Overcoming Challenges of Pigging the Unpiggable Pipelines

Carbon steel pipelines are used to transport hydrocarbons globally because carbon steel is relatively easier to fabricate, safe for use, raw materials are available and less expensive. Amidst these benefits, carbon steel is susceptible to severe corrosion and other anomalies. Pipeline corrosion is a significant concern in the oil and gas industry. It has caused several minor and catastrophic losses of containment with resultant fatalities, environmental pollutions, asset damage, and production downtimes. The increasing failures of in-service pipelines have led the Department of Petroleum Resources (DPR) to intensify regulatory scrutiny of pipeline integrity assessment and management in Nigeria to ensure strict compliance to the regulatory requirements by the Oil Producing Companies. According to DPR Act (Section 2.5.2.1), all pipelines greater than 6" size diameter must be inspected every five (5) years with intelligent pigs (inline inspection tools) that would provide the accurate condition of the pipeline. However, many pipelines in Nigeria are unpiggable or difficult to inspect with intelligent pigs due to the unavailability of pigging facilities (especially in brownfields), pipelines with short bend radiuses, dual diameters, flow parameters, etcetera. This paper explores case studies involving the use of advanced inline inspection technology to conduct inline inspection of difficult-to-inspect dual-diameter pipelines.