After thirteen years, at El Tordillo the team is now able to sweeten gas again, thanks to the overhaul of the CO₂ and H₂S removal plant using amine technology. Keeping pace with a rise in production and the challenges of assembling the new plant.

Saturday, February 26, 2022, was a special day for the team at El Tordillo as they completed an unprecedented and highly challenging task, involving work at height and in confined spaces, to start up the new amine treatment plant. This is a major step for the field, and means that they no longer have to inject chemicals to achieve this process, and can resume the use of amine technologies to sweeten gas.

The challenges involved in an agile and innovative assembly

"The entire process, from beginning to end, including assembly, pre-commissioning, commissioning and start-up, took eight months of work," explains Martín Godoy, the Works Manager in charge of the revamping process at the amines plant in El Tordillo. The team of fifteen clocked up 18,500 hours of work during which no incidents were recorded. "They managed to reach this impressive achievement thanks to the high level of commitment demonstrated by our people in the Facilities, Operations, and Health, Safety, and Environment (HSE) teams," highlights Martín. He adds that "We focused on achieving as much agility and efficiency as possible through effective planning, anticipating all the emergency response plans, and mitigating safety risks involved in each critical task."

Bruno Di Tulio, Operations Supervisor and one of the key figures leading the start-up of the unit, singles out the exemplary support provided by the El Tordillo Emergency Brigade which meant that internal components could be replaced vertically without having to disassemble equipment, involving the deployment of a series of unprecedented strategies. "It was a huge challenge as everything we had to deal with was extremely complex. The work undertaken on the towers was spectacular: there aren’t many people who’ve experienced this kind of task and pulled it off. We’d done something similar many years ago at Tecpetrol, but not to the same standard of professionalism," recalls Bruno enthusiastically.

The story of a recovery

The story began in 1999 when the company started up its historic amine plant at El Tordillo, a unit that continued to operate until 2013, when they shifted to injecting chemicals to remove H₂S and sweeten the gas, a process that continued until the present. However, this process is also more expensive and affects infrastructure. “For example, it deposits by-products in the gas pipes which build up over time and produce blockages,” explains Di Tulio. These are known as undesirable precipitates, and often mean that several meters of gas pipelines have to be replaced.

Another issue was that many of the wells in the field couldn’t be opened as they contained CO₂, leading to production losses, and in 2015 the plant was shut down. However, as amine processing guarantees optimum gas quality for sale, in 2019 work began to definitively reactivate the process

"During 2019, we developed a series of conceptual engineering proposals, the basic documents enabling you to analyze project feasibility," explains Martín, adding that initially, the main issue was to decide whether they should revamp the historic plant or rent a small mobile plant known as skid tanker from a third party. The conclusions that arose from the analysis were abundantly clear: the plant had to be modernized to enhance the assets owned by El Tordillo. The next steps involved developing basic engineering plans based on the current state of the equipment and machinery, given that these were no longer suitable, as they’d been subjected to corrosion over time.

At a technical level, the team contracted a range of assembly services in the charge of different experts with the specialties required. They also acquired new equipment, such as the internal parts of the contactor towers, the stripping equipment, reflux air coolers, and the new auxiliary reverse osmosis water treatment plant, all of which were aimed at improving efficiency and reducing volumes.

In addition, the plant was also equipped with a SCADA display system (supervision, control and data acquisition) to enhance remote decision-making from a control cabin.

The historic plant has come back to life in revamped and refurbished form after many years to serve the El Tordillo field for the foreseeable future. Its recent commissioning means that the volumes of gas produced by the second drilling rig scheduled to begin work in May can be fully treated onsite. Martín concludes that "This plant changes the way we work, as when we are working with closed wells, from now there will be no further restrictions when we talk about gas processing."

Tecpetrol Glossary: what is gas sweetening?

Acid gas is a particular type of natural gas or gas mixture containing significant amounts of hydrogen sulfide (H₂S) and carbon dioxide (CO₂). Before this gas can be used, it must be treated to reduce its impurities to acceptable levels, a process known as "sweetening" which uses amines. Amines are aqueous chemical solutions that absorb unwanted gases through pressure at room temperature.