Abstract

America's energy outlook is an everchanging thing; however, with the construction of Rig 76 Delta Drilling Company is declaring its faith in the future of ultra-deep drilling in this country. In addition to design criteria and specifications, this paper discusses unique problems encountered-prime mover flexibility, testing of various components, mud handling and solids control equipment, moving considerations, foundation requirements, rig-up and start-up operations, and the outlook for activity both now and in the future.

Introduction

Rig 76 is a raised floor, elevated drawworks design costing in excess of $5,000,000 and requiring 52 machinery loads when moving. At the time of construction, this rig had the only 147 foot mast with a capacity of 1,555,000 pounds. There are seven other rigs now operating with this hook load capacity that have 142 foot masts. There are approximately 150 rigs with raised floor masts and approximately forty rigs with elevated drawworks; however, this is the only rig that has an elevated drawworks with this hook load capacity.

DESCRIPTION

The beam-leg mast has a 147 foot clear height with a 30 foot base at a floor elevation of 34 feet giving an overall height to the top of the crown of approximately 189 feet. Beneath the floor there is 27 feet of clear space below the rotary beams. With this design, the floor is actually built into the leg sections of the mast while the mast is at ground level in the horizontal position. When the mast is raised the floor is then at the 34 foot level.

Rig 76 is a diesel-electric eight motor rig having three motors on the drawworks. It has a working hook load capacity of 1,555,000 pounds with 14 lines strung and a simultaneous set back capacity of 800,000 pounds. The complete structure and the mast pounds. The complete structure and the mast is of A-441 (70,000 psi), alloy steel. The racking stand has capacity for 322 stands of 5 in. drill pipe plus ten stands of 9 in. drill collars. An additional 12 stands of drill pipe may be racked in the alley on the driller's side, giving a total racking capacity of over 30,000 feet. With pipe racked, the mast is designed to withstand 100 mph winds.

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