Surface blowout prevention equipment (BOP) is that equipment used in land operations and operations where the wellhead is above the water level. Given in this article are the MINIMUM requirements for each working pressure classification.

1. 2000 psi WP classification

Where equipment of this classification will suffice, the BOP stack will consist of:

• One annular preventer, or a double hydraulic operated ram type preventer (one equipped with correct size pipe rams, the other with blind/shear rams).
• One full opening drilling spool with two 77.8 mm (3 1/16") bore side outlets.

The BOP stack should have two dual purpose kill- and choke lines. Each line should have two full bore valves of which one valve of each line is hydraulically operated. Both lines should be connected to the kill- and choke line manifold Section 6.31

When dual purpose kill- and choke lines are not employed, the BOP stack shall have one kill line and one choke line.

When the BOP stack consists of a double ram type preventer with proper size side outlets, the kill- and choke lines may be connected to the outlets of the lower preventer. In this case the drilling spool may be omitted.

The BOP stack, complete with drilling spool, side outlet valves, and kill- and choke lines is to be installed.

2. 3000 psi and 5000 psi WP classification

Where equipment of these classifications will suffice, the BOP stack shall consist of the following:

• One annular preventer.
• One double, or two single hydraulic operated ram type preventers; one of which must be equipped with correct size pipe rams (either fixed or variable), the other with blind/shear rams.
• One full opening drilling spool with two 77.8 mm (3 1/16") bore side outlets.

The BOP stack should have two dual purpose kill- and choke lines. Each line should have two full bore valves of which one valve of each line is hydraulically operated. Both lines should be connected to the kill- and choke line manifold Section 6.31.

When dual purpose kill- and choke lines are not employed, the BOP stack shall have one kill line and one choke line.

Provided that the bottom ram type preventer is equipped with proper size side outlets, the kill- and choke lines may be connected to the outlets of the bottom preventer. In that case the drilling spool can be omitted.

3. 10,000 psi WP classification

Where equipment of this classification is required, the BOP stack shall consist of the following:

·One annular preventer with a working pressure of 10,000 psi. A 5000 psi WP annular preventer on a 10,000 psi WP BOP stack is acceptable on existing stacks.

·Three single, or one double and one single, hydraulic operated ram type preventers; one of which must be equipped with blind/shear rams and the other two with correct size pipe rams. Variable Bore Rams (VBRs) may be used instead of fixed pipe rams, but at least one ram type preventer shall be equipped with fixed pipe rams.

·One full opening drilling spool with two 3 1/16" bore side outlets.

Provided that the middle and lower ram type preventers are equipped with outlets of the proper size, the kill- and choke lines may be connected to these outlets and the drilling spool omitted. The BOP stack complete with drilling spool, side outlet valves, and kill- and choke lines shall be installed as shown in Section 6.28

The BOP stack should have two dual purpose kill- and choke lines. Each line should have two full bore valves of which one valve of each line is hydraulically operated. Both lines should be connected to the kill- and choke line manifold Section 6.31

When dual purpose kill- and choke lines are not employed, the BOP stack must have two kill line and two choke line entries. Each entry should have two full bore valves of which one valve of each choke line shall be hydraulically operated. The lower kill- and choke lines shall be connected to the BOP stack below the bottom preventer and act as spare kill- and choke lines. The lines may be connected to the outlets of the bottom preventer, provided that the preventer is equipped with outlets of the proper size. When the lower kill- and choke lines cannot be connected to the outlets of the bottom preventer, they should be connected to the outlets of a drilling spool which is installed below the bottom preventer.

4. 15,000 psi WP classification

Where equipment of this classification is required, the BOP stack shall consist of the following:

• One annular preventer with a working pressure of 15,000 psi or a 10,000 psi WP unit, preferably with a body rated to 15,000 psi.
• A four ram stack is preferable. However, minimum requirements are three single, or one double and one single, hydraulic operated ram type preventers, one of which must be equipped with blind/shear rams and the other two with the correct size pipe rams. Variable Bore Rams (VBRs) may be used instead of fixed pipe rams, but at least one ram type preventer shall be equipped with fixed pipe rams.
• One full opening drilling spool with two 3 1/16" bore side outlets.

Provided that the middle ram type preventer is equipped with side outlets of the proper size, the kill- and choke lines may be connected to these outlets and the drilling spool omitted. The 15K BOP stack configuration of the three-ram-cavity stack is the same as the 10K

The BOP stack must have two dual purpose kill- and choke lines. Each line should have two full bore valves of which one valve of each line is hydraulically operated. Both lines should be connected to the kill- and choke line manifold.

When dual purpose kill- and choke lines are not employed, the BOP stack must have two kill line and two choke line entries. Each entry should have two full bore valves of which one valve of each choke line shall be hydraulically operated. The lower kill- and choke lines shall be connected to the BOP stack below the bottom preventer and act as spare kill- and choke lines. The lines may be connected to the outlets of the bottom preventer, provided that the preventer is equipped with outlets of the proper size. When the lower kill- and choke lines cannot be connected to the outlets of the bottom preventer, they have to be connected to the outlets of a drilling spool which is installed below the bottom preventer.

5 Control system requirements for surface BOP stacks

Control systems for surface BOP stacks shall consist of the following:

• One independent automatic accumulator unit rated for 3000 psi WP with a control manifold, clearly showing 'open' and 'closed' positions for preventer(s) and the hydraulic operated kill/choke line valves. It is essential that all air and hydraulic BOP operating units be equipped with 0-3000 psi regulator valves similar to the Koomey type TR-5 which will not 'fail open', causing complete loss of operating pressure.

Without recharging, the accumulator capacity shall be adequate for closing and opening all preventers and closing again the annular preventer and one ram type preventer, and holding them closed against the rated working pressure of the preventers. The unit shall be located in a safe area away from the drilling floor. It shall include a low pressure warning alarm and hydraulic fluid level indicator or low fluid level warning alarm.

• All BOP stack installations should have two graphic remote control panels, each one clearly showing 'open' and 'closed' positions for each preventer and the pressure operated choke line valves. Each of these panels to include a master shut-off valve and controls for regulator valves and for a bypass valve. One panel must be located near the driller's position, the other panel to be located near the exit of the location or near the rig supervisor's office.
• High pressure fire-resistant control hoses with a working pressure of 3000 psi are preferred, although steel swivel joints are acceptable. The hoses should be steel wrapped (co-flex type) to provide greater resistance to fire and improved durability.