Long-term Water Breakthrough Measurement in a … Water... · Long-term Water Breakthrough Measurement in a Bilateral ... seawater injection was used in four ... seawater breakthrough

Long-term Water Breakthrough Measurement in a Bilateral Wellbore Using Tracer Technology

RESERVOIR CHARACTERISATION

The Project

An offshore oilfield was developed using long multilateral

horizontal wells completed with swell packers and

stand-alone sand screens. To assist with recovery of

hydrocarbons, seawater injection was used in four

horizontal injection wells throughout the development area.

As part of the overall reservoir management strategy the

operator wanted a method to determine the source of

seawater breakthrough and the positional in-flow of water

into production wells.

Project Design

The project was designed to deliver:

• Unique interwell tracers to measure communication

pathways and sweep efficiencies between wells

• Long term dormant water tracers integrated into

sand screens to measure positional water in-flow

• Significant cost savings over other wellbore

surveillance technologies

• Zero additional rig time

Reservoir & Well Specification

• Sandstone reservoir

• 21 API Oil

• 1,200 metre bilateral horizontal production length

• 5 1/2" premium sand screens c/w swell packers

• Reservoir Temperature and Pressure; 174°F / 2830psi

Application of the Technology

Four unique long term water tracers were manufactured

in solid polymer form and integrated into the drainage

layer of wire wrap sand screens during their manufacture.

There was no requirement to change sand screen size

or design. The tracer – polymer mix was designed to

remain dormant during oil contact and start to slowly

release upon contact with water. Each of the sand

screens was labelled with the specific tracer material

to be referenced when running in hole. In addition to

sand screen tracers, four unique waterflood tracers

were manufactured and made ready for injection.

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RESERVOIR CHARACTERISATION

Sand screens containing tracer materials were transported

along with all other standard screens offshore. Each one

was unwrapped from its protective seal and placed within

the lower completion run sequence to locate it at specific

points along the two laterals. Two of the tracers were

located approximately two-thirds of the distance along

each lateral with the other two positioned around one-third

from the heel of each.

After each water injection well was brought on-stream and

stabilised over a few weeks, waterflood tracer was added

directly into the flow line using high pressure hydraulic

pumps over several hours with no disruption to normal

waterflood operations.

Sampling and Analysis

Production wells were tested once every two weeks to

determine water cut. Upon detection of water breakthrough

from each well a very small volume of water was taken and

sent to the nearest Tracerco laboratory for tracer analysis

using ultra-sensitive Gas Chromatography instrumentation

and optimised tracer detection methodology.

Results and Interpretation

The graphical data shown relates to one of the production

wells. This well started to increase water cut approximately

48 weeks after start of production (1). Tracer was detected

after 52 weeks (2) originating from the lower one-third

of lateral 2. Confirmation of the source of the water

started to emerge after 57 weeks (3) showing injector C

communication. The heel of lateral 1 was next detected

after 80 weeks of production (4) followed by the interwell

tracer injected into Injector A (5). It was also noted that

tracer located towards the heel of lateral 2 was detected

at the surface although its shape was somewhat flat (6).

It is believed that this is due to slight internal contact

between water flowing inside the production tubing from

the toe of the well accessing the heel tracer through the

perforated base pipe providing limited but direct contact

with tracer in the drainage layer.

Data provided by the application of both interwell

and inflow tracer technologies has provided valuable

information on injected water communication pathways

and effectiveness of hydrocarbon sweep within the

reservoir strata. This has allowed the rebalancing of

injection water to minimise water production and maximise

reservoir fluid contact.

Billingham, UK Tel: +44 (0) 1642 375500

Norway Tel +47 55 36 55 40

Abu Dhabi, UAE Tel +971 (0) 2 5541672

Kuala Lumpur, Malaysia Tel +603 7803 4622

Pasadena, USA Tel: +1 281 291 7769

Rio de Janeiro, Brazil Tel +55 21 3535 7600

www.tracerco.com/reservoir-characterisation. For all email enquiries please contact: [email protected] Limited is a subsidiary of Johnson Matthey Public Limited Company, 5th Floor, 25 Farringdon Street, London EC4A 4AB. Registered in England No. 4496566. Tracerco is a trading name of Tracerco Limited. TRACERCO and the Johnson Mathey logo are trademarks of the Johnson Matthey group of companies.

If you would like to find out more about this technology please contact a Tracerco Technical Advisor at one of our global

operational bases.

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