multilateral wells
TRANSCRIPT
Multilateral technology revives
old wells in Southeast Asia
Production was waning from a commer-
cially successful field in the Beihei Bay.
Pressure had slowly depleted, and elec-
trical submersible pumps were being
installed in production wells. As oil pro-
duction declined, continued use of these
pumps raised the drawdown pressure
and increased the volume of water pro-
duced from the field. Because the low
oil-to-water production rate for a number
of wells made them economically unvi-
able, they were marked for temporary
abandonment, and drilling new wells
was considered.
Schlumberger multilateral technology
offered a solution that would make
these wells more productive. A work-
over program and assessment of the
reservoir began after the selection of
a candidate well.
First, the lower uneconomical produc-
tion zones were isolated. A directional
pilot well was drilled through the reser-
voir and into the lower water-contact
zone. The pilot well was logged and eval-
uated, providing valuable information on
the current water-contact level in the field
and within the producing reservoir. Then
the pilot well was isolated with cement.
A directional plan was formulated
to allow the drilling of a long horizontal
lateral in the reservoir above the water-
contact level. The lateral motor assembly
was controlled and directed 900 m with
a logging-while-drilling and measurement-
while-drilling package. The production
lateral was completed with screens and
isolated by a long external casing packer.
The RapidConnect multilateral comple-
tion system was employed to tie the pro-
ducing lateral to the main wellbore, and
it provided additional reinforcement at
the junction against overburden pressure
from the formation. The well continues
to produce significantly above its initial
production rate.
The RapidConnect system will enable
reentry to the lateral and main wellbore
for future operations and isolation of the
lateral whenever required.
Well production tripled by
world’s first multilateral with
expandable sand screens
In a debut that exceeded all produc-
tivity and efficiency expectations, an
operator combined the Schlumberger
RapidConnect multilateral completion
system, which provides selective drain-
hole access and connectivity, with expand-
able sand screens in a well in the Java
Sea, offshore Indonesia. A team of five
different service companies collaborated
on this project, with Schlumberger acting
as the main service provider under pro-
ject management during the planning,
drilling, and completion phases.
Following careful study of reservoir
data, well placement was optimized using
the Bima, a Schlumberger multipurpose
service vessel, to drill two sacrificial ver-
tical wells. This refinement of target loca-
tion helped exploit a net oil pay zone that
was much thicker than expected.
The use of a synthetic oil-base mud
in combination with VISION* formation
Oilfield Bulletin Technology focus on
multilateral wells
The placement of the RapidConnect junction is
based on a reservoir drainage model (a). The junction
can be placed either above the reservoir (b) or in
the reservoir (c).
Junction and lateral in pay zone
(c)
Junction in shale formationand lateral in pay zone
(b)
(a)
Reservoir drainage
Schlumberger multilateral technology is used to reduce drilling and
completion costs, increase production from existing fields, and even
revive old wells.
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*Mark of Schlumberger
evaluation and imaging services and
PowerPak* steerable motors allowed
technicians to mill a window in less than
21 ⁄ 2 hr and drill the two laterals. The
RapidConnect system provided optimal
mechanical protection of the junction
between the two lateral wellbores with
the least amount of flow restriction.
Shaker screens helped minimize forma-
tion damage by optimizing particle size
for mudcake and flowback. During the
completion, the drill-in fluid was allowed
to flow back through the screens. The
use of expandable sand screens, rather
than a more conventional type of comple-
tion, is believed to have had a significant
effect in reducing skin and delivering a
much improved productivity index.
Since the startup of production, this
multilateral well has surpassed all previ-
ous field productivity levels, with a stabi-
lized rate of 5500 BOPD and 4.5 MMcf/D
of gas. These rates are three to four times
the net oil production of the field’s next
best well.
From spud to electrical submersible
pump startup, the job was completed
in 36 days, 2 days ahead of schedule.
In collaboration with China National
Offshore Operating Company (CNOOC),
Schlumberger designed, drilled, and
installed the world’s first TAML Level 6
intelligent completion. A Level 6 comple-
tion, which provides full mechanical and
pressure integrity in each lateral, is the
highest rating for a multilateral well
in the Technology Advancement for
Multilaterals (TAML) rating system.
The NE Intan A-24 well, a two-leg multi-
lateral, was drilled from the NE Intan A
platform in the south Java Sea offshore
Indonesia in approximately 75 ft of water.
Now the RapidSeal* multilateral comple-
tion system is enabling dual laterals to
drain the reservoir by providing selective
drainhole access and connectivity with a
pressure-sealed connection. Production
efficiency is increased because the
RapidSeal system enables control of sep-
aration distance and prevents communi-
cation between the laterals. The resulting
ability to influence near-wellbore flow
patterns improves control of water con-
ing and gas migration. CNOOC retains
the flexibility to produce through either
isolated tubing string with different pres-
sure regimes or configure production
using one string as an injector and the
other as a producer.
The installation includes hydraulic flow-
control valves and sensors that measure
pressure, temperature, and flow rate for
each well branch and a RedaPump* elec-
trical submersible pump system with a
variable-speed drive. Phoenix* permanent
downhole sensors and gauges are inte-
grated with surface data collection and
metering facilities and a remote control
system to allow real-time monitoring and
control of production from the multiple
zones of the reservoir.
By saving the costs of an additional
platform and horizontal well, the A-24
completion brought on new production at
lower capital expense and with reduced
operating costs for CNOOC. The intelli-
gent multilateral completion is expected
to improve production and ultimate
reserves recovery, helping to maximize
net present value.
The high-strength RapidConnect junction is designed
for multilateral sandface completions.
5-in. tieback seals
Landing tool
RapidConnect connector
World’s first intelligent Level 6 multilateral completion saves the
costs of an additional platform and horizontal well
A RapidSeal multilateral completion system—combined with a RedaPump ESP, a Phoenix artificial lift
monitoring system, and a variable-speed drive—made the NE Intan A-24 the first intelligent TAML Level 6
multilateral completion.
RapidSealliner-hanger packers
RapidSeal deflector
95 ⁄ 8-in. RapidSeal junction
Electricalsubmersible
pump
Hydraulicflow-control valve
FloWatcher* sensor
0
1000
2000
3000
0 500
Horizontaldeparture (ft)
95 ⁄ 8-in.RapidSealjunction
T r u e v e r t i c a l d e p t h ( f t )
1000
133 ⁄ 8-in.
casing
Lateral 1Lateral 2
N o r t h -
S o u t h d e p a r t u r e ( f t )
1000 500
East-Westdeparture (ft)
0
1500
1000
500
0
500
Lateral 1
Lateral 2
95 ⁄ 8-in. RapidSealjunction
N
133 ⁄ 8-in. casing