Procedure for Identifying Deformations in Oil and Gas Pipelines Subject to External Forces, Based on Primary ILI Data

Author(s):  
Adriana Galvis Fuentes

Oil and gas pipelines that pass through mountainous terrain are subject to an increase in the number of sections affected by the bending deformation’s resulting from external forces, which, when coupled with the construction and operational processes of the systems, cause mechanical damage to the pipelines that has led to containment losses, resulting in operational cost overruns and harmful effects on the environment and on nearby communities, while leaving at high risk the integrity of the petroleum infrastructure. By using primary data obtained through so-called “smart” in-line inspections or intelligent line inspections (ILIs), the occurrence and magnitude of these deformations and displacements of the pipelines can be determined. With the aid of geotechnical analytical techniques, this information can facilitate the interpretation of the processes that induce these thrusts. The starting point is the existing knowledge of the characteristics of the installation of the pipelines and of the clearances permitted by the rules and/or reference standards of the industry. The next step consists of comparing that data against the XYZ Data inertial mapping data (obtained through rotations of the XGP geometric tool) in one or more ILI runs, as part of the mechanical analysis procedure. As a recommended practice, an algorithm is developed for handling the ILI data, showing in parallel the geotechnical zoning data, illustrating it with a study algorithm.

Author(s):  
Husain Mohammed Al-Muslim ◽  
Abul Fazal M. Arif

Mechanical damage in transportation pipelines is a threat to its structural integrity. Failure in oil and gas pipelines is catastrophic as it leads to personal fatalities, injuries, property damage, loss of production and environmental pollution. Therefore, this issue is of extreme importance to Pipeline Operators, Government and Regulatory Agencies, and local Communities. As mechanical damage can occur during the course of pipeline life due to many reasons, appropriate tools and procedures for assessment of severity are necessary. There are many parameters that affect the severity of the mechanical damage related to the pipe geometry and material properties, the defect geometry and boundary conditions, and the pipe state of strain and stress. Moreover, multiple damaged areas may exist and interact like in the case of a hit by a multiple-tooth excavator. The main objective of this paper is to determine the distance and orientation where interaction of multiple dents is significant. The strain and stress fields are evaluated for static pressure loading and the stress range and fatigue life are evaluated for cyclic pressure loading. Accordingly, guidelines are developed for the integrity assessment of multiple dents in oil and gas pipelines. The input parameters of the problem including the pipe material, pipe geometry, dent dimensions, and distance and orientation between two dents have a great variability. Therefore, probabilistic design approach is applied to determine the sensitivity and correlation between the output and input parameters. The base case deterministic FEA model has been validated with full-instrumented full-scale tests conducted by Pipeline Research Council International as part of their active program to fully characterize mechanical damage.


1982 ◽  
Vol 1 (18) ◽  
pp. 145
Author(s):  
Alan D. Crowhurst

Development of oil and gas fields offshore presents new problems in the design of the civil engineering works since in many cases little is known about prevailing conditions on the bed of the sea over the considerable lengths involved. Movement of pipelines after construction, is, therefore, not uncommon and may result in the failure of the line. Consequent losses can be considerable. Pipelines are also vulnerable to mechanical damage by anchors and by fishing activities, the latter giving rise to political problems where the pipelines are laid across existing fishing grounds. To give protection to oil and gas pipelines as well as to marine outfalls and cables a method of protection has been developed using the well known concept of rock filled wire mesh or gabions. To adapt this method to use in underwater works another well proven material, sand mastic asphalt, has been combined with the gabion mattresses to give the required qualities of strength, durability, flexibility together with sufficient weight to restrain movement in the pipeline.


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