Swellable packer as a well barrier

21 April 2024

In an existing geothermal water injector well drilled back in 2009 a swellable packer has been used to form a barrier between two sandstone formations.  Please see the attached diagram.

The upper sandstone formation is not an injection zone and is a different reservoir. The lower sandstone is the geothermal reservoir formation used by the injector. A geothermal production well where the water from the reservoir is pumped to surface using an ESP. The hot water is used for space heating. The water from the production well goes through a heat exchanger and is then pumped back down the injector well.

A swellable packer has been used in the annulus to isolate the two sandstone formations. Regulator is now asking how the swell packer can be tested and be confirmed as a well barrier.

Pressure testing is not possible, applying pressure down the tubing simply injects water down into the lower reservoir. Applying pressure from above is not possible with the liner hanger sealing. 
Inflow testing is not possible the well is sub hydrostatic and both reservoirs contain formation water and both reservoirs are in the same pressure regime.
Looking for answers to the following questions

• Can a USIT or ultra sonic log be used to confirm the swellable packer is sealing against the formation?
• Can a temperature log be used to confirm the packer is isolating between the two sandstones?
• Are there any other methods available that could confirm integrity of the swellable packer in the open hole?

With thanks

Steve

Documents uploaded by user:

Well sketch.pdf

11 Answer(s)

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