Annular BOP FHZ53-21shenkai FHZ54-14
Annular BOP is the key part of well control device and its main purpose is to control
wellhead pressure to effectively prevent blowout accident and realize safe construction
during drilling, well repair, well test and other processes. Its appearance sees Fig.1-1.
The annular BOP shall be used only after a BOP hydraulic control device is equipped,
and it is always used in match with ram BOP or works independently. The annular BOP
can be used for doing the works below:
Sealing annular spaces of different sizes with one packer when there is drilling
tool, oil pipe or sleeve in the well;
Sealing the whole wellhead when there is no drilling tool in the well;
Sealing the annular spaces formed by the drilling rod, coring tool, cable, steel
wire rope and the like with the shaft in case of overflowing or blowout during
drilling, coring, testing well and other works;
Forcibly lifting and lowering down the drilling tool through drill pipe sub of 18°
circular bead under the condition that the hydraulic control device with the
pressure releasing and regulating valve is used or the buffering energy storage
device performs control
Sealing wellhead: feeding high-pressure oil conveyed through the hydraulic control
device from lower oil port of the shell into lower closed chamber of the piston to
push the piston to move upwards when well kick occurs and shut-in is needed, the
piston will push the taper-face sealing packer to move upwards, the packer moves
upwards and toward the center of the wellhead along the taper surface of the piston
and the anti-wear plate while moving upwards under the limitation of the anti-wear
plate until the rubber among the supporting ribs is extruded out to tightly hold the
drilling tool or seal the whole wellhead, so as to reach the purpose of sealing the
well.
Opening wellhead: feeding high-pressure oil from the upper oil port in the shell into
the upper opened chamber in the piston to push the piston to move downwards, on
that basis, the extruding force on the anti-wear plate is removed, the packer is
gradually restored under the effect of elastic force of self, and as a result, the
purpose of opening the well is reached.
Structural features of annular BOP
1. The shell, bonnet, piston and other main parts are casted and molded through
quality alloy structural steel, their materials meet the provisions of NACE MR-01-75, and
the requirements of working conditions with acid medium are met. The materials are
subjected to special heat treatment, the hydrostatic pressure test is performed according
to the regulations of API 16A during manufacturing the product, in order to ensure safe
and reliable use under its working pressure.
2. Three dynamic sealing parts of the annular BOP are equipped with lip-type sealing
rings which bring pressure-based self-sealing performances, the wear of the sealing rings
is reduced, the sealing reliability is ensured, and leakage is avoided (Fig.3-1).
◆ Piston O.D.: packing pressure of opening chamber and closing chamber of oil
cylinder on the outside diameter of the piston;
◆Piston I.D: packing well pressure and closing chamber pressure on outer sleeve;
◆ Inner sealing part of bonnet: packing well pressure and pressure of oil cylinder
opening chamber on bonnet;
3. The piston travel measuring hole is formed in the bonnet and used for
continuously comparing the piston travel to Measure the service life of the packer.
4. The shell is connected with the bonnet through 20 jaw chucks (Fig.3-1), the
connection is reliable, the force on the shell is uniform, and mounting and disassembling
are convenient. Two O-shaped sealing rings that can prevent the jaw chucks and the
bonnet from rusting integrally are arranged on the screw of each jaw chuck.
5. The upper inner chamber of the piston is conical and is directly contacted with the
taper surface of the packer. The taper is small, so the force for pushing the piston to
realize sealing is also small. The outside diameter is smaller than that of the annular BOP
of other types;
6. Detachable anti-wear plate (Fig.3-1) is assembled on the frictional surface in
which the top part of the inner chamber of the bonnet is contacted with the top plate of the
packer supporting plate, which can protect the bonnet and is convenient to replace.
3.3 Sealing principle of tapered packer
The sealing of annular BOP includes two steps, the first step is that the piston
pushes the tapered packer under the effect of hydraulic oil to move upwards, the packer
is driven to move upwards and toward the center of the wellhead along the taper surface
of the piston and the anti-wear plate, the supporting ribs are close to each other to
extrude the rubber to the center of the wellhead, so as to realize initial sealing; the
second step is that the piston further moves upwards under the effect of the internal well
pressure under annular area of the upper part of the inner chamber of the piston when
there is pressure in the well, thus the packer can be tightly sealed, and as a result, the
sealing performance of the packer is improved, namely, the effect of assisting sealing
with the well pressure is realized.
7Manual of FHZ54-14 and FHZ53-21 Annular BOP Rev.A1
3.4 Structural features of tapered packer
1、The outer side surface of the packer is a taper surface, the bus of the taper
surface is in a certain included angle relative to the axis of the packer. The packer is
formed by vulcanizing a plurality of supporting iron cores and rubber, and the supporting
iron cores are radially arranged along the circular ring (Fig.3-3).
2. Large rubber storage capacity: the rubber among the supporting iron cores of the
packer can be extruded toward the wellhead to form sealing, and the amount of rubber is
far more than the volume of the space to be sealed. Therefore, drilling tools of different
shapes and different sizes can be sealed, and the whole wellhead can also be sealed. If
the hydraulic control pressure is under the control of the pressure releasing and
regulating valve or the buffering energy storage device, the packer can forcibly lift and
lower down the drilling tool to pass through the drill pipe sub of 18° circular bead. In case
that the rubber storage capacity is large and the packer is damaged a little, the sealing
can also be performed, and the service life can be measured. When the annular BOP
works, the packer is continuously worn, the travel of the piston is increased to extrude
more backup rubber to supplement. If the piston reaches the maximum travel (the piston
reaches the upper top point), or the upper end surface and the lower end surface of the
packer supporting iron cores are close to each other, the backup rubber of the packer
runs out, namely, the packer cannot be reliably sealed even after the hydraulic control
pressure is increased. Therefore, the service life of the packer can be measured by
measuring the travel of the piston.
Installation and Use
4.1 Preparation for use
he annular BOP shall be subjected to sealing pressure test until reaching the rated
working pressure before installation and shall be transported to the well site only after
passing the test. The annular BOP shall be installed according to the form of combination
of BOP as specified by the well control regulations. The direction of the oil pipe joint shall
be the same as that of the ram BOP.
4.2 Pressure test and test run
The annular BOP shall be fixed firmly after installation. Whether the blowout
controller, well controller and choke manifold are connected well, the hydrostatic pressure
test shall be performed together with the complete set of wellhead device, in order to
examine the reliability of each connecting part and the sealing performance, and they just
can be used after passing the test.
The annular BOP shall be started and stopped twice on the drill stand and remote
control panel, in order to check whether the starting and stopping are consistent with the
actual starting and stopping, and whether the pipeline is connected correctly. The air in
the oil line shall be exhausted. When in general drilling, the annular BOP shall be in
startup position.
The wellhead device shall be comprehensively subjected to pressure test according
to related well control regulation. Each connecting bolt shall be fastened once after
pressure test, in order to avoid non-uniform elasticity. The tightening torque of the flange
bolt
Usage and matters needing attention
1. The annular BOP is equipped with individual pressure releasing and regulating
valve, the pressure shall be controlled to be less than or equal to 10.5MPa in general,
and the pressure is in a certain proportional relation with the internal well pressure and
the size of the sealing drilling tool. If the drilling tool is of a large diameter or the internal
well pressure is small, the control pressure shall be corrESPondingly reduced to prolong
the service life of the packer.
2. When in well kicking, the wellhead shall be sealed through the annular BOP,
long-time sealing shall be avoided when possible because the packer is easily damaged
early, and locking device for locking is not provided. The annular BOP shall be not used
to seal empty hole unless special conditions occur.
3. The examination on the annular BOP shall be reinforced after entering the
targeted layer. The annular BOP shall be started and stopped once each day under the
condition that there are drilling tool and no well pressure in the well, in order to prevent
the packer from blocking.
4. When operating the annular BOP to lift and lower down the drilling tool without
well control, the drill pipe sub of 18° circular bead shall be used. If the energy storage
device can be assembled on the closing oil line of the hydraulic control system of the
annular BOP, besides the individually provided pressure releasing and regulating valve,
the hydraulic impact in the chamber can be closed to realize buffer, and therefore, the
service life of the packer can be prolonged. When forcibly lifting and lowering down the
drilling tool, the hydraulic pressure shall be reduced when possible on the premise that
the sealing is ensured, and meanwhile, the speed of lifting and lowering down the drilling
tool shall be controlled strictly, the drilling tool is particularly slowly lifted and lowered
down during passing through the sub.
5. After well cementing operation, open and close annular BOP three times to
discharge the cement in Body sleeve to prevent the cement solidification lead to the
piston cannot be moved.
6. Whether the annular BOP is completely started shall be examined while starting Manual of FHZ54-14 and FHZ53-21 Annular BOP Rev.A1
each time, in order to prevent the packer from being hung and damaged.
7. Releasing internal well pressure by opening the packer of the BOP is prohibited.
8. The drilling tool can be moved up and down, rather than rotating when the
annular BOP is in the state that the pipe is closed.
9. The hydraulic oil shall be kept clean.
Recommended Hydraulic Oil for the Hydraulic System for BOP Stacks
ISO Brand: HM32 (used for plunger pump system with low or no Zn)
Mobil Brand: D.T.E24 (used for plunger pump system with low or no Zn)
Shell Brand: Tellus32 (used for plunger pump system with low or no Zn)
Note: The kinematic viscosity of hydraulic oil is 17-33 mm2 /s when the temperature
is at 50℃.
