Integrity Assessment of Marine/ Off-shore Networks through Flowline/Wellhead Inspection Campaign
J.E. Mbamalu, Frederick Obataimen Edeko · 2004
Abstract This work involves flow line/ wellhead Inspection Campaign in the Delta region of Nigeria. The work scope includes provision of manual thickness measurements (scanning) of critical areas of flow lines/wellhead on OML 100/102 platforms by ultrasonic means. The OML 100 is located off-shore Akwa Ibom state of Nigeria about 80km west of Bonny Terminal and OML 102 is located 40km from OML 100 both are accessible by air (helicopter) and sea boat. The UT survey runs from Afia, Edikang, Ime, Odudu, and Ofon fields. This survey was carried out with the view of determining the integrity of the marine structures and facilities using D-meter/Amdata UT inspection equipment. This study therefore seeks to generate corrosion data with a view to determining weak sections of the flow lines/wellhead structural facilities and installations. The offshore corrosion survey is also aimed at ascertaining the effectiveness of the CP system and integrity of the Crude Oil/Gas networks. A four phased survey procedure adopted in this work include: Initial condition assessment, flow line/wellhead cleaning, UT Intraspect Imaging, and Manual UT scanning using D-meter. The values obtained were used to evaluate changes in physical state of the structures with respect to the environment, location/severity/population of “hot spots” (corroding areas), potential areas of coating disbondment, holidays, blistering, seam tenting, cracking and wrinkling and location of areas that are subject to stray current electrolysis. Using all the accumulated data; a risk assessment is presented to determine the present integrity of the flow line/wellhead networks. The assessment would reveal if the networks were safe for continued operation under its present condition. Further, it would reveal if a repair program is required or if segments of the structure must be replaced in order to bring the system to an acceptable level of operational safety and product availability.