On July 2, 2016, BOURBON's MPSV vessel, Bourbon Evolution 802, conducted an acidizing operation. Report by Marc-Antoine Peron Le Goff, the BOURBON Subsea Project Engineer.
12: that's how many days it took to acid treat a well operated by Total.
The goal: stimulating the well and improving its production. It was an operation that also required long, painstaking preparation: "BOURBON conducted studies over a year and a half to develop the procedures for mobilization and operation at sea,", explains Marc-Antoine Peron Le Goff.
For this operation, the 4th in one year for BOURBON with Total, the vessel dispatched was the Bourbon Evolution 802. Equipped with a large deck area, it can accommodate all the equipment required for acidizing."Equipment for Schlumberger - pump, tanks, and chemicals, for Total - injection pipe, for OneSubsea – interface tool for the wellhead, AKA the running tool - and for BOURBON - tools for deploying the pipe and the connection interface.". This phase, the mobilization phase, lasted 3 days.
"BOURBON conducted studies over a year and a half to develop the procedures for mobilization and operation at sea."Marc-Antoine Peron Le GoffBOURBON Project Engineer
Cleaning without polluting
Next, they headed for the field, where they deployed the ROVs needed to prepare the wellhead. "The platform shuts down the well, after which the running tool is deployed onto the wellhead and the pipe is connected to the running tool using the BOURBON connector. These installations are performed using the vessel's crane, monitored by the ROV," says Marc-Antoine Peron Le Goff. Then, there just remains the task of injecting the mix of chemicals which were prepared on board the vessel when the equipment was installed. "Before injection, we tested all the valves and the wellhead in order to rule out any risk of leaks".
Total operation time: 8 hours. Once the injection was finished, the platform took all the chemicals back on board using the pipelines. Nothing was left behind. The pipe was then disconnected and the equipment was brought back to the surface piece by piece: production could then resume.
Communicate is key
In all, 70 people were onboard the vessel during the operation, engineers and technicians from the 4 entities involved, in addition to the usual onboard personnel. The key to meeting the challenge? Good communication. Signs, barriers, announcements on the PA for sensitive operations...all resources are mobilized. "Communication is key! In particular, communication with the platform is crucial during the injection of chemicals: in the event of a problem, we must be able to inform them immediately in order to close the well and prevent any risk of pollution".
Communication is also what brings together all the elements of a broader safety arsenal. "During the preparation of chemicals, we electrically isolate all equipment which is not ATEX, i.e. anti-fire in themselves in the presence of flammable products. We also have all FiFi equipment in place from the start," the BOURBON engineer explains.
Over a year of preparation for twelve days of intervention: well stimulation is never routine. It requires total mastery of each of the steps of the operation, a high performance vessel and experienced personnel...