In Q4 of 2023, Viewport3 were approached by a longstanding international client — a Norwegian operator we’d supported on several previous underwater photogrammetry campaigns.
Following the installation of a Subsea Christmas Tree (XMT), electrical testing revealed a puzzling issue – there was no communication with the Downhole Gauge (DHG) via the Tubing Hanger (TH) connection, despite all hydraulic checks (which relied on the same interface) passing just fine.
Initially, we were provided with a technical drawing of the TH mating face and asked to perform a 3D scan to determine whether the DHG connector had been installed in the correct position, and was within the correct tolerance.
With vessel availability quickly running out and our 3D photogrammetry dataset confirming beyond doubt that the DHG connector was in the correct position, we recommended a full 3D scan of the entire worksite — captured at technical-grade accuracy and resolution. Having already invested significantly in trying to resolve the issue, the client pragmatically agreed.
Thanks to a skilled and efficient ROV crew, our offshore team captured high-quality, high-density data across the entire area of interest — ensuring that whatever questions emerged onshore, we’d have the 3D data to answer them reliably.
Disturbing the sealing surface at the top of a wellhead is an extremely costly problem to fix. To avoid any risk, we designed a custom camera mount that allowed us to collect images in and around the wellhead and TH internals without the risk of the camera or ROV coming into contact with any critical surfaces.
Apart from being mercilessly trolled by a particularly persistent Starfish who was adamant that they should be present in all images(!) this phase was completed smoothly.
Anticipating that alignment questions would form part of the onshore discussions, we took extra care with the geometry of the Guide Post receptacle cones. Since the Guide Posts themselves aren’t rigidly fixed, they couldn’t serve as reliable datum for angular measurements — but their receptacles could. By capturing this geometry in high 3D detail, we ensured future alignment measurements would be technically robust.
Various geometry questions were then posed and answered during the onshore discussions — but none revealed an obvious cause for the DHG comms failure.
Eventually, a representative from the original equipment manufacturer joined the discussion and requested alignment checks be carried out on the Tubing Hangar (TH) locking dogs, using the Guide Post cones positions as a reference datum. From this, we confirmed the TH was misaligned to the Production Guide Base (PGB) by 2.8 degrees — exceeding the acceptable tolerance of 1.8 degrees.
We were then asked to re-check the data not once, but three times, as the experts had “never seen such a large deviation before.” We understood the gravity: the client was preparing to commission an adaptor plate — a custom-engineered component that would ‘bridge’ the misalignment — at considerable cost.
In a final call, the project manager asked, “We’re about to spend hundreds of thousands of dollars to fabricate an adaptor — is there anything you’d like to recheck?”
There wasn’t. The deviation was 2.8 degrees. It was time to act.
Weeks later, we received confirmation: the 2.8-degree adaptor plate had been installed, and the DHG was operational.
With three identical XMTs still to be installed, the operator asked us to conduct similar scans on the remaining units. The outcome? One more was out of tolerance, one was within spec, and one sat right on the limit.
Viewport3 has now completed over 25 projects where our technical-grade 3D data has been used to fabricate ‘first-time fit’ solutions. In this case, we were particularly pleased by the faith the customer placed in the accuracy of our data, and being able to help the client resolve a high-stakes issue with confidence and precision.
The pragmatism shown by the operator was pivotal in realising the success of the project – when we suggested collecting technical grade data from the entire site, the engineering team agreed.
Had the offshore team not been given such an opportunity, a less accurate dataset with a mere 2mm error in the position of the TH locking receptacles would have created a 0.9 degree base error in alignment calculations.
This had the potential to cause 2 TH to PGB alignment angles to be reported as being out of tolerance, when in reality they were comfortably within. Thanks to the accuracy of Viewport3’s methods and measurement techniques however, we were able to avoid having a squad of engineers spending lots of resources trying to alleviate a problem that didn’t actually exist(!)
