An Integrated Engineering Model for Prediction of Strain Demands in Pipelines Subject to Frost Heave

2006 ◽  
Author(s):  
Joe Zhou ◽  
Gordon Craig ◽  
Beez Hazen ◽  
James D. Hart
Keyword(s):  
Life Cycle Cost ◽  
Cost Optimization ◽  
Axial Direction ◽  
Gas Pipeline ◽  
Frost Heave ◽  
Engineering Model ◽  
Long Distance ◽  
Demand Prediction ◽  
Discontinuous Permafrost ◽  
Differential Frost Heave

Long distance pipelines are actively pursued by the industry to transport natural gas from remote arctic regions to markets. A chilled gas pipeline is one of the options to minimize the environmental impact resulting from operation of such pipelines. When a chilled gas pipeline crosses discontinuous permafrost areas, differential frost heave can occur. The result is pipe being subjected to potentially high strains, primarily in the axial direction. Reliable prediction of strain demands is one of the key components for a strain-based design process and it is essential for both ensuring pipeline integrity and facilitating life-cycle cost optimization for the design and maintenance of pipelines. The prediction of strain demands resulting from frost heave of chilled gas pipelines involves three fundamental engineering analysis processes. They are gas hydraulic analysis, geothermal analysis and pipeline structural analysis. Not only are these three processes complex, they are also mutually interdependent. To reliably predict strain demands and fully capture the interactions among these processes, TransCanada Pipelines Ltd. (TransCanada) and its partners developed an integrated engineering model on the basis of three well established programs for the three individual engineering processes. This paper will briefly review the integrated model for strain demand prediction.

scholarly journals Numerical analysis of temperature fields around the buried arctic gas pipeline in permafrost regions

2020 ◽  
pp. 248-248
Author(s):  
Xinze Li ◽  
Huijun Jin ◽  
Yanjing Wei ◽  
Zhi Wen ◽  
Yan Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Ambient Air ◽  
Gas Pipeline ◽  
Frozen Soil ◽  
Temperature Fields ◽  
Frost Heave ◽  
Positive Temperature ◽  
Discharge Temperature ◽  
Discontinuous Permafrost ◽  
Permafrost Table

Based on one planned arctic natural gas pipeline engineering which will cross continuous, discontinuous, sporadic and non-permafrost areas from north to south, with different pipeline temperatures set, a thermal model of the interaction between pipeline and permafrost is established to investigate the influence of pipelines on the freezing and thawing of frozen soil around pipeline and thermal stability of permafrost. The results show that different pipeline temperatures influence the permafrost table greatly. Especially in discontinuous permafrost areas the permafrost table is influenced in both positive temperature and negative temperature. The warm gas pipeline of 5?C could decrease the value of permafrost table about 1 to 3 times pipe diameter and aggravate the degradation of permafrost around pipeline; -1?C and -5?C chilled gas pipeline can effectively improve the permafrost table and maintain the temperature stability of frozen soil , but the temperature of soils below pipeline of -5?C decreases obviously, which may lead to frost heave hazards. In terms of thermal stability around pipeline, it is advised that transporting temperature of -1?C is adopted in continuous permafrost area; in discontinuous permafrost area pipeline could operate above freezing in the summer months with the station discharge temperature trending the ambient air temperature, but the discharge temperature must be maintained as -1?C throughout the winter months; in seasonal freezing soil area chilled pipeline may cause frost heave, therefore pipeline should run in positive temperature without extra temperature cooling control.

Modelling of pipeline under differential frost heave considering post-peak reduction of uplift resistance in frozen soil

2006 ◽  
Vol 43 (3) ◽  
pp. 282-293 ◽  
Author(s):  
Bipul C Hawlader ◽  
Vincent Morgan ◽  
Jack I Clark
Keyword(s):  
Analytical Solution ◽  
Frozen Soil ◽  
Frost Heave ◽  
Large Strains ◽  
Peak Reduction ◽  
Numerical Predictions ◽  
Discontinuous Permafrost ◽  
Nonlinear Stress ◽  
Uplift Resistance ◽  
Differential Frost Heave

The interaction between buried chilled gas pipelines and the surrounding frozen soil subjected to differential frost heave displacements has been investigated. A simplified semi-analytical solution has been developed considering the post-peak reduction of uplift resistance in frozen soil as observed in laboratory tests. The nonlinear stress–strain behaviour of the pipeline at large strains has been incorporated in the analysis using an equivalent bending stiffness. The predicted results agree well with our finite element analysis and also with numerical predictions available in the literature, hence the simple semi-analytical solution can be considered as an alternative to numerical techniques. A parametric study has been carried out to identify the influence of key factors that can modify the uplift resistance in frozen soil. Among them, the residual uplift resistance has been found to be the important parameter for the development of stresses and strains in the pipeline.Key words: pipeline, frost heave, discontinuous permafrost, semi-analytical solution, uplift resistance, frozen soil.

Development of X80M Line Pipe Steel for Spiral Welded Pipes With Low Temperature Toughness and Excellent Weldability

2014 ◽  
Author(s):  
Nuria Sanchez ◽  
Özlem E. Güngör ◽  
Martin Liebeherr ◽  
Nenad Ilić
Keyword(s):  
Low Temperature ◽  
Life Cycle Cost ◽  
Volume Fraction ◽  
Large Diameter ◽  
Pipe Production ◽  
Strain Accumulation ◽  
Long Distance ◽  
Line Pipe ◽  
Low Temperature Toughness ◽  
Welded Pipe

The unique combination of high strength and low temperature toughness on heavy wall thickness coils allows higher operating pressures in large diameter spiral welded pipes and could represent a 10% reduction in life cycle cost on long distance gas pipe lines. One of the current processing routes for these high thickness grades is the thermo-mechanical controlled processing (TMCP) route, which critically depends on the austenite conditioning during hot forming at specific temperature in relation to the aimed metallurgical mechanisms (recrystallization, strain accumulation, phase transformation). Detailed mechanical and microstructural characterization on selected coils and pipes corresponding to the X80M grade in 24 mm thickness reveals that effective grain size and distribution together with the through thickness gradient are key parameters to control in order to ensure the adequate toughness of the material. Studies on the softening behavior revealed that the grain coarsening in the mid-thickness is related to a decrease of strain accumulation during hot rolling. It was also observed a toughness detrimental effect with the increment of the volume fraction of M/A (martensite/retained austenite) in the middle thickness of the coils, related to the cooling practice. Finally, submerged arc weldability for spiral welded pipe manufacturing was evaluated on coil skelp in 24 mm thickness. The investigations revealed the suitability of the material for spiral welded pipe production, preserving the tensile properties and maintaining acceptable toughness values in the heat-affected zone. The present study revealed that the adequate chemical alloying selection and processing control provide enhanced low temperature toughness on pipes with excellent weldability formed from hot rolled coils X80 grade in 24 mm thickness produced at ArcelorMittal Bremen.

High Consequence Areas (HCAs) Assessment for Long-Distance Oil/Gas Pipeline

ICPTT 2011 ◽  
2011 ◽  
Author(s):  
Jianlin Ma ◽  
Liqiong Chen ◽  
PengpPh.D. Zhang ◽  
Sizhong Wang
Keyword(s):  
Gas Pipeline ◽  
Long Distance ◽  
Oil Gas

Flow Assurance in Deep-Water Gas Pipelines: Locating Hydrate Plugging Position in a Fast Way

2021 ◽  
Author(s):  
Jing Yu ◽  
Cheng Hui ◽  
Chao Wen Sun ◽  
Zhan Ling Zou ◽  
Bin Lu Zhuo ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Deep Water ◽  
Pipe Wall ◽  
Gas Pipeline ◽  
Flow Assurance ◽  
Gas Pipelines ◽  
Long Distance ◽  
Hydrate Layer ◽  
Hydrate Deposition ◽  
Water Gas

Abstract Hydrate-associated issues are of great significance to the oil and gas sector when advancing the development of offshore reservoir. Gas hydrate is easy to form under the condition featuring depressed temperature and elevated pressure within deep-water gas pipeline. Once hydrate deposition is formed within the pipelines, the energy transmission efficiency will be greatly reduced. An accurate prediction of hydrate-obstruction-development behavior will assist flow-assurance engineers to cultivate resource-conserving and environment-friendly strategies for managing hydrate. Based on the long-distance transportation characteristics of deep-water gas pipeline, a quantitative prediction method is expected to explain the hydrate-obstruction-formation behavior in deep-water gas pipeline throughout the production of deep-water gas well. Through a deep analysis of the features of hydrate shaping and precipitation at various locations inside the system, the advised method can quantitatively foresee the dangerous position and intensity of hydrate obstruction. The time from the start of production to the dramatic change of pressure drop brought about by the deposition of hydrate attached to the pipe wall is defined as the Hydrate Plugging Alarm Window (HPAW), which provides guidance for the subsequent hydrate treatment. Case study of deep-water gas pipeline constructed in the South China Sea is performed with the advised method. The simulation outcomes show that hydrates shape and deposit along pipe wall, constructing an endlessly and inconsistently developing hydrate layer, which restricts the pipe, raises the pressure drop, and ultimately leads to obstruction. At the area of 700m-3200m away from the pipeline inlet, the hydrate layer develops all the more swiftly, which points to the region of high risk of obstruction. As the gas-flow rate increases, the period needed for the system to shape hydrate obstruction becomes less. The narrower the internal diameter of the pipeline is, the more severe risk of hydrate obstruction will occur. The HPAW is 100 days under the case conditions. As the concentration of hydrate inhibitor rises, the region inside the system that tallies with the hydrate phase equilibrium conditions progressively reduces and the hydrate deposition rate slows down. The advised method will support operators to define the location of hydrate inhibitor injection within a shorter period in comparison to the conventional method. This work will deliver key instructions for locating the hydrate plugging position in a fast way in addition to solving the problem of hydrate flow assurance in deep-water gas pipelines at a reduced cost.

Stress Analysis of Pipeline Subjected to Differential Frost Heave

2013 ◽  
Author(s):  
Yan Di ◽  
Jian Shuai ◽  
Lingzhen Kong ◽  
Xiayi Zhou
Keyword(s):  
Strain Analysis ◽  
Element Model ◽  
Frozen Soil ◽  
Computational Method ◽  
Frost Heave ◽  
Safe Operation ◽  
Stress Strain ◽  
Segregation Potential ◽  
Differential Frost Heave ◽  
Design Construction

Frost heave must be considered in cases where pipelines are laid in permafrost in order to protect the pipelines from overstress and to maintain the safe operation. In this paper, a finite element model for stress/strain analysis in a pipeline subjected to differential frost heave was presented, in which the amount of frost heave is calculated using a segregation potential model and considering creep effects of the frozen soil. In addition, a computational method for the temperature field around a pipeline was proposed so that the frozen depth and temperature variation gradient could be obtained. Using the procedure proposed in this paper, stress/strain can be calculated according to the temperature on the surface of soil and in a pipeline. The result shows the characteristics of deformation and loading of a pipeline subjected to differential frost heave. In general, the methods and results in this paper can provide a reference for the design, construction and operation of pipelines in permafrost areas.

Life cycle cost optimization of biofuel supply chains under uncertainties based on interval linear programming

2015 ◽  
Vol 187 ◽  
pp. 6-13 ◽  
Author(s):  
Jingzheng Ren ◽  
Liang Dong ◽  
Lu Sun ◽  
Michael Evan Goodsite ◽  
Shiyu Tan ◽  
...  
Keyword(s):  
Linear Programming ◽  
Life Cycle ◽  
Supply Chains ◽  
Life Cycle Cost ◽  
Cost Optimization ◽  
Interval Linear Programming ◽  
Interval Linear
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