Bop Stack Equipment
Floating drilling rigs may be equipped with either a 'one stack' or a 'two stack' BOP system. The two stack system is a combination of a 2,000 or 3,000psi large bore stack and a 5,000, 10,000 or 15,000psi stack. A one stack system is either a 10,000 or 15,000psi system.
The following list gives the common sizes and various configurations:
a) Single stack systems
183/4" - 10,000 and 15,000psi WP
163/4" - 10,000 and 15,000psi WP
b) Two stack systems
21V4" - 2,000 and 3,000psi WP
c) Configurations
4 rams and 2 annulars 4 rams and 1 annular 3 rams and 1 or 2 annulars
The most common configuration consists of a 13 4" single stack system with 4 rams and 2 annulars (Refer to figure 5.a). This configuration is used in this section as an example to describe BOP equipment bearing in mind that same principles apply to all types.
A conventional BOP stack consists of two sections, the lower which contains:
- Wellhead connector
- Ram preventers
- One annular preventer and the upper part which contains:
- Hydraulic connector
- Annular preventer
- Control system pods
- Flex joint to the top of which the riser is connected.
This upper part is referred to as the lower marine riser package (LMRP), the term stack being applied to the lower part. If it ever needs to be repaired during the course of the well, the package can be retrieved with the riser leaving the stack in position on the wellhead.
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ENI S.p.A. Agip Division |
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