Jack-up Operational Guidelines

ABSTRACT In the time interval between 1956 and 1977.Zapata Off-Shore Company has operated eleven jack-up rigs for a total of 127 rig-years of operating experience. All of these rigs were built by the Marathon-LeTourneau Company and. in design concept, span the entire evolutionary development spectrum of mobile offshore jack-up units. AS a result of the wide experienced gained in operating these units-on a world-wide basis. Zapata has developed an extensive set of operating instructions and guidelines. This paper presents a summary of many of the significant operating instructions and guidelines proven by field experience to have made Zapata's operations with jack-up rigs more reliable and safe. The instruction and guidelines presented in this paper cover field transit, ocean transit, moving on to location, jacking, preloading, severe storm and moving off location conditions. The operating guidelines and instructions presented in this paper can serve as a basis for development of similar operating procedures by other jack-up rig owners for their specific units. The paper also discusses the general evolution of the jack-up unit and the role these mobile offshore units have played in the Offshore Oilfield Development. INTRODUCTION Zapata Off-Shore Company has played a continuing role in the development of the mobile offshore jack-up unit. In the mid-1950's. Zapata cooperated with R.G. LeTourneau in developing a workable arrangement and layout of equipment and work spaces on LeTourneau's innovative jack-up rig design. That first jack-up rig built by LeTourneau and delivered in 1955 was contracted for construction by Zapata. For both company's, that historic rig, the SCORPION, was the beginning of a long term commitment involving offshore drilling rig construction and operation (Figure 1). Since that time, LeTourneau and other major rig builders have built and commissioned over 200 jack-up units. As of December 1977, there were 172 jack-up rigs in existence and 20 more units committed for building programs under construction contracts. The existing jack-up rigs constitute 45% of the total existing offshore fleet of 386 rigs. The total operating experience accumulated by the 192 existing jack-up units is 1118 rig-years. The total operating experience accumulated on all types of mobile offshore rigs - jack-ups, drill ships, barges, submersibles, and semi submersibles - is 2376 rig-years. Thus, 48% of the accumulated offshore operating experience of the Industry has been on jack-up units.(Table A). The growth of the Industry's jack-up fleet has increased from an estimated 4 units in 1955 to 172 units in 1978 (Figure 2). During that 23 year time period, the jack-up unit has proven itself to be the "old reliable workhorse" of the industry. It has been used extensively on a world-wide basis in every major offshore exploratory and development program. It played a key role in enabling the Petroleum Industry to sever its ties with the continental coastal shorelines and step out boldly into the continental shelf regions of the oceans.