Steady-State Multiphase Flow—Past, Present, and Future, with a Perspective on Flow Assurance

2012 ◽  
Vol 26 (7) ◽  
pp. 4145-4157 ◽  
Author(s):  
Mack Shippen ◽  
William J. Bailey
Keyword(s):  
Steady State ◽  
Multiphase Flow ◽  
Flow Assurance ◽  
Flow Past

scholarly journals The Influence of Burial Depth and Soil Thermal Conductivity on Heat Transfer in Buried CO2 Pipelines for CCS: A Parametric Study

2020 ◽  
Author(s):  
Babafemi Olugunwa ◽  
Julia Race ◽  
Tahsin Tezdogan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Thermal Resistance ◽  
Parametric Study ◽  
Flow Assurance ◽  
Burial Depth ◽  
Soil Thermal Conductivity ◽  
Dense Phase ◽  
Pipeline Transportation

Abstract Pipeline heat transfer modelling of buried pipelines is integral to the design and operation of onshore pipelines to aid the reduction of flow assurance challenges such as carbon dioxide (CO2) gas hydrate formation during pipeline transportation of dense phase CO2 in carbon capture and storage (CCS) applications. In CO2 pipelines for CCS, there are still challenges and gaps in knowledge in the pipeline transportation of supercritical CO2 due to its unique thermophysical properties as a single, dense phase liquid above its critical point. Although the design and operation of pipelines for bulk fluid transport is well established, the design stage is incomplete without the heat transfer calculations as part of the steady state hydraulic and flow assurance design stages. This paper investigates the steady state heat transfer in a buried onshore dense phase CO2 pipelines analytically using the conduction shape factor and thermal resistance method to evaluate for the heat loss from an uninsulated pipeline. A parametric study that critically analyses the effect of variation in pipeline burial depth and soil thermal conductivity on the heat transfer rate, soil thermal resistance and the overall heat transfer coefficient (OHTC) is investigated. This is done using a one-dimensional heat conduction model at constant temperature of the dense phase CO2 fluid. The results presented show that the influence of soil thermal conductivity and pipeline burial depth on the rate of heat transfer, soil thermal resistance and OHTC is dependent on the average constant ambient temperature in buried dense phase CO2 onshore pipelines. Modelling results show that there are significant effects of the ambient natural convection on the soil temperature distribution which creates a thermal influence region in the soil along the pipeline that cannot be ignored in the steady state modelling and as such should be modelled as a conjugate heat transfer problem during pipeline design.

Fast-Tracking an FLNG Relocation in Malaysia

2021 ◽  
Vol 73 (04) ◽  
pp. 39-40
Author(s):  
Judy Feder
Keyword(s):  
Steady State ◽  
Cost Minimization ◽  
Flow Assurance ◽  
Transient Operation ◽  
Fast Tracking ◽  
Engineering Studies ◽  
Offshore Technology ◽  
State Study ◽  
Common Support ◽  
Minimal Modification

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper OTC 30440, “Floating LNG 1 Relocation: Another World’s First,” by Muhammad Fakhruddin Jais, Wan Mahsuri Wan Hashim, and Ariff Azhari Ayadali, Petronas, et al., prepared for the 2020 Offshore Technology Conference Asia, originally scheduled to be held in Kuala Lumpur, Malaysia, 17–19 August. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. Floating liquefied natural gas (FLNG) allows LNG to be processed hundreds of kilometers away from land to unlock gas reserves in remote and stranded fields previously uneconomical to monetize. The complete paper describes the operator’s fast-tracking of a 450-km FLNG unit relocation from Sarawak to Sabah offshore Malaysia. The time from selecting the new field to unloading LNG at the new location was 13 months. The complete paper discusses pre-execution and engineering studies, relocation preparation and execution, and challenges encountered, including timeline, cost minimization, and manning. Introduction Since 2016, Petronas has operated its first floating LNG production, storage, and offloading facility offshore Sarawak. During the tenure of operation, cargo was delivered successfully to customers worldwide. An opportunity to help a different gas supplier monetize another stranded field offshore Sabah, approximately 450 km away from the unit’s original location, presented itself. The new opportunity was deemed feasible for several reasons. - The identified location is still within Malaysian waters and thus is subject to similar authority and regulations. - Operation within the same country ensures common support from vendor and contractors to some extent. - The two fields have similar gas profiles and water depth. The project team determined that these factors would result in minimal modification at both FLNG and up-stream facilities to meet minimum shut-down from project sanction until first LNG cargo was produced. Pre-Execution and Engineering Studies To fast-track the project, an evaluation was conducted of the new feed-gas composition and modification of both up-stream and FLNG facilities. Long-lead items (LLIs) were identified, and studies were conducted to secure the items. One of the identified LLIs was the flexible pipeline from the upstream facilities to the FLNG. A flow-assurance study covered the steady-state and transient operation for the flexible line. This study confirmed the size of the pipeline and defined the functional requirement for the flexible pipeline procurement. Among the key parameters identified were the pipeline’s thermal conductivity and design pressure. During the feasibility stage, a steady-state study was conducted to determine the length of the flexible line in order to meet the landing pressure and temperature at the FLNG. Instead of requiring additional cooler, the flexible line was extended 2 km to take advantage of the Joule-Thomson cooling effect resulting from the pressure drop across the pipeline. In addition to defining the LLI properties, the flow-assurance study also examined the transient operation for both upstream and FLNG upon the closure of the riser shutdown valve. The study assessed flow-assurance issues, such as hydrates and adequacy of the slug receiver during the transient operation, that might arise, and defined the start-up and commissioning sequence for the facilities.

Dynamic Characteristics of Deep-Water Risers Carrying Multiphase Flows

2018 ◽  
Author(s):  
Bowen Ma ◽  
Narakorn Srinil
Keyword(s):  
Steady State ◽  
Free Vibration ◽  
Multiphase Flow ◽  
Deep Water ◽  
Slug Flow ◽  
Internal Dynamic ◽  
Gas Flows ◽  
Time Space ◽  
Slug Flows ◽  
Oscillation Frequencies

Deep-water flexible risers conveying hydrocarbon oil and gas flows may be subject to internal dynamic fluctuations associated with the spatial variations of phase densities, velocities and pressure drops. Many studies have focused on single-phase flows in pipes whereas understanding of multiphase flow effects is lacking. This study aims to investigate the planar free-vibration characteristics of a long flexible catenary riser carrying the steady-state, multiphase slug oil-gas flows in order to understand how the inclination-dependent internal slug flows affect riser natural frequencies and modal shapes. The influence of slug characteristics such as phase velocities on the riser vibration is also studied. The catenary riser planar motions are mathematically described by a two-dimensional continuum model capturing coupled horizontal and vertical responses. Based on the selected two-phase flow rates at the wellhead, riser geometric configurations and specified slug unit lengths, a steady-state slug flow model is considered by taking into account several empirical closure correlations and riser mechanical properties, solving for the multiphase flow aspects including pressure, velocities, liquid holdup and gas fraction. By assigning an undamped free-vibration shape of an empty catenary riser as initial displacement conditions, the space-time numerical simulations are performed using a finite difference approach. Comparisons of oscillation frequencies, time histories, phase planes, time-space varying responses and dynamic stresses of catenary risers with and without slug flows are presented, identifying the dynamic modifications arising from the internal slug-induced mass momentum change and pressure loss. To understand the influence of slug flow properties, parametric studies are carried out with different gas velocities. Numerical results highlight the reduced riser tensions, decreased oscillation frequencies, multiple oscillation modes, amplified amplitudes and stresses. These key observations will be useful for the forced vibration analysis of catenary risers subject to combined internal (multiphase) and external (vortex-shedding) flow excitations.

Low-Dimensional Modeling of Transient Two-Phase Flow in Pipelines

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Amine Meziou ◽  
Majdi Chaari ◽  
Matthew Franchek ◽  
Rafik Borji ◽  
Karolos Grigoriadis ◽  
...  
Keyword(s):  
Steady State ◽  
Multiphase Flow ◽  
Transmission Line ◽  
Transmission Lines ◽  
Mechanistic Model ◽  
Phase Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
Low Dimensional ◽  
State Pressure

Presented are reduced-order models of one-dimensional transient two-phase gas–liquid flow in pipelines. The proposed model is comprised of a steady-state multiphase flow mechanistic model in series with a transient single-phase flow model in transmission lines. The steady-state model used in our formulation is a multiphase flow mechanistic model. This model captures the steady-state pressure drop and liquid holdup estimation for all pipe inclinations. Our implementation of this model will be validated against the Stanford University multiphase flow database. The transient portion of our model is based on a transmission line modal model. The model parameters are realized by developing equivalent fluid properties that are a function of the steady-state pressure gradient and liquid holdup identified through the mechanistic model. The model ability to reproduce the dynamics of multiphase flow in pipes is evaluated upon comparison to olga, a commercial multiphase flow dynamic code, using different gas volume fractions (GVF). The two models show a good agreement of the steady-state response and the frequency of oscillation indicating a similar estimation of the transmission line natural frequency. However, they present a discrepancy in the overshoot values and the settling time due to a difference in the calculated damping ratio. The utility of the developed low-dimensional model is the reduced computational burden of estimating transient multiphase flow in transmission lines, thereby enabling real-time estimation of pressure and flow rate.

Sizing Wet-Gas Pipelines and Slug Catchers With Steady-State Multiphase Flow Simulations

1998 ◽  
Vol 120 (2) ◽  
pp. 106-110 ◽  
Author(s):  
J. J. Xiao ◽  
G. Shoup
Keyword(s):  
Steady State ◽  
Multiphase Flow ◽  
Simulation Models ◽  
Gas Pipelines ◽  
Flow Simulations ◽  
Wet Gas ◽  
Starting Point ◽  
Operational Information ◽  
Exit Speed ◽  
Steady State Simulation

The design of wet-gas pipelines and slug catchers requires multiphase flow simulations, both steady-state and transient. However, steady-state simulation is often inadequately conducted and its potential not fully utilized. This paper shows how mechanistic steady-state simulation models can be used to obtain not only pressure drop, liquid holdup and flow regime, but also to extract important operational information such as pig transit time, pig exit speed, liquid buildup rate behind the pig, and the time for the pipeline to return to a steady-state after pigging. A well-designed set of steady-state simulations helps to determine pipeline size, slug catcher size, and pigging frequency. It also serves as a starting point for subsequent transient multiphase flow simulations.

Liutex-Based Investigation of Vortex in Multiphase Flow Past 2-D Cylinder Using GPU-Accelerated LBM

2021 ◽  
pp. 123-137
Author(s):  
Pengxin Cheng ◽  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
Shengyao Jiang ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Flow Past
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