Note: Descriptions are shown in the official language in which they were submitted.
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SCRUBBING DEBRIS FROM A BORED WELL
CROSS-REFERENCE TO RELATED APPLICATION
This patent application claims the benefit of priority to U.S. Provisional
Patent Application Serial No. 61/787,037, filed March 15, 2013. The
aforementioned patent application is incorporated by reference herein in its
entirety for any purpose whatsoever.
BACKGROUND
1. Field of the Disclosure
The present disclosure relates to a methods and compositions for
scrubbing debris from a bored well, and the use of a liquid suspension
containing
scrubbing fibers to do so.
2. Background of the Disclosure
Drilling into the earth is a process that necessarily generates a great deal
of
debris in the bored well, likely to interfere with the continued drilling
process if
not continuously removed. Various liquids have been injected as a means of
flushing the debris from the bored well, to varying effect.
David, 6,164,380 and 6,753,081 disclose a method for cleaning debris
from a bore and includes injecting hydrophilic fibers selected from the group
consisting of polyolefins, polyesters and nylons, suspended or dispersed in a
water based or oil based liquid into the bore and forcing the suspension
through
the length of the bore, to its open end. In particular, the suspension is
directed
through sections of the bore holding quantities of debris formed from the
drilling
operation. The suspension loosens the debris and sweeps substantial quantities
of debris from the bore, and acts to suspend the debris in the liquid in
static
suspension at times when the liquid is not being forced through the bore.
It appears that some candidates for bored well injection for purposes of
debris removal may inhibit the drilling process due to their effect on liquid
viscosity. Thus, it would be beneficial to find an agent that when injected
into a
bored well, improved debris removal without impeding the drilling process by
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increasing viscosity.
SUMMARY OF THE DISCLOSURE
The specific fiber types described in the patents referenced above, based
on Applicant's experience, have been shown to offer sub-optimal suspension
characteristics due to multiple factors, including the fiber denier ( linear
density),
the fiber volumetric density, the fiber diameter, and the fiber lengths.
Specific
issues relate to the buoyancy of these types of fibers when suspended in
liquids,
as well as the fiber quantity available per unit weight (kg) as they relate to
a
three-dimensional cross-section of a fiber web in solution used to suspend and
sweep debris from a well bore.
In this disclosure, new embodiments arising from new types of fibers have
been identified for these applications and have been shown to offer
unexpectedly
superior sweep characteristics when subjected to the same test procedures used
in the reference prior art. In various implementations herein, acrylic fibers,
such
as acrylonitrile fibers of suitable deniers, diameters and volumetric
densities,
provide such performance. This specific class of fiber type was not included
in
the prior art known to Applicant, and experimental evidence has shown superior
well bore sweep characteristics, as evidenced from the tests detailed in this
disclosure, due to the fiber physical and chemical properties.
As used herein, the term "scrubbing fibers" shall be understood to mean
acrylate fibers and acrylonitrile fibers.
As used herein, the term "acrylate fibers" shall be understood to mean
fibers synthesized from acrylate monomers and co-polymers of the acrylate
monomers.
As used herein, the term "acrylate monomers" shall be understood to
mean that genus of compounds comprising vinyl groups (CH2CHC00-),
including but not limited to methyl methacrylate, methyl acrylate, ethyl
acrylate,
2-chloroethyl vinylether, 2-ethylexyl methacrylate, hydroxyethyl methacrylate,
butyl acrylate and butyl methacrylate.
As used herein, the term "acrylonitrile" shall be understood to mean fibers
synthesized from acrylonitrile monomers, co-polymers of acrylonitrile monomers
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and polyacrylonitriles.
As used herein, the term "substantially vertical" in reference to a bored
well shall be understood to mean within 30 degrees of the vertical direction.
As used herein, the term "non-vertical" in reference to a bored well shall
be understood to mean greater than 30 degrees from the vertical direction.
As used herein, the term "substantially parallel to a ground surface" shall
be understood to mean within 20 degrees of parallel to ground surface.
Bored wells that are comprised of one or more linear segments that
individually satisfy the criteria of "substantially vertical," "non-vertical"
or
"substantially parallel to the ground" shall be understood to satisfy these
criteria.
Embodiment A.1 comprises a method of cleaning unwanted materials
from a substantially vertical bored well comprising:
injecting under pressure a liquid suspension into a conduit inserted into
said bored well wherein the conduit and the bored well define an annulus there
between;
sweeping unwanted materials from the annulus by directing the liquid
suspension through the annulus to the unwanted materials;
wherein the liquid suspension comprises scrubbing fibers suspended in a
liquid.
Embodiment A.2 is a further variation of Embodiment A.1, wherein the
scrubbing fibers are from about 2MM to about 10 mm in length.
Embodiment A.3 is a further variation of Embodiment A.1, wherein the
scrubbing fibers are from about 4 mm to about 10 mm in length.
Embodiment A.4 is a further variation of Embodiment of A.1, wherein
about 0.5 to about 6 lb of scrubbing fibers are added per 42 gallons of
liquid.
Embodiment A.5 is a further variation of Embodiment A.1, wherein about
0.5 to about 2 lb of scrubbing fibers are added per 42 gallons of liquid.
Embodiment A.6 is a further variation of Embodiment A.1, wherein the
scrubbing fibers are acrylonitrile fibers.
Embodiment A.7 is a further variation of Embodiment A.6, wherein the
scrubbing fibers are acrylonitrile fibers coated with a hydrophilic
surfactant.
Embodiment A.8 is a further variation of Embodiment A.1, wherein the
scrubbing fibers are formed by co-polymer extrusion of acrylonitrile and
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methacrylate.
Embodiment A.9 comprises a method of cleaning unwanted materials
from a substantially vertical bored well having debris present therein and
having
two ends wherein one end of the bored well is open and the other end is remote
from the open end, the method comprising the steps of:
directing a liquid suspension into the bored well to a location between the
remote end of the bored well and the debris to be removed therefrom;
causing the liquid suspension to move toward the open end of the bored
well past the debris, thereby carrying the debris to the open end;
directing the debris containing suspension out of the bored well;
wherein the liquid suspension is comprised of a plurality of scrubbing
fibers suspended in a liquid.
Embodiment Ado is a further variation of Embodiment A.9, wherein the
scrubbing fibers are from about 2 TIM to about 10 mm in length.
Embodiment A.ii is a further variation of Embodiment A.9, wherein the
scrubbing fibers are from about 4 mm to about 10 mm in length.
Embodiment A.12 is a further variation of Embodiment A.9, wherein
about 0.5 to about 6th of scrubbing fiber are added per 42 gallons of liquid.
Embodiment A.13 is a further variation of Embodiment A.9, wherein
about 0.5 to about 2 lb of scrubbing fiber are added per 42 gallons of liquid.
Embodiment A.14 is a further variation of Embodiment A.9, wherein the
scrubbing fibers are acrylonitrile fibers.
Embodiment A.15 is a further variation of Embodiment A.14, wherein the
scrubbing fibers are acrylonitrile fibers coated with a hydrophilic
surfactant.
Embodiment A.16 is a further variation of Embodiment A.9, wherein the
scrubbing fibers are formed by co-polymer extrusion of acrylonitrile and
methacrylate.
Embodiment A.17 comprises a method for sweeping debris from a
substantially vertically bored well comprising the steps of:
pumping a suspension of scrubbing fibers into a conduit positioned in the
bored well, the conduit extending from an open end to a remote end of the
bored
well and defining an annulus between the conduit and the bored well;
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directing the suspension to the remote end of the bored well, then through
the annulus to the open end of the bored well such that the suspension carries
debris contained within the annulus to the open end of the bored well.
Embodiment A.18 is a further variation of Embodiment A.17, wherein the
scrubbing fibers are from about 2 TIM to about 10 mm in length.
Embodiment A.19 is a further variation of Embodiment A.17, wherein the
scrubbing fibers are from about 4 mm to about 10 mm in length.
Embodiment A.20 is a further variation of Embodiment A.17, wherein
about 0.5 to about 2 lb of scrubbing fiber are added per 42 gallons of liquid.
Embodiment A.21 is a further variation of Embodiment A.17, wherein the
scrubbing fibers are acrylonitrile fibers.
Embodiment A.22 is a further variation of Embodiment A.21, wherein the
acrylonitrile fibers exhibit about 1.5 to about 6 denier per filament (dpf).
Embodiment B.1 comprises a method of cleaning loose materials or debris
from a bored well in a bored well having loose material or debris present
therein
and having two ends wherein one end of the bored well is open and the other
end
is remote from the open end, the method comprising:
injecting under pressure a liquid suspension into a conduit inserted into
the bored well wherein the conduit and the bored well define an annulus
therebetween, the bored well being oriented in a non-vertical position; and
sweeping at least a portion of loose materials or debris from the annulus
by directing the liquid suspension through the annulus to the materials;
wherein the liquid suspension comprises scrubbing fibers suspended in a
liquid.
Embodiment B.2 is a variation of Embodiment B.i, wherein the scrubbing
fibers are from about 5 mm to about 25 mm in length.
Embodiment B.3 is a variation of Embodiment B.i, wherein the scrubbing
fibers are from about 5 mm to about 7 mm in length.
Embodiment B.4 is a variation of Embodiment B.i, wherein about 0.1 to
about 6 lb. of scrubbing fibers are added per 42 gallons of liquid.
Embodiment B. is a variation of Embodiment B.i, wherein about 0.25 to
about 2 lb. of scrubbing fibers are added per 100 gallons of liquid.
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Embodiment B.6 is a variation of Embodiment B.i, wherein about 1/4 lb.
of scrubbing fibers are added per 100 gallons of liquid.
Embodiment B.7 is a variation of Embodiment B.i, wherein the scrubbing
fibers are acrylonitrile fibers.
Embodiment B.8 is a variation of Embodiment B.7, wherein the
acrylonitrile fibers are coated with a hydrophilic surfactant.
Embodiment B.9 is a variation of Embodiment B.i, wherein the scrubbing
fibers are grafted.
Embodiment B.io is a variation of Embodiment B.i, wherein the
scrubbing fibers include an additive designed to create ultra-violet
stability.
Embodiment B.ii is a variation of Embodiment B.i, wherein the scrubbing
fibers are formed by co-polymer extrusion of acrylonitrile and methacrylate.
Embodiment B.12 comprises a method of cleaning loose materials or
debris from a bored well in a bored well having loose material or debris
present
therein and having two ends wherein one end of the bored well is open and the
other end is remote from the open end, the method comprising:
directing a liquid suspension into the bored well to a location between the
remote end of the bored well and the material to be removed therefrom, the
bored well oriented substantially parallel to a ground surface;
causing the liquid suspension to move toward the open end of the bored
well past the material, thereby carrying at least a portion of the material to
the
open end; and
directing at least a portion of the material containing suspension out of the
bored well;
wherein the liquid suspension is comprised of a plurality of scrubbing
fibers suspended in a liquid.
Embodiment B.13 is a further variation of Embodiment B.12, wherein the
scrubbing fibers are from about 5 mm to about 25 mm in length.
Embodiment B.14 is a further variation of Embodiment B.12, wherein the
scrubbing fibers are from about 5 mm to about 7 mm in length.
Embodiment B.15 is a further variation of Embodiment B.12, wherein
about 0.1 to about 6th. of scrubbing fibers are added per 42 gallons of
liquid.
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Embodiment B.16 is a further variation of Embodiment B.12, wherein
about 0.25 to about 2 lb. of scrubbing fibers are added per 100 gallons of
liquid.
Embodiment B.17 is a further variation of Embodiment B.12, wherein the
scrubbing fibers are acrylonitrile fibers.
Embodiment B.i8 is a further variation of Embodiment B.17, wherein the
acrylonitrile fibers are coated with a hydrophilic surfactant.
Embodiment B.19 is a further variation of Embodiment B.12, wherein the
scrubbing fibers are grafted.
Embodiment B.20 is a further variation of Embodiment B.12, wherein the
scrubbing fibers include an additive designed to create ultra-violet
stability.
Embodiment B.21 is a further variation of Embodiment B.12, wherein the
scrubbing fibers are formed by co-polymer extrusion.
Embodiment B.22 comprises a method for sweeping loose solids material
from a bored well, comprising:
pumping a suspension of scrubbing fibers into a conduit positioned in the
bored well, the conduit extending from an open end to a remote end of the
bored
well and defining an annulus between the conduit and the bored well, the bored
well oriented substantially parallel to a ground surface; and
directing the suspension to the remote end of the bored well, then through
the annulus to the open end of the bored well such that the material carries
at
least a portion of the material contained within the annulus to the open end
of
the bored well.
Embodiment B.23 is a further variation of Embodiment B.22, wherein the
scrubbing fibers are from about 5 mm to about 25 mm in length.
Embodiment B.24 is a further variation of Embodiment B.22, wherein the
scrubbing fibers are from about 10 mm to about 15 mm in length.
Embodiment B.25 is a further variation of Embodiment B.22, wherein
about 0.1 to about 2 lb. of scrubbing fibers are added per 100 gallons of
liquid.
Embodiment B.26 is a further variation of Embodiment B.22, wherein the
scrubbing fibers are acrylonitrile fibers.
Embodiment B.27 is a further variation of Embodiment B.22, wherein the
scrubbing fibers are acrylonitrile fibers coated with a hydrophilic
surfactant.
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Embodiment B.28 is a further variation of Embodiment B.22, wherein the
scrubbing fibers are grafted.
Embodiment B.29 is a further variation of Embodiment B.22, wherein the
scrubbing fibers include an additive designed to create ultra-violet
stability.
Embodiment B.3o is a further variation of Embodiment B.22, wherein the
scrubbing fibers are formed by co-polymer extrusion of acrylonitrile and
methacrylate.
Embodiment B.31 is a further variation of Embodiment B.22, wherein the
suspension is comprised of the scrubbing fibers, a foaming agent, a liquid and
compressed air to form a foam.
Embodiment B.32 comprises a method of suspending loose materials in a
substantially non-vertical bored well, comprising:
injecting under pressure a liquid suspension into a conduit inserted into
the bored well wherein the conduit and the bored well define an annulus there
between; and
directing the liquid suspension to the materials to suspend at least a
portion of the materials in the liquid suspension;
wherein the liquid suspension comprises scrubbing fibers suspended in a
liquid.
Embodiment B.33 is a further variation of Embodiment B.32, further
comprising sweeping at least a portion of the loose materials from the annulus
by
directing the liquid suspension through the annulus to the materials.
Embodiment B.34 is a further variation of Embodiment B.32, wherein the
scrubbing fibers are acrylonitrile fibers.
Embodiment B.35 is a further variation of Embodiment B.32, wherein the
scrubbing fibers are acrylonitrile fibers coated with a hydrophilic
surfactant.
Embodiment B.36 is a further variation of Embodiment B.32, wherein the
scrubbing fibers are grafted.
Embodiment B.37 is a further variation of Embodiment B.32, wherein the
scrubbing fibers include an additive to create ultra-violet stability.
Embodiment B.38 is a further variation of Embodiment B.32, wherein the
scrubbing fibers are formed by co-polymer extrusion of acrylonitrile and
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methacrylate.
Embodiment B.39 is a further variation of Embodiment B.7, wherein the
acrylonitrile fibers exhibit about 1.5 to about 6 dpf.
Embodiment C.1 is a method of sweeping loose material from a bored well
comprising injecting under pressure a liquid suspension into a conduit
positioned
in the bored well wherein the conduit and the bored well define an annulus
between them.
Embodiment C.2 is a further variation of Embodiment C.i, wherein the
liquid suspension is directed through the annulus, to an open end of the bored
well, to a settling tank.
Embodiment C.3 is a further variation of Embodiment C.i, wherein the
liquid suspension is directed through the annulus, to an open end of the bored
well, to a series of screens wherein the material and fibers are removed from
the
liquid by agitation and filtration.
Embodiment C.4 is a further variation of Embodiment C.3, wherein the
liquid is preferably recycled for further use in the drilling and/or clearing
operation.
BRIEF DESCRIPTION OF THE DRAWINGS
The characteristics and advantages of the present disclosure may be better
understood by reference to the accompanying drawings, wherein like reference
numerals designate like elements and in which:
FIG. 1 provides a schematic section view of a bored well sweeping
operation as one form of the present disclosure; and
FIG. 2 provides a schematic section view of a bored well sweeping
operation as another form of the present disclosure.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It is to be understood that the figures and descriptions of the present
disclosure have been simplified to illustrate elements that are relevant for a
clear
understanding of the present disclosure, while eliminating, for purposes of
clarity, other elements. Those of ordinary skill in the art will recognize
that
associated equipment and other items may be employed in the implementation of
the present disclosure. However, because such associated equipment and items
are well-known in the are, and because they are not necessary for a complete
understanding of embodiments of the present disclosure, they will not be
discussed herein.
Also, the embodiments of the disclosure and devices to which
embodiments of the disclosure may be attached or with which they may be
practiced may be described herein in the normal operating position, and terms
such as top, bottom, upper, lower, front, back, horizontal, vertical,
proximal,
distal, etc., may be used with reference to only one operating position of the
referenced device or element. It is to be understood, however, that this
description is non-limiting, and that the devices and methods of the present
disclosure may be manufactured, stored, transported, used, and sold in
orientations other than those described.
In the present detailed description of the disclosure, particular emphasis is
placed on one form of the disclosure as a bored well drilling system, for
drilling
bored wells for oil, gas, or other subterranean wells, typically considered to
be
oriented substantially vertical to the ground surface. It should be
understood,
however, that the disclosure is not limited to embodiment in such form and may
have application in whatever angled orientation of bored well is desired.
Accordingly, all non-vertical bored well orientations relative to the ground
surface are also contemplated by the present disclosure. For example, as will
be
more fully discussed, one of ordinary skill in the art will appreciate that
the
method of the present disclosure may be used to clear substantially horizontal
subterranean bored wells that are, typically, oriented parallel to the ground
surface, for receiving, for example, gas, water, telephone, electrical,
sewage,
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cable, fiber optic or other utility lines. It is contemplated that the phrase
"oriented parallel to the ground surface" as used herein includes bored well
orientations having some inclination, curvature or angulation along the length
of
the bored well. Thus, while the present disclosure is capable of embodiment in
many different forms, this detailed description and the accompanying drawings
disclose only specific forms as examples to the disclosure. Those having
ordinary
skill in the relevant art may be able to adapt embodiments of the disclosure
to
application in other forms not specifically presented herein based upon the
present description.
Furthermore, in the present detailed description of the disclosure,
particular emphasis is placed on a method of forcing liquid suspension through
the bored well, typically by a pumping operation, to remove debris therein.
One
skilled in the art will appreciate, however, that for debris not removed from
the
bored well, the liquid suspension of the present disclosure also acts to
maintain at
least a portion of this material in static suspension. This may occur, for
instance,
when the pumping operation is suspended or interrupted.
The drilled material will be described herein as "debris," "unwanted
material," or "cuttings" as this type of material is typically removed from
bored
wells during drilling operations. One of ordinary skill in the art will
appreciate
however, that embodiments of the present disclosure may be employed in mining
operations where some or all of the material may have some recovery value once
removed from the bored well and will not therefore, be "unwanted" for all
purposes.
Various embodiments of the present disclosure include injecting scrubbing
fibers suspended or dispersed in a liquid into a bored well to clear the bored
well
of loose materials. The liquid suspension may then be forced through the
length
of the bored well, to its open end. In particular, the suspension is directed
through sections of the bored well holding quantities of debris formed from
the
drilling operation. The suspension loosens the debris and sweeps substantial
quantities of debris from the bored well without increasing the viscosity of
the
drilling liquid and thereby slowing the drill.
Referring to FIG. 1, there is shown schematically those aspects of a typical
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bored well and drilling system pertinent to one method of the present
disclosure.
A bored well 12 is drilled into a formation by means of any suitable known
drilling equipment, including a drill pipe 14 and accompanying drill bit 18.
For
purposes of the present disclosure, the drill pipe 14 is a hollow conduit
through
which a liquid may pass. An annulus 20 is defined between the exterior of the
drill pipe 14 and the wall 21 of the bored well 12. A settling tank 30 is
fluidly
connected to a suction pump 26 which in turn is fluidly connected to the
hollow
interior of the drill pipe 14. A liner 40 may be inserted into the bored well
12 to
maintain its integrity. The liner 40 preferably has a cap 28 and outlet
conduit 32
which empties into the settling tank 30. Debris 16, such as rock, dirt and
clay, is
created by the drilling. To remove the debris, the method of the present
disclosure can include directing the liquid fiber suspension from the settling
tank
30, through the drill pipe 14 and through the annulus 20 where the suspension
contacts the debris and carries it to the surface of the bored well 12 to
outlet
conduit 32. The suspension thereby sweeps the debris from the bored well 12 as
it
is forced through the annulus 20.
The fibers used in liquid suspension of the method of the present
disclosure are preferably wet-able in various liquids, particularly in fresh
water,
salt water, water based drilling fluids and in oil based drilling liquids.
Moreover,
unlike the conventional additives heretofore used, the preferred fibers
disperse in
each of the foregoing liquids to create a homogenous matrix of suspended
fibers
which will suspend or reduce the velocity of settling solids in static
conditions but
which will behave like a fluid when pumped or agitated. In this regard the
suspension exhibits excellent thixotropic properties.
Preferably, from about 0.1 to about 6 lbs. of fibers, and more preferably
about 0.25 to about 2 lbs. of fibers, are used per 42 gallon barrel of liquid.
In
some conditions, it may be preferable to use a fiber concentration of about 1
pound per 42 gallon barrel, or about 15 pounds of fiber in a standard 15
barrel
sweep. In extreme or difficult situations, it may be preferable to use about
30
pounds of fiber in a 30 barrel sweep. Variation in the concentration can be
tolerated, as any effective amount of fiber may be used. For example, for non-
vertical bored wells, which will be discussed, about 0.11bs. of fibers per too
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gallons of liquid effectively may be sufficient.
The fibers are most preferably comprised of a plurality of filaments
processed in a tow form in bundles, from about one to two hundred, and
preferably from about 1 to about 6 denier per filament (dpf), and most
preferably
from about 1.5 to about 6 dpf. The fibers may be any length that is
dispersible
and pumpable. Lengths between about 3 and about 12 millimeters are more
preferred, and lengths of about 5 to about 7 millimeters are most preferred.
The fibers may be naturally hydrophilic or may be coated with a
hydrophilic coating, such as a surfactant. In addition to external surface
treatment, one skilled in the art would appreciate that it is also possible to
create
hydrophilic properties by internal methods. This could be accomplished, for
example, by way of chemical and polymer grafting. The attachment of graft
coatings is accomplished by forming a covalent bond between the substrate and
the monomers via the graft initiator. As a result, when compared to
conventional
coatings much thinner coatings can be obtained while providing good strength
and adhesion properties of the material. The chemical reaction that takes
place
provides subsurface penetration and chemical bonding. Coating thickness can be
adjusted according to specification. Other internal methods, such as, for
example, co-polymer extrusion and the addition of additives during the
extrusion
process also may be employed to achieve desired hydrophilic properties. For
example, a simple additive designed to create ultra-violet stability in a raw
material may also cause the end result to be hydrophilic.
The various synthetic fibers disclosed herein can be evaluated for their
suitability for use in the methods of the present disclosure by the methods
disclosed in U.S. Patent No. 6,164,380, Experiments 1-6, incorporated by
reference herein.
The hydrophilic characteristic of the fibers is believed necessary to
adequately sweep the debris from the bored well. However, the hydrophilic
character of the fiber may be inherent in the material itself, it may be
attributed
to the extrusion process in which the fibers are made, or it may be due to the
addition of a hydrophilic coating, such as a hydrophilic surfactant. Any
suitable
known hydrophilic coating will suffice such as:
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Alkyl sulfates, including ammonium lauryl sulfate, sodium lauryl sulfate
(SDS), sodium dodecyl sulfate, another name for the compound and the related
alkyl-ether sulfates sodium laureth sulfate, also known as sodium lauryl ether
sulfate (SLES), and sodium myreth sulfate;
Docusates, including dioctyl sodium sulfosuccinate,
perfluorooctanesulfonate (PFOS), perfluorobutanesulfonate;
Linear alkylbenzene sulfonates (LABs), including alkyl-aryl ether
phosphates and the alkyl ether phosphate;
Alkyl carboxylates (soaps), including sodium stearate, sodium lauroyl
sarcosinate and carboxylate-based fluorosurfactants such as
perfluorononanoate,
perfluorooctanoate (PFOA or PF0);
pH-dependent primary, secondary, or tertiary amines;
Octenidine dihydrochloride;
Alkyltrimethylammonium salts including cetyl trimethylammonium
bromide (CTAB), a.k.a. hexadecyl trimethyl ammonium bromide, cetyl
trimethylammonium chloride (CTAC);
Cetylpyridinium chloride (CPC);
Benzalkonium chloride (BAC);
Benzethonium chloride (BZT);
5-Bromo-5-nitro-1,3-dioxane;
Dimethyldioctadecylammonium chloride;
Cetrimonium bromide; and,
Dioctadecyldimethylammonium bromide (DODAB).
In addition, chemical and polymer grafting, co-polymer extrusion, the
addition of additives during the extrusion process, or other internal
hydrophilic
methods may be employed to achieve the desired properties and characteristics.
In use, the suspension is premixed, perhaps in the settling tank 30. Fibers
cut into lengths up to 25 mm, and preferably from about 3 mm to about 12 mm,
and more preferably from about 5 mm to about 7 mm, most preferably around 6
mm, are added to the desired liquid and stirred to evenly disperse the fibers
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throughout the liquid. From about 0.1 to about 6 pounds of fiber are added for
each barrel of liquid, with good results being achieved with 0.1, 0.25, 0.5,
and one
pound applications per barrel. Each barrel holds about 42 gallons.
In the preferred embodiment of the debris removal method, a liquid
suspension comprised of 6 mm 1.5 denier acrylate fibers coated with a
hydrophilic surfactant suspended in either a water based or an oil based
liquid in
a concentration of about 2 lbs. of fibers for each 42 gallons of liquid are
pumped
from tank 30 by means of pump 26 into the top end 22 of the drilling pipe 14
and
forced to the bottom end 24 of the drilling pipe 14 past a drill bit 18 into a
remote
end of the bored well 12. The suspension enters the annulus 20 defined between
the wall 21 of the bored well 12 and the exterior of the drilling pipe 14. The
annulus 20 will contain the drill cuttings--rock, dirt, clay and similar
debris--
from the drilling operation. The continuing flow of liquid suspension being
pumped into the bored well 12 through the drilling pipe 14 forces the
suspension
from the remote end towards the open end of the bored well 12. The suspension
carries the debris with it to the open end at cap 28 and to the outlet conduit
32
for delivery back to the settling tank 30. Alternatively, the outlet 32 may
lead to a
series of troughs (not shown) having screened bottoms and equipped with
agitation mechanisms for filtering the liquid from the solids removed from the
bored well 12. Debris remaining in the bored well is held in suspension so as
not
to retard the drilling operation. This is also the case when pumping
operations
are suspended or interrupted.
FIG. 2 illustrates a second drilling system pertinent to another method of
the present disclosure. Unless specifically provided for herein, the equipment
components, their operation, and the method used for drilling are the same as
described in the previous embodiment. This embodiment is directed to drilling
systems that are employed to drill substantially horizontal subterranean bored
wells that are oriented parallel to the ground surface. Examples or such
drilling
systems are those that are used for laying pipe or conduit, for example, gas,
water, telephone, electrical, sewage, cable, fiber optic or other utility
lines. The
drilling system in this embodiment is oriented such that the bored well 112
and
associated wall 121 and annulus 120 are horizontally formed, substantially
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parallel to the ground surface.
It should be understood that generally horizontal bored wells, such as
those disclosed in FIG. 2, and bored wells for running certain utility lines
will
typically require a smaller portion of the drilled cuttings to be removed from
the
bored well when compared to vertical bore systems (such as disclosed in the
first
embodiment, FIG. 1) or bored wells for oil or gas production. This is so
because
material loosened when drilling generally horizontal bored wells falls to the
sides
of the bored well and does not usually fall to the remote end of the bored
well
where the cuttings can interfere with the drill bit during the drilling
process.
Where it is not necessary to draw resources from the bored well, and only
space
of sufficient size to lay utility lines is needed (and not to recover all or
substantially all of the drilled material such as, for example, in mining),
only that
portion of the debris 16 that would otherwise hinder the drilling process or
interfere with the utility lines and conduit or pipes need be removed from the
annulus 120. In this regard, for non-vertical bored wells the amount of fiber
per
gallon of liquid necessary to clean the bored well may be less than that
needed for
vertical bored wells. Although any effective amount of fiber may be used for
non-
vertical bored wells, a range of 0.1 to 0.6 lbs. of fiber per too gallons of
liquid is
preferred, and a range of 0.25 to 2 lb. of fiber per 100 gallons of liquid is
more
preferred.
It should be understood, however, that the drilling systems hereinbefore
described and shown in FIGS. 1 and 2 are illustrative only, as the disclosure
is not
limited to use with vertically or horizontally disposed bored wells. The
disclosure
has application in whatever angled orientation of bored well is desired.
The methods of the present disclosure provide a useful and much needed
means of cleaning debris from a bored well which may be used with a variety of
drilling fluids and which will not retard the rate of penetration of the drill
through the geologic formation.
In an alternative embodiment of the disclosure, the fibers described herein
and a foaming agent are added to a drilling fluid. Compressed air is injected
into
the mixture to create a foam. The foam is used to clear a bored well in those
cases where there is no circulation liquid, typically when pneumatic drills or
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rotary drills are employed. The foaming agent is preferably a sodium laurel
sulfonate but a variety of different surfactants or foaming agents may be
used.
Foaming agents may be selected from among the list of surfactants disclosed
above.
Also within the scope of the present disclosure are pre-measured form
factors of scrubbing fibers for the convenient and precise charging of proper
quantities of scrubbing fibers for preparation of the liquid suspension in a
mixing
vessel (perhaps the settling tank 30). Such a form factor may comprise
scrubbing
fiber granules compacted into a tablet or a brick. In an alternative
embodiment,
such a form factor may comprise loose granules contained in paper, cardboard
or
polymer bags or boxes. In yet a further embodiment, such a form factor may
comprise scrubbing fibers in a liquid pre-mix. Pre-measured quantities for the
form factors of scrubbing fibers may be any that are likely to be convenient
for
the to achieve the dosing required at the bored well site. Preferred pre-
measured
quantities for the form factors include about 0.11b, about 0.25 lb, about 0.5
lb,
about 1 lb, about 2 lb and about 5 lb.
The present disclosure also encompasses methods of cleaning loose
materials from a vertical or non-vertical bored wells, comprising:
injecting under pressure a liquid suspension into a conduit inserted into
the bored well wherein the conduit and the bored well define an annulus
therebetween, the bored well being oriented in a substantially non-vertical
position; and
sweeping at least a portion of loose materials from the annulus by
directing the liquid suspension through the annulus to the materials;
wherein the liquid suspension comprises acrylate fibers suspended in a liquid;
and,
wherein said liquid suspension was prepared from a pre-measured form
factor.
EXPERIMENTAL RESULTS
The following is a description of three experiments that were performed at
an independent, third party certified lab. The scope of the subject
experiments
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was to determine the suitability of the disclosed fibers for use as a hole-
cleaning
agent when mixed and distributed in various fluids that are known in this
market
and to compare with other fiber products using the same methods.
The two materials selected for these experiments included a polypropylene
fiber, and an acrylic fiber. The polypropylene fibers were 7 dpf cross section
having a length of 12MM. These polypropylene fibers are treated with a
hydrophilic surfactant and are currently used as a sweep- product in the
relevant
market. Exemplary disclosed fibers that were used for comparison included
6mm acrylic fiber having 1.5 dpf cross section as taught herein. These fibers
are
hydrophilic, and are therefore not surface treated.
For the first two experiments, 350 ml of each solution was placed in a
5ooml plastic beaker. Pre-weighed quantities of each fiber were added to each
solution and then mixed until evenly dispersed. A single weighted object was
placed on the surface of each beaker and the depth of the settlement was
measured upon the initial displacement, at one hour, and at twenty four hours
of
elapsed time. The testing was conducted at 72 F. This was repeated for each
fiber dosage using three different objects of increasing weight. Results of
the
testing are reported in Tables 1 and 2 below for tap water and for salt water
having a salinity matching seawater, respectively.
Table 1 ¨ Settlement Teat Rer ¨ Tap. Water
Fiber Type Polypropyterie Fiber Acrylic Fiber
0:Nsei Type
ibr 6.0g -1õ.00 2,1r.7 4t.N. 2.6$ Z.W=
Tiber {pram)
isialarrApIt (el) )..5:10.
oaa grms
INyas- 4,N
Shag ==:ibat 4,5 haa
-14 hems (in.) 4..0:2 4.W 4.0
4JW
1,5 grams: hob 4.::* 4.
awe; Bemi
2.4 heor .00 :th.): 4 ,0 3._ 4: .00 43) 4,0
4 4.0 40
51 prams = tir: A,'; .4 .N7;
; e- 'A:: = A' NI
.3teel Nat 12 ez.la '"" 4
2$ii 4. 4,g'j 0..W 3 .00. 4.0
4.0 4.0
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Table 2 ¨ &ttlemaent Test Remit St Wt (331.ti)
Titer Typelyprapylene Fiber Acrylic Fiber
Obezt Type-
:Q332..g&.af
1,,N1 070 .1W. IN 2.
tif
Elbff: i]graurs)
Depth (Ea) .50. 6.0 4 .0 C; .0 10
.Erains
1m
o.00
4 4 a': aa :n 3..(4C! 4O
GIzas.Eiek
4M 4.0
1 30
.S.,0 gram&
. 4,W 4.0 4
aeel Nut IaLs. ' "
24 4:,N 4 4 4 (..W 4.(fiC!
As is clearly evident from the above data, the acrylic fiber substantially
outperforms the polypropylene fiber in these tests, indicating superior
properties
that are very favorable for use as a hole-cleaning agent.
The third experiment included column settlement using a weighted
plunger. For this experiment, the both types of fibers were introduced into a
respective clear PVC pipe with an internal diameter of 3 inches and a height
of 24
inches. The pipe was filled with tap water to a level of 22 inches and each
fiber
type was added to the water and mixed until evenly dispersed at 72 F. The
acrylic fibers described above were added at an equivalent dosage of to lbs
per 42
gallons of water and the polypropylene fibers were added at an equivalent
dosage
of 15 lbs per 42 gallons of water. The PVC tube was then placed in an
apparatus
to the measure height change of a weight plunger assembly which was initially
placed on the surface of the solution. The plunger assembly consisted of a
0.25"
diameter steel rod, 12 inches in length, attached to a 2.50" diameter steel
circular
plate. The total weight of the plunger assembly was 200 grams. The plunger was
released and periodic measurements were taken to determine the depth of
settlement. Test results are reported in Table 3.
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Table s3 Cam= Settle:suit Test Remits
Dept sf Musgel- an.)
.Palvpro,..p.sleneAyIi Fib.er
Dopaed
= Gg;
LsAia 1.32.7-5 1.32.75
2
512 7:75
Net .3etleriant .5..1 .5.15
Even though only two thirds as much acrylic fiber was added by weight,
equivalent performance was achieved essentially matching the performance of
the polypropylene fiber. This further demonstrates superior properties of the
acrylic fibers over the polypropylene fibers.
Those of skill in the art will understand that the descriptions of the present
disclosure herein presented are instructive only and that the embodiments
exhibited herein are not to be interpreted as limiting the scope of the
disclosure,
but rather as illustrative examples of possible variations within the spirit
and
scope of the inventor's conception and disclosure, and that many other
variations
not explicitly described here are also within the spirit and scope of the
present
disclosure.
