INTRODUCTION
The big challenge for any oil and gas pipelines operators is to keep safe operations regarding the transportation of its product, produced at the wellheads to offshore and onshore processing facilities, across the pipeline network transport fluids.
As the pipeline operation continues, a significant portion of such pipelines is getting mature and several pipelines in operation have reached or may exceeded their design life. Pipeline operators must carry out some pipeline integrity activities recently to ensure the integrity of existing subsea pipelines.
In order to ensure that pipelines operate with as little damage and environmental impact as possible while still being economic, there is a need to establish a Pipeline Integrity Management system (PIMS) for all the pipelines in a framework of people, processes, procedures, methodologies and software used to ensure the pipelines integrity.
The task of PIMS is to determine the overall process for the integrity assessment of pipelines and thus to control the operative implementation of inspections, maintenance, and repairs of the pipeline network. The goal was to provide system-technical support for the PIMS sub-processes for the determination and evaluation of the line condition.
HINGENEERING SCOPE OF SERVICES
HINGENEERING Consulting would develop an integrated pipeline integrity management system in terms of Plan-Do-Check-Act & Continuous Improvement. The integrity Plan stage consists of Reliability & Risk analysis and ranking, Fitness of service, and Pipeline operation plans. The Do stage includes all field prevention, inspection, and mitigation plans. While the Check stage contains the reliability and risk assessment of the integrity plans, effectiveness and efficiency metrics, and safety metrics. Act stage is activated if the Check metrics are not meeting integrity targets. The continuous improvement stage is the outcomes from each integrity cycle along with failure investigations. The integrated PIMS provides a world class safety approach achieving an optimized pipeline operation with the highest level of safety. In the following sections, more details will be discussed regarding the proposed pipeline integrity management system (PIMS).
PIPELINE INTEGRITY MANAGEMENT SYSTEM (PIMS)
During pipeline operation, maintenance is of vital significance for sustaining technical integrity. Preserving technical integrity and the need to use suitable management systems is required by the relevant regulations and standards. The goal of Pipeline Integrity Management System (PIMS) is to ensure safe pipeline operations with as little damage and environmental impact as possible while still being economic. Fig. 1[1] illustrates the interaction between the maintenance measures to be performed in order to minimize potential risk and the resulting financial expenses. The possibility of creating a balance between both aspects depends mainly on knowledge of the network status.
Fig. 1: Interaction between potential risk and expense
Based on the knowledge of the pipeline status, appropriate rehabilitation and maintenance measures can be planned. The derivation of measures requires a standardized description of the pipeline status and a uniform status assessment.
The status assessment (integrity) of a pipeline is obtained by consolidating and evaluating various sources of information. They arise from the areas of operational organization, data documentation, and technical operational management.
The task of PIMS is to determine the overall process for the integrity evaluation of lines and thus to control the operative implementation of inspections, maintenance, and repairs of the pipeline network. It thus forms the connection between management, organization, information, and technology. The use of PIMS should be integrated into the existing operative processes of the network technology from the beginning. The maintenance process and the PIMS process is outlined in Figure 2 (1).
In general, it is essential to determine the pipeline status of the entire line network. Furthermore, it is also important to record any inspections conducted throughout the pipeline operations and to report every individual inspections can lead to an integrity evaluation. Initiated by network operations, the pipeline is evaluated in PIMS. By involving network engineers and experts in the evaluation of the result, any peculiarities of a pipeline can be considered. Based on the assessment outcomes, further inspection measures can be recommended. The gathered information from this is then considered in a new evaluation run.
METHODOLOGY
The principles of the proposed Pipeline Integrity Management System” (PIMS) will rely on the following standards and specifications:
American Society of Mechanical Engineers (ASME B31G): Manual of Determining the Remaining Strength of Corroded Pipelines
American Petroleum Institute (API) recommended practice 1162: Public Awareness Programs for Pipeline Operators
American Petroleum Institute (API) recommended practice 754: Process Safety Performance Indicators For The Refining And Petrochemical Industries
Canadian Standards Association (CSA) Z622: Oil and gas pipeline systems
Industry best practices from Canadian Energy Pipelines Association (CEPA), Interstate Natural Gas Association of America (INGAA), Pipeline Research Council International (PRCI) in addition to HSE.
Phase 1: Data gathering, review, and data integration
As part of Phase 1 of the project, few site visits are needed in order to obtain an overview of the pipeline system, its operational and integrity strategies and to start the long process of collecting the data required for the PIMS. The data collection required a joint effort between pipeline owners and their subcontractors performing most of the data source identification and gathering in addition to converting the information into usable data. Sample of the required information includes but not limited to the following:
Alignment sheets for the pipelines
Center lines for each of the pipelines
Condition monitoring data for each of the pipelines. The main techniques for inspecting the condition of pipelines are by means of ROV's, Auto UT surveys/corrosion coupons and Cathodic Protection. In-line inspection (ILI) using intelligent pigging will be performed also.
The condition monitoring data imported into the GIS database included:
The pipeline product composition, production rate data and corrosion control information for each of the pipelines
Additional data elements for use in the risk and Fitness For Purpose (FFP) assessments will be were entered.
Data Gap Analysis Report will be developed as soon as the data gathering and review process phase is completed. The gap analysis report will discuss the mandatory parameters to conduct the required scope of work, review the source documents, analyze the types and quality of data collected, identify any gaps in the data for the pipelines and recommend the further course of actions to be undertaken in relation to the data gathering phase of the project.
Phase 2: Engineering Evaluation of Fitness For Purpose (FFP)
The Engineering Evaluation of the FFP phase involved performing a condition assessment on each of the pipelines. These assessments involve the following steps:
A. A review of the historical and current Inspection, Repair and Maintenance (IRM) activities and records (ILI, Caliper, automated-UT (Auto-UT), corrosion, ROV inspections, etc.). Feature and significant event summaries will be provided for each pipeline based on the available most recent survey data and accounting for any remedial and intervention work conducted since the last survey.
B. An FFP evaluation of the most recently known condition of the pipeline utilizing industry best practice. Such evaluation will require the determination of the current and historical operational parameters associated with each pipeline, the assessment of the severity of any reported pipeline anomalies (corrosion, dents, weld anomalies, mill faults, etc.), the determination of the maximum allowed (critical) span length and assessment of any reported spans or other stability anomalies, identification and recommendation of the necessary actions that should be taken to ensure the current and on-going FFP of the pipeline based on its most recently known condition.
C. An external Corrosion Review to assess of the effectiveness of the pipeline corrosion protection system including a review of the external survey data relating to the Cathodic Protection system and an assessment of sacrificial anode depletion involving the determination of the remaining life for each anode and the estimated time to replacement.
D. An Internal Corrosion Review to review the on-going risk from internal corrosion in the 9 pipelines including an in-depth operational analysis of the transported products, operating conditions (temperature, pressure, flow-rate), inhibition, produced water, solids, bacterial contamination, leak history in order to evaluate the internal corrosion threat to each of the pipelines and to estimate corrosion deterioration rates.
Phase 3: Probabilistic Assessment of Pipeline Failure (PAPF) and Consequence Assessment
The Probabilistic Assessment of Pipeline Failure and Consequence Assessment on each of the pipelines involved the following steps:
A. The development of the probabilistic assessment models for each applicable threat to the safe operation of the subject pipelines and the evaluation of the probability of pipeline failure by threat and by pipeline segment.
B. The identification of probabilistic industry benchmark levels and comparison against the results for the pipelines.
C. Evaluation of the consequences associated with a failure (i.e., a loss of containment event causing either a leak or rupture release).
D. The combination of the probability of failure results and the consequence of failure results to give the overall risk of failure for each pipeline and each pipeline segment.
E. A summary of the recommended remedial activities per pipeline will be prioritized according to the level of risk and demonstration of the benefits in terms of reduction in risk after the remediation activities are performed.
The threats applicable to the pipelines in the study were concluded to be:
Internal Corrosion
External Corrosion
Mechanical Damage
Sour Cracking
Weather and Outside Force and
Incorrect Operations
The probability of failure (per year) will be estimated by threat and by pipeline segment.
Phase 4: The development of The Pipeline Integrity Management System (PIMS)
Managing pipeline integrity requires a comprehensive system in place to support it. As a minimum, that system must address process, people, and activities to manage the pipeline. In this Phase of the project, the PIMS algorithm that ties the three elements (process, people, and activities) together in a seamless and integrated system will be developed. The PIMS algorithm will guide the pipeline owners through the pipeline integrity management cycle (Figure 3).
Figure 3 – Pipeline Integrity Management Cycle
WHAT HINGENEERING WILL PROVIDE
Pipeline risk registry
Review available pipelines specific properties, inspection & mitigation data, and historical failures
Benchmark pipelines to industry performance
Develop an integrated PIMS framework
Develop Plan-Do-Check-Act & Continuous Improvement Processes
Develop deterministic and probabilistic fitness for purpose approaches
Develop a risk analysis and assessment framework
Set dynamic integrity targets as a function of pipeline classes and effectiveness & efficiency metrics.
Define ACT rules and response mechanism
Develop a continuous improvement plan
The goal of the “Pipeline Integrity Management System” (PIMS) is to allow the client to efficiently manage the pipelines in a safely manner. This can be established by mitigating the risk of pipelines failure, higher productivity and longer pipeline service life. [1] “Pipeline Integrity Management System”, Ruhe, M. and Rathlev, F., 7th Pipeline Technology Conference 2012, Hannover, Germany.