Inspection and Evaluation of Offshore Pipelines in the Bay of Campeche

Abstract

In October 1995 Hurricane Roxanne damaged offshore installations in the Bay of Campeche. To assess the condition of significant pipelines. a major inspection program involving over 450 km of pipelines was conducted to survey the location of the pipelines and to determine their relationship to the seabed. Lines not fully buried were visually inspected by multiple video cameras. The results of the inspections were presented on charts, data files and video tapes. These results were utilized along with existing design information to assess the condition of the pipelines and to identify locations where remedial work was needed. The hydrodynamic stability of all exposed pipelines was analyzed to determine the need for pipeline burial. Damage to the pipes, weight coatings and corrosion protection systems was analyzed on a case-by-case basis. 'The paper will review the pipeline inspection objectives, procedures, and results. Evaluation procedures using this information will be described along with a summary of the conclusions of the study. This is one of the largest and most comprehensive evaluations of existing pipelines ever conducted worldwide and provides a model for future evaluations of aging or damaged pipelines. The improved location and condition information provide a sound basis for appropriate maintenance and operational planning for these lines. Introduction When hurricane Roxanne passed through the Bay of Campeche in 1995, the area's petroleum production infrastructure experienced extreme environmental conditions that put the physical integrity of the pipeline systems at risk. Pipeline failures caused by this event had a considerable financial impact. These failures were identified and repaired shortly after the hurricane in most cases.@ After an event like hurricane Roxanne, an assessment of the condition of the pipeline systems that were damaged or of strategic importance was needed. In order to make an assessment, through inspections of selected submarine pipelines and risers were needed in order to obtain detailed information about the condition of the system and to identify damage caused by the hurricane not associated with obvious failures.@ In order to properly evaluate the condition of the facilities it was also necessary to determine if the existing metocean criteria used to design the facilities needed to be revised. To achieve this purpose, a hindcast was needed of the weather and sea state conditions during the passage of hurricane Roxanne. Hindcasts were also needed of other hurricanes and strong storms that have affected the Bay of Campeche. This information could then be used to develop a statistical estimate of the 100-year storm conditions which are commonly used for design and evaluation purposes. Using data obtained from the special inspections and from the 100-year storm criteria. mathematical models of the pipelines and risers could be prepared and analyses be made to check the stress and stability on each pipeline component.