U.S. patent number 3,568,782 [Application Number 04/883,193] was granted by the patent office on 1971-03-09 for method for controlling drilling mud loss in a wellbore.
This patent grant is currently assigned to Tenneco Oil Company. Invention is credited to Jack C. Cox.
United States Patent |
3,568,782 |
Cox |
March 9, 1971 |
METHOD FOR CONTROLLING DRILLING MUD LOSS IN A WELLBORE
Abstract
A method for controlling drilling mud loss from a wellbore
penetrating a thief formation. It includes the steps of storing a
supply of unpopped cereal grain, such as popcorn, at the well site.
Upon the indication of loss of drilling mud to the thief formation,
a supply of the cereal grain is popped by passing the same through
a heating zone to thereby expand the same and thereafter pumping
the expanded material down the wellbore with the drilling mud until
the thief formation is plugged.
Inventors: |
Cox; Jack C. (Houston, TX) |
Assignee: |
Tenneco Oil Company (Houston,
TX)
|
Family
ID: |
25382150 |
Appl.
No.: |
04/883,193 |
Filed: |
December 8, 1969 |
Current U.S.
Class: |
175/72; 507/104;
166/294 |
Current CPC
Class: |
E21B
21/003 (20130101) |
Current International
Class: |
E21B
21/00 (20060101); E21b 021/04 () |
Field of
Search: |
;175/72,65
;166/292,294,282,283 ;252/8.5 (L.C.)/ |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Rogers, Composition and Properties of Oil Well Drilling Fluids, 3rd
Edition, (1963) Gulf Publishing Co. Houston, Texas, page 664. TN
861.R63.
|
Primary Examiner: Novosad; Stephen J.
Claims
I claim:
1. In a method for controlling drilling mud loss from a wellbore
penetrating a thief formation, the combination of steps
comprising:
storing a supply of unpopped cereal grain at the well site;
upon the indication of loss of drilling mud to said thief
formation, passing a supply of said cereal grain through a heating
zone to thereby heat and expand said cereal grain;
pumping said expanded cereal grain down said wellbore with said
drilling mud and into said thief formation; and
continuing said pumping of expanded cereal grain until said thief
formation is plugged by said expanded cereal grain.
2. The invention as claimed in claim 1 including: flattening said
popped cereal grain prior to pumping thereof down said
wellbore.
3. The invention as claimed in claim 1 wherein: a portion of said
unpopped cereal grain is substantially continuously popped and
pumped down said wellbore until said thief formation is
plugged.
4. The invention as claimed in claim 1 wherein: said cereal grain
is popcorn.
5. The invention as claimed in claim 1 wherein:
said cereal grain is popcorn;
a portion of said popcorn is substantially continuously popped and
pumped down said wellbore until said thief formation is plugged;
and
and said popped popcorn is flattened prior to pumping thereof down
aid wellbore.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for controlling drilling mud
loss to a thief formation which is penetrated by a wellbore during
the drilling of a wellbore.
2. Description of the Prior Art
During the drilling of wells, as for example oil wells, it often
develops that the drilling fluid, such as drilling mud, escapes
through a thief formation which is not structured to withstand the
pressures to which it is subjected. The loss of drilling mud
through the thief formation may be the result of a crack or fissure
in the formation, or because of its general porosity, for example.
In the past, it has been common practice to pump different
materials down the wellbore and into the formation for the purpose
of attempting to stop up or otherwise plug the thief formation.
These conventional lost circulation-type materials are commonly
transported, stored or sold in the form in which they are pumped
down the well. These materials are usually very bulky and present
storage problems by virtue of their large volume. Transportation
to, and storage of, such material at certain drilling sites, as for
example on offshore drilling rigs, is a problem because of the bulk
involved, the storage capacity required and the transportation
costs involved.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide an improved
method for controlling drilling mud loss from a wellbore
penetrating a thief formation, which method overcomes the aforesaid
problems.
Briefly stated, the method of this invention includes the storing
of a supply of unpopped cereal grain, such as popcorn, at the well
site. In the unpopped state, the cereal grain requires a minimum of
transportation costs in transporting to the well site and requires
a minimum storage capacity while being stored at the well site.
Upon indication of a loss of drilling mud to the thief formation, a
supply of the cereal grain is passed through a heating zone to
thereby heat and expand the cereal grain, thereby greatly
increasing its volume. The expanded cereal grain is then pumped
down the wellbore with the drilling fluid into the thief formation.
This pumping of the expanded cereal grain is continued until the
thief formation is plugged by the expanded cereal grain. In certain
instances, it may be desirable to flatten the popped cereal grain
prior to pumping the same down the wellbore. Further, it may be
desirable to continuously pop a portion of the cereal grain during
the pumping operation so as to minimize the storage space required
for the popped cereal grain.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference to the DRAWING will further explain the invention.
The numeral 11 generally designates a platform at the well site
which has mounted thereon a support frame 12 which supports
thereabove a large popcorn popper generally designated by the
numeral 13, which is comprised of a metal kettle 14 having an auger
mounted therein, which auger is comprised of an auger shaft 16
having an auger blade 17 both of which extend down into kettle 14
and are arranged for elevating the popped popcorn therefrom. Auger
shaft 16 is arranged to be driven by motor 24 through gearbox
25.
Kettle 14 also has an inlet means in the lower part thereof in the
form of conduit 19 which connects with feeder hopper 20 having a
supply of raw or unpopped popcorn 21 therein. Kettle 14 also has an
outlet shoot 22 by which the popped popcorn escapes from kettle
14.
Mounted on platform 11 adjacent to support frame 12 is a table 27
which supports an endless conveyor belt 28 which is mounted on
pulleys 30 and 31, one of which is driven so as to advance any
material deposited upon the upper surface of conveyor belt 28 to
the right as shown in the drawing. Conveyor belt 28 is also
arranged to pass over a pressure plate 33 mounted between pulleys
30 and 31, as shown. Table 27 also supports an upper housing 35
which has mounted therein a plurality of adjustable pressure
rollers 36, the axes of which are generally transverse to the line
of movement of conveyor belt 28.
The popped popcorn is discharged from chute 22 onto the left end of
conveyor belt 28, as shown in the drawing, and thereafter passes
under rollers 36 which are arranged to flatten the popped popcorn
by the pressure applied against belt 28 and pressure plate 33.
The flattened popped popcorn is discharged from conveyor belt 28 to
a chute 38, which is arranged to discharge into conventional
drilling mud tank 39. Mud tank 39 may be provided with agitating
means (not shown) to thoroughly mix the popped popcorn with the
drilling mud. The mud, so mixed, is thereafter drawn from mud tank
39 and pumped downwardly through the wellbore by conventional
means.
In operation, a supply of unpopped popcorn is always maintained at
the drilling site. In the unpopped state, the popcorn requires a
small amount of storage space and the transportation costs required
for transporting it there are at a minimum.
Upon the first indication of loss of drilling mud to a thief
formation, a supply of the raw popcorn is then flowed into popcorn
popper 13 through conduit 19 from hopper 20. Metal kettle 14 is
arranged to be heated by gas burner 18 supported therebelow, to
provide the desired heating conditions to metal kettle 14.
Temperature in kettle 14 is maintained at the desired temperature
to effect popping of the popcorn. As the popcorn is popped, it
expands greatly as shown by the numeral 23. It is removed from
kettle 14 by operation of auger shaft 16 and auger blade 17. The
popped popcorn is then discharged out chute 22 onto conveyor belt
28 where it is flattened and thereafter discharged into mud tank
39, from which it is then circulated down the wellbore, as by
pumping in conventional manner. The pumping of the expanded cereal
grain down the wellbore with the drilling mud is continued until
the thief formation is plugged by the expanded cereal grain.
Other cereal grains besides popcorn can be used, as for example
puffed wheat, puffed rice, and the like, all of which grains
experience a tremendous increase in volume when rapidly heated,
which expansion will generally be referred to as popping.
It will thus be apparent that this invention eliminates the need
for a large storage volume for storing conventional loss
circulation materials at a well site. By continuously operating the
apparatus described above, there is no requirement for the storage
of a large amount of expanded material for use as loss circulation
material. It therefore eliminates the costs of storing a large
volume of material and of transporting such materials.
Further modifications and alternate embodiments will be apparent to
those skilled in the art in view of this description.
* * * * *