PRACTICAL RISKS OF RIG MOVING Brief Presentation Synopsis

- A Rig move Master’s Perspective-case study
- Pro-active Measures with industry intelligence
- RELOCATION OF A JACK-UP DRILLING UNIT – CASE STUDY ON RIG MOVE
- The intended purpose of the operation was to relocate the jack-up drilling unit from an open sea location to a port for lay-up. The distance was about 300 nm and the season was winter but the port lay in a location where as the tow progressed towards it, the weather would improve due to change in latitude. The unit was refloated and the tow commenced.
- The Problem Starts…….
- The owner instructed the rig mover to order the tugs to make for the new location. The original certificate of Approval (C of A) for the voyage no longer applied and the warranty survey (WS) company advised the owner of this fact.
- Original C of A was for a move classed as “an extended field move”, lower than the now contemplated “ocean move”.
- CONSEQUENCES
- Tow ran into a series of heavy gales, severe strains on the tow gear parted first one then the other towline.
- Suffering structural damage in way of the hull where the legs passed through.
- Began to take green seas on deck which broke the lashings on cargo.
- Equipment broke ventilators and hatches resulting in down flooding, loss of power and pumping ability.
- The barge was now in serious trouble and sinking.
- The crew were removed by helicopter in a remarkable display of seamanship before the unit sank.
- The unit underwriters did not pay the full insured value of the unit due to the negligence of the owner and the warranty survey company.
- Assessment of intact stability criteria
- Assessment on dynamic effects on stability & water impact loads
- Establishing the final distances and criteria for jack-up
- Maneuvering in close proximity of platforms
- Guidance on fatigue of jack-up rigs during towing
- Detection of water ingress in floating condition
- Continuous and better dialogue between weather prediction service providers.
- The starboard leg has punched through. By jacking down the hull on the Port side, the Starboard leg will be able to move within the crater it has made. If binding should occur in the guides of the Port leg then this can be relieved by raising the Starboard leg allowing the weight of the barge on the low side to be taken by buoyancy.
- If the Starboard led is driven down to try and raise the low side, the result will be to force the Port leg hard into its guides thus moving the hull to Port. Because the port leg is restrained, severe bending could occur at or near the mud line.