Objectif
The aim of the project is to demonstrate the feasibility of safe and effective manned intervention at simulated depths of 450, 360 and 200 msw and to enable the verification of a range of equipment trials.
It was a simulated operational dive and was therefore conducted as closely as possible to a commercial offshore operation. Four divers from Stilt Comex Seaway were compressed over a period of 48 hours to the storage depth (450 msw). The compression phase of the dive, critical in deep diving to minimize the effects of the high ambient pressures on the central nervous system, was very successful and the divers reached the storage depth in excellent condition. They started diving almost immediately and each diver had completed one 'familiarisation' dive within 60 hours of leaving surface. The divers then spent a further 7 days at 450 msw conducting a range of trials at 450/470 msw. The most important feature of these trials was the evaluation of three underwater breathing apparata and their capability to deliver sufficient gas to the diver to allow him to return to the bell in the event of an emergency. This aim was successfully achieved in all three systems and this represented a significant achievement in the development of individual diver's equipment. Two trials were conducted with a simultaneous main gas and hot-water supply cut-off and these resulted in a significant reduction in performance of the bail-out. This would suggest that it is perhaps thermal balance that is now the issue rather than gas supply to the diver in the event of a severed umbilical. Thermal, welding, communication and inspection task trials were all carried out successfully at 450/470 msw and these were supported by a range of scientific studies.
The divers decompressed to 308msw where a lost bell simulation was conducted. This hilighted that tests of survival in simulated conditions are as much as test of the man himself as of the equipment and in this case it was difficult to draw firm conclusions as to the state of the equipment. Further diving and trials were conducted for a 4 days at 200 msw and the divers then continued to decompress to surface. Decompression and post-excursion periods were measured using an innovative ultrasound scanning device at pressure. This results in the real time analysis of the decompression profile independent of any overt symptons of decompression sickness. Two divers were treated for Type 1 DCS at 3 msw and otherwise the decompression was uneventful.
The three primary objectives of the project were all successfully met. It was clearly demonstrated that safe and cost effective manned subsea intervention could be carried out at 450/470 msw. Individual equipment manufacturers were able to exploit the technology that they had already developed at more conventional depths and the confidence in deep manned intervention was heightened among oil majors and authorities.
Significant success points include the compression profile, the communications, the duration of the secondary life-support systems of the diver's personal breathing apparatus, the level of productive work achieved on real subsea tasks at 450/470 msw and the decompression profile.
AURORA'93, a simulated operational dive to 450/470 msw, took place at the National Hyperbaric Centre in Aberdeen. Primary objective was to demonstrate safe and cost effective manned subsea intervention at 450 msw, thus enabling diving contractors and equipment manufacturers to address the substantial EC and international markets. The secondary objective was to enable individual equipment manufacturers to exploit the technology they have developed through participation in a simulated deep dive and to facilitate diving contractor's personnel hands-on experience of deep diving.
The tertiary objective was to heighteen confidence among clients and authorities in deep manned intervention and subsequently accelerate the safe and cost effective recovery of hydrocarbons from oilfields.
The divers spent 8 days at 450 msw with three days of excursions to 470 msw. Their primary activity was the testing of 3 different underwater breathing apparatus in both primary and secondary modes. In primary mode a range of sub-sea tasks were carried out including MPI, metrology, wet welding, and pipe work construction and pressure testing. During the bail-out trials the divers excercised on either an arm ergometer or a step test at approximately 20 or 40 litres per minute ventilation rate to simulate emergency world levels. The divers also tested and evaluated a range of hot-water suits and communication systems throughout the bottom phase. A number of studies supported the operational aims of the dive by providing data on topics such as compression, respiration, lung function, thermal balance, and decompression.
The divers decompressed to 308 msw to conduct a simulated lost bell trial. Three different survival systems were evaluated: two active and one passive system from two manufacturers. Further diving took place over 4 days whilst at 200 msw to establish the efficiency of standard bail-out systems and to further prove the three different closed-circuit systems already testedat 450-470 msw.
Throughout the decompression ultrasound monitoring was conducted to evaluate the decompression profile selected. A number of other projects were also continued to track the recovery of a range of diver functions as the pressure was slowly reduced.
The advantages of the three storage were numerous :
- comparison of equipment performance accross depths to permit maximum testing and evaluation
- addressing not only the deep saturation market, but also the Norwegian Continental Shelf at 360 msw and the UK North Sea sector at 200 msw.
- a linear'dose response picture can be developed for all trials and a clear demonstration made of deep manned intervention viability to clients and authorities.
The dive programme was split into the following phases :
(a) Pre-dive and familiarisation
(b) Compression to, and diving at 450/470 msw
(c) Decompression to 308 msw followed by one day work programme
(d) Decompression to 200 msw followed by four day work programme
(e) Decompression to surface
Programme(s)
Appel à propositions
Data not availableRégime de financement
DEM - Demonstration contractsCoordinateur
AB2 5FA Aberdeen
Royaume-Uni