Escravos Lagos Pipeline Integrity Project

The development of the Escravos Lagos Pipeline (ELP) system in Nigeria was designed and managed by Penspen in the 1980's and will be a critical element in the supply of natural gas to the planned West Africa Gas Pipeline (WAGP) project. Penspen was commissioned by the WAGP sponsors to undertake a detailed integrity review of the ELP system to confirm its condition and potential to supply the WAGP over the lifetime of the project.



 

Pipeline Risers from Swamp onto Node Pig Traps.




The West Africa Gas Pipeline will enable transportation of natural gas from Nigeria to the neighbouring states of Benin, Togo, Ghana and Cote d'Ivoire. A consortium of major international companies are sponsoring the project including Chevron Nigeria Limited (Managing Sponsor), Shell Petroleum Development Company of Nigeria Ltd and the national oil corporations of Nigeria, Benin, Togo and Ghana. The WAGP will comprise some 600 km of pipelines, mainly offshore, together with onshore spurlines and receipt facilities.

Penspen was awarded the contract for the ELP Integrity Project by Chevron Nigeria Limited in competitive tender against several other engineering firms. The Penspen Project Director, Dave Adams explained: "We were able to offer an unrivalled knowledge of the ELP system as Penspen has undertaken every stage of the system development in Nigeria. This experience combined with the leading pipeline integrity expertise of our Andrew Palmer and Associates division gave us a significant advantage over our competitors."


 

20" Pig Retriever at Warri Gas Treatment Plant.

 


The main part of the ELP system is a 36 inch diameter pipeline, some 340 km in length which runs between Warri and Lagos incorporating major river crossings and swamp areas along the route. The system also includes two main branch pipelines of 20 and 24 inch diameter, each around 28 km long.

The ELP Integrity Project is in two stages, the first of which comprises on-site surveys to establish the existing status of the system. The Penspen team has visited the above-ground parts of the pipeline to inspect the numerous stations, valves and general condition of the pipeline to identify the levels of degradation and any other damage which the system may have suffered. An in-depth report on these observations is currently being prepared to identify any essential repairs to be carried out immediately and to make recommendations as to the extent of intelligent pigging to be undertaken in the second stage of the project.

After all essential repairs and maintenance have been carried out, such as the repair of leaking valves, the second stage will commence consisting of internal inspection of the ELP system using intelligent pigging techniques. Penspen will manage and co-ordinate specialist subcontractors to undertake the pigging operations.


 

24" Pig Retriever at Oben Metering Station

 

 

Cleaning pigs will first be used to ensure that all surfaces are clean and exposed. Gauging pigs will also be used to make sure that there are no deformities in the pipeline which may cause damage to the intelligent pigs and cause them to become stuck in the pipeline. Moving at approximately two metres per second, intelligent pigs will record every weld and valve and every defect in the pipe (internal and external) together with the exact locations.

Once the digital data has been collected and processed, Andrew Palmer and Associates integrity specialists will scrutinise and interpret the information. Detailed recommendations will be made for any repair and refurbishment works required to ensure the continued integrity of the ELP system over the lifetime of the WAGP project.