Every mature field carries inventory that never shows on a rig schedule: zones logged and passed over decades ago, intervals that watered out and got abandoned while pay sat untouched uphole, wells produced from one horizon while three others wait behind the same casing. A recompletion goes and gets that inventory. The hole is drilled, the casing is cemented, the road and the tank battery exist; what's left is days of rig work instead of weeks of drilling, which is why the cheapest new well an operator can buy is so often hiding inside an old one.
Diagnosis first: what the well still has
The candidate list starts in the file room. Original open-hole logs show every zone the bit crossed, not just the one that got perforated, and the field's production history says what neighbors made from each. Then the modern look: cased-hole logging, pulsed neutron tools chief among them, reads fluid saturations through casing as they stand today. Old fields surprise in both directions, zones swept clean and zones barely touched, and the log settles arguments the archives can't.
The second question is cement. Perforations produce whatever the annulus connects them to, so a new interval is only as good as the isolation behind it. A cement bond log across the target, run before the guns, tells you whether you're completing into rock or into a channel, and a squeeze job repairs the bond where it's poor. Skipping this step is how recompletions "fail" on zones that were fine all along.
The plug-back
Moving uphole means sealing off downhole. The workhorse is the cast iron bridge plug, set on wireline or tubing at a measured depth, capped with cement and the cap tagged to prove it's where the plan says. A straight cement plug does the same duty without hardware, at the price of waiting-on-cement time and the same obligation to tag or pressure test, because an unverified plug is a hope, not a barrier. The choice that matters long-term is drillable versus permanent: a retrievable plug leaves the door open to the zone below if prices or ideas change, while a CIBP under cement is a decision you drill out to reverse. Good operators make that call deliberately, on reserves, not on what's on the truck that day.
Perforating the new zone
With isolation verified below, the guns go in: casing guns run on wireline with the tubing out, or through-tubing guns where the completion stays put. Shot density, phasing, and interval come from the log and the reservoir, and correlation, depth-tying the guns to the formation, gets the respect it deserves, because perforating two feet off pay is a permanent mistake. After the shots: swab or flow to see what the zone gives, and often a small acid job to break down perforations and clean up damage before judging it. A new zone deserves a fair test before anyone calls it a disappointment.
One zone or several: the commingling question
Adding perforations without plugging back, producing two or more zones up the same string, multiplies rate but comes with rules. State regulators treat commingling as an application, not a default, because allocation between zones affects royalty owners and correlative rights; Texas operators know the drill with the Railroad Commission. Mechanically it also has to make sense: zones with mismatched pressures rob each other, the strong one pushing into the weak one instead of both going up the tubing. Where pressures and paperwork line up, commingling is free rate; where they don't, dual completions or a choice of zone serve better.
The economics
A recompletion spends rig days, guns, cement, and logging against reserves already under lease, no drilling, no new location, no new surface commitment. Risked properly, the log says the zone is there, the bond log says it's isolated, the offsets say what it should make, it's the fastest payout work in the field. The discipline is treating each candidate like the small exploration decision it is: evidence first, then the rig, and a plan for what the well becomes if the new zone underdelivers, because a plugged-back well with a weak uphole zone is also a candidate for the P&A conversation nobody schedules but everybody eventually has.
Common questions
How long does a recompletion take?
Commonly a few days to a week of rig time: pull the completion, set and verify the plug, log if needed, perforate, test, and re-run. Add time for squeezes, stimulation, or surprises the well file didn't mention, and the file is usually what decides between the two.
Can you recomplete below the current zone?
If deeper pay exists behind pipe, yes, without a plug-back at all, though deeper usually means questions about casing condition and cement that the same logging suite answers. Most recompletions move uphole because old wells were typically drilled to their deepest objective first.
What does the operator need in hand before the rig arrives?
The well file again: casing and cement records, original logs, current completion details, and the regulatory approvals if zones change or commingle. Rigs are bad places to discover the casing size from memory.
The series, and where Vexon fits
Previous: cleanouts. Next: remedial cementing and casing repair, the precision side of the trade. The pillar guide is workover rig services. Vexon provides recompletion and workover rig services to qualified operators: get in touch and ask for our qualification form.