The Challenge
A global operator had plans to dewater a 4” fuel gas line in the North Sea that did not have a pig receiver. A service company recommended EVO-Pig because of its exceptional dewatering capabilities and Aubin were approached to prove that EVO-Pig could perform the job to the operators specifications.
To prevent expensive delays and mitigate any potential issues that might be encountered during the offshore operation, the operator wanted to test the proposed solution at a specially engineered pipeline test facility that enabled them to prove the concept prior to any field operations.
Aubin ran a series of trials using a commissioned pig testing loop, designed and assembled by Aubin engineers at the Ellon, UK site. The trial required the EVO-Pig to meet the clients performance criteria for 3 different areas: durability for 4km, dewatering performance and extrusion using Aubins 130m pipeline test loop.
What Happened?
Aubin’s engineering team designed and assembled the 130m long pipeline test loop with 4” diameter that included two 1m PVC sections to allow the team to visually assess the tests. Two EVO-Pigs were inserted into the pipeline loop with a 0.5m gap that was filled with water to represent MEG. To test durability, the pig train was pushed through the 130m long pipeline loop for 31 rotations to reach 4km.
During the successful test, videos of the pig passing the PVC pipe were taken at different intervals. Throughout the run, the separation between pigs remained constant and water colour between the pigs was noticeably different from the rest of the water in the line (Fig. 1). These showed that a seal had been made and the pigs were not allowing any bypass.
Both EVO-Pigs were in completely the same condition as they had been upon loading, far exceeding the pass criteria of being >90% of original mass. This demonstrated EVO-Pig to be suitable for travelling at least 4km in a liquid filled line with minimal damage or wear.
To test dewatering performance, two EVO-Pigs were loaded into the pipe with 1m air gap between them and the loop was filled with a volume of 602.5L of water, while air was vented out. The EVO-Pig train was pushed using compressed air through the loop, displacing the water into a pre-weighed IBC. Once the pigs had been extruded into the IBC, the IBC was weighed to quantify water removal and the test was repeated with fresh EVO-Pigs.
As shown in Table 1, both dewatering runs were successful with all the water recovered.
Table 1: Quantity of water removed from pipe.
The line was also visually inspected to find that all water was removed as seen below in Fig 2.
Fig 2. Visual line inspection dewatering test.
Continuing the dewatering tests, the ability of the EVO-Pig train to extrude through a 4x2” tee and 2m 2” hose was measured. Both EVO-Pigs were successfully extruded completely, exceeding the agreed 95% removal success criteria as shown in Fig 3.
Fig 3: The second EVO-Pig was extruded with a pressure of 7.4 bar.
The Result
Aubin qualified the performance of EVO-Pig in a series of factory acceptance tests conducted at their Ellon, UK facility. EVO-Pig passed each test set out by the client and performed exceptionally and the client is scheduled to perform the operation on their asset shortly
