PIPELINE INTEGRITY ASSESSMENT AND MITIGATION TECHNIQUES IN UNSTABLE SOIL CONDITIONS BASED ON COMPARISON OF IN LINE INSPECTION RESULTS

摘要

The Andes Mountains, rich in geographical features and diversity, poses a significant threat to the integrity of oil and gas pipelines due to geohazards. Land movement and unstable soil conditions can trigger changes in the original trajectory of the pipeline resulting in undesired bending strain which can result on failure of the facility. OCENSA - Oleoducto Central S.A. from Colombia assesses the pipeline condition in geotechnical unstable places by comparison of In Line inspection results taking into account pipeline movements and bending strains changes along the zone of study. Bending strains in the pipe are compared against allowable values and emergency values which constitute the criteria to execute mitigation and/or remediation activities that must be done in order to maintain the pipe integrity. To project the pipeline behavior in time, 3D finite element models are developed, allowing the programming of future activities. This paper presents results obtained in a study case to show how pipeline is assessed and how different mitigation activities are developed. Mitigation Techniques such as stress relief procedures and EPS (Expanded Poly-Styrene) blocks incorporations are explained. These techniques are executed in order to reduce the pipe response due to soil displacements during landslide events and creeping slopes, with the final scope of assuring a safe operation.