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Inflow test (dry test)
20 April 2010
Does anybody know what the cons and pros of inflow test on liner lap are?
This method is still performed in some areas but in some others has became obsolete.

Thanks
4 answer(s)
snas
Well Engineering Consultant and Instructor
Olango Consulting
Total Posts: 20
Join Date: 23/03/16

A liner lap must be inflow tested. The cement around the liner is a well control barrier. It is designed to prevent flow from a potential source of flow (reservoir zone) into the production casing. Even if a liner top packer is set the liner lap must be tested. For a liner lap to be considered as a barrier it must be tested in the direction of flow.

From Norsok D10 “Wells with a source of inflow/reservoir shall have two independent mechanical well barriers. This also applies to wells which could develop an inflow potential due to injection. Wells with no source of inflow/reservoir shall as a minimum have one mechanical well barrier. For wells with only one mechanical barrier, inflow tests at pre-determined intervals are required to confirm that the well will not flow.

There are a couple of challenges with regards to inflow testing.

  • Amount of drawdown (how much underbalanced is required) to inflow test
  •  A barrier should have zero leak rate, so how do we measure the leak rate
  • Interpretation of the results from the test (flow or pressure buildup)

The big challenge with inflow testing is interpretation of the test results. According to well control regulations, inflow tests should be confirmed with a Horner plot of the results with the flow rate recorded so that it can be proven that there is no flow. In hot deep wells this can be a real challenge as the well will continue to flow for a considerable time due to thermal effects.

Creating and interpreting Horner plots is not something that is easy. Most manuals state that a Horner plot must be made, but very few if any provide details on how the plot is to be interpreted.

I have attached guidance for Horner plots and some data from a well control manual that can be used to try and interpret if the test is valid.The example data runs for 310 minutes (just over 5 hours) see if you can test that long on a deepwater rig






simonleiper
MSc Drilling and Well Engineering Student & SME owner
Robert Gordon University
Total Posts: 10
Join Date: 17/04/09
Hi
Im researching inflow testing as part of my Masters thesis paper and was looking for SPE papers or any publications which might be of use.  Did any of the responders to this come across any publication which discuss liner inflow testing?  I am currently trolling SPE papers but have not found anything specific to inflow testing yet.
Thanks
mjenkins
Drilling Engineer
ConocoPhillips
Total Posts: 1
Join Date: 19/05/09
Amir, I would agree with Aberdeen2Win. We test all production liner laps in the North Sea even if there is a production packer above the liner top. This is because any flow from the back of the liner would flow though 9 7/8" casing which is not designed to withstand the corrosive reservoir fluids, the chrome completion is. If we had prolonged flow from behind the liner top and into the 9 7/8" casing, we could find integrity problems later. It is not time consuming or difficult to inflow test as part of the pre-completion cleanout run/displacement, however it is if you find a leak!

I believe in parts of the middle east it is policy to inflow test the liner cement job before setting the liner top packer and most cement jobs are seen to leak. Therefore, it is relatively safe to assume the liner top packer is your only barrier a lot of the time so maybe making sure it is OK is not a bad idea.
Aberdeen2Win
Central Sales Manager
MI-Swaco
Total Posts: 5
Join Date: 10/02/09
The decision to test is depend on whether the production packer is above or below the liner lap. If the production packer is above then you may not require a test as the liner lap will only see minimal differential from reservoir drawdown.

If the liner top is above the packer then the liner forms an integral part of the 'A' annulus. Therefore you should test its integrity.

Finally if the completion fluid underbalanced the well from a safety standpoint you should test the liner integrity.

Best to inflow test on the same run an the mechanical and chemical cleanup.
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