Application of Titanium Alloy in Petroleum and Natural Gas Exploration & Development--I
I. Titanium Alloy Drill Pipe
In recent years, in order to improve oil recovery, reduce the production cost and extend the development life of oil and gas fields, more and more complex structure wells, such as extended-reach wells, short-radius horizontal Wells, and old Wells with windowing lateral horizontal wells, have been developed. Conventional drill pipe applications in these complex wells have encountered some difficult problems. For example, in ultra-short radius horizontal Wells, the borehole curvature is very small (<18 m), which causes large alternating stresses in conventional drill pipe. Fatigue fracture of drill pipe caused by alternating stress often happens, which brings great loss to oil field. In order to solve these problems, foreign countries began to develop titanium alloy drill pipe, aluminum alloy drill pipe, composite drill pipe and other new materials to replace the conventional drill pipe.
Titanium alloy drill pipe is also used in ultra-deep and extended-reach Wells. Due to the low density of titanium alloy, hook load can be reduced by 30%, torque can be reduced by 30% ~ 40%, tension margin and safety factor of drilling tools can be improved significantly, and the ability to deal with complex accidents can be improved.
II. Titanium Alloy Pipeline
The stress corrosion fatigue strength of titanium alloy pipe is over 10 times higher than that carbon steel, because it is easy to bend, and has extremely high dynamic stress corrosion fatigue strength, which caused by sea wave impact and platform movement. At the same time, the titanium alloy pipe can adapt to the bending deformation condition in the laying process of sea pipe. Titanium alloy pipeline welding performance is good, single-sided welding and double-sided forming technology to ensure uniform and reliable weld, and titanium alloy pipeline mechanical performance is excellent, through the tube tensile mechanical property test, oscilographic impact test, tube flattening test, fracture toughness KIC test.
