GRE Pipe is a proven technology to combat against corrosion. It has horizontal uses in surface applications like line pipe and around facilities.
• Natural gas, LPG Line pipe
• Desalination Systems
• Potable Water Systems
• Water Treatment Systems
• Water Distribution Networks
• Chemical Processing Facilities
• Fire Fighting Systems
• Wastewater, Sewage and Municipal Waste Systems
FROM PIPELINE TO DRILL PIPE
Modern day production techniques have allowed for strengthening advancements in composite pipe technology
Traditionally, vertical well applications have been a risk due to lack of strength.
GRE pipes are designed with these horizontal applications in mind. In these applications the pipe body is never exposed to high collapse or tensile loads which are so typical in vertical applications.
Collars have been a weak spot for GRE pipe and to support this issue manufactures have resorted to build much thicker joints or reinforce with steel or carbon fiber. Thicker collars limit applications in slim holes and the metallic elements restrict the logging benefit of a Non-Metallic tubular.
Filament winding is a fabrication technique mainly used for manufacturing open (cylinders) or closed end structures (pressure vessels or tanks). The process involves winding filaments under tension over a male mandrel. The mandrel rotates while a wind eye on a carriage moves horizontally, laying down fibers in the desired pattern. The most common filaments are carbon or glass fiber and are coated with synthetic resin as they are wound. Once the mandrel is completely covered to the desired thickness, the resin is cured, often the mandrel is placed in an oven to achieve this, though sometimes radiant heaters are used with the mandrel still turning in the machine. Once the resin has cured, the mandrel is removed, leaving the hollow final product. For some products such as gas bottles the 'mandrel' is a permanent part of the finished product forming a liner to prevent gas leakage or as a barrier to protect the composite from the fluid to be stored.
As a result of the filament winding production method air and moisture from the air are trapped in the pipe body. These micro voids enable chemicals to enter the composite matrix causing degradation and the risk of explosive decompression. Stress will concentrate around the voids and will lead to micro-cracking. Another feature of filament wound pipes that becomes critical in vertical applications is the orientation of fibers. These run at an angle with the length of the pipe creating weakness and internal friction under stress. Where fibers cross micro-cracks will develop causing degradation of performance with time and the possibility that chemical enter the composite matrix
The rotary casting method, rotational molding or rotocast, is a process for producing items which are hollow, like composite pipes. The basic method involves positioning the fibers in the right quantity in both radial and axial directions into the (OD) casing mold. The mold is then heated and rotated by a centrifuge to create hundreds of g-forces when the resin is injected. The resin is forced through the fiber structure effectively evacuating all air inclusions from the material. The tool is then allowed to cool and contract as it detaches from the (ID) mold as a High Strength Composite Tubular.
Rotational casting produces an ultra- strong tubular with smooth finishes allowing for maximum throughput with minimal resistance. Fibers run in the direction of the major forces in a downhole application and there are no voids with moisture or air. Chemicals cannot propagate into the pipe wall and no micro-cracking will occur from internal friction of fibers. The Energy Industry optimistically looks to this method for breakthroughs in increased tensile strength and tensile moduli.
Akiet is a company who produce composite tubulars via the rotational casting process. They have refined the process to enable them to have greater control of the manufacturing process. They produce pipes with a constant inner and outer diameter, "High Strength Composite Tubulars which was recently used to break the world record depth in the deepest composite casing application. The use of Akiet HSCT will extend the reach of horizontal drilling. HSCT piping is near buoyant in drilling mud enabling the string to float out to very long horizontal sections. HSCT is 80% lighter than steel assisting drillers with much lighter hook loads and the ability to use smaller rigs. The geothermal energy industry will benefit from its use as well in the battle against corrosion.
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