Petrobras executives outlined major advancements in production that the company has made since first discovering pre-salt reservoirs and the subsea technologies it will use to develop them further. Speakers from Brazil’s national oil company gave SPE members a presentation covering the company’s production and exploration operations in pre-salt fields during a special session.
First discovered in 2006 offshore southwest Brazil, the deepwater pre-salt reservoirs consist of heterogeneous microbial carbonate rocks found underneath a layer of salt more than 2000 m thick. Separated into two areas known as the Campos and Santos basins, the pre-salt fields now contribute almost 330,000 BOPD to Brazil’s overall output.
“After 7 years, we have all these new facilities in place,” said Carlos Tadeu da Costa Fraga, pre-salt executive manager for Petrobras.
Fraga, keynote speaker at the special session, was pointing to a map of offshore Brazil showing the location of multiple offshore facilities that included nine floating production, storage, and offloading (FPSO) units. Since the first field was identified, 10 other major discoveries in the pre-salt have been made, Fraga said.
“(Production of) 330,000 BOPD is eight times more than what we produced from these fields in 2010,” he said, “so it is a very fast increase in production in that area.”
The entire volume of oil produced to date in the pre-salt amounts to 250 million BOE, Frag said, adding “a lot more is to come, but these are very significant results that we have already made.”
Supporting his optimism is the fact that only one-third of the pre-salt area is under contract for development while the rest remains largely unexplored. To address future needs, Petrobras and its partners are busy building research and support facilities that will train the next generation of engineers to develop the vast reserves that remain trapped in pre-salt fields.
Petrobras said it has plans to complete pre-salt wells with up to three pay zone intervals and will use new technologies to prevent hydrate formation. One of the advanced operations that Petrobras will use to extend the life of its pre-salt wells is known as water alternating gas (WAG) injection. WAG uses reinjection wells for waterflooding to stimulate a reservoir along with the reinjection of produced gas and CO2. Other advanced technologies Petrobras is using to develop pre-salt reservoirs include managed-pressure drilling to prevent the loss of drilling mud by using a closed-loop system. The company is also spending more money on smart completions, where equipment to monitor temperature and pressure is installed inside the well to give operators critical information they can use to enhance production over the life of a well.
Petrobras conducted extensive geologic surveying that included extracting more than 500 m of core samples to determine where to drill in its newest pre-salt development, the Lula field. The first test well in the Lula field was drilled in May 2009, and the production pilot was completed in 2010, 4 years after discovery. A second extended well test was conducted in 2011, a year after gas injections began, and Petrobras started waterflooding operations last year.
In the presentation, a map of the Lula field, which is 44 miles long and 25 miles wide, was superimposed over the greater New Orleans area. “This gives you an idea of the large area we are developing,” said Antonio Carlos Capelerio Pinto, pre-salt development projects design manager at Petrobras.
Petrobras recently connected an FPSO at the Lula field to a well there that has a production potential of 25,000 BOPD, but the company is limiting that to just 13,000 BOPD because of gas-output restrictions. Petrobras will install reinjection and processing equipment and has completed one gas line to take away associated gas that would otherwise be flared. Petrobras said it has plans to build two more export lines by 2017 to distribute even more pre-salt gas to onshore facilities. Other plans include advanced flow monitoring and the extended use of 4D seismic through the deployment of seismic nodes to detect changes in the reservoirs over time.