Coiled tubing is a pipe made of low carbon alloy steel with good flexibility, also known as coiled tubing. A coil of coiled tubing is several kilometers long. It can replace conventional tubing for many operations. The coiled tubing operation equipment has the characteristics of pressure operation and continuous lifting and lowering. The equipment is small in size, fast in operation cycle and low in cost. Coiled tubing originated from the Allied “PLUTO” during World War II in the 1940s.

Coiled tubing

The plan is for the Allies to lay a submarine oil pipeline between the United Kingdom and France that passes through the English Channel and has a total length of nearly 49,000 meters. This oil pipeline is composed of 23 pipelines, of which the continuous steel pipe with inner diameter of 76.2mm and butt welding is used.

In 1962, California Oil Company and Bowen Oil Tools Company jointly developed the first portable coiled tubing workover device. It is for sand flushing operations for oil and gas wells in the Gulf of Mexico. After the 30th anniversary of the birth of coiled tubing, its value was truly recognized by people. By the 1990s, coiled tubing technology had developed by leaps and bounds. The coiled tubing operating device has been known as the “universal operating machine” and is widely used in oil and gas field workover, drilling, completion, logging and other operations, and runs through the entire process of oil and gas production.

The development of the number of coiled tubing equipment in the world is as follows: in 1962, the first coiled tubing equipment in the world was born; in the mid-1970s, there were about 200 units; in 1993, there were about 561 units; in early 2001, there were about 850 units; At the beginning of 2004, there were about 1050 units, mainly distributed in North America, South America and Europe. At the beginning of 2011, there were about 1,881 units, with 61 units in China.

Coiled tubing initially gained a foothold in the market as a cost-effective wellbore cleanup tool. The economic revenue of well workover and completion operations accounts for more than 75% of the total revenue of coiled tubing operations, and the application scope of coiled tubing in oil and gas fields around the world continues to expand. In fact, coiled tubing has the advantages and application value of under-balanced operation with pressure, fast and efficient operation, low damage to the formation, low cost (from the simplification of the process), etc.

It was only really recognized in the 1990s. Since then, coiled tubing has been widely used in oil and gas field workover, drilling, completion, logging and other operations, and has played an increasingly important role in oil and gas field exploration and development. After the 1990s, coiled tubing fracturing technology and coiled tubing drilling technology have developed rapidly in process technology and practical applications.

With the gradual maturity of downhole operation technology, domestic coiled tubing operation technology has developed rapidly, but the design of the coiled tubing seal suspension device still has defects, and there are many leaks. If the sealing component fails, the seal housing needs to be removed to replace the seal components.

The operation is more complex. Among the two existing operating windows, the threaded manual operating window has the disadvantages of low switching window efficiency and high labor intensity, while for the double hydraulic cylinder operating window, two hydraulic cylinders has no pressure feedback function resulting in unbalanced liquid supply. When the cylinder needs to be reversed, it needs staff to climb manually, and the oil supply interface of the manual pump is changed, which is inconvenient to operate and has potential safety hazards.

For this reason, Sanjack Company has developed a coiled tubing seal suspension device with fewer leaks, convenient seal replacement, and reliable sealing, and a special operation window for installation of sealed suspension device with two lifting hydraulic cylinders that can be automatically balanced, and the oil intake direction of the lifting hydraulic cylinder that can be operated on the ground for coiled tubing.

The device includes: coiled tubing sealing device: tubing head (17), tubing hanger (18), sealing tiedown screw (19), tubing sealing device (20), pressure test port (21), etc. Special operation window: adapter flange (1), upper positioning flange (2), lifting hydraulic cylinder (3), sealing ring (4), cylinder barrel (5), pull plate (6), sealing ring (7) , Lower positioning flange (8), pressure gauge (9), high pressure check valve (10), synchronization valve (11), quick coupling (12), hydraulic pipeline (13), manual reversing valve (14), portable pump (15), struts (22), etc.

Working principle: The integrated tubing head structure is adopted for the coiled tubing sealing suspension device housing, which reduces leakage points, and reduces the height of the device, and is easy to operate; due to the synchronization valve set in the hydraulic control pipeline, the two lifting hydraulic cylinders can realize synchronous movement; The portble pump outlet is equipped with a three-position four-way reversing manual valve, which can adjust the oil supply direction of the hydraulic cylinder on the ground, which greatly reduces the labor intensity of the workers who switch the operating window and improves the switching efficiency.


The new design of Shengji Company solves the shortcomings of the current coiled tubing sealing suspension device with many leaks, the increased height of the sealing suspension device after installation, low switch efficiency for the installation of special operation window, and the problem of the lifting hydraulic cylinder not synchronized, and the high labor intensity.