Mars TLP Topsides Facilities Cycle Time Reduction
Authors: Crawford N.A. , Pippin A.E. , Samudio R. , Thomas C.J. , Melancon J.A. 
Published: October 2008

The Mars Tension Leg Platform (TLP) Project was a $1.0 billion capital investment in record water depth of 2940 ft. in Mississippi Canyon Block 807. The project was completed and oil production initiated on July 8, 1996. Partners were Shell Deepwater Development Inc. (Shell) and BP Exploration & Oil Inc. (BP). It was Shell's second Gulf of Mexico TLP that incorporated many experiences and lessons learned from the first, the Auger TLP. Minimizing the time to design and fabricate the topsides facilities was a key factor in improving the Mars project economics sufficiently to achieve project sanctioning. The project team developed a strategy of overlapping the design and fabrication processes and eliminating the traditional bid/evaluate/award cycle. This "design while build" process involved an accommodating contracting arrangement, high performing integrated teams for both design and fabrication and "state-of-the-art" design and drafting tools. The topsides schedule was reduced approximately eight months, most of which is credited to this strategy. This Mars approach has continued on Shell's ongoing projects for Ram/Powell and Ursa.

Introduction

The Mars TLP superstructure consists of a structurally integrated hull and deck to resist lateral forces and support the topsides drilling and production equipment. The TLP is held in position by 12 tendons, 3 at each column, which are connected to tendon porches on the TLP hull and latched into foundation piles driven 375 ft. into the seabed. Total displacement is 53,000 ST. Oil and gas are exported via 18- and l4-inch pipelines, respectively, to a pipeline hub platform in WD-143, The structure is designed to support 24 wells and the topside deck. The deck consisted of five modules:process module containing primarily oil and gas processing equipment,power module hosting the electrical power generation, oil sales and pump station equipment,wellbay module supporting the drilling rig, production riser assemblies and well testing equipment,drilling module supporting the drilling packages, andquarters module which contained personnel accommodations.

This modular design allowed for dockwise mating of the hull and deck sections.

The topsides equipment includes full production facilities designed for continuous processing rates of 100,000 BPD oil, 110 MMSCFPD gas and 25 MBPD produced water, living quarters for 106 people, 12 MW electric power generation, 17,500 HP gas compression, utilities and a leased skiddable platform drilling rig. Provisions were made for future gas lift and waterflood facilities and facilities to receive production from future subsea wells.

The five modules were fabricated at the J. Ray McDennott yard in Amelia, Louisiana. The Field Gas Compressor was fabricated by Turbofab in Houston, Texas, the Vapor Recovery Compressor at Mosby Enterprises in New Orleans, Louisiana and the H&P Drilling Rig Modules by Amfels in Brownsville, Texas. The five major modules were loaded-out and transported by barge to the Aker Gulf Marine yard in Corpus Christi, Texas where they were lifted and set on the hull along with the drilling, compressors and other equipment.