Brazil Parque Das Conchas Project Sets Subsea Separation, Pumping ...
NEW FIELD DEVELOPMENT
Brazil Parque das Conchas Project Sets
Subsea Separation, Pumping Milestone
Joel Parshall, JPT Features Editor
As first oil flowed on July 12 at the Shell-operated deepwater made six discoveries. The project was declared commercial
Parque das Conchas development offshore Brazil, it marked a in 2005, and major contracts were awarded in November
major advance in the production of Brazil’s abundant heavy-
2006. For Shell, Parque das Conchas is the first Brazilian
oil reserves and became the world’s first full-field development
project the company has taken all the way from explora-
based on subsea oil and gas separation and subsea pumping.
tion to production, as opposed to inheriting a project from
Situated 75 miles southeast of Vitória, off Espirito Santo another operator or initiating a project that it had to turn
state, Parque das Conchas (formerly known as BC-10) lies over to someone else to operate.
in approximately 4,900 to 6,500 ft of water at the northern
edge of the Campos Basin (Fig. 1). Parque das Conchas in Challenges to Project’s Economics
its first phase will produce from three fields, with oil ranging “There were a number of challenges we faced to make the
in gravity from 17 to 42°API. The fields will produce through project economic,” said Kent Stingl, Parque das Conchas
subsea trees and flowlines tied into the centrally located project manager for Shell. “We had heavy oil in relatively
floating production, storage, and offloading vessel (FPSO) low-pressure reservoirs in an ultradeepwater environment.
Espirito Santo (Fig. 2). Turret-moored in 5,840 ft of water, Hence, we had to determine how to pump from this depth
the double-sided FPSO is equipped to process peak daily and process on the production facility. But there was more
project production of 100,000 BOE, with 1.4 million bbl of to it than that. There are four dispersed reservoirs, small
oil-storage capacity. Parque das Conchas is a joint venture of to medium in size, with widely divergent oil gravities
Shell (50%), Petrobras (35%), and ONGC (15%).
and different gas/oil ratios (GORs). We needed to find an
The development grew out of a substantial exploration economic way of commingling and bringing production
and appraisal program, in which Shell drilled 13 wells and from the various reservoirs back to a central facility, with
artificial lift (AL) required and subsea gas/oil separation for
some reservoirs.”
A further challenge was that the reservoirs, though in deep
water, are only approximately 3,300 ft beneath the mudline.
Vitória
“Starting from vertical at the seafloor, we had to kick the
Espirito Santo Basin
wells out at a tremendously high angle to drill the horizontal
wellbores required to drain these reservoirs,” Stingl said. “We
BRAZIL
operated from only a few drilling centers to minimize the
need to move the rig. So these horizontals extended more
Parque das Conchas
than 3,000 ft, and all were completed with gravel packs.”
The Parque das Conchas complex is designed to tie in
production from the Abalone, Ostra, Argonauta B West,
Rio de Janeiro
and Argonauta O North fields (Fig. 3). The fields are all
Campos Basin
named for shells, hence the name Parque das Conchas
(Portuguese for Shell Park). At present, production is flow-
Santos Basin
ing from Abalone, with 42°API oil, and Ostra, with 24°API
oil. Argonauta B West, with 17°API oil, will be brought on
stream later this year. These three fields constitute phase 1 of
the project. The Argonauta O North field, with 16°API oil,
will be phase 2 and is slated to come on stream in 2013.
Surface BOP for Drilling, Completions
To drill and complete the wells, Shell used a surface blowout-
preventer (BOP) system that enabled it to contract a genera-
Fig. 1—Parque das Conchas location. (Accompanying tion 3 floater, the Transocean Arctic 1, rather than requiring
images courtesy of Shell.)
a much heavier, more expensive generation 5 rig that would
38
JPT • SEPTEMBER 2009
Fig. 2—The turret-moored FPSO Espirito Santo.
employ a heavier subsea BOP and an 183/4-in. marine riser. shortly. Argonauta B West includes two production wells
Shell pioneered the surface BOP system in deepwater drilling and an AL module.
in 2003, but Parque das Conchas marked the first time it was
used to handle deepwater completions, as well. The system Vertical Caisson Separator System
used in the drilling phase consisted of a standard surface The key innovation of the Parque das Conchas subsea pro-
BOP stack and a 135/8-in. high-pressure riser descending duction system is the separation and AL technology, the
into a shut-in device on the seafloor. After well tubing spools vertical caisson separator system developed by Shell and
were set, a slim-bore tubing hanger system enabled comple-
FMC. This system consists of a caisson more than 300 ft
tions to be performed with the surface BOP stack.
long driven into the seabed, with a cylindrical cyclonic gas/
“When you reduce the diameter and weight of the riser by liquid separator at the top and a 1,500-hp electrical submers-
the amount we did, it allows a smaller and lighter rig to oper-
ible pump (ESP) housed further down inside the caisson
ate at this depth,” said Chris Howell, Shell Surface Facilities (Fig. 4a and b).
team leader for Parque das Conchas. “The project was sanc-
Multiphase flow from production wells enters the caisson’s
tioned in 2006, when the drilling market was very tight. The top-end assembly and flows into the separator through a pur-
ability to use a surface BOP system expanded our options for posefully angled and tangential inlet. Liquid and gas separate
selecting a rig, helped us to set an expedited timetable, and as the flowstream travels downward in a spiral pattern. Further
dramatically reduced our costs.”
separation occurs as the heavier liquid is thrown by centrifugal
Producing the reservoirs at Parque das Conchas required
a subsea system that could efficiently commingle production
from multiple fields, provide AL, and perform gas/oil separa-
tion, where necessary to minimize hydrate and slugging risk.
It also included a dynamic-process-control system to operate
and safeguard the AL pumps.
Wells are produced through nine vertical deepwater trees
supplied by FMC, which feature an enhanced, slim-bore
configuration to enable completions from smaller rigs using
a surface BOP system. Abalone is a one-well field, with
production routed through a 10.5-mile flowline to Ostra
for separation and boosting. Ostra contains six production
wells and one serving as a gas injector for now. Gas injec-
tion, for storage and flaring avoidance, will continue until a
planned gas-export line at the nearby Petrobras Jubarte field
is installed and a Parque das Conchas connection can be
built. For the oil at Ostra, two manifolds receive well pro-
duction and are used to direct and control the flow of pro- Fig. 3—Subsea production scheme for the four fields
duction into a separation and AL module, to be described of Parque das Conchas.
JPT • SEPTEMBER 2009
39
NEW FIELD DEVELOPMENT
Pumped liquid outlet
Separated
Multiphase
gas outlet
tangential
inlet
Host
Separated
gas
Falling
liquid film
Liquid
Gas
Wel l Multiphase fluids
Caisson-ESP
Gas-liquid
separator
interface
Mudline
Pump
Separated
ESP
Seal
liquid
Motor
(a)
Motor
Shroud
(b)
Fig. 4—(a) Flow schematic of production well and caisson-ESP separator system. (b) Detailed flow schematic
of caisson-ESP separator.
and gravitational forces to the wall of the separator. The liquid ments, while allowing for an efficient single-phase boost of the
then flows down to the caisson sump, where it is pumped liquid by means of the industry-proven ESP.
upward by the ESP into a flowline leading to the host facility.
Simultaneous to Parque das Conchas, Shell faced a similar
The liberated gas flows upward under its own pressure (i.e., need for subsea separation and boosting at its Perdido project
caisson pressure) into a separate flowline to the host. Separation
in the deepwater Gulf of Mexico (GOM). This led to the com-
of gas and liquid enables minimization of the hydrate and slug-
pany building and testing a caisson separator/ESP system at
ging risks typically associated with ultradeepwater environ-
its Gasmer prototype facility in Houston, before giving a green
light to proceed with the technology in both projects.
“We drilled a caisson some 300 ft into the ground, put differ-
ent 1,500-hp ESPs into it, incorporated the proposed top-end
separation assembly, and actually flowed oil and gas into it,”
Stingl said. “We wanted to see how efficient the pumps were,
after we had monitored liquid levels. Pumps are great, but if
you don’t operate them the right way, they are going to burn up
in days. It was a valuable opportunity because from the ground
down, Parque das Conchas and Perdido are the same.”
The caisson system has been developed by FMC into a
modular installation with four slots for separation and boost-
ing (Fig. 5) and is commonly referred to as a mobo (a term
derived from Portuguese for boosting module). Parque das
Conchas features the world’s first mobos to go into opera-
tion, with one unit each installed at Ostra and Argonauta B
West. The ESPs on these modules are capable of delivering
2,000 psi of boost pressure. The Argonauta mobo includes
Fig. 5—Four-slot AL manifold with boosting modules.
the caisson ESP without the gas/oil separator.
40
JPT • SEPTEMBER 2009
TM
NEW FIELD DEVELOPMENT
Turret-moored FPSO
Riser hangoff
Departure angle
Water depth
Upper
at host location
catenary
Water depth
section
at touchdown location
Buoyancy
Lower
section
section Lower
Flowline-riser
catenary
transition
Bottom section
Seafloor
section
Horizontal span
Fig. 7—Cross section of 9½-in. dynamic, steel-tube
Horizontal span + bottom section length
hydraulics and high-voltage umbilical.
Flowline Riser
Fig. 6—Schematic of steel lazy-wave riser.
moored FPSOs in the world. A 1975-vintage VLCC tanker,
originally in shuttle service, the hull had served as a floating
“With the oil from Abalone and Ostra, the GOR is too storage and offloading system in Nigeria for the 11 years
high to operate ESPs without first separating gas from the before its conversion for Parque das Conchas. A major part
pumping stream,” Stingl said. “However, the oil at Argonauta of the conversion, carried out in Singapore, was the addition
B West contains such a small amount of gas that it is no of sponsons to provide double-hull protection for safety and
danger to the pumps. And with the heaviness of the oil, we environmental reasons. The sponsons consist of 24 modular
want to keep the gas entrained to lower the oil’s viscosity and structures—240 tons individually—each attached to the
improve production.”
original hull by a separate lift. The sponsons, more than
5,000 tons of steel in all, extend over the length of the vessel’s
Steel Lazy-Wave Risers
oil-storage space.
To carry production from the subsea wells to the Espirito
The 8,500-ton topside of the Espirito Santo holds three
Santo, a system of seven lazy-wave steel-catenary risers parallel separation and treatment trains for crude from each
(SCRs) was designed (Fig. 6). With diameters ranging from field and includes large heating capacity to handle the heavy
6 to 10 in., these are the industry’s first lazy-wave SCRs to be oil. Specially designed gas and steam turbines onboard can
connected to a turret-moored FPSO. The challenging work generate up to 68 MW of electrical power to run the ESPs,
of completing those unprecedented connections required with the flow of electricity (15 MW) and the pump speeds
pulling the top ends of the stiff steel risers into an I-tube controlled by variable-frequency drives.
descending from the turret. Until Parque das Conchas, I-tube
A unique dynamic, steel-tube umbilical, 91/2 in. in diam-
connections had been performed only with flexible risers. eter, was designed that holds all of the hydraulics and multi-
SCRs, until now, have been tied into the basket-type connec-
circuit high voltage needed to control subsea trees and other
tion facilities found on spread-moored FPSOs, tension-leg valves and to power the caisson ESPs (Fig. 7).
platforms, spars, or various other hosts.
“Instead of having to run multiple umbilicals from the
A lazy-wave configuration for the risers (and umbili-
FPSO to the seafloor for chemical injection, power, and
cals) places additional buoyancy in the system to reduce signals, we were able to combine it all into one per subsea
fatigue on the lines and ensure their ability to withstand the hub and eliminate some expensive additional installations,”
dynamic loads generated by the floating host. The lazy-wave Howell said.
design has been used previously, but not in a connection to
The umbilical is run through the turret, which is moored
a turret-moored FPSO.
in a fixed position, while the rest of the FPSO—including
Had flexible risers been used on Parque das Conchas, it the topside that holds the power-generation and -transmis-
would have required many more risers, raised costs, and sion facilities—moves in a weathervane pattern around the
risked congestion beneath the FPSO, according to Stingl. A turret with the prevailing weather conditions. The needed
flexible-riser system would have thwarted the commingling connections from topside to turret were made by SBM in a
objective of Parque das Conchas, he noted, because each dis-
sophisticated process that routed them through the moving
tinct crude oil would travel through a separate riser and most, swivel portion of the turret. The effort involved the two larg-
if not all, of the crude streams would require multiple lines, est high-voltage swivels that SBM has ever used.
due to the lower capacities of flexible risers. “The use of SCRs
Also onboard the Espirito Santo is 75,000 bbl of water-
enabled us to design the project with a much smaller host injection capacity, preinstalled in anticipation of phase
facility than we would have needed otherwise,” Stingl said.
2—the startup of Argonauta O North—in 2013. The heavy-
oil field will require waterflooding and AL. Seven producers
FPSO Conversion and Facilities Design
and four injectors are planned. Beyond that, the development
The Espirito Santo, owned by a joint venture between SBM program is still in concept-selection stage. But if phase 1 is
Offshore and MISC and leased to Shell, is one of the deepest-
any indication, there will be plenty to discuss.
JPT
42
JPT • SEPTEMBER 2009
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