Abstract

This paper is a case history of what is believed to be the firstever utilisation of Coiled Tubing on a FPSO (FloatingProduction Storage Offloading) vessel to dissolve hydrate(s) inthe riser. The main focus of this paper is to:

  1. Publish actual job results pertaining to friction factors(drag co-efficient) of the coiled tubing inside the FPSOriser.

  2. Highlight the innovative solution developed to allow for apossible emergency disconnection of the coiled tubingand CT Lubricator to allow the vessel to weathervanearound the turret if required.

  3. Explain the technique used to dissolve the FPSO Riserhydrate(s).

Introduction

The Asgard field is a sub-sea development 200 kilometers offthe Norwegian coast. Water depths vary between 240 and 310meters. This field contains the gas reservoir Midgard and thereservoirs Smorbukk and Smorbukk South, which contain oil, condensate and gas.

The sub sea production facilities consist of 50 production andinjection wells (located on 16 subsea manifolds) connected tothe FPSO vessel, Asgard A, the gas platform, Asgard B andthe storage ship for condensate, Asgard C.Asgard A started producing oil the first quarter of 1999, whilethe gas platform, Asgard B, started production the third quarterof 2000.

The Asgard fields will from year 2007, alone, deliverapproximately 10 billion cubic meters gas per year, which isabout 15 percent of Norway's annual gas production, makingNorway one of Europe's leading gas exporters/producer. Inaddition, the field may obtain a peak production as high as200,000 bbls/day of oil and 60–70,000 bbls/day of condensate.This is equivalent to approx. 10 percent of Norway's totaldaily production.

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