Hi Lajpat,
P&A requirements are ultimately set by regulators: what are the rules in Pakistan? As for best practices, NORSOK D-010 lays out a few minimum standards:
- Two plugs isolating the reservoir, with corresponding qualified annular cement and a caprock. Mind that you may also have to isolate further intervals with additional plugs.
- A third surface plug to rule out communication between rocks and (now open) top of the well.
- Abandonment barrier elements have to last a long time, that's why NORSOK D-010 rules out elastomers - and steel. So the plugs have to be cement plugs.
A single bridge plug may be an acceptable temporary barrier, but its durability beyond a decade or so is questionable. Setting cement plugs through dump bailer is also not particularly indicated: volumes are small and fluid displacement haphazard. What little information is available, it suggests that they are not reliable.
So I'm afraid general answer to your question is: yes to rigless, no to the proposed program. It's difficult to see how you can set good cement plugs without at least CT.
However it all depends on the actual well risk: if you have a reservoir with gas, most definitely not. Same if you have high pressure intervals (with, say, brine). If all you have is a thoroughly depleted oil reservoir, low corrosion potential and good annular cement, then there may be room for a more expedient approach.
Hope it helps,
Matteo
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Matteo Loizzo
Well integrity consultant
Berlin
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