Severe Wax Blockage

A UK offshore 8" condensate pipeline suffered a severe wax blockage that could not be removed using conventional methods, resulting in a prolonged production outage. To restore flow assurance, the decision was taken to cut out and replace the affected section with a 23km bypass.

With saturation divers required to work in close proximity to the system, it was critical to thoroughly clean the line, prevent hydrocarbon discharge and ensure the highest levels of diver safety and environmental protection.

SANCCUS was engaged to deliver a controlled chemical solution that enabled the operation to be completed efficiently while maintaining personnel safety and environmental integrity.

Solution

Step 1

2 hot stabs were installed on either side of the blockage area as per the diagram and 2" downlines were connected to the Diver Support Vessel (DSV).

Step 2

Aqualink Gel, J-Clean 1 and Pipesurf 10 were pumped from the DSV through the hot stabs 1 and then 4 to clean and deoil the line.

Step 3

Glycostat Gel were injected through the hot stabs 2 and then 3 to form a 300m long environmental barrier on each end of the blockage.

Step 4

Cut out the pipeline section containing the blockage and replaced it with a bypass.

Result

Value

SANCCUS Gel technology provided a controlled, chemistry-led solution to a blockage scenario where conventional mechanical methods were not viable.

By combining targeted cleaning with long-length environmental barriers, the operation was executed safely while protecting both personnel and the marine environment. This approach significantly reduced DSV time, fluid handling, and overall offshore time, delivering clear cost and schedule benefits without compromising safety or compliance.

The project set a new benchmark for subsea intervention, representing one of the largest environmental Gel barriers deployed in saturation diving and ROV operations to date.