Page 179 - Well Control for Completions and Interventions

Well Control Surface Equipment 171

driven by an electric motor, and a separate air driven plunger pump. The
API specification 16D requires that:
• With the accumulator isolated and with one pump or one power sys-
tem out of service, the remaining pump system shall have the capacity
within 2 min to:
• Close one annular BOP on open hole;
• Open the hydraulically operated choke valve;
• Provide final pressure at least equal to the grater of the minimum
operating pressure recommended by the manufacturer of both the
annular BOP and choke valves.
• The cumulative output capacity of the pump systems shall be sufficient
to charge the entire accumulator system from precharge pressure to
the system rated working pressure within 15 min.

4.9.4 The manifold system
The manifold directs and regulates the flow of pressurized fluid from the
accumulator bottles to the BOP, and directs hydraulic fluid back to the
reservoir. The accumulator bottles are connected to the high-pressure
section of the manifold. For most API approved units, this section of the
manifold has a working pressure of 3000 psi. In a 3000 psi operating pres-
sure system, the manifold regulator takes fluid from the accumulator bot-
tles and regulates it down to 1500 psi for the ram type preventers and
HCR valves. Similarly, a separate regulator reduces the pressure to that
required to operate the annular preventer. In most, system annular pres-
sure can be adjusted at the accumulator or the remote station. Gauges on
the manifold should read accumulator bottle, ram preventer, and annular
preventer pressure. The setting on most 3000 psi systems are 3000 psi for
the accumulator, 1500 psi for control the manifold, and 800 1200 psi for
the annular preventer. The manifold returns fluid from the BOP to the
fluid tank.
Manifold valves are used to direct accumulator pressure to a BOP pre-
venter or HCR valve, with each valve controlling a single function.
These valves are normally three position four-way valves. The three posi-
tions are:
• Open: Connects the manifold with the opening hydraulic chamber on
the BOP.
• Closed: Connects the manifold to the closing chamber on the BOP.
• Neutral: Connects the BOP to the fluid reservoir (Fig. 4.25).