U.S. patent application number 11/697084 was filed with the patent office on 2008-06-05 for drill cuttings transfer system and related methods.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. Invention is credited to Daniel Bruce, Alexander R. Harper, Glynn M. Hollier.
Application Number | 20080128173 11/697084 |
Document ID | / |
Family ID | 38581826 |
Filed Date | 2008-06-05 |
United States Patent
Application |
20080128173 |
Kind Code |
A1 |
Hollier; Glynn M. ; et
al. |
June 5, 2008 |
Drill Cuttings Transfer System and Related Methods
Abstract
A system for handling drill cuttings conveys cuttings into bulk
tanks via a conduit. The bulk tanks have a lower portion that
converges to an elongated opening. A conveyance member positioned
at the elongated opening forces the cuttings out of a discharge
port at the bottom of the bulk tank. Once suitable conveyance
member is a screw-type conveyor coupled to a motor that applies a
motive force to the cuttings. The bulk tank lower portion can be
formed as a wedge or trough that generally conforms to the
configuration of the conveyance member. The bulk tanks hold the
cuttings until it can be discharged via the discharge port to a
transport vessel for processing or disposal. For offshore
operations, the system includes a separation unit on the rig that
forms the cuttings from fluid returning from the wellbore and a
cuttings flow unit that conveys the cuttings from the separation
unit to the bulk tanks.
Inventors: |
Hollier; Glynn M.; (The
Woodlands, TX) ; Harper; Alexander R.; (Inverurie,
GB) ; Bruce; Daniel; (Aberdeen, GB) |
Correspondence
Address: |
MADAN, MOSSMAN & SRIRAM, P.C.
2603 AUGUSTA DRIVE, SUITE 700
HOUSTON
TX
77057-5662
US
|
Assignee: |
BAKER HUGHES INCORPORATED
Houston
TX
|
Family ID: |
38581826 |
Appl. No.: |
11/697084 |
Filed: |
April 5, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60789395 |
Apr 5, 2006 |
|
|
|
Current U.S.
Class: |
175/212 ;
175/207; 175/88 |
Current CPC
Class: |
E21B 21/065
20130101 |
Class at
Publication: |
175/212 ;
175/207; 175/88 |
International
Class: |
E21B 21/00 20060101
E21B021/00; E21B 21/06 20060101 E21B021/06 |
Claims
1. A system for handling a return fluid formed of drilling fluid
and entrained cuttings recovered while drilling a wellbore in an
earthen formation, comprising: (a) a separation unit at least
partially separating the drilling fluid from the return fluid, a
slurry of cuttings thereby being formed; (b) a cuttings flow unit
receiving the cuttings from the separation unit, the cutting flow
unit conveying the cuttings through a conduit coupled thereto; (c)
at least one tank coupled to the conduit, the tank having a lower
portion converging to an elongated opening; and (d) a conveyance
member positioned adjacent to the elongated opening receiving the
cuttings from the lower portion and flowing the cuttings out of the
at least one bulk tank.
2. The system of claim 1, further comprising a flow device
receiving the flow of cuttings from the conveyance member and
conveying the cuttings to a selected location.
3. The system of claim 2, further comprising a gas source providing
a pressurized gas to the at least one tank to at least partially
offset a pressure increase associated with operation of the
cuttings flow device.
4. The system of claim 1, further comprising a gas source providing
a gas to the at least one tank to fluidize at least a portion of
the cuttings in the at least one tank.
5. The system of claim 1, wherein the lower portion is wedge shaped
and wherein the conveyance member includes an auger longitudinally
aligned with the elongated opening.
6. The system of claim 1, wherein the at least one tank includes a
cylindrical upper portion, the cuttings flowing from the upper
portion to the lower portion.
7. The system of claim 1 wherein the conveyance member operates in
a first mode to flow the cuttings and a second mode to mix the
cuttings.
8. A method for handling a return fluid formed of drilling fluid
and entrained cuttings recovered while drilling a wellbore in an
earthen formation, comprising: (a) separating the drilling fluid
from the return fluid to form a slurry of cuttings with a
separation unit; (b) conveying the cuttings through a conduit
coupled to the separation unit using a cuttings flow unit; (c)
receiving the cuttings into at least one tank coupled to the
conduit, the bulk tank having a lower portion converging to an
elongated opening; and (d) flowing the cuttings out of the at least
one tank using a conveyance member positioned adjacent to the
elongated opening.
9. The method of claim 8, further comprising conveying the cuttings
to a selected location using a flow device that receives the flow
of cuttings from the conveyance member.
10. The method of claim 9, further at least partially offsetting a
pressure increase associated with operation of the flow device
using a gas source that provides a pressurized gas to the at least
one tank.
11. The method of claim 8, further comprising fluidizing at least a
portion of the cuttings in the at least one tank using a gas source
that provides a gas to the at least one tank.
12. The method of claim 8, wherein the lower portion is wedge
shaped and wherein the conveyance member includes an auger
longitudinally aligned with the elongated opening.
13. The method of claim 8, wherein the at least one tank includes a
cylindrical upper portion, the cuttings flowing from the
cylindrical upper portion to the lower portion.
14. The method of claim 8 further comprising operating the
conveyance member in a first mode to flow the cuttings and a second
mode to mix the cuttings.
15. A system for handling cuttings separated from a return fluid
formed of drilling fluid and entrained cuttings, comprising: (a) a
tank for receiving the cuttings, the tank having a cylindrical
upper portion and a wedge shaped lower portion converging to an
elongated opening; and (b) a conveyance member positioned adjacent
to the elongated opening receiving the cuttings from the wedge
shaped lower portion and flowing the cuttings out of the tank.
16. The system of claim 15, further comprising a flow device
receiving the flow of cuttings from the conveyance member and
conveying the cuttings to a selected location.
17. The system of claim 16, further comprising a gas source
providing a pressurized gas to the tank to at least partially
offset a pressure increase associated with operation of the
cuttings flow device.
18. The system of claim 15, further comprising a gas source
providing a gas to the tank to fluidize at least a portion of the
cuttings in the tank.
19. The system of claim 15 wherein the conveyance member operates
in a first mode to flow the cuttings and a second mode to mix the
cuttings.
20. The system of claim 15 wherein the lower portion is defined by
a first set of walls and a second set of walls, each of the walls
of the first and second set of walls having an angle selected to
cause mass flow of the cuttings.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application takes priority from U.S. Provisional Patent
Application Ser. No. 60/789,395, filed Apr. 5, 2006.
BACKGROUND OF THE DISCLOSURE
[0002] 1. Field of the Disclosure
[0003] This disclosure relates generally to handling of waste
materials, especially particulate drill solids.
[0004] 2. Description of the Related Art
[0005] In the drilling of oil and gas wells, drilling fluids or
"muds" are used to provide well bore lubrication, to cool the drill
bit, to protect against corrosion and to provide a pressure head to
maintain formation integrity. There are two main types of drilling
muds: water-based and oil-based. Generally, surface pumps circulate
drilling mud down the tubular drill string. The mud exits at the
drill bit and flows up the annulus between the drill string and the
bore. The returning fluid (or return fluid) carries the drill
cuttings away from the bit and out of the wellbore. Oil-based
drilling muds are stable oil external-water internal emulsions
including wetting agents to hold solids such as drill cuttings in
the oil phase. The drill cuttings thus tend to become oil wet,
trapping large quantities of oil-based mud in their intergranular
spaces and creating environmental concerns regarding disposal of
the oil-contaminated drill cuttings.
[0006] In the prior art, drill cuttings contaminated with oil-based
drilling muds were often collected in settling tanks where
re-usable drilling mud was drawn off the top of the tank and
contaminated drill cuttings, as bottoms, were transported to
appropriate disposal sites. Such storage and transportation
operations are costly and environmentally undesirable especially in
offshore drilling operations. Typically, oil-contaminated cuttings
contain about fifty percent (50%) by volume of oil-based liquid.
The value of this large volume of entrained oily liquids is
considerable, and there is a strong incentive to recover the
oil-based drilling mud both for economic as well as environmental
reasons.
[0007] Accordingly, the cuttings are commonly separated from the
drilling fluid by devices such as shale shakers, which remove
cuttings and large solids from the drilling fluid during the
circulation thereof. Basically, such a device has a sloping, close
mesh screen over which fluid returning from the hole being drilled
passes. The solids captured on the screen travel down the sloping
surface to be collected in the shaker ditch or cuttings trough. It
is also desirable to recover as much of the expensive drilling
fluids as possible. Therefore, other devices, which play a role in
the separation of solids from drilling fluids, include cyclone
separators and centrifuges. The cuttings discharged from the
shakers, cyclones and centrifuges that are collected in the shaker
ditch or cuttings trough are still highly contaminated with the
drilling fluids and therefore form a slurry or heavy sludge.
Typically the slurry is conveyed into containers or skips, which
are then periodically moved by crane from the rig onto a
vessel.
[0008] This process is disadvantageous for a number of reasons.
First, the skips take up considerable valuable space on the rig
floor. Moreover, the handling of the skips requires the use of the
rig crane, which may divert the crane from other important duties.
One prior art device uses a pneumatic conveyance arrangement to
convey materials out of a bulk tank that has a conical hopper
section. It is believed that one drawback of such an arrangement is
that using pressurized air as a sole means for discharging cuttings
may not adequately evacuate the bulk tank of cuttings. It is
believed that another drawback is that the circular opening of the
conical hopper section could get plugged with cuttings.
[0009] The present disclosure addresses these and other drawbacks
of the prior art.
SUMMARY OF THE DISCLOSURE
[0010] In aspects, the present disclosure provides efficient
systems and methods for processing, storing and transporting drill
cuttings that are generated while drilling hydrocarbon-producing
wellbores. These cuttings as noted earlier are entrained in a
drilling fluid returning from the wellbore (return fluid). After
the return fluid is separated to form a slurry of cuttings, the
cuttings are conveyed into one or more bulk tanks via conduits such
as hoses, pipes or tubing. The bulk tank has a lower portion that
converges to an elongated opening at which a cuttings conveyance
member is positioned. To discharge cuttings, the cuttings
conveyance member, when energized, applies a motive force that
causes the cuttings to flow out of a bulk tank discharge port to a
transfer line. As the cuttings flow out of the bottom of the tank,
gravity pulls more cuttings into the cuttings conveyance member.
The cuttings conveyance member may be operated in a first mode to
flow cuttings and a second mode to mix cuttings. One suitable
cuttings conveyance member includes a rotating screw-type conveyor
or auger coupled to a motor.
[0011] In one embodiment, the lower portion of the bulk tank has a
wedge or trough shape that feeds cuttings to the cuttings
conveyance member. In contrast to a conical shaped lower portion
that is defined by a single inclined wall that converges to a
circular exit opening, the wedge shaped lower portion is defined by
at least two walls that converge to an elongated slot-like exit
opening. Advantageously, due to its relatively large size, the
elongated slot-like exit opening is less susceptible to plugging
during discharge operations. Additionally, the elongated slot-like
exit opening can be configured to conform with a horizontally
aligned cuttings conveyance member such that cuttings are evenly
fed into the cuttings conveyance member.
[0012] To further assist the discharge of cuttings out of the bulk
tank, pressurized air can be fed into one or more locations in the
bulk tank. One function for this pressurized air is to balance the
pressure between the bulk tank and devices connected to the bulk
tank. In some arrangements, the cuttings conveyance member feeds
cuttings into a transfer line in communication with a pneumatic
flow device. The pneumatic flow device uses high pressure air to
propel cuttings along the transfer line. To prevent back flow of
cuttings into the tank, it may be desirable to balance the pressure
inside the tank with the pressure at the pneumatic flow device.
Thus, in one aspect, pressurized air is fed into the bulk tank at a
pressure value that compensates for increased pressures generated
by the pneumatic flow device. In another aspect, pressurized air
can be used to fluidize the cuttings in the bulk tank. For example,
when the cuttings have been kept in the bulk tank for an extended
time, the weight of the cuttings can force liquids to flow out of
the cuttings at the bottom of the tank. Thus, a form of
stratification occurs wherein a relatively dense cuttings layer
forms along the interior surfaces of the lower portion of the bulk
tank. This dense cuttings layer can slow or even choke off the flow
of cuttings out of the bulk tank. To break up or reduce the
viscosity of this relatively dense cuttings layer, pressurized gas
such as air can be introduced at one or more points near the lower
portion of the bulk tank. The inflowing gas penetrates this
relatively dense cuttings layer and reduces its density and/or
physically displaces this layer. In one arrangement, a first
pressurized gas line at a top of the tank pressure balances the
tank and a second pressurized gas line fluidizes the relatively
dense cuttings layer. In another arrangement, the pressurized gas
line for fluidizing the relatively dense cuttings layer provides
gas at a pressure value that also pressure balances the bulk
tank.
[0013] In one arrangement suited for offshore operations, the
system includes a separation unit on the rig that forms the slurry
of cuttings. The separation unit can include one or more shakers,
centrifuge-type separators and/or other suitable devices. A
cuttings flow unit conveys the cuttings from the separation unit to
the bulk tanks or other selected location. The cuttings flow unit
can include, for example, an auger type conveyor and pump or blower
device to flow the cuttings and one or more diverter valves that
can direct the cuttings flow as needed. In one arrangement, a
controller controls the flow of cuttings into the plurality of bulk
tanks. Sensors positioned on each of the bulk tanks produce signals
indicative of the volume of cuttings in an associated bulk tank.
The controller controls the flow of cuttings in response to the
sensor signals. The bulk tanks can be filled simultaneously,
sequentially or by any other scheme. The bulk tanks can hold the
cuttings until it can be discharged to a transport vessel or
vehicle for processing and/or disposal. The transport vessel or
vehicle can have a bank of containers adapted to receive the
cuttings from the bulk tanks.
[0014] Examples of the more important features of the disclosure
have been summarized (albeit rather broadly) in order that the
detailed description thereof that follows may be better understood
and in order that the contributions they represent to the art may
be appreciated. There are, of course, additional features of the
disclosure that will be described hereinafter and which will form
the subject of the claims appended hereto.
BRIEF DESCRIPTION OF THE FIGURES
[0015] For detailed understanding of the present disclosure,
reference should be made to the following detailed description of
the preferred embodiment, taken in conjunction with the
accompanying drawing:
[0016] FIG. 1 schematically illustrates a system for processing,
storing and offloading drill cuttings made in accordance with one
embodiment of the present disclosure;
[0017] FIG. 2A schematically illustrates a side view of a bulk tank
in accordance with one embodiment of the present disclosure;
[0018] FIG. 2b schematically illustrates an end view of a bulk tank
in accordance with one embodiment of the present disclosure;
[0019] FIG. 3 schematically illustrates an wedge shaped lower
section of a bulk tank made in accordance with one embodiment of
the present disclosure;
[0020] FIG. 4 schematically illustrates a bulk tank and pressurized
air supply system in accordance with one embodiment of the present
disclosure; and
[0021] FIG. 5 schematically illustrates a bulk tank in accordance
with one embodiment of the present disclosure used in an offshore
drilling environment.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0022] The present disclosure relates to devices and methods for
processing, storing and transporting a slurry of drill cuttings.
The present disclosure is susceptible to embodiments of different
forms. There are shown in the drawings, and herein will be
described in detail, specific embodiments of the present disclosure
with the understanding that the present disclosure is to be
considered an exemplification of the principles of the disclosure,
and is not intended to limit the disclosure to that illustrated and
described herein. Further, none of the described elements or
combination of elements should be considered essential features of
the present teachings unless the description expressly describes
the element or combination of elements as essential.
[0023] As shown in FIG. 1, in one embodiment particularly suited
for use on an offshore drilling rig, a cuttings handling system 10
may include a separation unit 12, cuttings flow units 14, 15, and
one or more bulk tanks 16. The system offloads the cuttings to one
or more suitable containers 18 on a transport vessel (not shown).
In one mode of operation, the system receives return fluid, which
has entrained cuttings, from a wellbore being drilled. The
separations unit 12 separates some of the drilling fluid from the
return fluid for re-use in further drilling and also forms a slurry
of cuttings. The cuttings flow unit 14 conveys the cuttings via a
conduit 20 to the bank of bulk tanks 16. After the bulk tanks 16
are filled with cuttings, a mechanically driven and gravity
assisted conveyance member discharges the cuttings from the bulk
tanks 16. The cuttings flow unit 15 propels the discharged cuttings
via a transfer line 22 to the container(s) 18 or bulk tanks of the
transport vessel (not shown). Thus, in contrast to conventional
cuttings handling arrangements, less human intervention is needed
to collect, store and move drill cuttings on a rig. The elements
making up the FIG. 1 embodiment are discussed in further detail
below.
[0024] The separations unit 12 extracts the relatively expensive
drilling fluid from the return fluid. In one arrangement, the
separations unit 12 can include one or more shale shakers 21.
Within the shale shaker 21, the return fluid and entrained solids
are discharged over a vibratory separator that has one or a series
of tiered screens. The screens catch and remove solids from the
return fluid flowing therethrough. The separations unit 12 can also
include other separation devices, such as a centrifugal separator
22, that are also configured to extract drilling fluid from the
cuttings. Such separation devices and techniques are known in the
art and will not be discussed in further detail. The effluent or
output of the separations unit 12 is a relatively viscous slurry
made up of oil or additive-covered rock, earth and debris. The
terms cuttings and slurry will be used interchangeably.
[0025] The cuttings flow unit 14 transports the cuttings from the
separations unit 12 to other devices such as the bulk tanks 16 or
another location such as the vessel storage tanks 18. In one
embodiment, the cuttings flow unit 14 includes an auger-type device
that continually conveys the cuttings to a dense phase blower 24
that impels the cuttings through a conduit 20 such as piping or
hoses. Suitable valves such as a diverter valve can be used in the
conduit 20 to selectively direct flow of the cuttings.
[0026] Referring now to FIGS. 1 and 2A-B, the bulk tanks 16 receive
and store the flow of cuttings from the conduit 20. The tanks 16
have an upper cylindrical portion 26 and a lower portion 28 that
converges to an elongated opening 29. In a manner described in
further detail below, the lower portion 28 promotes mass flow of
cuttings through the tank 16. Positioned at a bottom end of the
lower portion 28 is a conveyance member 32 that applies a motive
force that impels the cuttings out of the bulk tanks 16.
Pressurized gas, such as air, from a source 34 is fed into one or
more locations in the bulk tank 16 to maintain a pressure balance
in the system 10 and/or to fluidize the cuttings in the bulk tank
16.
[0027] The filling of the bulk tanks 16 can be controlled manually,
automatically or a combination thereof. In one arrangement, a
controller 35 receives signals from sensors 36 positioned on the
bulk tanks 16. The sensor signals indicate the amount of cuttings
in the bulk tanks 16. Thus, in one arrangement, a controller 35 can
have a programmable logic circuit (PLC) that directs flow into a
bulk tank 16 until the associated sensor 36 indicates that the bulk
tank 16 is full. Thereafter, the PLC stops flow to the bulk tank 16
by actuating appropriate valves and initiates flow into the next
bulk tank 16. This process can continue until all of the bulk tanks
16 are filled. While a sequential filling process has been
described, it should be appreciated that two or more bulk tanks 16
can be filled at the same time. While in some embodiments, the tank
can be constructed to hold 100 BBL of drill cuttings having a
specific gravity of 2.34, other sizes and configurations can also
be used.
[0028] As explained earlier, the slurry of cuttings can be
relatively viscous and not flow effectively under the effect of
only gravity. Therefore, the conveyance member 32 forcibly impels
the cuttings out of the bulk tanks 16. In one embodiment, the
conveyance member 32 is a rotating screw conveyor driven by a motor
drive 33. A screw flight portion extends horizontally along a long
axis of the wedge shaped portion 28. Rotation of the screw propels
the cuttings to the transfer line 22 and the cuttings flow unit 15.
In some arrangements, the conveyance member 32 is right and left
hand reversible. In the right hand rotation mode, the cuttings flow
downward to a port 36. In the left hand rotation mode, the cuttings
are mixed to maintain material consistency. This is advantageous
when the cuttings are stored for long periods of time, since
heavier material will settle to the tank bottom and lighter fluids
will flow to the top. This stratification of materials can make it
difficult to empty the tank of the cuttings. In such circumstances,
the left hand rotation will mix the cuttings and enable the
cuttings to flow out of the tank. In still other embodiments, two
or more conveyance members can cooperate to expel the cuttings out
of the bulk tank 16. A screw or auger is merely one illustrative
member suitable for applying a motive force throughout the body of
the cuttings. It should be appreciated that the conveyance member
32 positioned within the bulk tank is susceptible to numerous
variations that can adequately apply a motive force to expel the
cuttings out of the bulk tank 16. For example, suitable conveyance
mechanisms include pneumatic systems, progressive cavity pumps, and
vacuum pumping systems.
[0029] Referring now to FIGS. 2A-B and 3, the lower portion 28
cooperates with the conveyance member 32 to discharge flow out of
the tank 16. In one embodiment, the lower portion 28 has a wedge,
chisel or trough shape that is generally defined by two sets of
walls 40 and 42. For convenience, such a shape will be referred to
as a wedge shape. Each set of walls 40 and 42 has an associated
angle 46 and 48 from horizontal, respectively. The angles 46 and 48
are selected such that the first drill cuttings that enter into the
tank are the first drill cuttings to exit the tank, i.e., mass
flow. The walls 40 and 42 converge to the opening 29 that is
longitudinally aligned with the conveyance member 32. As should be
appreciated, in contrast to a conical shaped section that converges
to a circular opening, the opening 29 presents a relatively large
elongated slot-like cross-sectional flow area through which the
cuttings can flow. Thus, there is a reduced risk that cuttings can
occlude or plug the opening 29. Furthermore, it should also be
appreciated that the wedge shaped portion 28 and elongated opening
29 can evenly distribute cuttings across a relatively large portion
of the conveyance member 32. Other elongated or non-conical shapes
can also be used in certain applications.
[0030] In an exemplary operating mode for discharging cuttings,
gravity pulls the cuttings into the conveyance member 32, which
then conveys the cuttings out of the tank 16. As the cuttings exit
the tank 16, additional cuttings fall into the conveyance member
32. Advantageously, the wedge shaped portion 28 cause a mass flow
of cuttings that substantially uniformly loads the conveyance
member 32 during this process. Thus, in one aspect, the system 10
discharges cuttings out of the tank 16 using a mechanically driven
and gravity assisted arrangement.
[0031] To support the cutting discharge operation, there is shown
in FIG. 4 a source 60 that provides pressurized gas such as air for
pressure balancing the tank 16 and/or fluidizing the cuttings in
the tank 16. In one embodiment, ports 62a and 62b that are coupled
to the source 60 via suitable conduits 64 introduce pressurized gas
at one or more points along the bulk tank 16. One or more of the
ports 62a can be positioned to break up or reduce the viscosity of
settled cuttings that layer the interior surfaces of the lower
wedge shaped portion 28. The gas flowing through such ports 62a
penetrates this relatively dense cuttings layer and reduces its
overall density. That is, the gas intermixes with or "fluffs" the
cuttings layer. The inflowing gas can also physically displace or
dislodge portions of this layer from the interior surfaces of the
tank 16. One or more ports 62b can also be positioned at or near a
top of the tank 16 to provide pressure balancing gas. In the FIG. 4
embodiment, the source 60 operates as the cuttings flow unit 15
(FIG. 1) by supplying high pressure gas to propel cuttings through
the transfer line 22. For example, the source 60 can supply a
continuous flow of high pressure air into the transfer line 22 at
the same time the conveyance member 32 (FIG. 2A) feeds cuttings
into the transfer line 22. Because the source 60 and the bulk tanks
16 are in fluid communication via the transfer line 22, the high
pressure gas in the transfer line 22 can apply a back pressure at
the tank 16. This applied back pressure can restrict the flow of
cuttings out of the tank 16. To compensate for the operating
pressure generated by the source 60, pressurized gas fed through
the ports 62b increases the pressure in the tank 16 to at least
partially offset this applied back pressure. Of course, in certain
embodiments, the pressurized gas flowing through ports 62a can both
fluidize the relatively dense cuttings layer and provide gas at a
pressure value that also pressure balances the bulk tank.
[0032] A number of instruments and device can be utilized to
control the flow of pressurized gas. For example, valves 70 for
selectively feeding gas into the ports 62a and 62b can be
controlled by solenoid controls 72. A solenoid 64 control unit can
also be used to control a valve 74 feeding pressurized air into the
transfer line 22. Additionally, suitable gauges 76 such as pressure
gauges and level gages can be positioned as desired on the tank 16.
In many applications, the pressurized gas can be air, but other
gases such as nitrogen can be used.
[0033] Referring now to FIG. 5, there is shown an embodiment of the
present disclosure that is suited for offshore drilling
applications. As is known, platform, floater, jack up or work over
drilling operations utilize a surface facility such as an offshore
rig 70 from which a drilling riser 72 or other device conveys a
drill string 74 into a subsurface well (not shown). Positioned on
the offshore rig 70 is cuttings handling system 71 that processes
the return fluid from the subsurface wellbore (not shown) using
equipment previously discussed and conveys the cuttings to a bank
of bulk tanks 76. During drilling, the return fluid is processed
and the cuttings continuously conveyed and stored in the bulk tanks
76. A controller fills the bulk tanks 76 using preprogrammed
instructions and signals from suitably positioned sensors.
Periodically, a transport vessel 78 such as a barge is moored
adjacent to the rig 70 and storage tanks 80 in the barge 78 are
connected to the cuttings handling system 71. Thereafter, high
pressure gas is fed into the bulk tanks 76 to fluidize the cuttings
and balance the pressure in the bulk tanks 76. Once the conveyance
device 32 (FIG. 2A) is energized, cuttings flow out of the bulk
tanks 76 and to the barge 78.
[0034] It should be appreciated that the cuttings handling systems
described above offer enhanced safety due to the reduced number of
handling operations such as interventions by personnel to hook up
containers to the crane, manual shoveling of cuttings into
containers, transfers of containers around the rig floor, use of
the crane rig, etc. Furthermore, the transport vessel to which the
cuttings is offloaded is only temporarily moored adjacent the rig.
A continuously moored transport vessel could pose a hazard to the
rig and itself during rough seas. Thus, reducing the time the
transport vessel is moored to the rig also reduces the risk that
inclement weather will interfere with drilling operations.
[0035] While the foregoing disclosure is directed to the preferred
embodiments of the disclosure, various modifications will be
apparent to those skilled in the art. It is intended that all
variations within the scope of the appended claims be embraced by
the foregoing disclosure.
* * * * *