Insulation Materials for Ultra deep Sea Flow Assurance : Evaluation of the Material Properties
Authors: Choqueuse Dominique , Chomard Angèle , Bucherie Christian 
Published: October 2008

Flow assurance and particularly the selection of insulation materials is a major consideration and the focus of much industry interest for deepwater applications.

The offshore industry is taking up this challenge through developments such as those in the Gulf of Guinea. A wide evaluation program on materials suitable for the thermal insulation of pipelines and risers down to 3000 meters water depth is being carried out. This involves operator, contractors, certification authority, and research centers.

Based on the parameters required for the exploitation of ultra deep sea, a material requirement has been established. About 10 materials of different nature have been selected after consultation with the major suppliers of insulation material and exhaustive characterization of candidate materials has been carried out.

The paper : describes the experimental program defines the methodology of characterization for critical functional parameters (thermal conductivity, hydrostatic compression, water aging behavior, ...) gives some examples of results obtained.

Presentation

The thermal behavior of fluid transport pipelines must be increasingly taken into account in new field development, to prevent production of waxes or hydrates. The deepest developments (depth &gt;1500m) are particularly sensitive to these problems and solutions are needed for such depths. The current solutions, coated pipe, pipe-in-pipe, syntactic foam, have to be adapted to ultra deep sea, as there are limitations in terms of thermal conductivity, hydrostatic pressure, and installation possibilities (ref 1).

Thus more satisfactory solutions have to be found for the different installation procedures currently in use. The objective of this project is to propose test methodologies to evaluate the potential of materials for the insulation of pipes in ultra deep sea and to collect a large database on materials likely to be used.

This 1M$ program (ref 2-3) started in 1999 and has brought together actors from all areas of the offshore industry(operator, contractors, certifying authority, research centers).

System requirements

Different solutions for flow management have already been studied (ref 4-8). In this study partners decided to focus on on-jacketed insulation systems, such as coated linepipe or molded shells around the line pipe.

The main driving parameter of this project is a water depth of 3000 meters. Based on this, general operating parameters have been defined by the operator and contractors (table 1).

Table 1 : System requirements(available in full paper)

The specific criteria of exploitation for each field and the possible applications for different systems (riser tower, SCR, ...) bring a new set of problems in terms of materials, so it appears that a general requirement in terms of material performance can not be precisely established.

Nevertheless the thermal conductivity, the capacity to withstand the pressure of immersion and the long term behavior appear to be the parameters for the material which are most critical for the deepest applications.