Summary

This paper describes how an integrated team approach was applied to the design, construction, start up, and ultimately the operation of a high technology drilling rig. The rig was built to conform, wherever possible, to the stringent regulations in the Norwegian sector of the North Sea. The paper, which also contains a technical description of the rig itself, also addresses the issue of automation and it's effect on manning of a complex drilling unit and the importance of high quality training of the personnel selected to operate the rig.

In 1994, Phillips Petroleum Company Norway, the operator of the Greater Ekofisk Area fields in the central North Sea, signed a contract for the construction of a state of the art, fit for purpose drilling rig to be located on the new Ekofisk 2/4 X wellhead production platform. The rig was an element of major importance to the Ekofisk II project, the redevelopment of one the largest fields in the North Sea. The start up of drilling on the 2/4 X platform was the first major milestone in the Ekofisk II project and the timely redrilling of the Ekofisk field wells from the new rig was vital to maintain production levels.

On 26th October 1996, exactly on schedule, the first well on the 2/4 X platform was spudded. To date six wells have been drilled by the rig including the fastest well ever drilled in the Ekofisk field. The drilling program is currently on schedule and the rig has operated at an average availability of 98%.

The success of this project can be attributed to a number of factors, however, one element stands clearly as the key success factor—a truly integrated team approach to all phases of the delivery of the rig! From the very beginning, representatives of the real customer of the product, the offshore drilling team, joined the rig supplier's design team to work shoulder to shoulder on the specification and preliminary design of the rig. As the design process moved forward, the customer representation on the team was strengthened. Ultimately, the customer participated in an active manner in all aspects of design, construction, commissioning, and start up of the rig.

This paper will detail both the underlying philosophy and the practical process by which this state of the art rig was successfully built and put to work.

The paper includes a description of the rig itself, a review of how the integrated team approached the various phases of delivery of the rig and an outline of how the project was managed.

The paper then discusses the issue of whether an automated rig can lead to a reduction in manning levels and covers the unique way in which the rig crews rig were trained. Some equipment performance figures are included to demonstrate the successful operational capabilities of the rig, and finally some conclusions are drawn from the lessons that have been learned.

Introduction

The 2/4 X platform is part of a complex of facilities located at the center of the Ekofisk field. Ekofisk is one of eight producing fields making up the Phillips Norway Group's Greater Ekofisk Area (production license 018) located in the southern corner of the Norwegian Sector of the North Sea. The Ekofisk field, discovered in 1969 and put on production in 1971, has recently entered into a new phase of redevelopment. Increasing operating costs, the result of ageing facilities and the need to mitigate the effect of seabed subsidence caused by reservoir compaction, has been the root cause of the redevelopment.

Although the field has been on production for nearly 28 years, Ekofisk still has enormous potential. Through 1994, the field had produced some 1,788 MMBOE. It is estimated that by 2028 the field will have produced over 3,200 MMBOE. The total estimated original oil in place is close to 8,000 MMBOE.

A number of solutions for redeveloping the field were proposed, however the optimal solution was to locate a single 50 slot drilling and production platform at the geographical center of the field and then to systematically replace the existing wells. Well failure due to the effects of subsidence and compaction is common in the Ekofisk field, therefore the replacement of failed producing wells is the fundamental strategy of the redevelopment program. The strategy of replacing all producing wells in the field from a single central location raised significant drilling challenges involving the planning of long reach, horizontal, and multilateral wells to be able to realize the full potential of the field.

With the large number of wells that would have to be drilled, plus the probability of the need to redrill wells which may fail as subsidence and compaction continues, the relatively high cost of a platform based drilling rig was justified. This decision was further supported by the long-term doubt of the availability of harsh environment mobile drilling units that could also provide drilling facilities for 2/4 X in the future. Further value could also be realized if the abandonment of the older production facilities could be accelerated, thus reducing operating costs. To accelerate the redrilling program, plans to locate a jack-up rig at 2/4 X (in cantilever mode) were developed. The jack-up would drill replacement wells parallel with the platform rig for at least the initial 18 months of drilling. Once an optimum level of production has been achieved from the 2/4 X platform, the jack-up will be removed.

This content is only available via PDF.
You do not currently have access to this content.