Progress Towards Zero-Based Hookup
- Ian Hume (AMEC Offshore Services)
- Document ID
- Society of Petroleum Engineers
- SPE Production & Facilities
- Publication Date
- May 2001
- Document Type
- Journal Paper
- 68 - 72
- 2001. Society of Petroleum Engineers
- 4.2 Pipelines, Flowlines and Risers, 4.5.5 Installation Equipment and Techniques, 7.3.3 Project Management, 4.2.4 Risers, 4.5 Offshore Facilities and Subsea Systems, 1.6.9 Coring, Fishing, 4.1.5 Processing Equipment
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This paper charts the step change continuous improvements achieved in U.K. completion system (CS) hookups from 1992 through 1998. Fig. 1 shows that improvements to this process have caused the man-hours/tonne required to hook up and commission (HUC) large offshore installations (greater than 20,000-tonne topsides) to fall from an industry average of 75 man-hours/tonne to less than 10 man-hours/tonne.
The change process has been complex. It was necessary not only to challenge technical sacred cows but also philosophical, cultural, and organizational core beliefs prevalent in our industry during this period.
The story is not complete yet. There are still significant activity level reductions to be delivered, some of which have been targeted already. We have no doubt that we or others will deliver yet more.
In 1991 AMEC sponsorship of the BP Bruce HUC contract was at the stage of preparing to go offshore. Table 1 shows that among its peer group, Bruce HUC was a success story delivering at or marginally better than the industry norm and significantly ahead of its contemporaries, Miller, Piper B, and Saltire. Its significance for future hookups was that it introduced a number of concepts which, when developed, proved fundamental to achieving today's benchmark performances.
The most significant concepts incorporated were an integrated HUC team and a completions-management team. In the form present with the Bruce project, they would be virtually unrecognizable as they are practiced today; however, they served as a catalyst to realize what was possible.
Although a success story for its day, the Bruce HUC performance could have been better. It was necessary to identify the major sources of man-hours in the base scope and to categorize the prime drivers for scope growth. Scope growth typically meant increasing base scope by factors of 2 or 3, on average, and as much as 5 times in extreme cases. In the case of Bruce, scope grew from a base of 750,000 man-hours to 1.6 million man-hours at completion, or 60 man-hours/tonne.
Analysis of Bruce and previous project HUC statistics identified the major contributors to offshore man-hours as fabrication-yard incompletion (carryover), offshore-scope growth, base-scope activity levels, and design changes.
The base scope man-hours were driven primarily by hookup-spools fabrication; field welding, nondestructive testing (NDT) and hydrotest; electrical and instrumentation cable pulling, cutting, termination, and testing; and system-leak testing for helium and nitrogen.
This information was used to develop proposals to Amerada Hess for their Scott development hookup. We further developed the learning from Bruce HUC by introducing an improvement on the previous systems-completions approach.
On Bruce, the systems-completions group was effectively an inspection/certification function which acted as an interface between construction and commissioning groups. The development of this approach is described more fully under "Interface Management."
An innovation introduced by Amerada Hess on Scott was the design of an incentive contract focused on their main driver, early first oil production. This was the first time such an approach had been employed on major hookup contracts. We believe without doubt that this provided the environment in which innovation has flourished.
First Steps Towards Zero-Based Hookup
The Amerada Hess Scott HUC marked the start of a continuous process of innovation built on applied learning which evolved through four successive HUC projects, delivering benchmark performance each time. The key success factors and subsequent learning from Scott were primarily in the areas of interface management, pressure and leak testing, dimension control, cable splicing, and flowlines.
Scott was the first project presenting an opportunity to implement our version of a systems-completion approach to HUC. Client and contractor goals were aligned by means of the contract strategy. The primary target was oil production within the last quarter of the year which required a clear focus on oil-related systems not only offshore but also during the yard phase.
The principle of systems completion provides the commissioning team with the maximum opportunity to commission predefined subsystems progressively in a predetermined optimum sequence. The adopted completions strategy provided for carrying out subsystem commissioning much earlier in the schedule than traditionally experienced, thereby reducing the potential for surprises and growth during the offshore phase.
The principle of system ownership was also a significant move away from tradition in that the engineers who would construct and commission the facilities were allocated systems to progress to completion. The completions and commissioning engineers then were responsible for the multidisciplinary completion of the system, including the inspection and acceptance from the yards.
No inspectors other than welding and coating disciplines were employed. The systems-engineering team carried out inspection functions as part of their roles and responsibilities. This was the first application of self-certification. Other than for specialist NDT, no inspectors have been required on any subsequent hookup.
Pressure and Leak Testing.
The opportunity was pursued to develop the principle of "golden weld" dispensation, traditionally granted for pipeline tie-in welds, (i.e., jacket to topsides), within the topsides facilities. The golden weld is granted a dispensation from pressure testing provided that alternative means of testing are carried out to determine integrity.
The certifying authority agreed that if all the hookup components were pressure tested and the offshore tie-ins were welded, there would be no need to repeat the leak testing offshore. The flare system had two 24-in. tie-in welds to complete offshore. The tie-in spool was measured after installation and prefabricated onshore. The spool was then pressure-tested to the specification, coated, and sent offshore for installation. Tie-in welds were completed offshore and the nondestructive testing was completed. No pretested joints within the flare system were disturbed through this process, therefore, no additional leak testing was required offshore.
Accepting the described pressure and leak-testing philosophies opened the door to extend the principles to piping spools with mechanical connections. Dimensional control techniques available to the industry had moved into the laser-survey arena. Survey companies would guarantee precise fit-up if they were made responsible for measuring offshore and during the fabrication process. This approach was used where possible with significant success. The key limitation was that the design of the tie-in spools did not always provide the opportunity to maneuver them physically in one piece into position. This problem was addressed in later hookups.
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