The BOP is used to close the wellhead during oil testing, workover, completion, and other operations to prevent blowout accidents. It integrates the two functions of full sealing and semi-sealing, and has the characteristics of simple structure, easy operation and high-pressure resistance. It is a safety sealing wellhead device commonly used in oil fields to prevent blowouts.
When drilling oil, it is installed on the wellhead casing head and used to control high-pressure oil, gas and water as the blowout preventer device. When the oil and gas pressure in the well is very high, the blowout preventer can seal the wellhead (close it). When the heavy mud is pressed into the drill pipe, there is a four-way under the ram, which can replace the mud that has been invaded by gas, and increase the pressure of the liquid column in the well to suppress the ejection of high-pressure oil and gas.
Its types are divided into ordinary blowout preventer, universal blowout preventer and rotary blowout preventer. The universal blowout preventer can be activated in an emergency to cope with drilling tools and empty wells of any size; the rotating blowout preventer can realize the drilling operation while spraying. In deep well drilling, in addition to two common blowout preventers, a universal blowout preventer and a rotating blowout preventer are often added, so that three or four combinations are installed at the wellhead.
Annular Blow-out Preventer is usually equipped with a large gate of ram-type BOP, which forms a sealed annular space between the pipe string and the wellbore during operation. In the case of a pipe string in the well, it can also be used separately to finish the well closure, but it is not enough to use it for a few times, and long-term well closure is not allowed.
Due to the many and complex uncertainties in the formation, every drilling operation has the possibility of blowout, which puts forward higher requirements for well control technology and well control equipment. As the most important well control equipment, the blowout preventer needs to be started and shut down quickly in the event of an emergency situation such as overflow, kick, blowout, etc. during drilling operations. Bad accident like blowout will occur in case BOP is not working well. Therefore, the rational design of the blowout preventer plays an important role in ensuring the smooth progress of drilling operations and personal safety.
BOP is the most important well control device and plays an important role in drilling, especially in the process of underbalanced drilling. BOPs are designed to close the wellbore under pressure, maintain continuous control of the well, and circulate formation fluids entering the well.
There are two main types of hydraulic BOPs: ram BOP and annular BOP. Ram BOP is mainly composed of shell, side door, oil cylinder, cylinder head, piston, piston rod, locking shaft, seals, ram and so on. Its working process is to use hydraulic pressure to push the piston to drive the ram to close or open, so as to close or open the wellhead to achieve the purpose of closing and opening the well. The ram of the ram BOP can be divided into four kinds of rams: full sealing, semi-sealing, variable diameter and shearing, which are used to realize the well-sealing and semi-sealing rams to seal the related drill pipe and tubing, etc. under different conditions. And it also could hang the drill tools when necessary.
When there is no pipe in the well, the fully-sealing ram can completely seal the wellhead. In special cases, the shearing ram can cut off the drilling tool. In addition, the flange outlet on the side of the shell can perform drilling fluid circulation and choke and kill operations. The type of annular BOP can be divided into conical annular BOP and spherical annular BOP according to the shape of its sealing rubber core. Its structure is mainly composed of four parts: shell, top cover, rubber core and piston. When there are drilling tools, tubing or casing in the well, the annular BOP can use a rubber core to seal various annular spaces of different sizes.
When there is not drill tool, it could seal the well. During the operation of the well, such as drilling, coring and logging, it could seal the annular space between the rectangular drill pipe, coring tool, the cables and steel wires and the wellbore. Under the condition of using a pressure reducing and pressure regulating valve, the drilling tool can be forcibly tripped up and down through the drill pipe.
The BOP plays an important role in the process of drilling and completion, so it is particularly important to install the BOP quickly and accurately. In the process of drilling and overhaul operations, the workover rig is used to cooperate with the workover platform for operation. Under this working condition, the blowout preventer group is installed with the big hook as main role and the small hook as help, which has high labor intensity and low work efficiency and many potential safety hazards.
To solve this problem, Sanjack has designed a rapid installation device for the blowout preventer, which can realize the rapid installation of the blowout preventer.
The device includes a fixed base (1), a trolley base (2), a hoisting trolley (3), a fixed guide rail (4), a workover platform (5), etc.
Working principle: The top of the hoisting trolley is equipped with a load-bearing top cover, and 4 lifting devices are installed between the load-bearing top cover and the load-bearing frame. The lifting devices are sequentially connected with the connecting rod, transmission box, and lifting motor. The four corners of the load-bearing cover are equipped with guides column. The two lifting lugs are designed in the middle. The lifting lugs can lift the BOP with the lifting device; the load-bearing frame is installed on the walking trolley, and the walking trolley is installed on the trolley base, and the trolley rail on the trolley base is connected to the fixed rail. The walking trolley can walk back and forth on the trolley rail and the fixed rail, so that the blowout preventer can be transported to the wellhead for installation.
The structure developed by Sanjack is simple and easy to operate. No other equipment is required to complete the installation operations of the blowout preventer, such as hoisting, transportation, and wellhead alignment, to realize the rapid installation of the blowout preventer.