Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: PURGING FLUID CIRCUITS IN WELLBORE CONTROL DEVICES
TECHNICAL FIELD
[0001] Technical Field: The subject matter generally relates to systems and
techniques in the field of oil and gas operations. When a well site is
completed,
pressure control equipment may be placed near the surface of the earth. The
pressure control equipment may control the pressure in the wellbore while
drilling,
completing and producing the wellbore. The pressure control equipment may
include
blowout preventers (BOP), rotating control devices (RCDs), and the like. The
RCD is
a drill-through device with a rotating seal that contacts and seals against
the drill
string (drill pipe with tool joints, casing, drill collars, Kelly, etc.) for
the purposes of
controlling the pressure or fluid flow to the surface.
BACKGROUND
[0002] RCDs and other pressure control equipment are used in underbalanced
drilling (UBD) and managed pressure drilling (MPD), which are relatively new
and
improved drilling techniques, and work particularly well in certain offshore
drilling
environments. Both technologies are enabled by drilling with a closed and
pressurizable circulating fluid system as compared to a drilling system that
is open-
to-atmosphere at the surface. Managed pressure drilling is an adaptive
drilling
process used to more precisely control the annular pressure profile throughout
the
wellbore. MPD addresses the drill-ability of a prospect, typically by being
able to
adjust the equivalent mud weight with the intent of staying within a "drilling
window"
to a deeper depth and reducing drilling non-productive time in the process.
The
drilling window changes with depth and is typically described as the
equivalent mud
weight required to drill between the formation pressure and the pressure at
which an
underground blowout or loss of circulation would occur. The equivalent weight
of the
mud and cuttings in the annulus is controlled with fewer interruptions to
drilling
progress while being kept above the formation pressure at all times. An influx
of
formation fluids is not invited to flow to the surface while drilling.
Underbalanced
drilling (UBD) is drilling with the hydrostatic head of the drilling fluid
intentionally
designed to be lower than the pressure of the formations being drilled,
typically to
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improve the well's productivity upon completion by avoiding invasive mud and
cuttings damage while drilling. An influx of formation fluids is therefore
invited to flow
to the surface while drilling. The hydrostatic head of the fluid may naturally
be less
than the formation pressure, or it can be induced.
[0003] Due to the nature of oilfield drilling, sealing elements within the
ROD often
become worn and need to be replaced. When doing so, the bearing is removed
from
the ROD body, and a new bearing is reinstalled into the ROD body. After
reinstallation, one existing problem is that the hydraulic fluid circuit needs
to be
cleansed of contaminants in the nature of wellbore fluid and debris before
lubrication
and drilling operations recommence. There exists a need for an improved
contaminant removal system and method to remove contaminants from the ROD
[0004] US Pub. No. 2006/0144622 proposes a system and method for cooling a
ROD while regulating the pressure on its upper radial seal. Gas, such as air,
and
liquid, such as oil, are alternatively proposed for use in a heat exchanger in
the ROD.
A hydraulic control system is proposed to provide fluid to energize a bladder
of an
active seal to seal around a drilling string and to lubricate the bearings in
the ROD.
[0005] U.S. Pat. Nos. 6,554,016 and 6,749,172 propose a rotary blowout
preventer with a first and a second fluid lubricating, cooling, and filtering
circuit
separated by a seal. Adjustable orifices are proposed connected to the outlet
of the
first and second fluid circuits to control pressures within the circuits.
[0006] The above discussed U.S. Pat. Nos. 6,554,016 and 6,749,172, and Pub.
No. US 2006/0144622 are incorporated herein by reference for all purposes in
their
entirety. All of the above referenced patents and patent publications have
been
assigned to the assignee of the current invention.
SUMMARY
[0007] The disclosure relates to purging a ROD including a bearing of
contaminants with a fluid circuit, the fluid circuit having at least one
housing adjacent
to the ROD, a first plurality of valves within the bearing, a second plurality
of valves
within the housing, at least one inlet port located on the ROD, each inlet
port being
connected to the housing, at least one outlet port located on the ROD, each
outlet
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port being connected to the housing, and a purge outlet in fluid communication
with
the fluid circuit.
[0008] As used herein, the terms "line" and "circuit" may be interpreted to
mean
any structural form used in the transport of fluid including flexible conduits
such as
hosing or tubing, drilled channels, ports, orifices, voids, outlets, vents and
the like.
[0009] As used herein the term "ROD" or "RCDs" and the phrases "pressure
control
equipment", "pressure control apparatus" or "pressure control device(s)" shall
refer to
well related pressure control equipment/apparatus/device(s) including, but not
limited
to, rotating-control-device(s), active rotating control devices, blowout
preventers
(B0P5), and the like.
BRIEF DESCRIPTION OF THE FIGURES
[0010] The embodiments may be better understood, and numerous objects,
features, and advantages made apparent to those skilled in the art by
referencing
the accompanying drawings. These drawings are used to illustrate only typical
embodiments of this invention, and are not to be considered limiting of its
scope, for
the invention may admit to other equally effective embodiments. The figures
are not
necessarily to scale and certain features and certain views of the figures may
be
shown exaggerated in scale or in schematic in the interest of clarity and
conciseness.
[0011] Figure 1 depicts a schematic overview of an embodiment of a ROD
hydraulic purge system.
Figure 2 depicts a schematic overview of an embodiment of a fluid circuit
which may be used in the purge system.
Figure 3 depicts a schematic overview of an embodiment of a lubrication
fluid circuit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0012] The present application claims the benefit of US provisional
application no.
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61/792,940 filed March 15, 2013 the disclosure of which is hereby incorporated
by
reference. The description that follows includes exemplary apparatus, methods,
techniques, and instruction sequences that embody techniques of the inventive
subject matter. However, it is understood that the described embodiments may
be
practiced without these specific details.
[0013] Figure 1 depicts a schematic overview of an embodiment of a ROD
hydraulic purge system or fluid circuit 100. The purge system 100 is connected
to a
pump 102. The pump 102 in Figure 1 pumps a volume of purge fluid 105 through
purge system 100 to facilitate the cooling and lubrication of ROD bearing 124.
Examples of a ROD body or ROD 122 with a bearing 124 may be U.S. Pat. Nos.
6,554,016 B1 and 6,749,172 Bl, and Pub. No. US 2006/0144622 Al. The purge
fluid
105 may be the same fluid used for lubrication or any other suitable
contaminant
removal fluid as known to those having ordinary skill in the art. For
simplicity and
advantageous operation, as seen in Figure 3, the supply line 104, bleed line
106 and
return line 108 used in the purge system 100 in one embodiment may be the
exact
same lines as used in the working ROD lubricating (and/or cooling) circuit.
Referring
back to Figure 1, the pump 102 is connected to the supply line 104 and a tank
103 of
purge or lubrication fluid 105. The purge system 100 empties or may be emptied
via
a purge line 110 or the like into a waste area 132. Waste area 132 may be any
area
or container suitable for housing the purge fluid 105 with contaminants for
further
processing, or it may be the wellbore itself. The hydraulic lines 101 may
include a
supply line 104, a bleed line 106, a return line 108, and a purge line or
purge outlet
110 and may have hose diameters selected by one skilled in the art to best
achieve
the desired flow pressure and rate for pressure controlled drilling
conditions,
lubrication, seal activation, and purging operations.
[0014] The flow of the fluid through purge system 100 may be controlled by
a
four-port directional control valve 112 connected to supply line 104 and bleed
line
106. The bleed line 106 is connected to filter 114 and the return line 108 is
connected to filter 116.The size and type of filters 114 and 116 may be
adjusted as
desired so as to prolong the usable lifetime of said filters. The hydraulic
lines of
purge system 100 are connected to valves 118a-h housed within manifold valve
blocks or housing(s) 120a-b. While the embodiment in Figure 1 illustrates the
valves
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118a-h as housed within manifold valve blocks 120a-b, it is to be appreciated
that
the components may also be discrete elements, components or housed in
cartridges. In Figure 1, valves 118 are shown as pilot-to-open check valves,
but it is
to be appreciated that any kind of valves which can be manipulated to allow
and/or
prevent or otherwise control, the flow of fluid may be used including check
valves,
pilot-to-close check valves, relief valves, manual, remote, or automatic
valves. Valve
blocks 120a and 120b flank ROD body 122 which contains inlet/outlet ports 126
that
allow for fluid to travel through the supply journal region 130c, bleed
journal region
130a and return journal region 130b between the ROD body 122 and bearing(s)
124
(i.e. outside but around the bearing(s)). Although the embodiment in Figure 1
illustrates the valve blocks 120 on opposite sides of ROD body 122 with inlet
ports
126a separated by generally one-hundred-and-eighty degrees from the outlet
ports
126b, both facing the respective valve blocks 120, the valve blocks 120 and
inlet/outlet ports 126 may be positioned in any manner such that fluid may
travel
between the valve blocks 120 and inlet/outlet ports 126. Further, the valve
blocks
120 may be bolted or otherwise secured to the side of the ROD body 122. The
hydraulic lines 101, including supply line 104, bleed line 106 and return line
108,
connect to the bearing 124 and to the bearing lubrication circuit valves 128
housed
within ROD body 122. The bearing 124, along with the bearing lubrication
circuit
valves 128, may be inserted into and removed out of ROD body 122 as required
by
the demands of the drilling operation. The bearing lubrication circuit valves
128 may
also be any kind of valves which may be manipulated to allow and/or prevent or
otherwise control the flow of fluid. Further, the purge system 100 may have
one or
more pressure gauges 134 installed on the supply line 104, bleed line 106,
return
line 108, or purge line 110 to monitor the pressure at a particular point in
the lines
104, 106, 108 or 110. Moreover, the purge system 100 may include one or more
pressure-temperature gauges or PT gauge 136 on the supply line 104, bleed line
106, return line 108 or purge line 110 to monitor the pressure and/or
temperature at
a particular point in the lines 104, 106, 108 or 110.
[0015] Figure 2 depicts a schematic overview of an embodiment of the purge
fluid
105 flow path 200 through the purge system 100. When the purge system 100
initiates, the pump 102 begins circulation of purge fluid 105 through the
supply line
104 until it reaches the four-port directional control valve 112. The control
valve 112
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redirects the purge fluid 105 flowing in from supply line 104 into the bleed
line 106.
The purge fluid 105 then travels through the bleed line 106 and through valve
118a
in valve block 120a. Thus, the purge fluid 105 travels through valve block
120a and
through the inlet/outlet ports 126 on ROD body 122, to the outer periphery of
bearing
124. When purging, the bearing lubrication circuit valves 128 are closed to
the flow
of fluid through the bearing 124, so as to allow the purge fluid 105 to
circulate
through the bleed journal region 130a captured between ROD body 122 and
bearing
124. Circulation of the purge fluid 105 through the journal regions 130
removes
wellbore fluids and debris, such as drill cuttings, from the journal regions
130
captured between bearing 124 and ROD body 122 and prepares the ROD body 122
for a subsequent lubrication cycle. After the purge fluid 105 circulates
through the
bleed journal region 130a, the pump 102 continues to move the purge fluid 105
out
of the ROD body 122 via inlet/outlet ports 126 and to valve block 120b. In
valve block
120b, the valve 118b is piloted to open to allow the purge fluid 105 to next
flow
through valve 118c back to the ROD body 122 and around bearing 124. As the
bearing lubrication circuit valves 128 are kept in a closed position 129 to
the passage
of fluid in Figure 2, the purge fluid 105 will circulate around return journal
region
130b. The purge fluid 105 then flows out of the ROD body 122 into valve block
120a,
where the purge fluid 105 then flows through valve 118d. After passing through
valve
118d, the purge fluid 105 flows into ROD body 122 and circulates through
supply
journal region 130c. The purge fluid 105 then exits the ROD body 122 to valve
block
120b. In the embodiment shown, the purge fluid 105 then flows through valve
118e
(which is piloted to open), and through valve 118f. The purge fluid 105 exits
the
purge system 100 via one of the hydraulic lines 101, for example, the purge
line 110,
emptying and/or dumping contaminants and/or cuttings from the drilling
equipment to
waste area 132.
[0016] The purge system 100 as described utilizes or integrates the
existing
lubrication circuit and pump in the ROD body 122, without the need for
expensive or
time consuming modifications to the existing hydraulic lubrication circuitry.
Such
existing ROD lubricating circuits contemplated include U.S. Pat. Nos.
6,554,016 and
6,749,172, and Pub. No. US 2006/0144622. Figure 3 also illustrates one such
lubricating circuit 400 with lubrication flow path 402, wherein the bearing
circuit
lubrication valves 128 are in an open position 127, allowing purge or
lubrication fluid
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105 to circulate within the bearing 124, thus cooling and lubricating the
bearing 124
and ROD body 122.
[0017] Further, in one embodiment at least one sensor, flow meter or
detection
device 300, for example, an electrical, mechanical, or hydraulic sensor, may
be
positioned in the purge line 110. It is contemplated that the sensor or
sensors could
be mechanical, electrical, or hydraulic and may be used additionally for
measuring
temperature, pressure, density, flow rate, particulate matter, and/or fluid
levels. In
one working example, an operator may wish to quantify the flow of the purge
fluid
105 via a flow metering or detection device 300 (e.g. to determine when five
gallons
of purge fluid 105 have flowed through the meter).
[0018] In a working example, the bearing(s) 124 may run in the working
environment for a period of from about two days to about three weeks prior to
removal and insertion of the same and/or other bearing(s) 124. Preferably but
not
limited to absolutely, the purge system 100 will be performed when the bearing
assembly(ies) 124 are inserted before lubrication begins (by way of example
only,
purged once using five gallons of purge fluid 105).
[0019] While the embodiments are described with reference to various
implementations and exploitations, it will be understood that these
embodiments are
illustrative and that the scope of the inventive subject matter is not limited
to them.
Many variations, modifications, additions and improvements are possible. For
example, while the embodiments described are in reference to RCDs with
lubrication
circuits, it will be understood that the inventive system, method, and
apparatus are
equally applicable to cooling circuits in RCDs, to dual lubricating and
cooling circuits
in RCDs, to other equipment with fluid circuitry such as seal activation
circuits in
BOPs (see e.g. U.S. Pat. Nos. 6,554,016 and 6,749,172, which are incorporated
herein by reference) and latch mechanism control circuits (see e.g. U.S. Pub.
Nos.
2006/0144622 and 2012/0013133, which are incorporated herein by reference),
amongst others, including non-rotating control devices which contain hydraulic
feeds.
Further by way of example, the techniques used herein may be applied to
equipment
needing lubrication and/or purging, as used in mining, food, or construction
industries.
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[0020]
Plural instances may be provided for components, operations or structures
described herein as a single instance. In general, structures and
functionality
presented as separate components in the exemplary configurations may be
implemented as a combined structure or component. Similarly, structures and
functionality presented as a single component may be implemented as separate
components.
These and other variations, modifications, additions, and
improvements may fall within the scope of the inventive subject matter.
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