Centralized Production Facilities
Authors: Rench S.D. , Folse K.A. , Johnson C.M. , Chan J.H-C. 
Published: December 2007

This paper describes the development of the central production platform(CPP) in Green Canyon Block 52. It describes production platform (CPP) in GreenCanyon Block 52. It describes some of the unique features of the platform, its schedule, and key management decisions that affected platform design, construction, and installation.

Introduction

The CPP is a major component of the Jolliet and Marquette projects, which develop oil and gas reserves in the Green Canyon projects, which develop oil and gas reserves in the Green Canyon area of the Gulf of Mexico. Installed in616 ft of water, the CPP is connected by pipelines to the tension-leg wellplatform (TLWP) and it is connected by bridge to the Marquette platform. Space has been allocated on the CPP for future developments within the Green Canyon area. As the name implies, oil, gas, and produced water are brought to the CPP from outlying platforms. There are no wells on the CPP. Oil and gas are treated and conditioned to meet their respective pipeline specifications. Produced water is treated (oil is removed to enable its disposal overboard) and may be used ultimately for reservoir pressure maintenance. Having these processing facilities at a central location allows space, weight, processing facilities at a central location allows space, weight, and manpower to be minimized at the outlying platforms. Fig. 1 is a geographic overview of the CPP. Conceptual engineering of the CPP occurred in Jan. through June 1987. Detailed engineering took 14 months (June 1987 through Aug. 1988). Jacket fabrication began in April1988, and deck/facilities construction started in July 1988. Onshore fabrication was complete for the jacket in April 1989 and for the deck in Aug.1989. Offshore hookup and commissioning were done from Sept. through Nov. 1989.Refs. 1 through 3 give additional information on the Jolliet project and the CPP.

Jacket

The jacket is primarily a conventional design with a few unique features(see Table 1). It is installed at a depth of 616 ft, with a weight in air of8,260 tons. The jacket is a four-leg design with two skirt piles per corner and no main piles. Total pile penetration is 340 ft; total weight of all eight piles is 2,250 penetration is 340 ft; total weight of all eight piles is 2,250short tons. The jacket was built with eight J-tubes for pipelines. Four pipelines currently are pulled into the J-tubes, with four J-tubes pipelines currently are pulled into the J-tubes, with four J-tubes reserved for future pipelines. Other jacket appurtenances include four personnel miniboat landings, four barge bumpers, eight pump caissons, and two skim piles. Perhaps the most unusual jacket feature is the half-depth launch box. It is a cross-sectionally square steel tubular frame from a jacket elevation of - 132 ft down to a jacket elevation of -616 ft. The launch box was designed to bear the weight and stresses of the entire jacket during load out, transport, and launch. The half-depth launch box and the main jacket frame are not rigidly connected, which allows them to react to thermal and other environmental stresses somewhat independently,

Deck

The CPP deck is a three-level, eight-leg, plate girder design. The main and cellar decks are roughly 110 x 195 ft, and the subcellar deck is 90 x 200 ft. Total deck area is approximately 62,000 ft2 (1.4 acre). Deck elevations are 56,77, and 102 ft above mean sea level. Because of weight considerations and derrick barge lift capacities, the deck was designed to be built in any one of three potential configurations: a four-piece configuration with a potential configurations: a four-piece configuration with a vertical split down the middle of the deck and a horizontal split between subcellar and cellar decks, a two-piece configuration with a vertical split only, or a one-piece configuration. In June 1988, fabrication and installation bids were evaluated simultaneously. This was a key management decision to reduce costs. The bid for offshore deck installation was awarded very early to enable a more economical fabrication/installation combination to be selected. In the end, a two-piecedeck configuration was selected. Therefore, in effect, two four-pile-type decks were built. A second key decision was to require the fabricator to build the two deck halves (east half and west half) in correct spatial proximity to each other.

JPT

P. 464