Deepwater well abandonment rarely attracts the engineering investment that drilling does — yet it can consume just as much time and money. Off the coast of Sub-Saharan West Africa, a major operator running exploratory and development wells faced exactly that reality: a standard abandonment program requiring five stacked cement plugs, executed over eight days at a cost of $3.1 million.
The question was whether a single tool could change that equation entirely.
The cost of doing it the old way
Conventional deepwater abandonment follows a straightforward but time-consuming logic: each hydrocarbon-bearing zone must be isolated individually, with a separate cement plug placed and verified before the next one can begin. That waiting-on-cement period isn’t optional — it’s a fundamental quality-control step. Multiply it across multiple zones, though, and the hours accumulate fast.
For this operator, the baseline was already established. A previous exploratory well required five stacked cement plugs, completed successfully over eight days at a total rig-time cost of $3.1 million. The program worked. It just didn’t work efficiently.
Conventional multi-plug programs also carry compounding risks beyond those waiting intervals. Each additional plug placement means another run-in-hole operation, another verification step, another opportunity for the work string to become stuck — a scenario that can turn a planned delay into something far more expensive. The more plugs required, the greater the exposure to every one of those risks.
One tool, one plug, one operation
Halliburton’s proposed solution was the BHKA Disconnect plug-setting tool, built around a straightforward principle: instead of placing several shorter plugs sequentially, place one continuous plug of effectively unlimited length.
What makes this possible is a controlled disconnection between the work string and a sacrificial tail pipe. After cement placement, the work string releases cleanly from the tail pipe, which stays in the hole. This eliminates the need to retrieve the entire assembly before the cement sets — and with it, the waiting periods between consecutive plugs.
That disconnection also addresses the stuck-string risk directly. Because the work string separates from the tail pipe at a defined pressure differential, the operator isn’t managing a string that must be held stationary while cement hardens around it. The hazard doesn’t get mitigated — it gets removed from the operation entirely.
Two trial deployments put the tool to the test
Rather than committing the tool across its entire well program immediately, the operator agreed to a structured proof-of-concept trial across two applications.
The first involved permanently abandoning the 12¼-in. pilot hole of a deepwater producer well. Halliburton deployed a 5-in. outside-diameter BHKA tool with 400 meters of 4½-in. sacrificial tail pipe, run in hole on a combined drillpipe work string. A releasing dart was deployed from the cement head and displaced to trigger the single-collet release mechanism at a differential pressure of 2,600 psi. The tail pipe released as designed, achieving the planned cement coverage above the target zones.
The second deployment came in an exploratory well, where the goal was to replace two consecutive 200-meter cement plugs with a single operation. Using similar tubulars and the same tool configuration, the cement operation proceeded without deviation — the sacrificial tail pipe released at 2,200 psi of differential pressure on the landed dart, and the required 100 meters of isolation above the target zone was confirmed on the first attempt.
Both operations executed as planned. That consistency mattered not just as technical validation, but as a confidence-building exercise for the operator’s team, who needed familiarity with the tool’s procedures before committing to broader deployment.
What the numbers revealed
Results from the pilot hole abandonment alone were enough to define the tool’s value proposition clearly. Modifying that single operation using the BHKA Disconnect tool produced an estimated $2.3 million in savings and eliminated 132 hours of rig time.
For context: the previous five-plug abandonment program cost $3.1 million over eight days. Compressing that kind of program into a single continuous operation doesn’t just trim time at the margins — it restructures the cost profile of abandonment entirely.
On the strength of those results, the operator has committed to deploying the BHKA Disconnect tool across four additional wells in the region. If savings scale proportionally, cumulative reductions could reach up to $13 million across that expanded program.
A proof of concept with broader implications
Deepwater abandonment is a universal cost pressure, not a regional one. Operators across the Gulf of Mexico, the North Sea, Southeast Asia, and beyond face the same fundamental challenge: isolation programs designed for reliability rather than efficiency, driving up the non-productive time component of well costs.
The West Africa trial is notable partly because of where it succeeded. Shelf and deepwater operations in Sub-Saharan Africa present technically demanding conditions — variable pressures, complex well geometries, logistical constraints — that stress-test any new tool. Performing reliably in that environment strengthens the case for applicability elsewhere.
The four-well rollout now planned for the region will be the more telling test. Proof-of-concept results answer whether a tool works; a multi-well program answers whether it works consistently, at scale, and across the operational variability that a single trial can’t fully capture. That data, when it emerges, will be what the broader industry watches.
