Composite Drill Pipe, A New Technology Development

Advanced composite drill pipe

The new composite drill pipe (CDP) is made of carbon fiber and epoxy resin. The principles are with high temperature curing the metal core shaft, and then extract the core shaft, the curing of the pipe section to complete the processing. Final preparation involves the addition of standard elastomeric centralizers before the pipe is run in the hole. Both the centralizers and the abrasion resistant coating can be repaired in the field. More serious wear can be in plant maintenance as long as it is not completely destroyed. Mechanical properties of CDP are similar to that of steel but less than half the weight of steel.

Advantages of CDP compared with conventional steel pipe

• CDP demonstrates the economic utility in the oil and gas sector. Because CDP combines light weight (less than ½ the weight of steel) with the performance properties of steel pipe, it will be applied to the ultra deep, deep orientation, resource development and other technical research. Onshore, it will allow existing rigs to drill to greater depths. CDP also has significant potential to embedded cables or optical fibers wires in the field of high speed communication technology (Intelligent Drilling Technology). With the weight of the CDP at 40 to 50 percent of steel, the loads to be transported and the weight that must be supported by drilling platforms are significantly reduced. These reductions can provide very substantial cost savings for deep drilling and deep water drilling activity.
• CDP can easily be customized to meet specific requirements for specific applications.  For example, to increase tension and compression strength, more longitudinal fibers are used.  Similarly, more hoop fibers can be added to increase pressure capability . And an increase in fibers angled at 45 degrees will improve torque capacity.  In this manner, CDP can be designed for a particular application, loading conditions and specifications into the program to get a specific slice of production needs.
• Tool joints made from various metals, including non-magnetic stainless steels, can be furnished as an option. This can facilitate the CDP and non magnetic composite connection. It is beneficial to the requirement of directional drilling tools.

 

Technology used in the manufacture of composite materials

Spray-up

This applied in the mold, to establish the required thickness of the material.The process is faster and cheaper than wet lay-up, but mechanical properties are lower.The process is typically used for large, relatively simple structures such as bathtubs, boat hulls and storage tanks.

Compression moulding

This process can generate a high surface finish of the metal plate, mainly used in the automotive industry.The high investment in heated tooling means that the process is only suitable for medium to high volume production.

Injection moulding

Bulk moulding compound is heated and injected into a heated mould, where it is held under pressure until the resin has cured. The process is used for relatively small components for which a short cycle time can be achieved. The high cost of tooling means that the process is suitable only for medium to high volume production.

Resin transfer moulding

The process is suitable for complex, highly-loaded parts, and is used in a wide range of industries. Tools that reduce the load, and therefore allow for cheaper, larger tools to be used to manufacture large structural ship hulls or wind turbine blades

Filament winding

The process is designed to achieve the required thickness of the fiber, the use of high temperature when necessary. In the process, pre-impregnated fibre tows or slit prepreg can be used, the removal of waste using a resin bath but need high temperature curing stage.

Pultrusion

Combined with the previous model, cured resin obtained uniform extrusion part.The process can be automated and uses low-cost raw materials, making it suitable for high volume applications.

Prepreg

Prepreg (pre-impregnated fibre) consists of fibres, fabrics or mats impregnated with resin. Thermosetting prepregs include hardeners in the resin, and therefore have a limited shelf life and are usually stored under refrigeration. Before use, the prepreg is brought to room temperature to avoid condensation. Prepreg is used where high mechanical properties are required and the high cost of processing can be justified. Examples include aerospace structures, sporting goods and wind turbine blades.

Market outlook

As the oil and gas production environment and conditions become more and more complex, the drilling cost and drilling risk continues to improve, the traditional sense of the drill pipe has been unable to meet the use requirements. A new generation of drill pipe towards high strength, high toughness, intelligent, digital, corrosion, safety and environmental protection direction. Thus it causes oil drill pipe manufacturers and materials manufacturers more concerned about the super high strength drill pipe,whose purpose is the adaptability of the improvement of drilling pipe. With the continuous improvement of manufacturing process and improvement, the price of the product is constantly improved, and the new generation of drill pipe will be further development and wide application, which provide strong support for oil and gas exploration and development.