The diameter of coiled tubing is increasing, the manufacturing materials are developing from carbon steel to quenched and tempered alloy steel, titanium alloy and other alloy materials and composite materials, the strength is developing from low strength to high strength, and the welding technology is developing from more welds to less welds, until there is no weld.
The accurate simulation of fatigue failure of coiled tubing improves the reliability of drilling operation.
The development of coiled tubing injector is remarkable. The forced entry capacity of hr480 injector can reach 180kn, the maximum pull force at low speed can reach 450kn, and the maximum pull force at high speed can reach 180kn. The injector chain can be replaced.
Significant progress has also been made in process control system, cable installation system, data acquisition system, etc.
The development and test of electric coiled tubing drilling system are successful. The core component of the system is the bottom hole electric drilling assembly. It uses electric submersible pump motor instead of conventional positive displacement motor. The electric submersible pump motor is connected with the planetary gearbox, which can reduce the output shaft speed to the speed suitable for the drilling conditions. The motor is controlled by a portable computer on the ground connected with a variable speed drive device. Through field test, the downhole electric drilling assembly has many advantages:
It can make bit rotation independent of drilling fluid flow, obtain downhole data, change rotation direction, use underbalanced pressure drilling, achieve dynamic balance between circulating pressure and formation pressure, realize automatic control of well deviation and azimuth, reduce the times of tripping bottom hole drilling tool assembly, and improve the service life of coiled tubing.