Abstract

The FPSO industry will soon have the first LPG FPSO in operation. The SANHA LPG FPSO is the first gas related FPSO. With the installation of the LPG FPSO for ChevronTexaco's Sanha field development project offshore Angola by April 2005, SBM will set a new benchmark for offshore processing of LPG. The LPG FPSO will receive LPG from the Sanha Condensate Complex and several production platforms via two subsea pipelines and flexible risers. Each stream will be pressurized at near-ambient temperature when loaded on the LPG FPSO.

Onboard the two streams will be comingled and then separated into butane and propane fractions by means of distillillation, refrigerated, depressurized to athmospheric pressure and stored into the cargo tanks. The paper will address the main commercial, technical and exectution challenges that the project team has faced and highlight the key success factors as well as "lessons learnt".

Introduction

A new era in the offshore industry will be ushered in with the start up of the Sanha LPG FPSO. The Sanha LPG FPSO represents the first time that a purpose built LPG processing plant will be installed on a floating structure. The Sanha LPG FPSO is a key part of the Sanha Condensate Project. The Sanha Condensate Project is to eliminate routine gas flaring while collecting and injecting collected gas to increase oil and LPG production in areas B and C of block 0, offshore Cabinda, West Africa (figure 1). The project will reduce routine flaring in Block 0 by more than 40 percent. The reduction in routine flaring will eliminate 2.2 million tons of carbon dioxide emissions per year. The Sanha field is located offshore Cabinda, Angola, and approximately 30 miles offshore from the onshore Cabinda Gulf Oil Company's Malongo terminal in Block 0. The Sanha Condensate Project will have a peak production of over 100,000 barrels of liquid per day (oil, condensate and LPG). ChevronTexaco's Angolan affiliate, Cabinda Gulf Oil Company (Cabgoc, 32.2%) operates the block on behalf of its partners, including Sonangol (41%), Total (10%) and ENI (9.8%). Cabgoc and Sonasing (a joint venture between Sonangol and SBM) are to share in the operations of the Sanha LPG FPSO.

Background

In early 2000, a small team of Single Buoy Moorings Inc. (SBM), and ChevronTexaco personnel formed a joint team to develop the contractual and technical specifications for a commercial tender package for the engineering, design and fabrication of the Sanha LPG FPSO. The philosophy was that Sonasing (a joint partnership of Songangol and SBM) would own the FPSO and lease the vessel to Cabgoc for an eight-year period and that the vessel would be jointly operated with personnel from both Cabgoc and Sonasing.

In May 2002, a contract was executed between SBM and Cabgoc for the design, procurement, fabrication and transportation for the Sanha LPG FPSO with the exception of the turret mooring system. Two major subcontractors of IHI Marine United Inc's were JGC for the engineering and construction of the depropanizer module and HKSE for the engineering and construction of the refrigeration and reliquefaction plants.

This content is only available via PDF.
You can access this article if you purchase or spend a download.