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.

 

www.slb.com/oilfield

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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