Pipeline abandonment refers to permanently taking a pipeline out of service. Depending on a number of factors, sections of pipeline may be abandoned in place as short or long segments. Pipe materials abandoned in place will degrade over time. This study by NOVA Chemicals was commissioned by the PTAC Pipeline Abandonment Research Steering Committee (PARSC) to better understand the risks posed by pipe coating degradation products. Background information about PARSC is provided below.
This is a review of pipeline coating materials and their fate when pipelines are left in place at the end of their useful lifetime. The makeup and effects of materials capable of being leached out of the coating materials were assessed. Published information suggests that easily leachable chemical compounds in coatings have been in the process of being leached from coatings from the moment they were first put into the ground. Therefore, the chemicals that are soluble in water and easily removed have probably already leached out of the coating materials during the lifetimes of the pipelines.
The coating chemicals that are less likely or able to be dissolved in water, will not be easily leached and for the most part will remain in the coating material. It is expected that over time some minimally slow leaching will probably occur. For example, coal tar and asphalt coatings contain what are called polyaromatic hydrocarbons or PAHs. These relatively large chemical compounds prefer to be associated with other hydrocarbon rather than water. Very low concentrations may dissolve in water in the soil where the pipeline is located but they will preferentially be absorbed by soil organic carbon (for example: decayed plant material or soil humus) and will this will prevent them from migrating through soil water or to groundwater where they may travel to other locations. Additionally, these molecules can be biodegraded slowly by soil bacteria and fungi over time. Because leaching and degradation of pipeline material components have been ongoing for many years, by the time a decision has been made to abandon a pipeline and leave it in place, no additional risks from the coating materials are anticipated.
PIPELINE ABANDONMENT RESEARCH STEERING COMMITTEE BACKGROUND
The Canadian Energy Pipelines Association (CEPA), the National Energy Board (NEB), the former Alberta Energy Utilities Board (successor organization is the Alberta Energy Regulator), and the Canadian Association of Petroleum Producers have collaborated on technical and environmental issues associated with pipeline abandonment. In 1996, these four organizations published a review document titled “Pipeline Abandonment – A Discussion Paper on Technical and Environmental Issues”. In 2007, CEPA published a report titled “Pipeline Abandonment Assumptions” which discussed technical and environmental considerations for development of pipeline abandonment strategies. A comprehensive review was undertaken by the NEB as part of the Land Matters Consultation Initiative (LMCI) which involved four discussion papers on the different topic areas, 45 meetings and workshops in 25 communities across Canada, and written submissions from 13 parties. The final LMCI report, published in 2009 recommended that knowledge gaps on the physical issues of pipeline abandonment be addressed. Thus, DNV was commissioned to conduct a literature review regarding the current understanding worldwide with respect to the physical and technical issues associated with onshore pipeline abandonment and use the results of the literature review to critically analyze and identify gaps in current knowledge, and make recommendations as to potential future research projects that could help to fill those gaps. DNV published this Scoping Study in November 2010.
CEPA and PTAC have established the Pipeline Abandonment Research Steering Committee (PARSC) as a framework for collaboration to guide and direct innovation and applied research, technology development, demonstration, and deployment in order to address knowledge gaps summarized in the DNV Scoping Study. Research findings from the PARSC projects will be shared on a broad scale throughout the pipeline industry, the oil and gas industry, as well as with regulators, government agencies, and other stakeholders.