Page 146 - Well Control for Completions and Interventions

138 Well Control for Completions and Interventions

Having secured the well, additional equipment is needed to restore
the primary well control barrier. This includes:
• Fluid pumps.
• Fluid storage tanks.
• Choke manifold.
• Mud gas separator (poor-boy).
• BOP control system.
Most of the components that make-up the well kill systems are per-
manent and necessary parts of the drilling equipment, and have functions
unrelated to well control. For example, the mud pits and fluid pumps that
are used daily during the drilling and completion of the well become a
necessary part of well kill equipment following a kick.
This chapter provides an overview of well control surface equipment.
It concentrates on equipment requirements and configuration, rather than
providing detailed nuts and bolts descriptions of every component.

4.2 THE BLOW OUT PREVENTER STACK

A BOP is a large valve designed to shut-off flow from the well. To
enable flow to be shut-off under all circumstances during completion of a
well or during a range of workover operations, several BOP valves, each
with a different function, are assembled to make the BOP stack.
Configuring the stack will depend on the maximum anticipated surface
pressure, and the type of operation to be performed. Most completions are
installed immediately after drilling the well. Since the stack will have been
configured for the drilling operation some modifications may be required
before the completion can commence. For example, pipe ram inserts may
have to be changed to match the diameter of the production tubing.
Stack configuration has a direct impact on operability. Optimum con-
figuration of the rams and outlet spools allows more operability during a
well control incident. When configuring the stack, the following should
be considered:
• Positioning the pipe ram above blind rams allows the well to be iso-
lated and the ram inserts changed out.
• There should be a drilling spool (inlet/outlet) below the blind ram to
allow circulation and pressure monitoring.
• To enable tubing to hang off in pipe rams before disconnection or
shearing above the rams, the stack should be configured to allow the