Automatic drill pipe inside wiper

A direct acting slug and wipe tool for use in drill pipe in drilling operations effects a cleaning operation by placing a rib inflated bladder in contact with the inside surface of a drill pipe in connection with a free floating pneumatic chamber. The inflatable bladder is toroidal and circumferentially disposed about and communicates with a sealed and closed chamber filled with a fixed amount or mass of gas. Weights may be added to the wiper in order to fix its equilibrium floating position. The wiper with the inflatable bladder is able to wipe the interior of the drill pipe even through those portions having a reduced inner diameter, such as at the drill pipe joints. Thus, as the drill pipe is tripped, the slug and wipe tool is longitudinally displaced with respect to the drill pipe through a plurality of drill pipe sections. In a second embodiment, a plurality or pair of intercommunicating ribbed inflatable bladders are circumferentially attached to the sealed and closed chamber thereby allowing one bladder to expand in a portion of the drill pipe having a normal sized diameter as the other bladder is simultaneously compressed when passing through a restricted diameter.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The field of the invention relates to oil well drilling tools and in 
particular to an apparatus and method from cleaning scale and other 
materials from the interior walls of a pipe or similar structure. 
2. Description of the Prior Art 
There has long been a recognized need to wipe the internal walls of 
cylindrical members used in drilling operations, such as drill pipe, 
tubing and casing. Mud, oil and scale, if thus not cleaned from the 
interior surface of such cylindrical members, spills onto the platform 
floor when the pipe is tripped from the bore. The spillage of such liquids 
is both hazardous and commercially uneconomical. The hazard is 
particularly accentuated in situations where the drilling operation occurs 
in freezing temperatures such as in the arctic. Fluid and dripping mud 
will freeze on the platform surface and in between the drill pipe in a 
pipe stand. Even in temperate environments, the spillage of fluids from 
the interior of the drill pipe creates personel hazards and impediments to 
secure operation. Thirdly, the hydraulic fluid or drilling mud used in 
many present day applications includes additives which are regarded as 
pollutants or potentially environmentally hazardous if spilled in oceans, 
bays and at other drilling sites. According to current drilling practices, 
a rust treatment is often applied to the interior of the pipe when it is 
tripped. In order for such a treatment to be effective mud, oil and ooze 
must first be scraped from the interior to allow direct access of the rust 
preventative to the pipe interior. 
One design for a prior art drill casing wiper is shown by Haggard, "Tubular 
Interior Wiper", U.S. Pat. No. 4,221,264 wherein a pair of flexible wipers 
36 and 42 are employed to provide a scraping action. 
Another wiper, employing a multiplicity of flexible disk elements 11 for 
wiping the pipe interior is shown by Cox, "Pipe Wiper", U.S. Pat. No. 
2,740,480. 
Hauk, "Apparatus and Method for Removing Scale and Wax from Oil Well 
Tubing", U.S. Pat. No. 3,285,778 shows a rigid mechanical scraper which is 
used in conjunction with compressed air to remove hard adhering materials 
from the interior of a drill pipe as it is removed from a bore hole. 
Greenfield, "Pipe Cleaner", U.S. Pat. No. 3,101,499 shows a hammering 
mechanism which is lowered into well casing, which remains in place, in an 
attempt to hammer hardened scale and debris from the interior surfaces of 
perforated sections of the casing. 
Finally Mcspaddan, "Method and Apparatus for Cleaning Wells", U.S. Pat. No. 
2,876,842 shows a prior art method where a plug of petroleum ceresin wax 
is used to remove scaled deposits from drill pipe as opposed to a 
mechanical scraping or hammering element. 
Each of the prior art attempts to provide a cleaning mechanism to the 
interior of pipe in drilling operations suffers from the defect that 
uniform and efficient cleaning or scraping action is dependent upon a 
substantially uniform interior diameter of the pipe. As a practical 
matter, this is not the case. Cylindrical members, where they 
interconnect, for example, will have a reduced diameter. In those 
situations where prior art mechanisms are incapable of compressing through 
reduced diameter sections, such as in the mechanism shown by Hauk, the 
scraper can be used to clean only one section of pipe at a time. In other 
cases where the scraping element is capable of resiliently compressing to 
thereby allow the tool to pass through a restricted section, the increase 
in softness of the scraping element thus required inherently detracts from 
the rigidity of the scraping element in that portion of the drill pipe 
having a normal inner diameter. In other words, if the scraping element is 
soft enough to squeeze through a restricted joint section, it was often 
soft enough to also be deformed by a harder deposit of wax, scale or tar 
elsewhere on the pipe interior. 
Therefore, what is needed is some type of drill pipe wiper which is capable 
of passing through multiple sections of drill pipe and yet capable of 
providing a uniform and strong scraping action throughout those portions 
of the drill pipe having a normal inner diameter. 
BRIEF SUMMARY OF THE INVENTION 
The present invention is a wiper for cleaning the interior surface of a 
tubular member as the tubular member is removed from a bore hole wherein 
the tubular member includes at least one portion with a restricted inner 
diameter. The wiper comprises a sealed pressurized chamber vessel which is 
injected with a predetermined fixed amount or mass of fluid, typically a 
compressible gas which is used for the purpose of pressurizing the chamber 
vessel. At least one resilient and inflatable bladder element is 
circumferentially disposed about the chamber vessel. The interior of the 
bladder element communicates with the interior of the pressurized chamber 
vessel. The bladder element is arranged and configured to contact the 
interior surface of the tubular member to thereby effect its cleaning. By 
virtue of this combination of elements, the inflatable bladder element is 
able to pass through restricted sections of the tubular member while 
maintaining an efficient cleaning action at all times even in the 
remaining unrestricted portions of the tubular member. 
In the preferred embodiment of the invention, a plurality of bladder 
elements are incorporated wherein each bladder element communicates with 
the interior of the chamber vessel thereby providing intercommuncation 
among the plurality of bladder elements. 
The invention also includes a method for cleaning the interior surfaces of 
a drill pipe which have an interior diameter characterized by restricted 
portions. The method comprises the steps of disposing a fixed amount or 
mass of compressible gas in a closed sealed chamber. The fixed amount of 
compressible gas is intercommunicated between the closed sealed chamber 
and at least one resilient inflatable bladder which is circumferentially 
disposed about the chamber. The bladder is inflated by the gas during this 
intercommunication by a degree sufficient to provide substantial contact 
between the bladder and the interior surface of the drill pipe. The drill 
pipe is then tripped thereby longitudinally displacing the drill pipe with 
respect to the inflated bladder. By this combination of steps, the drill 
pipe is cleaned as the inflated bladder is longitudinally displaced along 
the portions of the drill pipe having a normally sized inner diameter and 
the bladder is conpressed when it reaches or passes through the restricted 
portion of the drill pipe. 
In the preferred embodiment, wherein a plurality of bladders are used, the 
method includes the steps of compressing one of the plurality of bladders 
by longitudinally displacing that one bladder to and through a portion of 
the drill pipe characterized by the restricted inner diameter. Meanwhile, 
the remaining ones of the plurality of bladders are simultaneously 
expanded by the gas which is displaced from the compressed bladder. 
Expansion of the remaining ones or one of the bladder elements occurs by 
virtue of the intercommunication of these elements through the sealed 
closed chamber. The longitudinal displacement of the bladders on the wiper 
tool is sufficient so that one bladder is being compressed by the 
restricted inner diameter while the other bladder is being expanded in 
those portions of the drill pipe having a normal sized inner diameter.

Turn now to the detailed description which follows wherein the invention 
and its various embodiments are better described in light of the above 
Figures. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The drill pipe wiper of the invention is a direct acting slug and wipe 
tool. The tool is comprised of a cylindrical chamber having a rupturable 
seal at least at one end to allow for through pumping of hydraulic fluid. 
The cylindrical chamber, which is disposed inside the drill pipe, 
communicates with an exterior, toroidal, flexible, bladder wiper having a 
plurality of scraping ridges formed thereon. In a first embodiment one 
such bladder is provided and in a second embodiment two such bladder 
wipers are provided. In either case, the bladder pneumatically 
communicates with the cylindrical chamber and, in the case where two 
bladders are provided, pneumatically communicate with each other through 
the cylindrical chamber. As one bladder is squeezed through a restricted 
diameter within the pipe, gas or air is forced from the bladder into 
cylindrical chamber, and in the case of the two bladder embodiment into 
the adjacent bladder. Where two bladders are provided, one of the bladders 
will be passing through a narrowed constriction while the other bladder 
will be longitudinally displaced therefrom on the pipe wiper by a distance 
sufficient to place the adjacent bladder in a portion of the pipe having a 
normal diameter. 
Consider now the first embodiment as illustrated in FIG. 1. The wiper, 
generally denoted by reference numeral 10, includes a retrievable spear 
point 12 at its upper end. Spear point 12 is shaped and adapted for 
engagement with a wire line retrieval tool described in connection with 
FIG. 2 to permit easy handling and retrieval of the wiper from the 
platform. Spear point 12 also includes a rupture disk 14 disposed across 
the open end 16. Rupture disk 14 is secured within spear point 12 by 
mechanical capture within a shoulder 18 and by a threaded nose portion 20. 
A conventional O-ring 22 disposed between disk 14 and shoulder 18 
hydraulically seals end 16 of spear point 12. Rupture disk 14 is designed 
to fail at a predetermined pressure differential according to means well 
known in the art. 
Spear point 12 also includes a pneumatic pressurization port 24 disposed 
through the side of spear point 12. Pressurization port 24 provides a 
means for injecting a fixed amount or mass of gas, typically compressed 
air, into wiper 10 and more particularly into cylindrical chamber 26 
defined by cylindrical member 28. The use of pressurization port 24 will 
be described in greater detail below when the operation of wiper 10 is 
illustrated. 
Cylindrical member 28 is threadably coupled to spear point 12 in a 
conventional manner and hydraulically sealed thereto by means of O-ring 
30. Cylindrical member 28 also includes a plurality of ports 32 defined 
therethrough which communicates cylindrical chamber 26 to the interior 
space defined by a flexible bladder 34. Flexible bladder 34 is a resilient 
toroidal inflatable element circumferentially disposed about the exterior 
of cylindrical member 28 and in pneumatic communication through ports 32 
to cylindrical chamber 26. Cylindrical chamber 26 in turn pneumatically 
communicates to an axial chamber 36 defined within spear point 12 below 
ruptured disk 14. 
Inflatable bladder 34 is also provided with a plurality of ridges, ribs or 
other protrusions 38 defined on its exterior surface. In the preferred 
embodiment, integrally formed spiral or circular ribbing, generally lying 
in a plane perpendicular to the longitudinal axis of wiper 10, is 
contemplated. However, it must be clearly understood that many other types 
of protrusions or elements to assist scraping could also be provided on 
the exterior of bladder 34. For example, longitudinal ribbing could be 
integrally formed; ribbing could be replaced by a multiplicity of studs or 
fingers; or additional jackets could be provided on the outside of a 
smooth bladder for the purposes of carrying metallic studs, scrapers and 
other equivalent elements now known or later discovered. 
Cylindrical member 28 in turn is threadably coupled to valve sub 40. Valve 
sub 40 includes an axial chamber defined therethrough which communicates 
with a like axially defined chamber 44 defined within end plug 46. End 
plug 46 is also threadably coupled to the lower end of valve sub 40 and 
includes conventional means for attachment to a plurality of segmented 
sinker bars 48. Sinker bar 48 is a cylindrical solid member which is 
attachable to end plug 46 for the purposes of adding weight to wiper 10. 
Additional segmented sinker bars identical to bar 48 as depicted can be 
cascaded by attachment to lower end 50 of sinker bar 48 in substantially 
the same manner as bar 48 attaches to end plug 46. In the preferred 
embodiment, a lock twist flanged groove is provided t the lower end of end 
plug 46 and each sinker bar 50 into which groove a corresponding male 
member fits, which male member is provided at the top of each sinker bar. 
Valve sub 40 also includes a bypass sliding valve piston 52 which is 
longitudinally and temporarily secured to valve sub 50 by means of a 
radially disposed shear pin 54. Shear pin 54 is disposed through valve sub 
40 and into a mating indentation provided in bypass sliding valve piston 
52. Piston 52 in turn hydraulically seals chamber 42 of valve sub 40 in a 
conventional manner by means of O-rings 56. O-rings 56 also serve to seal 
off bypass port 58. According to principles well known in the art, shear 
pin 54 is designed to shear at a predetermined force. Therefore, when the 
pressure within chamber 42 reaches a predetermined magnitude, the force on 
the upper surface of piston 52 will be sufficient to shear pin 54, thereby 
causing piston 52 to be longitudinally displaced within valve sub 40 
toward end plug 46. Piston 52 in fact is displaceable by sufficient 
distance to uncover bypass port 58 thereby allowing hydraulic fluid to be 
pumped through wiper 10 and out port 58 into the drill pipe in a manner 
better described below. 
Turn now to FIG. 2 wherein a specialized wire line retrieval tool, 
generally denoted by reference numeral 60, is depicted. Tool 60 includes 
an upper member 62 threadably connected to lower member 64. Lower member 
64 includes a conventional end termination 68 adapted for resilient 
coupling to spear point 12. Included within lower member 64 is a axially 
disposed rod 66 lying along the longitudinal axis of tool 60. As described 
in greater detail below, when tool 60 engages spear point 12 of wiper 10 
as shown in FIG. 1, longitudinal rod 66 will extend downwardly into spear 
point 12 thereby rupturing disk 14. Where used, this will allow the rapid 
removal of wiper 10, even in those cases where hydraulic pressures 
exceeding the burst pressure of disk 14 are not achieved. Longitudinal rod 
66 is bolted in a conventional manner to lower member 64 and thus can be 
easily removed therefrom in the case where, as in normal opertion, rupture 
of disk 14 is not desired nor rapid removal of wiper 10 necessitated. 
Therefore, a wire line retrieval tool substantially as shown in FIG. 2 
with longitudinal rod 66 deleted may also be used during normal operation 
of wiper 10 as described in greater detail below. 
Before considering the second embodiment of the invention as depicted in 
FIG. 3, consider now the operation of wiper 10 as described in relation to 
FIG. 1. Wiper 10 is suspended above the drilling platform and drill pipe 
by a conventional means while a selected number of sinker bars 48 are 
attached in a cascaded manner to end plug 46. The number of sinker bars 
desired will depend upon the application at hand as determined by the 
pressure injected into wiper 10 through pressurization port 24, the 
density of the mud, the operation to be performed, the equilibrium depth 
below the well platform at which wiper 10 is desired. 
Wiper 10 is then lowered into the drill pipe while still being suspended. 
Before wiper 10 is fully inserted, a selected amount of gas or air 
pressure is injected into cylindrical chamber 26 through port 24. 
Typically, 30 to 70 psi (gauge) will be provided depending upon the 
application. 
Wiper 10 is thereafter released and allowed to free fall into the hydraulic 
fluid within the drill pipe in order to reach its equilibrium depth. 
Typically, wiper 10 will stabilize in a position 30 to 50 feet below the 
platform level. At this point, if desired, rust preventative may be poured 
into the drill pipe above wiper 10, which has scraped the interior pipe 
surface clean during this free fall descent. Bladder 34 will have been 
inflated and expanded to a sufficient degree to provide close and 
resilient contact with the drill pipe to provide an efficient scraping and 
cleaning action assisted by ridges 38. When wiper 10 reaches a constricted 
diameter of the drill pipe, the inherent resiliency of bladder 34 and its 
pneumatic inflation will cause the bladder to be compressed by forcing gas 
or air from the interior of bladder 34 into cylindrical chamber 26. After 
passing through the restriction, bladder 34 then reinflates to its initial 
scraping shape and size. If for any reason it is decided that wiper 10 
should be removed, a wire line retrieval tool as shown in FIG. 2 is 
lowered and engages spear point 12. Axial spear 66 ruptures disk 14 
thereby allowing for the depressurization of the bladder and rapid removal 
of the tool. 
In the event it is necessary to quickly repressurize the hydraulic fluid 
within the drill casing, such as in a kicking operation where a 
subterranean pressure or gas begins to cause a well blow-out, hydraulic 
pressure can be quickly increased thereby forcing wiper 10 downwardly 
within the drill string toward the drill collars. The increased hydraulic 
pressure will cause disk 14 to rupture and ultimately will shear pin 54. 
Thereafter, the increase of hydraulic pressure to the limits of operation 
capability may be continued to prevent well blow out. 
During normal operation, wiper 10 remains at its equilibrium point as the 
drill pipe is tripped. Ultimately, wiper 10 will be positioned just above 
the drill collars as the last segments of the drill string are retrieved 
from the bore hole. When the last joint of drill pipe is hanging in the 
slips, retrieval tool 60 is lowered and attached to wiper 10 which is then 
tripped. Wiper 10 is brought to the platform surface, depressurized, and 
then stored for next usage. If necessary, rupture disk 14 and piston 52 
may be repositioned and fitted and any defective O-rings replaced. Wiper 
10 is then ready for immediate reuse. 
Turn now to the second embodiment of the invention as illustrated in 
longitudinal, sectional view in FIG. 3. The identical elements used in the 
embodiment of FIG. 3 are denoted by the same numerals of the like elements 
as shown in FIG. 1. The second embodiment of FIG. 3 differs from that of 
FIG. 1 in that the second embodiment includes a pair of inflatable 
bladders 70 and 72. As before, each bladder 70 and 72 pneumatically 
communicates through a corresponding plurality of ports 74 and 76 
respectively with cylindrical chamber 26. The length of cylindrical member 
28 in the preferred embodiment is approximately eight feet (96 cm.) which 
allows bladders 70 and 72 to be attached and disposed on cylindrical 
member 28 at opposite ends thereof. Therefore, in the illustrated 
embodiment, bladders 70 and 72 will be approximately eight feet (96 cm) 
apart. This distance is sufficient so that when one bladder is being 
compressed by the restricted diameter of a drill pipe joint, the other 
bladder remains in a section of the pipe having a normal diameter. Gas or 
air thus injected into cylindrical chamber 26 is therefore free to 
communicate between bladders 70 and 72. When one of these bladders is 
being compressed, some of the air forced therefrom will flow into the 
opposing bladder thereby increasing the ease with which wiper 10 may pass 
through restricted sections. In addition, the use of two bladders 70 and 
72, carrying ribbed scraping elements 78 and 80 respectively, will provide 
for a redundant cleaning action as compared to the first embodiment of 
FIG. 1. Otherwise, the remaining elements of the second embodiment and 
their operation is substantially identical to that as shown and described 
in connection with the first embodiment of FIG. 1. 
It must be expressly understood that many modifications and alterations may 
be made by those having ordinary skill in the art without departing from 
the spirit and scope of the invention. For example, although the 
inflatable bladders 34, 70 and 72 have been shown generally toroidal 
rubber elements, it is entirely within the scope of the invention that 
these elements could include more complex structures, such as a 
multiplicity of inflatable intercommunicating toroidal elements shaped 
like a segmented catepillar body. In addition, although in the illustrated 
embodiment cylindrical chamber 26 is filled with a compressible gas, it is 
also possible that a noncompressible fluid may be substituted for part of 
the total volume in the second embodiment of FIG. 3, if desirable. 
However, in the preferred embodiment the compressibility of the gas is by 
far the biggest consideration when one of the bladders is collapsed within 
a restriction. 
Therefore, it must be understood that the illustrated embodiment has been 
shown only for the purposes of example and clarification, and should not 
be taken as limiting the scope of the invention as defined by the 
following claims.