The BC-10 development is planned for two phases. The first phase of the project will be the Abalone, Ostra and one of the reservoirs in the Argonauta complex. (Illustration courtesy of Shell Brasil)

A project that combines a number of difficult challenges is well under way offshore Brazil. Shell Brasil’s Parque Conchas or BC-10 development has to contend with ultra-deep water, heavy oil, thin reservoirs, and an environmentally sensitive location. According to Paul Dorgant, Shell Brasil BC-10 venture manager, Phase 1 of the project is on time and on budget.

Located offshore Vitoria, in Espirito Santo state waters, there are four commercial areas with six discoveries. API is from 16 to 42. Shell Brasil is the operator with a 50% share; Petrobas with 35% and ONGC with 15% comprise the remainder of the consortium developing BC-10. To meet BC-10’s challenges, Shell Brasil is deploying an array of advanced technologies in a phased development program.

Phased development

The first phase of the project will be the Abalone, Ostra, and one of the reservoirs in the Argonauta complex. Dorgant said these were chosen to get the lighter oil producing first and because they had aquifer support. “We don’t anticipate these reservoirs requiring water injection for reservoir maintenance.”

The development concept is to tie Abalone back to Ostra, where there are artificial lift manifolds. Production from two manifolds in Ostra will be co-mingled in electric submersible pump (ESP) caissons, which provide boost. Production will be sent up oil and gas risers to the floating production, storage, and offloading vessel (FPSO). The Argonauta field will also be produced through an ESP caisson.

“In Phase 2 we’re going to bring in the Argonauta O North,” said Dorgant. “It’s a fairly good reservoir that requires water injection. O South will come in at a later phase, and we will apply what we learned to develop it. Nautilus will be developed after we finalize unitization discussions with Petrobras.”

Ostra and Abalone at 24 API and 42 API, respectively, have relatively high gas volume fractions. To make the ESPs function more efficiently and produce better, Shell is using two-phase subsea separation to separate gas from liquids. Production goes into a caisson with a tangential separator, oil drops to the bottom, and gas goes to the top. Liquid is then pumped through the large ESPs that are inside the caisson and pumped to the surface.

Dorgant said that for the future the company is investigating twin screw pump technology and multiphase pump technology but pointed out that it is possible that ESP caisson technology may work in Phase 2 as well. All the fields require a substantial amount of boosting — in the range of around 2,000 psi — to overcome the backpressure on the well at the seafloor.

FPSO Espirito Santo

Heavy oil processing on the FPSO is a primary concern. The company selected SBM as a result of the bidding and qualification process. According to Dorgant, the strategy was that SMB would use its industry-standard solutions and make them work for the unique heavy oil and oil ranges in BC-10. “The contract as implemented is that they would design and build the FPSO as a contractor to us, and they will then operate it. So they own the FPSO and will operate it for the life of the field. We have options in the future to purchase the FPSO if that made sense. The intent is to build on industry standard solutions and what they have used effectively in Brazil. A number of the FPSOs in Brazil are operated by SBM. We’re building on the strengths of both Shell and SBM.”

The FPSO, which will be named the Espirito Santo, is being converted in Singapore and will travel under its own power to Brazil. With sponsons added, which give it double sides, the FPSO has 100,000 b/d of oil capacity. Shell has a 15-year lease with options to extend. Dorgant said the delivery date is to meet project goals — some time toward the end of the year or into next year. “We’re trying to manage all the different environmental licenses and all the other issues, so that’s the type of delivery time we are looking at.”

Upon arrival, it will be moored with preinstalled suction piles built in Vietnam. The suction piles have just been installed in the field. All engineering for the FPSO is being done at SBM’s headquarters in Monaco.

Artificial lift

“Why did we use ESP caissons rather than individual ESPs down each well?” Dorgant asked. “There’s an optimization that we tried to come up with to flow multiple wells into one caisson. The caisson is basically a large tubular that is a ‘false’ well that goes about 328 ft (100 m) down. Production goes into that caisson, and the ESP is inside the caisson. Production is co-mingled, and separation occurs inside the caisson. Liquids are pumped up a liquids line, and gas flows up a gas line. This has several benefits.

One, it has efficiencies in that it reduces the number of ESPs required; two, it helps us to manage any interventions or downtime we may have. Having ESP caissons, you can flow wells to different caissons if you have to change out an ESP. You can do so without necessarily impacting production. Three, it allowed us to have a more efficient use of flowlines and risers.”

The technology was first championed by Petrobras in early 2000. It was implemented by Petrobras on a small scale and is still operating. The technology is also being used on Shell’s Perdido development. In Houston, Shell has operated a full-scale caisson ESP test for about two years. Dorgant said that so far the test has been highly successful. “We’ve run different amounts of gas and types of liquids through it and we have learned a lot about the operating parameters of the caisson ESP. We’re counting on these to work to meet our production target, and we’re spending a lot of money to see that they do.”

Flow assurance

With high API viscosity oil flowing in the flowlines and up the risers, flow assurance is a primary concern. Phase 1 uses six ESP caissons — two non-separated, four separated. Powering the 1,500-hp ESPs requires high-powered umbilicals. When more power is going down an umbilical, it gets a lot heavier and harder to manage. The challenge was to come up with the right mixture of the strength and flexibility of the umbilical to make it work in deep water.

Steel “lazy waves” are used on risers and umbilicals and are meant to overcome the strength vs. fatigue issue. “When you’re trying to design something for strength, that usually goes against you when designing for fatigue life and vice versa. The lazy wave takes some of the load off the setdown point and the top-end connector. This allows us to design more efficient umbilicals and risers,” Dorgant said. “On the deepwater risers themselves we are using steel lazy waves as opposed to flexibles. This allows bigger risers with more throughput for each riser, and it reduces the number of risers required.” The technology was first used on the Na Kika platform in the Gulf of Mexico.

Surface BOPs

To achieve production targets in the shallow, spread-out reservoirs, the company plans long horizontal completions. To drill the wells, Dorgant said the company is using surface blowout preventers (BOPs) with high-pressure risers rather than heavy marine risers. “To achieve the wells, we’re using a surface BOP rather than a seafloor BOP. This is technology we’ve used since 2003 in Brazil. It allows us to have more rigs available to use. In this water depth and the types of drilling we require, we would normally require a Generation 5 rig, which are expensive and limited in number. Surface BOPs expand the number of rigs we can use. We’re using what is effectively a Generation 3 rig, the Transocean Arctic I. It reduces the weight the rig has to support by bringing the BOP up from the seafloor and using a smaller diameter, high-pressure riser system. The technology stretch with BC-10 is to not only drill the well but also to complete the wells with surface BOPs. It’s an extension of technology we are comfortable with. It’s effectively the same surface BOP technology as we have used on Mars, Ursa and other TLPs. We applied these learnings to MODUs.”

Umbilicals

High-voltage, high-power umbilicals power the six 1,500-hp ESPs used in Phase 1. The umbilicals provide power to the ESPs and also all the normal controls for the trees and valves. “It’s certainly a technology stretch in terms of the water depth, the voltage and the fact that we are using this umbilical in a dynamic mode with the FPSO, which, of course, is not heave-restrained,” Dorgant noted.

Subsea

The manifold bases are already installed, according to Dorgant. “Orientation and level are correct. Six conductors have been installed — two at the Argonauta template and four at the Ostra template. They were driven from an anchor handling vessel using subsea hammers. They form the foundation or base. Once the rig is on site, it will install the 42-in. liner that goes inside the 48-in. conductor. The template of the basic artificial lift manifold assembly is installed. The caisson is installed through the top of the manifold assembly. The caisson includes the valving and separator required for the tangential separation. Drilling operations with the Arctic I have begun, and the first well is finished. The rig uses a pre-set mooring system.

“BC-10 is on schedule and on budget,” Dorgant said. “Progress is as good as can be expected. Considering that people all over the world are working on it, it’s remarkable the cost and schedule control we have achieved. BC-10 is a great project for Shell to build on our deepwater experience worldwide. And we have started work on Phase 2 already.”

Shell in Brazil

Shell has been in Brazil for more than 90 years. Dorgant says the company’s EP investment there is growing substantially, with a lot of it in BC-10. “We’ve invested in 13 wells, and now we are investing heavily in other projects. We’ve added a lot of extra jobs in Brazil, both in Shell and indirectly with our contractors.”
Of the three basins Shell is involved in, the majority of production is in the Campos, with substantial production in the Santos basin as well. Espirito Santo is the third basin. Shell is in 10 exploration blocks — some operated by Shell, some by Petrobras — across the three basins.

“Our primary goal is no harm to people and no harm to the environment,” Dorgant noted. “We have many meetings and workshops to make sure that Shell staff, contractors, and everyone else associated with BC-10 understand that this is our primary driver. This is the guiding principle of every decision we make — not economics, not schedule.”