METHOD OF SEALING SUBTERRANEAN ZONES

METHODE DE SCELLEMENT DE ZONES SOUTERRAINES

English Abstract

A method of sealing subterranean zones is described. A first step involves preparing a liquid slurry. A second step involves mixing bits of rubber from recycled tires into the liquid slurry. A third step involves pumping the liquid slurry containing the bits of rubber down a well.

French Abstract

Méthode de scellement de zones souterraines. Une première étape comprend la préparation d'une boue liquide. Une deuxième étape comprend le mélange de morceaux de caoutchouc, provenant de pneus recyclés, à la boue liquide. Une troisième étape comprend le pompage de la boue liquide contenant les morceaux de caoutchouc vers un puits.

Claims

5
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of sealing subterranean zones, comprising the steps of:
preparing a liquid slurry;
mixing bits of rubber and reinforcing fibre from recycled tires into the
liquid slurry; and
pumping the liquid slurry containing the bits of rubber and reinforcing fibre
down a well.
2. The method as defined in Claim 1, wherein the bits of rubber are rubber
crumb bits.
3. The method as defined in Claim 1, wherein the bits of rubber are larger
chopped bits of a size
between 1/8 of an inch and 1 1/2 inches.
4. The method as defined in Claim 1, wherein the liquid slurry is a drilling
fluid.
5. The method as defined in Claim 1, wherein the liquid slurry is contains
cement.
6. A method of sealing subterranean zones, comprising the steps of:
preparing a liquid slurry of drilling fluid and cement;
mixing bits of rubber and reinforcing fibre from recycled tires into the
liquid slurry, the bits
of rubber being a mixture of rubber crumb bits and larger chopped bits of a
size between 1/8 of an
pumping the liquid slurry containing the bits of rubber and reinforcing fibre
down a well
under pressure, such that the bits of rubber and reinforcing fibre pack under
pressure into fractures
in the subterranean zone and, when pressure is reduced, expand.
inch and 1 1/2 inches; and
7. A method of sealing subterranean zones, comprising the steps of:
inserting bits of rubber and reinforcing fibre from recycled tires into a
well; and
pumping a liquid slurry into the well as a carrier fluid to wash the bits of
rubber and
reinforcing fibre down the well.

Description

CA 02461524 2004-03-18
1
TITLE OF THE INVENTION:
Method of sealing subterranean zones
FIELD OF THE INVENTION
The present invention relates to a method of sealing subterranean zones where
there is
loss of circulation during drilling or a need to seal in the well during
abandonment.
BACKGROUND OF THE INVENTION
United States Patent 6,448,206 (Griffith et al 2002) relates to an aqueous
rubber latex
composition and a method of using that composition to seal subterranean zones.
During
drilling, circulation of drilling fluid is sometimes interrupted when drilling
fluid is lost into
fractures in subterranean zones. When this occurs, drilling operations must be
terminated
until circulation is restored. The Griffith et al patent is an example of the
sophisticated
technology which has been developed to address this problem.
SUMMARY OF THE INVENTION
The present invention relates to an alternative method of sealing subterranean
zones,
which is also suitable for use in sealing in a well which is to be abandoned.
According to the present invention there is provided a method of sealing
subterranean
zones. A first step involves
providing bits of rubber from recycled tires. A second step involves using a
liquid to carry
the bits of rubber down a well.
As will hereinafter be further described, there are two ways that this can be
done. One
way is to mix bits of rubber from recycled tires into the liquid. Another way
is to insert the
bits of rubber directly into the well and then use the liquid to wash the bits
of rubber down the
well. Which approach is used depends upon the requirements and limitations of
the particular
application.The method, as described above, concurrently addresses two
problems. The first
problem is the sealing of subterranean zones. The second problem is that of
finding a useful
end purpose for used vehicle tires. There are mountains of used vehicle tires,
which have been

CA 02461524 2004-03-18
2
collected and are awaiting recycling. The used vehicle_ tires are either
ground to form rubber
crumb bits or chopped into somewhat larger bits. Although one can use either
the rubber
crumb bits or the larger chopped bits, a mixture of the two sizes is
preferred. The rubber
crumb bits can fit into smaller spaces. The larger chopped bits can fill
larger spaces. When
the bits of rubber are placed under pressure, they compress and are forced
into fractures in the
subterranean zone. When pressure is reduced, the bits of rubber expand to fill
voids and more
securely engage the fractures.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more apparent from the
following description in which reference is made to the appended drawings, the
drawings are
for the purpose of illustration only and are not intended to in any way limit
the scope of the
invention to the particular embodiment or embodiments shown, wherein:
FIGURE 1 is a side elevation, in section, depicting the sealing of fractures
in a
subterranean zone of well in accordance with the teachings of the present
method.
FIGURE 2 is a side elevation, in section, depicting the sealing in of well
which is to
be abandoned in accordance with the teachings of the present method.
FIGURE 3 is a side elevation, in section, depicting the sealing in of an open
hole well
which is to be abandoned in accordance with the teachings of the present
method.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred method of sealing subterranean zones will now be described with
reference to FIGURES 1 through 3.
Referring to FIGURE 1, a first step involves preparing a liquid slurry 12. It
is
preferred that the slurry be a mixture of drilling fluid and cement. It will
be appreciated that
drilling fluid alone could be used or a liquid cement could be used alone. In
the illustrated
embodiment, the mixing is taking place in the mud tanks 14 of the drilling
rig. A second step
involves mixing bits of rubber 16 from recycled tires into liquid slurry 12.
It is preferred that
the bits of rubber be a mixture of rubber cnunb bits and larger chopped bits
of a size between
1/8 of an inch and 1 1/2 inches. It will be appreciated that rubber crumb bits
alone could be

CA 02461524 2011-05-03
3
used or larger chopped bits alone could be used. The rubber crumb bits are
capable of fitting
into smaller spaces. The larger chopped bits are capable of filling larger
spaces. In the
illustrated embodiment, bits of rubber 16 are supplied out of a hopper 18. A
third step
involves pumping liquid slurry 12 containing bits of rubber 16 down a well 20
under
pressure. In the illustrated embodiment, this is done with a high pressure
pump 22. Every
drilling rig is equipped with such a high pressure pump 22. When pumped down
well 20, bits
of rubber pack 16 under pressure into fractures 24 in subterranean zone 26.
When pressure is
reduced, the bits of rubber 16 expand and more effectively fill fractures 24.
It is desirable to
include reinforcing fibre 28 from the recycled tires with the larger chopped
bits of rubber.
The reinforcing fibre 28 helps to bind the bits of rubber in position.
Referring to FIGURE 2, there is illustrated another application for the
method. In
this application, well 20 is to be abandoned. In such an application, liquid
cement is used in
liquid slurry 12 and all of well 20 is filled. As with the first application,
bits of rubber 16 are
compressed when under pressure and expand when pressure is reduced.
Referring to FIGURE 3, with open holes there is sufficient room to modify the
method somewhat. With an open hole, bits of rubber 16 can be inserted directly
into well 20.
It need not be mixed into liquid slurry 12. Liquid cement is used in liquid
slurry 12 and used
to push bits of rubber 16 down well 20. The process of doing so mixes liquid
slurry 12
containing cement with bits of rubber 16. Although the end result is
essentially the same,
dropping bits of rubber 16 into well 20 first is believed to result in a
greater density in the bits
of rubber 16 down well 20. The reason for this is that there are limits as to
the proportion of
bits of rubber 16, which can be passed through pump 22 without clogging pump
22.
In this patent document, the word "comprising" is used in its non-limiting
sense to
mean that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the
possibility that more than one of the element is present, unless the context
clearly requires that
there be one and only one of the elements.
The following claims are to be understood to include what is specifically

CA 02461524 2011-05-03
4
illustrated and described above, what is conceptually equivalent, and what can
be
obviously substituted. The scope of the claims should not be limited by the
preferred
embodiments set forth in the examples, but should be given the broadest
interpretation
consistent with the description as a whole.

Representative Drawing