Abstract

Crude oil transport is one important part of the oil industry. Wax deposition is a very complex phenomenon that in recent years is one of the major challenges in oil industry. Wax deposited on the inner surface of crude oil pipelines are capable to reduce or completely stop the oil flow and the oil industry imposing large costs. The main objective of this study was to present a novel approach for predication of wax deposition thickness in single-phase turbulent flow rate. Using experimental data set and Adaptive neural-fuzzy inference system (ANFIS) model was developed. From the results predicted by this model, it can be pointed out that the ANFIS model can be used as powerful tools for prediction of wax deposition thickness in single-phase turbulent flow rate with mean square error, absolute relative deviation error and average absolute deviation error which are 0.00077034, 0.015720 and 0.097961, respectively. Document type: Article

Abstract

Hydraulic capsule pipelines (HCPs) are the third generation pipelines transporting hollow containers, known as capsules. These capsules are filled with material/cargo to be transported. The shape of these capsules has a significant effect on the hydrodynamic flow characteristics within HCPs. As the variations in the pressure distribution within HCPs are directly linked to and the flow characteristics within pipelines, it is essential to critically evaluate the effect of capsule shape on the pressure drop across the pipeline. Published literature is severely limited in terms of establishing the effects of the shape of the capsules on the flow characteristics within pipelines. Hence, the present study focuses on using a well-validated Computational Fluid Dynamics tool to numerically simulate the flow of capsules of various shapes quantified in form of a novel shape factor in hydraulic capsule pipelines. Both on-shore and off-shore applications of such pipelines have been investigated in the present study, along-with pipe fittings, such as bends. Variations in flow related parameters within these pipelines have been discussed in detail for a wide range of geometrical parameters associated with the capsules and the pipelines. Pressure drop values have been used to develop novel semi-empirical prediction models as a function of the shape factor and other flow and geometric variables of the capsules. These prediction models have been embedded into a pipeline optimisation methodology, which has been developed based on Least-Cost Principle. The resulting novel optimisation methodology can be used for hydraulic capsule pipeline design. Performance charts for practical applications have been developed for easy implementation of the design methodology for the designers of hydraulic capsule pipelines transporting capsule of different shapes. Document type: Article

Abstract

This work presents a scoping model to predict ground-borne railway vibration levels within buildings considering soil-structure interaction (SSI). It can predict the response of arbitrarily complex buildings in a fraction of the time typically required to analyse a complex SSI problem, and thus provides a practical tool to rapidly analyse the vibration response of numerous structures near railway lines. The tool is designed for use in cases where the ground-borne vibration is known, and thus can be used as model input. Therefore in practice, for the case of a new line, the ground motion can be computed numerically, or alternatively, for the case of new buildings to be constructed near an existing line, it can be recorded directly (e.g. using accelerometers) and used as model input. To achieve these large reductions in computational time, the model discretises the ground-borne vibration in the free field into a frequency range corresponding to the modes that characterize the dynamic building response. After the ground-borne response spectra that corresponds with the incident wave field is estimated, structural vibration levels are computed using modal superposition, thus avoiding intensive soil-structure interaction computations. The model is validated using a SSI problem and by comparing results against a more complex finite element-boundary element model. Finally, the new scoping model is then used to analyse the effect of soil properties, building height, train speed and distance between the building and the track on structural-borne vibration. The results show that the scoping model provides a powerful tool for use during the early design stages of a railway system when a large number of structures require analysis. Ministerio de Economía y Competitividad (España) BIA2013-43085-P Document type: Article

Abstract

One of the fundamental questions that must be addressed in the effective design and operation of pipeline lubrication of heavy oil is; “how much time will be needed to restart a blocked core annular flow (CAF) line after shutdown due to fouling or pump failures”, if the pipe is to be cleaned using water only. In this work, laboratory results of shutdown and restart experiments of high-viscous oil conducted in a 5.5-m-long PVC horizontal pipe with internal diameter of 26 mm are first presented. A new correlation for the prediction of the restart time of a shutdown core annular flow line is then formulated. The predictive capabilities of the correlation are checked against measured restart time and pressure drop evolution data. Somewhat high but still reasonable predictions are obtained. The restart time correlation, together with the associated correlations formulated as well, can be of practical importance during the engineering design of high-viscous oil pipeline transportation facility for predicting restart process. Document type: Article

Abstract

Dramatic failures have occurred in recent earthquakes due to the interplay of surface structures with outcropping fault ruptures, highlighting the need to account for fault induced loading in seismic design. Current research into the mechanisms of fault rupture–foundation–structure interaction has revealed a potentially favourable role of caissons in comparison to other foundation types. This paper explores the mechanisms of normal fault rupture interaction with caisson foundations, with an integrated approach using both experiments and analysis. A series of centrifuge model tests were first conducted to study the response of a square (in plan) caisson foundation of dimensions 5 m x 5 m x 10 m, founded on a 15 m thick layer of dry dense sand. Nonlinear 3-D numerical simulation of the problem was then developed and adequately validated against centrifuge test results. Depending on its position relative to the fault, the caisson is found to interact with the fault rupture, sometimes modifying spectacularly the free field rupture path. Acting as a kinematic constraint, the caisson “forces” the rupture to divert on either one, or both, of its sides. The numerical study was extended to gain further insight into the effect of the exact position of the caisson relative to the fault outcrop. Different mechanisms taking place for different caisson positions are identified, and their effect on the response of the system is discussed

Abstract

Past observations showed that pipeline damages in liquefaction zones are significantly higher than the damages in areas where there was no liquefaction. Existing vulnerability relationships for the pipelines in liquefaction zones utilize parameters such as ground displacement, horizontal ground strain, angular distortion or both. These relationships are particularly useful in performance or risk assessment of pipeline systems. However, prediction of these parameters for pipeline damage estimates is difficult to perform and highly variable with current procedures. This paper proposes new correlations of asbestos cement (AC), cast iron (CI) and polyvinyl chloride (PVC) pipeline damage, expressed as repairs/km, with three different liquefaction parameters: liquefaction severity number (LSN), one-dimensional volumetric reconsolidation settlement (S-V1D), and liquefaction potential index (LPI). The pipeline damage data from 22 February 2011, Mw = 6.2 Christchurch earthquake and geotechnical information pertaining to liquefied area in Christchurch are utilized herein. Cone penetration test (CPT) based Boulanger and Idriss [1] liquefaction triggering procedure with 15th, 50th and 85th percentile cyclic resistance ratio (CRR) curves (corresponding to probabilities of liquefaction, PL, equal to 15%, 50%, and 85%) was used to calculate the parameters. It is shown that the relationships between AC, CI and PVC pipeline damages and LSN, S-V1D and LPI are strong, except for the correlation for AC pipeline damage versus LPI. Considering CI and PVC pipelines, both LSN and LPI correlations are comparable and slightly better than S-V1D correlations. Use of different probabilities of liquefaction triggering does not have significant effect on correlations with LSN and S-V1D whereas the same is not true for LPI correlations. Regarding the resilience of pipelines, PVC and AC pipelines performed the best and worst, respectively in all cases with CI pipelines in the middle. The correlations have the potential for use with existing or new liquefaction hazard maps for prediction of pipeline damage from future earthquakes. C1 [Toprak, Selcuk] Gebze Tech Univ, Dept Civil Engn, Kocaeli, Turkey. [Nacaroglu, Engin; Koc, Abdullah Cem; Manav, Yasemin] Pamukkale Univ, Dept Civil Engn, Denizli, Turkey. [van Ballegooy, Sjoerd; Torvelainen, Eric] Tonkin Taylor Ltd, 105 Carlton Gore Rd, Auckland 1023, New Zealand. [Jacka, Mike] Tonkin Taylor Ltd, 33 Parkhouse Rd, Christchurch 8042, New Zealand. [O'Rourke, Thomas Denis] Cornell Univ, Civil & Environm Engn Dept, Ithaca, NY 14853 USA.

Abstract

The damage on supply and drainage water networks is a serious cause of economic disruption for urban systems affected by earthquakes. Among various concerns, the ruptures of sewer pipes and manholes generated by liquefaction determine a particularly severe sanitary hazard and require extensive, costly and time-consuming repairs. Quantitative risk assessment carried out with the characterisation and geographical mapping of seismic hazard, subsoil susceptibility, physical and functional vulnerability of the exposed elements, enables to estimate losses, identify weaknesses, inspire strategies to mitigate the impact of earthquakes and improve resilience. The present study deals with the physical vulnerability of sewer pipelines. Empirical fragility functions are derived from the evidences of liquefaction induced in Urayasu (Japan) by the 2011 Tohoku-Oki earthquake (Mw9.0). The spatial distribution of seismic signals, subsoil characteristics, pipes and surveyed damages are reconstructed in a GIS platform. An articulated methodology is developed to correlate variables and compensate their limited spatial correspondence, exploiting the complete coverage of the area with terrestrial settlements measured by LiDAR and their strong correlation with damage. Finally, ruptures of pipes are probabilistically quantified adopting a common liquefaction severity indicator as engineering demand parameter and measuring the efficiency of relations with statistical tests.

Abstract

In this study we probe the ultimate potential Underground Gas Storage (UGS) capacity of the Netherlands by carrying out a detailed feasibility study on inflow performances of all onshore natural gas reservoirs. The Netherlands is one of the largest natural gas producers in Western Europe. The current decline of its national production and looming production restrictions on its largest field of Groningen -owing to its induced seismicity- have recently made necessary to upgrade the two largest UGS of Norg and Grijpskerk. The joined working volume of these two UGS is expected to replace the swing capacity of the Groningen field to continue guaranteeing the security of supply of low calorific natural gas. The question is whether this UGS configuration will provide the expected working storage capacity unrestricted by issues on reservoir performances and/or induced seismicity. This matter will be of paramount importance in the near future when production restrictions and/or the advance state of depletion of the Groningen field will turn the Netherlands into a net importer of high calorific natural gas. By then, the question will be whether the available UGSs will still be economically attractive to continue operating, or if additional or alternative UGSs will be needed?. Hence the characterization and ranking of the best potential reservoirs available today is of paramount importance for future UGS developments. We built an in-house automated module based on the application of the traditional inflow performance relationship analysis to screen the performances of natural gas reservoirs in onshore Netherlands. Results enable identifying the 72 best candidates with an ultimate total working volume capacity of 122±30 billion Sm 3 . A detailed sensitivity analysis shows the impact of variations in the reservoir properties or wellbore/tubing configurations on withdrawal performances and storage capacity. We validate our predictions by comparing them to performances of the UGSs currently operating in the Netherlands. Our results show that although Norg and Grijpskerk stand midst the best candidates, their working:cushion gas volume (wv:cv) ratios appear amongst the lowest. We found many other reservoir candidates with higher wv:cv ratios ("1) and working volumes between 3 and 10 billion Sm 3 geographically distributed across the Netherlands. Any of the current and future UGSs will have to compete with economically more attractive means of gas import via pipelines and liquefied natural gas. We suggest that only the strategic development of a network of efficient underground gas storages with wv:cv ratios "1, could increase its economical attractiveness. This can reduce future dependence on foreign gas supply for cases of import disruption or shortages during peak demand in winter periods. Future political and economic decisions and societal acceptance will determine the role that UGS will play in the security of supply of natural gas in the Netherlands and Western Europe.

Abstract

Recent earthquakes show that pipeline damage is severe in the areas where permanent ground deformations (e.g., liquefaction zones) occur. Ground movement hazard to pipeline systems can be assessed by using ground displacement measurements around the location of pipelines. There are many different ways of measuring ground displacements after an earthquake occur. This paper compares displacements measured in Avonside area, Christchurch, NZ, by using four different ways with respect to their effects on pipeline damage assessments. They are air photo, satellite, high resolution light detection and ranging (LiDAR) surveys data presented at 4- and 56-m grids acquired before and after the Mw6.2 22 February 2011 earthquake. Avonside area was in the liquefaction zones of the 22 February 2011 earthquake. Where possible, benchmark measurements were also included in the comparisons. In this study, the focus was on asbestos cement and cast iron water pipelines as the length of the pipelines and the number of damages in the study area was much higher compared to other pipe materials, providing sufficient repair rate data passing the screening criteria to develop linear regressions. The correlations between pipeline damage and lateral ground strains were developed by calculating the horizontal strains from these four different type displacements. The comparisons show that satellite imagery is good for estimating total movements but not so good for estimating lateral strains and conversely LiDAR surveys are not so good for estimating total movements, but much better for estimating lateral strains. Hence, pipeline damage correlations with LiDAR calculated strains provide higher determination coefficient (r2) value. The results of comparisons are presented and discussed. © 2018, Springer Science+Business Media B.V., part of Springer Nature.

Abstract

Bird impacts can be extremely critical events for the air transport safety. Since aircraft structures have become more and more complex components, the numerical prediction of the damage onset and evolution induced by a bird impact has become a very challenging task. The aim of this work is to provide a brief overview of the numerical techniques adopted for the prediction of the bird impact phenomenon on a leading edge of a regional aircraft wing. Smooth Particle Hydrodynamics (SPH), Rigid and Lagrangian models have been investigated and the results have been compared and critically assessed.