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- Long-Term Water Breakthrough Measurement in a Bilateral Wellbore Using Tracer Technology
Long-Term Water Breakthrough Measurement in a Bilateral Wellbore Using Tracer Technology
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.
The project was designed to deliver:
Reservoir & Well Specification
- 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
- Zero additional rig time
Application of the Technology
- 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
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.
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
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.
For more information about this technology please fill out an enquiry form detailing your requirements and we will get back to you.