The need for high performance,
robust and dependable products, has never been greater in the offshore
industry, especially as it continues to move towards even more challenging
applications. The thermal insulation of offshore pipelines, has an important
role to play to ensure the smooth running of a facility and as such, is a key
element of many offshore drilling projects. However, as budgets get leaner,
fluids get warmer and water depths get deeper, can the sector keep up? I say
“yes” and would argue that innovative synthetic rubber-based solutions not only
address these concerns and provide a reliable alternative, but are the only
true choice for offshore pipeline thermal insulation.
The offshore oil and gas industry is
notorious for continuously pushing the limits. The exploration of offshore
gas/oil has been moving to more and more deepwater fields and demanding that
wells be drilled deeper and reach further in order to provide more
cost-effective and safe well completions. In addition, the requirement to
extract more oil and gas than ever before, and exploit ever harsher reservoir
environments in new locations around the world, adds a further challenge.
As the water depth becomes greater
and the reservoir is located deeper underneath the seafloor, additional
pressure is put on the performance of oil and gas products which must now be
able to cope with much higher pressures and temperatures than shallow reservoir
products.
As such, particularly in this
difficult economic climate, customers require solutions which are not only
superior when it comes to performance, but more cost-effective, focusing more
on price and longer lifetime. Not long ago customers required products that
could last 20 years; now it’s often up to 40 years.
When it comes to material selection
to handle these challenges, rubber-based materials are, not surprisingly,
becoming a more popular solution within the offshore industry as rubber is an
extremely flexible and durable material. Compared to alternative materials,
such as steel and fiberglass, rubber has an extensive temperature range and
exceptionally high pressure resistance, it is a flexible material that can
damp, seal and protect, and most of all, has an extremely long lifetime.
GOING WITH THE FLOW
So, as exploration and drilling go
deeper, the need for reliable and efficient thermal insulation increases; flow
assurance is a critical element of deep and ultra deepwater developments, in
particular pipelines. Effective insulation of subsea structures helps maintain
flow rates, optimise productivity and reduce processing costs. It also provides
optimum defense against wax and hydrate formations.
When reservoir fluids reach the
subsea structure they are typically a high temperature mix of condensed
hydrocarbon gases, liquid paraffinic materials, waxes and water. As the fluid
progresses through the structure to the processing facility or during a system
“cool-down” cycle, heat loss is apparent to the surrounding ocean. As the
temperature decreases, waxes and hydrate crystals may deposit, leading to
potential flow loss and eventual system blockage. Insulation therefore becomes
a necessary part of this process in order to avoid this formation of hydrate
plugs and wax build-up (paraffin). The formation of wax and hydrates occurs
when the oil or gas composition is depressurised and exposed to the low seawater
temperature at the seabed.
A hydrate is formed when crystalline
water is stabilised and light hydrocarbon molecules are captured in the crystal
lattice. Hydrates can be formed at high pressures and at temperatures around
+68 °F to 77 °F (+20 °C to +25 °C). Without insulation the cold seawater would
rapidly cool the fluid, allowing it to create hydrate and wax formations, and
making it impossible for a safe flow.
Thermal insulation materials are
often applied in order to prevent formation of hydrate and wax during a
shutdown scenario. During shutdown, the extra insulation gives sufficient time
for inspection of the subsea pipe and equipment, so engineers can have time to
solve production problems and for methanol or glycol injection.
MEETING DEMAND
The increasing challenges faced by
the offshore industry have spurred manufacturers to consistently push to
develop products that can keep up with the demands of the offshore engineer.
However, it’s not always about
finding completely new solutions. Manufacturers must continuously look at their
current product portfolios to find new ways to make existing products work even
harder than they already do, if they are to stay ahead of the game.
As such, some leading manufacturers
are reassessing subsea thermal insulation materials, which have been
successfully installed throughout the subsea oil and gas industry for many
years, to see how best to enhance their performance in line with these growing
demands.
The latest generation of subsea
insulation solutions, an example of this dedicated improvement from one leading
manufacturer, have a k-value of 0.13 W/mK, can be used up to 9842ft (3000m)
deep and utilised of liquid temperatures up to +311 °F (155 °C), as well as
external temperatures as low as -31 °F (-35 °C). In order to provide even more
flexibility when it comes to design and logistics, it now also allows for
mobile production and can be installed on-site, at a water depth of 9842ft
(3000m).
A LAYERED APPROACH
These flexible insulation systems
consist of a three-layer buildup. First, an inner layer for corrosion and/or
Hydrogen Induced Stress Cracking (HISC) protection; this could be a Neoprene
compound that is qualified up to +203 °F (+95 °C), or an EPM compound that is
qualified up to +311 °F (155 °C). Both compounds provide excellent corrosion or
HISC protection, and have been extensively tested for adhesion, aging and
cathodic disbondment.
The middle layer has been designed
to provide the thermal insulation protection and various compounds are
applicable depending on the specific requirements. The compounds provide a
k-value of 0.13 W/m2K up to 0.19 W/m2K. The flexibility and stability of the
rubber makes this an excellent choice with respect to thermal expansion.
The insulation layer is protected by
the outer layer. This is a strong and robust layer that provides excellent
seawater and mechanical protection and has a successful track record as far
back as the early seventies in the North Sea.
The insulative elastomer coating
system used is a development based on ordinary rubber technology and consists
of a rubber elastomer chemically modified to give a very high insulating
property, while maintaining its inherent rubber properties in respect to
sea-water resistance, pressure resistance, mechanical properties and
temperature. By utilising a solid rubber-based coating, these new products have
very good thermal insulation properties while providing maximum corrosion
protection.
STANDING THE TEST OF TIME
With the lifetime of an oil field
expected to be a minimum of 25 years and design temperatures of the field var
ying throughout (up to +392 °F/ +200 °C), it is impor tant that products can
prove they stand the test of time. Continuous and extensive testing is the only
way to remain at the forefront of material development and lies at the heart of
material advances and product solutions.
Extensive test programming has been
carried out on these next-generation insulation solutions to prove their
integrity for the lifetime of the field. They are designed to last the life of
the subsea project (20 to 40 years), are maintenance free and will normally
never be replaced.
ALTERNATIVE INNOVATIONS
But it's not just about subsea
pipelines; leading manufacturers are also looking to develop, new and unique
solutions to maximise topside offshore pipe insulation.
This is because the insulation of
topside pipes usually involves the use of mineral wool to provide insulation,
with an outer shell of steel for protection. However, while this insulation
system is meant to be water tight, experience shows that this isn’t always the case
and humidity can often penetrate into the insulation. This will often result in
the corrosion of the steel protection layer and a reduction in thermal
performance.
Therefore, it is of high importance
that it’s a stratum of air is placed between the insulation and the steel pipe
to avoid any damage to the pipe. Historically engineers have made these air
gaps between the pipe and thermal insulation using an additional sheet of metal
applied in a wave pattern. However, this method can cause undesirable side
effects including corrosion of the metal sheet and injury to engineers during
work due to its sharp edges.
In a bid to provide a high
performance product, which not only provided a reliable solution, helping to
guarantee thermal performance, but one that eliminated the undesirable effects
that comes with traditional methods of creating an air gap, leading
manufacturers developed a new rubber-based alternative.
This unique solution has been
specifically developed to effectively create a one to two centimeter air gap
between the pipe and insulation, thereby avoiding the corrosion that can occur.
By stopping direct contact between the insulation material and the pipe, this
new solution prevents any damage to the corrosion protection on the pipe,
helping to guarantee thermal performance.
PEACE OF MIND
This latest innovation, which is
unique to the market, provides a reliable and extremely durable solution to a
common problem within the offshore topside insulation market. Furthermore, its
rubber construction means that it will last the life of an offshore project, as
well as being maintenance free, providing reassurance to the offshore engineer.
It can also be easily installed without using
hot work or special tools, and can be connected and split to the desired length
using just a pair of scissors, making the installation quick and easy and
without any additional safety actions, in turn reducing downtime.
Extensive testing has also been
undertaken to ensure that the product is qualified for lifetime performance; it
has been qualified for use up to +302 °F / +150°C continuous service
temperature, for more than 30 years.
CONCLUSION
As the offshore oil and gas industry
continues to push the limits when it comes to demanding offshore applications,
the need for reliable and durable solutions that deliver proven performance for
critical thermal insulation installations, has never been greater.
With the formation of hydrate plugs
and wax build up (paraffin), or corrosion of topside steel pipes, a real risk
for offshore engineers, rubber-based solutions provide a practically
incompressible, seawater and impact-resistant solution that has very good
thermal insulation properties and also provides maximum corrosion protection.
They are designed to last the life of the subsea project (20 to 40 years), are
maintenance free and will normally never be replaced, giving peace of mind to
the offshore industry.
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