In June Petrobras reached a record high oil and gas output of 2.81 MMboe/d, up 0.6% compared to the previous month. The figures released by Brazil’s state-owned oil company also indicate Petrobras and its partners in the presalt layer hit two new oil output highs: the monthly rate reached an average 1.35 MMbbl of oil and the single-day production hit 1.42 MMbbl on June 19.

The success in the presalt is being driven by large investments in research and technology, aiming to produce oil at a lower cost.

The presalt covers about 350,000 sq km (135,135 sq miles) in water depths up to 3,000 m (9,843 ft) off the southern coast of Brazil. In early 2012 Petrobras and Schlumberger initiated a multidisciplinary R&D project to reduce presalt drilling costs.

As a result of this project, three drilling systems were designed—from the project phase to field testing using conical diamond element technology. Two factors were key to the success of this project: the application of a system engineering methodology and collaboration between research groups, and engineering and operations teams at Schlumberger and Petrobras.

High well construction cost in this environment motivated the search for a drilling solution that would bring a step change in drilling performance. Such an effort would be very expensive and time-consuming if using a trial-and-error approach in deep water. This led Petrobras and Schlumberger to sign a joint research project to develop a system engineering approach to identify the causes of low performance when drilling complex presalt carbonates with a goal of developing a fit-for-purpose solution.

Known as the “Drilling Optimization in the Presalt” project, this approach aimed to tackle several challenges ahead for operators such as analyzing the low ROP and premature bit damage to design fit-for-purpose drilling systems and maximizing the amount of laboratory testing, particularly screening drillbits in a real scale drilling simulator. Petrobras invests about $476 million in R&D and innovation with a major focus in the E&P segment, which accounts for 75% of the budget.

“This value is higher than last year and will continue to grow in the coming years due to the increase in our production curve,” said Paulo Barreiros, technology management manager for CENPES, Petrobras’ R&D Center. “Our major focus on developing technology is to produce more at a lower cost.”

Among the strategies implemented was the design of a drillbit.

Named StingBlade, Model ER26769, this new drill design was developed through a technological cooperation agreement between Petrobras and Schlumberger, which was started in November 2011 and completed in November 2015.

According to CENPES, the drillbit was developed in 48 months. The first test was performed with an 8½ diameter drillbit. The other three tests were performed with a 12¼-in. drillbit. This technology greatly increased the presalt carbonate drilling yield, surpassing previous benchmarks and reducing the cost by between 15% and 20% in field-tested prototypes. The expected reduction in capex can reach the equivalent of the daily cost of drilling a well.

This drillbit was developed specifically for the presalt carbonate rock, which was not as well known by Petrobras beforehand. In the laboratory tests the characteristics of the test specimens (rocks), mainly hardness and heterogeneity, were adjusted to simulate the rocks found in the presalt carbonate.

In the last field test performed by Petrobras, use of this drillbit increased ROP by 11.5% and the drilled gap by 25%. The benchmarking values used were: 219 m (719 ft) of perforated interval with a penetration rate of 2.6 m/hr. “The technological difference of this type of drillbit is its cutter, which has shown potential to greatly increase the drilling efficiency of the presalt reservoir carbonate rocks. The methodology used in this development was considered as an example for future technological developments,” Petrobras said in a statement.

There is no depth limit for this type of drillbit since it has no moving parts, and depth does not pose limitations on its use. The type of tapered diamond cutter sets it apart from other drillbits used in the post-salt and presalt. This technology allowed the development of a cutter with greater resistance to impact and abrasion when compared to traditional cutters.

The StingBlade conical diamond element bits were launched in 2014 by Smith Bits, a Schlumberger company.

—Brunno Braga

Offshore