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Analysis

Simulated Service Vessel for Deepwater Pipeline Servicing

Tue, 01/22/2013 - 17:54

Pemex’s recent successes in deepwater exploration wells create the conditions for technological developments in Mexico’s deepwater oil and gas industry. Simulated Service Vessels (SSVs) is a technology that the NOC might need for deepwater pipeline servicing.

Insulation – or flow assurance – coatings are commonly applied to offshore pipelines to ensure the flow of hydrocarbons at elevated temperatures. The thermal properties of the insulation system can be readily modeled; however, the performance of the insulation needs to be verified under conditions similar to those encountered in deepwater environments. Simulated service testing is critical for both insulation coating systems that are currently used in the industry, as well as for innovative insulation systems. Current systems require validation prior to deployment of the pipeline to avoid extra costs due to downtime.

Historically, SSVs have been used in the oil and gas industry to test the performance of insulated offshore pipelines by submerging test pipe into pressurized water with constant water temperature, while controlling the elevated temperature inside the pipe. By measuring the heat flow, thermal conductivity and compressive creep of the insulating material, both the thermal efficiency and depth rating capabilities of the insulation can be confirmed. This data can also be used to validate the design and integrity of the insulation system.

As a consequence of the increasingly challenging industry requirements, ShawCor – a Canadian energy services company serving oil and gas companies around the world – has built a new state-of-the-art 82 tonne SSV, the largest such vessel in the world. The new SSV is essentially a large cylindrical autoclave, capable of accommodating pipes 6m long and up to 810mm external diameter. The test pipe is mounted onto a carriage which is attached to the vessel door on one end and rides on wheels on the inside of the vessel on the opposite end. Upon establishment of thermal equilibrium, the vessel is pressurized and held at the required pressure for the duration of the test. The pressure is increased in specific increments to assess the immediate and long term response of insulation properties to changes in pressure at a specific operating temperature which is set by internally heating the test pipe. Alterations in compressive creep and heat flow are also measured over time.

The ShawCor SSV has been designed to test an equivalent water depth of up to 3,000m at an internal pipe temperature of up to 180°C. Futhermore, it has the capability to compare the performance of three insulation coating systems simultaneously, with multiple measurements for each coating system. If required, the SSV can test for cool down time and provide accurate, real-time measurements of creep to evaluate long term reliability of the insulation. The conductive heating system provides tightly controlled temperature within each zone with a maximum variation of +/- 1°C at any point in the zone. A high capacity chiller system maintains a temperature of 4 °C to 6°C around the pipe. Another distinguishing feature of the new SSV is its capability to stream real-time data that can be accessed by the customer 24 hours a day during the entire duration of the test.

Pemex’s future projects will require pipeline insulation coatings and ShawCor is ready to support the NOC through its subsidiary Bredero Shaw Mexico, which offers a full range of end-to-end pipe insulation coatings. The new SSV will also be part of the story as a critical tool for validating the long-term performance of the insulation coating systems.