Abstract

Materials selection, welding fabrication and corrosion management for the Thunder Horse Deepwater facilities required first-in-class and cutting edge technology solutions for the subsea equipment, flowlines and riser systems.. These solutions were developed through application and understanding of new and challenging technologies that demanded innovation and a broad and in-depth technological understanding of new solutions for successful delivery of first production in June of 2008. The technology challenges faced came from the high pressure, high temperature (HPHT) conditions found in the reservoir; 270°F, 12,300 psi, pH 4.5, 4.5 psi H2S, 6.0 psi CO2, 32,000 ft TVD, and deepwater depths of approximately 6,500 ft where the external temperature and pressure are 4°C and 2,950 psi.

Significant technology challenges were addressed and implemented in the Thunder Horse HPHT development to the industry were:

  • Trees, manifolds and jumpers, not previously seen in subsea developments, with heavy-walled forgings and piping/fittings necessitated by strength, fracture toughness, welding and corrosion demands

  • Flowline and riser challenges including corrosion strategy, corrosion fatigue/sour service, thermal fatigue, and strength, toughness issues in thick-walled, microalloyed pipeline steels in sizes not produced previously with J-lay welding of sour service heavy-walled lines

  • Controls equipment materials requirements for miles of subsea umbilicals (15,000 psi)

  • Drilling riser materials and fabrication technology for longer-term drilling operations from both drillship and the Thunder Horse production facility

Introduction

Staff with deep competencies across a broad spectrum of technical fields were required to be successful in material selection, steel processing in pipe mills and forgemaster shops, welding fabrication and pipelay installation, corrosion inhibition, erosion, corrosion resistant alloy stress corrosion cracking, cathodic protection, sour service issues, materials fracture, and fatigue coatings/non-metallic materials.

This paper is an overview of the Thunder Horse materials, welding and corrosion (MWC) issues, the approaches taken and the solutions developed to enable Thunder Horse, a world-class production facility, to be delivered and become the premier operating asset for BP and in the Gulf of Mexico. These learnings lead the way to future development of deepwater, high production HPHT fields, employing world-class materials, welding, and corrosion-applied technology solutions for safe and reliable operations.

To solve these challenges successfully and deliver the Thunder Horse HPHT deepwater demands, an integrated approach was taken using BP's technical staff working with materials suppliers for forgings, pipe fittings, equipment fabricators and installation contractors.

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