Subsea Pipeline Operational Risk Management
Authors: Bell Richard L. , Lanan Glenn A. 
Published: October 2008

Resources used for inspection, maintenance, and repair of a subsea pipeline must be allocated efficiently in order to operate it in the most cost effective manner. Operational risk management aids in resource allocation through the use of risk assessments and cost benefit analyses. h identifies those areas where attention must be focused in order to reduce risk. When they are identified, a company's resources (i.e. personnel, equipment, money, and time) can then be used for inspection, maintenance, and or repair of the pipeline. The results are cost effective risk reduction and pipeline operation with minimum expenditure.

Introduction

The safety of subsea pipeline operation is often based on procedures which recommend performing specific inspection and maintenance activities throughout a pipeline's operating life. Basing these activities on procedures, however, creates the possibility that more inspection and maintenance is performed than necessary. As a result, more resources are expended than required for safe pipeline operation, In contrast, the possibility also exists that insufficient resources are used for risk minimization or that they are used inefficiently. Risk management minimizes these potential problems by optimizing the amount and method in which resources are spent for the objective of safe pipeline operation.

Risk Assessment

A risk management program is cyclical in nature and contains four main processes that are performed throughout the life of the system: risk assessment, cost benefit analysis, risk reduction, and updating the risk assessment model. A subsea pipeline risk assessment identifies the segments of a pipeline which contain the greatest risk and the risk contributing sources. A cost benefit analysis can then be performed to identify actions which cause the greatest risk reduction for the least amount of resource expenditures. Personnel, equipment, money, and time are utilized through inspection, maintenance, repair, and possibly replacement or upgrade for the objective of maintaining a safe pipeline. After the system has changed significantly, the risk assessment model must be updated so that it accurately reflects the current system. Fig. 1 outlines the risk management methodology.

System Definition.

The system of interest (i.e. subsea pipeline or pipelines) must first be defined in order to perform a risk assessment. t'z The pipeline is segmented into zones of similar characteristics such as terrain, environmental conditions, etc. Segments can then be compared to each other and ranked in terms of quantitative risk after the riskassessment is completed.

Data Collection.

Historical data are collected pertaining to the pipeline under study and other similar pipelines. In addition, as-built data for the pipeline and information on its current condition are obtained. Operating personnel should be interviewed in order to elicit risk-related information which cannot be gathered from records or inspection. The collected data provides information including but not limited to:Pipeline Characteristics - length, diameter, wall thickness, material grade, coating, burial, crossingsOperational Parameters - contents, operating pressure, MAOP, temperatureFacilities - tie-ins, risers, shore crossings, safety schematicOperation Procedures - SCADA system, pigging procedures, leak detection monitoring, inspection frequency