Q4000 Gulf of Mexico Well Intervention Project

Helix Performance Profile
Q4000 Gulf of Mexico
Well Intervention Project
objective
Quick Stats
Operations: Temporary
abandonment, choke change-out
Project duration: 18 days
Total downtime
incurred: 0
Wells serviced: 2
Project notes: Primary and
secondary scopes of work
completed simultaneously
In June 2012, Helix Energy Solutions Group, Inc.’s
U.S. well intervention subsidiary, Helix Well Ops,
Inc., performed well intervention services on two
subsea wells in the Garden Banks area of the Gulf of
Mexico, with no lost time incidents over the course
of the 20,000 man-hour project. All equipment was
deployed from Helix’s Q4000 semi-submersible to a
depth of 2,081 fsw.
scope of work
The primary scope of work entailed a temporary well
abandonment operation using Well Ops’ Intervention
Riser System (IRS). This required latching the IRS onto
the well’s vertical tree with a dual string riser system,
connecting it to the surface flowhead, and establishing
a closed return system.
Q4000’s Intervention Riser System
After function and pressure testing to 7,500 psi, the IRS was run and latched to the well,
facilitating multiple downhole intervention operations using slickline, electric line, and
coiled tubing based systems.
The secondary scope of work called for a choke replacement at an adjacent well that
produced back to the same host platform as the project’s primary target well.
h e l i x w e l l o p s q 4000
The operations in the primary target well are summarized
as follows:
• Bull head kill well operations with 11.8 lb per gallon of brine
until 282 barrels were pumped to a final pressure of 1,840 psi.
The operations team then allowed pressures to stabilize and
surface pressure fell to 0 psi.
• Coiled tubing operations deployed into the well while pumping
brine through coiled tubing. Once on the reservoir bottom,
coiled tubing established its target injection rate and squeezed
cement job of production perforations.
• Mechanical plug run and set on slickline in production tubing
above squeezed cement. The mechanical plug was pressure
tested to 1,000 psi.
• Electric line was rigged up and used to punch tubing above
the production packer.
• Circulated out annulus fluid with water based mud to surface
and annulus fluid disposed of properly.
• Cement balanced plug was set in the tubing and annulus
above the packer, through the punched tubing and then
tested to 1,000 psi.
• Once plugs were in place tubing was cut at 17,005 ft
measured depth.
• IRS was brought to the surface allowing the production tree
to be recovered by 360 mT crane.
• Open water portion of the project included the Q4000 recovering
approximately 15,000 ft of production tubing of various sizes from
4.5 in to 6 in from the well and laid out in sections.
• Installed wear bushing for future work and set a bridge plug
and surface plugs to finish the well work.
• The Q4000 demobilized and the client performed a final site
survey before the vessel transited to the next job site.
EQUIPMENT UTILIZED
Intervention Riser System
Surface Flowhead
Maximum Through
Bore Diameter
• 73⁄8 in production bore
• 21⁄16 in annulus line
Maximum Through
Bore diameter
• 73⁄8 in production
• 51⁄8 in wings
Maximum Working
Pressure (MWP)
• 10,000 psi
Maximum Working
Pressure (MWP)
• 10,000 psi
Maximum Working
Depth (MWD)
• 10,000 ft (EH control)
Hydraulics Operating
Pressure
1,500 psi operational
(3,000 psi maximum)
Hydraulics Operating
Pressure
• 2,500 psi operational
(3,000 psi maximum)
• 160 gallons subsea accumulation
Weight
• Flow head in air is 22,000 lb
Well Barrier Type
• 2 x 73⁄8 in hydraulic gate valve
• 2 x 51⁄8 in spring-assist fail-safe-closed
gate valves
Hydraulics Operating
Pressure
• 2,500 psi operational
(3,000 psi maximum)
• 160 gallons subsea
accumulation
Weight
• 120,000 lb (subsea package)
Well Barrier Type
• 73⁄8 in hydraulic cutting gate
valve (LCV)
• 2 x 73⁄8 in spring-assist fail-safeclosed gate valves (UCV & RTV)
• 3 x annular 21⁄16 in
failsafe-closed gate valves
Breakdown of Hours
Hours
Days
Total Time Spent on Wells
436
18.17
Total Time Operational
436
18.17
0
0
Total Man Hours Worked
On Project
20,256
—
Time Lost Due to Incident
0
0
Total Downtime
CONCLUSION
The project was completed in approximately 18 days, including offshore
mobilization and demobilization of all the equipment used. The Q4000
successfully carried out each of its tasks associated with the well and
30.30 ft
operated with 100 percent efficiency, recording zero downtime for repairs
or maintenance. The project was also completed without a single first-aid
incident, injury or any instance of equipment damage. More than 38 safety
meetings contributed to the project’s perfect safety record and as a result,
the client issued a safety and environment incentive bonus for the project.
The scope of work for this project originally comprised of only one well;
however, the client approached Helix Well Ops during the well campaign
and identified a potential side project. Because the Q4000 is able to manage
simultaneous operations, hosts two work class Remotely Operated Vehicles
(ROVs) and has a 360 mT subsea crane that can be operated in place of its
600 mT Multipurpose Tower, simultaneous work could be conducted over
the side in open water.
Using the 360 mT crane and a Helix ROV, Well Ops performed a choke
change out on an adjacent well in the field which incurred very little critical
path time for the vessel and provided an immediate cost savings back to the
client as they were not required to mobilize a separate ROV Support Vessel
with a subsea crane to perform this project.
12.9 ft at the bumper guards
90º out of rotation for clarity
Engineering Schematic of the Intervention Riser System
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