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Field-proven work

How we solve wellhead problems in the field.

A selection of representative jobs — onshore and offshore — showing how IWS approaches casing reconstruction, leak repair and in-situ welding. Technical and commercial details have been generalised to protect client confidentiality.

What these cases show

Repeatable engineering, not one-offs.

Every wellhead is different, but the discipline is the same: a written procedure, a qualified weld map, controlled preheat and post-weld heat treatment, and full NDE sign-off before the well goes back into service. The cases below are framed as challenge, approach and outcome.

Out of respect for our clients, these summaries omit field names where sensitive, exact dimensions, part numbers and any proprietary procedure markings. Where an end operator is named, it is for context only.

Offshore · Gas-lift increment

Gas-lift increment — major operator

Casing head 18-5/8" 13-3/8" 9-5/8" Access windows Re-stub welds
Schematic — illustrative, not to scale

The challenge

Three offshore gas-lift wells in the offshore field needed their wellheads rebuilt from the casing up. The existing casing head and spool had to be removed and three concentric casing strings — 18-5/8", 13-3/8" and 9-5/8" — recovered, re-stubbed and re-terminated, all on a live platform working to a tight drilling-rig schedule.

The IWS approach

Working to a written reconstruction procedure prepared for the end operator (the end operator), the crew cut access windows in the outer casing, recovered the old head and re-stubbed each string with new casing pups. Every joint was butt-welded to a qualified weld map under controlled electrical preheat, then verified by non-destructive examination. A new casing head was prepared offline, welded to a fresh stub, nitrogen pressure-tested, and lifted into place — with dummy-run casing-hanger checks confirming centralisation before final welding and pressure testing.

The outcome

All three wellheads were reconstructed, pressure-tested and handed back ready for BOP nipple-up, with complete heat-treatment, visual, MT and pressure-test records. The repeatable window-cut and re-stub method let the platform move from well to well without bringing in replacement casing strings.

  • Scope3 wells reconstructed
  • Strings18-5/8" · 13-3/8" · 9-5/8"
  • MethodWindow-cut & re-stub
  • VerificationVT · MT · N₂ pressure test
Offshore · Workover

Workover & casing-head replacement — major operator

New casing head Joint weld (4130↔K-55) Hot-tap / injectivity nipples Cut window
Schematic — illustrative, not to scale

The challenge

An offshore workover required hot-tap and injectivity testing across several casing strings, followed by removal of the existing wellhead and installation of a new casing head — all in an offshore environment where heat input, weather windows and access are tightly constrained.

The IWS approach

The crew first welded test nipples to the casings and carried out staged injectivity checks before cutting access windows and removing the wellhead. A new casing head was welded on using a qualified high-strength weld map, with offshore-rated electrical preheat, an outside-then-inside fillet sequence, and magnetic-particle inspection held until the weld had cooled to specification. All welds were accepted against the recognised piping code.

The outcome

The wellhead was replaced and re-certified offshore without demobilising the well, with the new casing head verified by NDE and the connection integrity confirmed by pressure test before the well was returned to the operator.

  • SettingOffshore platform
  • WorkHot-tap + head replacement
  • WeldHigh-strength, electrical preheat
  • CodeASME B31.3
Onshore · Leak repair

Conductor & casing leak repair — major operator

Base plate 48" conductor 40" casing Window cut & replace Butt-weld repair Gussets (staged removal)
Schematic — illustrative, not to scale

The challenge

A pin-hole leak had developed on a large-diameter conductor, with additional integrity concerns on a circumferential weld of the next casing string and on the gusset connections supporting the casing-head base plate. The repair had to restore pressure integrity without compromising the structural support of the wellhead.

The IWS approach

IWS cut and replaced a controlled window section around the conductor leak, re-welded the affected casing weld, and removed and reinstated the base-plate gussets in a planned sequence so the wellhead remained supported throughout. All repairs used a qualified weld map with controlled preheat and low-hydrogen electrodes, and were proven by ultrasonic and magnetic-particle inspection.

The outcome

Pressure integrity was restored on both the conductor and the casing, and the structural support of the casing head was maintained without interruption. The well was returned to service with a full inspection record package.

  • IssuePin-hole conductor leak
  • RepairWindow cut & butt weld
  • SupportStaged gusset reinstatement
  • NDEUT + MPI
Onshore · Water well

Water-supply well — casing-head leak repair

Lower base plate 40" conductor 24" casing CHSU welds inspected / repaired 8 gussets Jack support
Schematic — illustrative, not to scale

The challenge

A water leak had appeared at the casing-head support unit of a water-supply well, in the welds connecting the conductor and casing strings to the base plate. The support gussets had to be worked on without losing the load path that holds the wellhead in position.

The IWS approach

The team inspected and re-welded the conductor-to-base-plate and casing-to-base-plate connections, then removed and reinstated the support gussets progressively — using a temporary jack to carry the load while each gusset was worked. Welding followed a qualified procedure with controlled preheat and low-hydrogen electrodes; magnetic-particle inspection confirmed each repair, with contingency nipples available if pressure relief was needed during the work.

The outcome

The casing-head leak was sealed and the support structure fully reinstated, with the wellhead held secure throughout the repair. The job was delivered to the operator with complete inspection documentation.

  • AssetWater-supply well
  • IssueCHSU weld leak
  • Support3-ton jack, 8 gussets
  • NDEMPI sign-off
Onshore · Casing welding

Onshore casing reconstruction & re-stubbing

New head + stub Field cut Re-stub weld PWHT zone
Schematic — illustrative, not to scale

The challenge

Across a number of onshore wells, casing strings needed to be cut, re-stubbed and re-terminated to a new wellhead — often where the original casing had been damaged, corroded or left at the wrong elevation for the new completion.

The IWS approach

IWS applies the same controlled, code-compliant method used offshore: window cuts for access, qualified butt welds between casing and new stubs, electrical preheat and post-weld heat treatment matched to the casing grade, and a fresh casing head welded on and pressure-tested before hand-back. Every weld is mapped, heat-treated and inspected, and the documentation pack is built as the work proceeds.

The outcome

Wells were returned to service with reconstructed, fully certified wellheads — avoiding the cost and downtime of pulling and re-running entire casing strings, and giving the operator a documented, code-traceable repair.

  • ApplicationOnshore casing strings
  • MethodCut · re-stub · re-head
  • HeatGrade-matched PWHT
  • OutcomeFull record package
The common thread

Every case runs the same disciplined loop.

01

Procedure first

A written, client-approved procedure and a qualified weld map before any cutting or welding begins.

02

Controlled welding

Electrical preheat and post-weld heat treatment matched to the casing grade — the core of NACE-compliant sour-service work.

03

Verify & document

Visual, MT/UT and pressure testing on every joint, with a complete record package handed to the operator.

Have a similar problem?

Tell us about your wellhead.

If you're facing a casing leak, a wellhead that needs rebuilding, or an integrity repair on a live well, we can scope a procedure and a weld map for it.

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