Running & inflating ECP in 'Significant Continual Loss' environment (Annulus Isolation)

Hi folks

We would really value your experience of the following scenario.

The company barrier policy states that there must be adequate barriers in place in the annulus when breaking isolation (removing BOP) to install slip-type hanger and pack-off on this surface wellhead.

In our case, we encounter total losses when drilling the section, a situation which we cannot overcome (so, please, no need for suggestions about curing losses).  The casing is run and cemented and we are unable to achieve top of cement  back above the base of our loss zone and/or high enough to cover permeable zones contained in the open-hole.

The solution we applied was to incorporate a stage-collar and packer in the string, pump the first stage, inflate the packer, pump the second stage.  For reasons that we are still investigating, the casing failed the pre-drill-out pressure test and we traced it to the packer/collar assembly.  We fixed the problem by pumping cement, and additional pressure-testing, but it cost us a lot of time and compromised our well design.

We are still investigating the failure but it is likely that for the next well we will use different equipment.  It is likely we will run a Baker 9-7/8" ECP Payzone Packer and this will be installed in the string such that it can set inside the 13-3/8" x 9-7/8" annulus some distance above the 13-3/8" shoe and several thousand feet above the 9-7/8" casing shoe.

At the time that the Baker Payzone ECP packer is run the well is likely to be in a 'significant losses' situation with continual pumping of seawater into the annulus.  Once the primary cementation is complete, the ECP will be inflated using seawater; note that we have considered cement inflation but, for a variety of reasons, the preference is to use seawater.

We'd like you specific experiences running these packer in regard of:

1.     Have you run the 9-7/8" version (as opposed to 9-5/8")

2.     What experiences running in 'significant continual loss' situation ?

3.     What experiences inflating with seawater instead of mud ?

4.     Any failure experience with the small 4-valve inflation mechanism used in most ECPs (CTC heritage)

Whilst we are somewhat constrained by equipment availability, which will determine what we run, we would be interested in any novel approaches any of you are using to overcome this situation .. though our preference is to get a handle on any issues associated with what we currently plan.

Kind regards

Dave

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