In industrial settings such as oil and gas extraction, geological exploration, and shale gas development, blowout preventers (BOPs) serve as core equipment in well control systems, bearing the critical mission of preventing runaway blowouts and ensuring the safety of personnel and equipment. Their selection not only affects operational efficiency but also directly determines risk control capabilities in high-risk environments. From pressure rating matching to structural and functional design, from material manufacturing processes to operational compatibility, BOP selection requires a comprehensive evaluation system that considers multiple technical parameters and actual operating conditions.
Precise pressure rating matching is the primary principle in BOP selection. According to industry standards, the rated pressure of the BOP must be consistent with the minimum of the following three values: the highest formation pressure in the open hole section, the casing’s internal pressure resistance, and the rated working pressure of the casing four-way valve. For example, in shale gas development, if the target formation pressure is 70 MPa, a BOP combination with a pressure rating of 70 MPa or higher must be selected, such as a composite structure of “annular BOP + semi-sealed gate BOP + fully sealed gate BOP”. Insufficient pressure matching can lead to well control failure; excessive configuration increases equipment cost and operational complexity. Furthermore, well sites containing corrosive gases such as hydrogen sulfide require sulfur-resistant materials conforming to SY/T6610-2005 standards to prevent equipment failure caused by hydrogen embrittlement or stress corrosion.
The selection of the nominal diameter must be closely related to the wellbore structural design. The blowout preventer (BOP) diameter must be slightly larger than the outer diameter of the connected casing to ensure smooth passage of the drill string, casing, and other tubing. For example, for a casing with an outer diameter of 244.5 mm, a 280 mm BOP should be selected; if the diameter is too small, it may cause scraping and wear between the tubing and the BOP inner wall, even leading to stuck pipe. In field practice, 230 mm, 280 mm, 346 mm, and 540 mm are the most widely used diameter specifications, corresponding to different well depths and casing sizes.
The structural and functional design must adapt to diverse operational scenarios. Gate-type blowout preventers (BOPs) achieve complete wellhead sealing through quadruple protection of front, top, side, and shaft seals. Their floating sealing structure and well pressure-assisted sealing technology automatically compensate for sealing surface wear, extending service life. Annular BOPs, on the other hand, utilize the deformability of their conical or spherical cores to achieve dynamic sealing of tubing strings of different sizes, making them particularly suitable for special conditions involving forced tripping during well sealing. For example, in deep well operations in high-pressure formations, a combination of annular BOP and dual gate-type BOP is often used; the former provides rapid wellhead control, while the latter provides long-term sealing. Furthermore, BOPs equipped with shear gates can cut off the tubing string in emergencies, making them an essential configuration for high-pressure gas wells.
Operational compatibility and ease of maintenance directly affect equipment efficiency. Hydraulic BOPs must be strictly matched to the number of control points and pressure level of the control system. For example, a 70MPa BOP requires a 70MPa hydraulic control console, with backup control points reserved to handle hydraulic valve failures. Meanwhile, the installation of blowout preventers (BOPs) must adhere to the principle of “leveling and stability,” with connecting bolts tightened diagonally to prevent seal failure due to installation deviations. During routine maintenance, regular checks of the rubber core wear, piston stroke, and steel ring groove cleanliness are necessary. For example, the remaining life of a tapered rubber core can be determined by measuring the piston stroke through a probe hole; it must be replaced immediately when the remaining stroke is zero.
The selection of a blowout preventer is a comprehensive consideration of technical parameters, operating conditions, and safety standards. From precise calculation of pressure ratings to strict matching of bore diameter, from scenario-based design of structural functions to optimization of ease of operation and maintenance, every aspect must adhere to the principle of “safety first, efficiency priority.” For oil and gas exploration and production companies, selecting BOP products that meet industry standards and are certified by authoritative bodies, and establishing a full life-cycle equipment management system, are essential to building a solid well control safety line under complex geological conditions and providing sustainable technical support for energy development.
