sshceeBuennprssBcroouerr,nrssrteeewttnuutapps..wgaesngereanteerdaatendd (1) alansdteldasutnedtiluant tlielaastt w3lemahseitnre3aγmfteiirsnttahhfeeteflsroptwehceviffeilcloowwcietvyigeblhoetccaoitmfywebeastctaeabrm;lesewissthatehbnleendwoisshtcaeonnucnreooacslcocuonrugrertdoh.ceTcpuherurrsei,mdth.eTetehvruaorsfi,attthhioeenvpsaiiprnieatlhtiineoenr;espaiAdniantnhgdes wpscBeoarurerecdpoimodrpenlopettreoelscyscuruerrce.oFarotdrSetdehn.esTochraesseAtos twaanlhddeurBer,asrtceioosupnreocdftiiadvetoelycsct,ucaran,sdreewa AdaiBsngabsisowuthetre8eatrorecc1ol0erndmgeitdnh for the cases where ubnettiwl teheensSceonusrohrsoAle aexntdenBd, ewdhtiochthise 2fu0lml lemn.gTthhiosfetqhueaptiiopneliisned.erived from the definition in Sumer et al [2]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
