WO2014145131A1

WO2014145131A1 - Scrubbing debris from a bored well

Info

Publication number: WO2014145131A1
Application number: PCT/US2014/029838
Authority: WO
Inventors: David E. Ronner; Michael W. Cook
Original assignee: Icf Mercantile, Llc
Priority date: 2013-03-15
Filing date: 2014-03-14
Publication date: 2014-09-18
Also published as: US20140262300A1; CA2906874A1

Abstract

The present disclosure provides methods and compositions for scrubbing debris from a bored well and includes injecting a suspension of acrylonitrile fibers, into the bored well to its open end. The suspension of acrylonitrile fibers scrubs the bored well of loose debris without substantially impeding the drilling capability of the rig by raising the effective liquid viscosity in the bored well. Also provided are pre-measured form factors of the acrylonitrile fibers for convenient and precise preparation of the acrylonitrile fiber suspension at the bored well site.

Description

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 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 (CH₂CHCOO-), 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 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 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 A.10 is a further variation of Embodiment A.9, wherein the scrubbing fibers are from about 2 mm to about 10 mm in length.

Embodiment A.11 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 6 lb 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; 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 mm 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.1, wherein the scrubbing fibers are from about 5 mm to about 25 mm in length.

Embodiment B.3 is a variation of Embodiment B.1, wherein the scrubbing fibers are from about 5 mm to about 7 mm in length.

Embodiment B.4 is a variation of Embodiment B.1, wherein about 0.1 to about 6 lb. of scrubbing fibers are added per 42 gallons of liquid.

Embodiment B.5 is a variation of Embodiment B.1, wherein about 0.25 to about 2 lb. of scrubbing fibers are added per 100 gallons of liquid. Embodiment B.6 is a variation of Embodiment B.1, wherein about 1/4 lb. of scrubbing fibers are added per 100 gallons of liquid.

Embodiment B.7 is a variation of Embodiment B.1, 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.1, wherein the scrubbing fibers are grafted.

Embodiment B.10 is a variation of Embodiment B.1, wherein the scrubbing fibers include an additive designed to create ultra-violet stability.

Embodiment B.11 is a variation of Embodiment B.1, 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;

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 6 lb. of scrubbing fibers are added per 42 gallons of liquid. 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.18 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. 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.30 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 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.1, 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.1, 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. 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 art, 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, 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 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 0.1 lbs. of fibers per 100 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: 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 PFO);

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-i,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 throughout the liquid. From about o.i to about 6 pounds of fiber are added for each barrel of liquid, with good results being achieved with o.i, 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 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 100 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 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 0.1 lb, 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 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 500ml 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.

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 10 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.

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.

Claims

Claims What is claimed is:

1. 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 therebetween;

wherein the liquid suspension comprises acrylonitrile fibers suspended in a liquid.

2. The method of claim l wherein the acrylonitrile fibers are from about 3 mm to about 12 mm in length.

3. The method of claim 1 wherein about 0.5 to about 6.0 lb of acrylonitrile fibers are added per 42 gallons of liquid.

4. The method of claim 1 wherein the acrylonitrile fibers are coated with a hydrophilic surfactant.

5. The method of claim 1 wherein the acrylonitrile fibers are grafted.

6. The method of claim 1 wherein the acrylonitrile fibers include an additive designed to create ultra-violet stability.

7. The method of claim 1 wherein the acrylonitrile fibers are formed by copolymer extrusion.

8. A method of cleaning loose materials from a 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 therebetween, the bored well being oriented in a substantially non-vertical position; and

9. The method of claim 8 wherein the acrylonitrile fibers are from about 3 mm to about 12 mm in length.

10. The method of claim 8 wherein about 0.1 to about 6.0 lb. of acrylonitrile fibers are added per 42 gallons of liquid.

11. The method of claim 8 wherein the acrylonitrile fibers are coated with a hydrophilic surfactant.

12. A pre-measured form factor of acrylonitrile fibers for the convenient and precise charging of proper quantities of acrylonitrile fibers for preparation of liquid suspension for sweeping of at least a portion of loose materials from a bored well, said form factor comprising:

a pre-measured quantity of acrylonitrile fibers,

wherein said pre-measured quantities are selected from the group consisting of about 0.1 lb, about 0.25 lb, about 0.5 lb, about 1 lb, about 2 lb and about 5 lb.

13. The pre-measured form factor according to Claim 12 further

comprising acrylonitrile fiber granules compacted into a tablet or a brick.

14. The pre-measured form factor according to Claim 12 further comprising loose acrylonitrile granules contained in paper, cardboard or polymer bags or boxes.

15. The pre-measured form factor according to Claim 12 further comprising acrylonitrile fibers in a liquid pre-mix.

16. A method of cleaning unwanted materials from a substantially vertical bored well comprising:

wherein the liquid suspension comprises acrylonitrile fibers suspended in a liquid; and

wherein said liquid suspension was prepared from a pre-measured form factor according to Claim 12.

17. A method of cleaning loose materials from a 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 therebetween, the bored well being oriented in a substantially non-vertical position; and

wherein the liquid suspension comprises acrylonitrile fibers suspended in a liquid; and,

18. 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 therebetween; and

wherein the liquid suspension comprises acrylate fibers suspended in a liquid.

19. The method of claim 1, wherein the acrylonitrile fibers are from about 2 mm to about 10 mm in length.

20. The method of claim 1, wherein the acrylonitrile fibers are from about 4 mm to about 10 mm in length.

21. The method of claim 1, wherein the acrylonitrile fibers are from about 5 mm to about 25 mm in length.

22. The method of claim 1, wherein the acrylonitrile fibers are from about 5 mm to about 7 mm in length.

23. The method of claim 1, wherein the acrylonitrile fibers are from about 10 mm to about 15 mm in length.