EQUIPMENT FOR MINING

FIELD OF THE INVENTION

[0001] The present invention generally relates to the field of mining. More particularly, the invention relates to mining equipment, and the use and manufacture thereof.

BACKGROUND TO THE INVENTION

[0002] Any reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge in Australia or elsewhere.

[0003] In the oil and gas industry, in particular in a downhole operation, sucker rods are connected together between an above ground reciprocating pump or drive head and the bottom of the downhole assembly. Deviation in the well components is a recognized problem in the art, and significant wear can be experienced by the sucker rod when they are subjected to friction. Wear is also experienced in vertical wells. This wear ultimately leads to sucker rod failure.

[0004] Sucker rod failure requires the system to be stopped and, as a result, leads to a loss of production because the failed sucker rod needs to be isolated, removed and replaced. It will be appreciated that this is a significant problem in the industry. Furthermore, this friction results in energy loss.

[0005] One attempt to alleviate this problem is to include a centralizer disposed on the sucker rods and/or couplers therebetween to minimize wear on the sucker rods by centralizing the sucker rods and by acting as a sacrificial wear device. That is, the centralizer is subjected to friction rather than the sucker rod itself. In order to minimize friction, lubricant is added to the centralizer. However, these centralizers wear over time and ultimately the sucker rods are again subjected to friction and fail. Alternatively, hole-in-tube failure may occur through friction between the production tube and the centralizer. Another issue with the use of lubricants is that it can be difficult to apply lubricant to the desired areas further down the downhole.

[0006] A typical solution in the prior art is to provide a centralizer that is formed of a nylon/glass filled material. Whilst strong, these centralizers have been known to fail due to higher wear rates, cracking and splitting. Particularly, these centralizers result in an abrasive effect of the fiberglass material on production tubing.

[0007] Further to the above, it would also be advantageous to be able to pre- emptively address imminent failure of a sucker rod.

[0008] It will be appreciated by the person skilled in the art that it would be advantageous to provide a device that alleviates the above problems, or at least provides the consumer with a commercial alternative.

SUMMARY OF THE INVENTION

[0009] In a first aspect, although it need not be the only or indeed the broadest form, the invention resides in a guide for a pumping system, the guide comprising a centralizer that is formed of a self-lubricating polymer.

[0010] In one embodiment, the self-lubricating polymer comprises a lubricant in an amount between about 0.1% to about 10%, between about 1% to about 5%, between about 1% and about 4%, or between about 1% to about 3% by weight.

[0011] In certain embodiments, the lubricant is selected from the group consisting of silicon oil, polymerized siloxanes, fluorocarbons and silicon-based organic polymers. Suitably, the lubricant is selected from the group consisting of silicon oils, siloxanes, and Teflon. Preferably, the lubricant is polymerized siloxane or a derivative thereof. [0012] In an embodiment, the centralizer comprises a passageway for fluid flow. Suitably, the centralizer comprises a spiral formation. Alternatively, the centralizer comprises a plurality of ribs that define the passageway. The passageway is suitably angularly disposed in relation to the longitudinal axis of the guide. In one embodiment, the passageway comprises a flared opening and a flared exit.

[0013] In certain embodiments, the guide further comprises a detectable component in a cavity therein. Suitably, the detectable component is selected from the group consisting of dyes, RFID chips, fluorescent compounds and magnetic components.

[0014] In a further form, the invention resides in a sucker rod comprising the guide of the first aspect.

[0015] In yet a further form, the invention resides in a coupler comprising the guide of the first aspect.

[0016] In a second form, the invention resides in a method of manufacturing a guide comprising the steps of: a. providing a polymer; b. mixing the polymer with one or more lubricants to form a compounded mixture; and c. forming a guide comprising a centralizer from the compounded mixture, to thereby form a guide comprising a centralizer that is formed of a self- lubricating polymer.

[0017] In a third form, the invention resides in a method of extracting fluid from a downhole including the step of: a. connecting a reciprocating pump to a sucker rod; b. connecting a coupler to the sucker rod; c. connecting a further sucker rod to the coupler; d. repeating steps b) and c); and e. connecting the lowest sucker rod to a downhole pump assembly, wherein at least one coupler and/or sucker rod comprises the guide of the first aspect, to extract fluid from a downhole.

[0018] The various features and embodiments of the present invention referred to in the individual sections above and in the description which follows apply, as appropriate, to other sections, mutatis mutandis. Consequently, features specified in one section may be combined with features specified in other sections as appropriate.

[0019] Further features and advantages of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, in which:

FIG 1 shows a guide integrally molded on a sucker rod;

FIG 2 shows an alternate guide integrally molded on a coupler;

FIG 3 shows the coupler of FIG 2 connected to sucker rods, and the surface dynamics thereof; and

FIG 4 shows a simplified cross-section of a sucker rod comprising a guide in relation to production tubing.

DETAILED DESCRIPTION OF THE INVENTION

[0021] Embodiments of the present invention reside primarily in a guide. Accordingly, the device and method steps have been illustrated in concise schematic form in the drawings, showing only those specific details that are necessary for understanding the embodiments of the present invention, but so as not to obscure the disclosure with excessive detail that will be readily apparent to those of ordinary skill in the art having the benefit of the present description.

[0022] In this specification, adjectives such as top and bottom, left and right, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order.

[0023] As used herein, terms such as “comprises” or “includes” are intended to define a non-exclusive inclusion, such that a method or device that comprises a list of elements does not include only those elements but may include other elements not expressly listed, including elements that are inherent to such a process, method, article, or apparatus.

[0024] As used herein, the term ‘about’ means the amount is nominally the number following the term ‘about’ but the actual amount may vary from this precise number to an unimportant degree.

[0025] The invention is predicated on, at least, the finding that well components (e.g., a centralizer and/or guide and/or production tube) being formed of a self-lubricating polymer, in particular with a sucker rod and/or coupler and/or production tube, alleviates the problems associated with wear and failure thereof. In this regard, the self-lubricating polymer allows the well components to experience less friction and thus less wear. As a result, the well components have a longer lifetime. In one embodiment, the invention generally lies in the use of self-lubricating polymers in downhole pump components and/or devices.

[0026] As used herein, the term ‘self-lubricating polymer’ refers to a composite material that contains a lubricating material in a polymer matrix. The lubricating material is exposed as the self-lubricating polymer is subjected to friction. As such, external lubricant is not required or the need thereof is alleviated. In one embodiment, the self-lubricating polymer is an abrasion resistant self-lubricating polymer. [0027] In one aspect, although it need not be the only or indeed the broadest form, the invention resides in a guide for a pumping system, the guide comprising a centralizer that is formed of a self-lubricating polymer.

[0028] The self-lubricating polymer refers to a polymer matrix that comprises one or more lubricants therein. The self-lubricating polymer can be viewed as a polymer impregnated with one or more lubricants.

[0029] The self-lubricating polymer maintains a low co-efficient of friction and wear through the release of the lubricant. This advantageously combats friction and wear in a variety of sliding, rolling and rotating mechanisms. Furthermore, advantageously, the use of a self-lubricating polymer alleviates the need of any external lubricants or reliance on production fluid discharge to reduce downhole friction.

[0030] Advantageously, the use of a self-lubricating polymer alleviates the requirement of relubrication during an oil and gas operation. In one embodiment, the guide is formed of self-lubricating polymer. That is, the guide and the centralizer are formed of self-lubricating polymer.

[0031] During operation, the friction experienced by the self-lubricating polymers results in lubrication. In this regard, the lubricant contained in the pores of the polymer migrate to the surface and/or are exposed to the surface, and thus provides a lubricating effect and reduction in friction. Without being bound to any particular theory, this is believed to result in less friction and thus extends the lifetime of the guide and/or centralizer by reducing the effect of steel to steel contact wear between the sucker rod and/or coupler with tubing. In one embodiment, the guide is a centralizing guide.

[0032] Furthermore, as the lubricant is encapsulated within the polymer matrix, from an environmental point of view, there is less risk of the lubricant escaping into the environment and causing environmental damage.

[0033] As mentioned above, the self-lubricating polymer is a polymer matrix that comprises one or more lubricants therein. The person skilled in the art will appreciate that any polymer can be utilized to form a self-lubricating polymer.

[0034] Suitably, the polymer is a cross-linked polymer material. More suitably, the polymer is a chemo-synthetic cross-linked polymer. In one embodiment, the polymer comprises a backbone formed of carbon. The polymer may suitably be a co-polymer. Preferably, non-limiting examples of the polymer include nylon, polyphenylene sulfide, polyacetals, polyethylketones, polyurethanes, polyethylenes, polyphenylene sulfide, polyolefin ketone, polyphthalamide, and combinations thereof.

[0035] Preferably, the polymer exhibits abrasion-resistance, impact- resistance, tear and kink-resistance, oil-resistance, grease-resistance and/or excellent resistance to hydroloysis and microbiological attack. The preferred polymer provides elasticity with some degree of flexibility.

[0036] The polymer may further comprise additives to modify specific properties thereof. Non-limiting examples of such additives include UV- stabilizers, corrosion inhibitor and plasiticisers. Preferably, the polymer and/or lubricant should be inert, non-toxic, organic, non-flammable, resistant to corrosion and have a low affinity for moisture (e.g, to water and/or brine).

[0037] One method of producing the self-lubricating polymer is to compound one or more polymers with one or more lubricants prior to molding. The molding is suitably high temperature injection molding. The lubricant is preferably substantially uniformly dispersed throughout the polymer. The self-lubricating polymer may be molded, preferably injection molded. Alternatively, the self- lubricating polymer may be extruded. In one form, the guide and centralizer are integrally formed. That is, the guide and centralizer are formed from a single material (in this case, a self-lubricating polymer).

[0038] In one embodiment, the self-lubricating polymer does not comprise any fibers and/or filling materials. In this regard, the self-lubricating polymer and guide are absent of fibers and/or filling materials. This advantageously prevents surface wear through abrasion caused by fibres and/or fillers in the polymers.

[0039] The lubricant is suitably a liquid lubricant, a gel lubricant, a wax lubricant or a solid lubricant. Preferably, the lubricant is a liquid lubricant, gel lubricant or a solid lubricant. The lubricant is suitably selected from the group consisting of silicon oil, fluorocarbons and silicon-based organic polymers. More suitably, the lubricant is selected from the group consisting of silicon oils, siloxanes, and Teflon. Preferably, the lubricant is a polymerized siloxane or a derivative thereof. A non-limiting example of the polymerized siloxane is polydimethylsiloxane. The person skilled in the art will appreciate that the above list of lubricants represents merely a few types of lubricants and that other lubricants not explicitly listed can be utilized. Given that downholes may extend 3000 ft below the surface, lubricant selection may depend on anticipated environments at this depth.

[0040] The self-lubricating polymer has a density of suitably greater than 1.00 kg/L, more suitably greater than 1.10 kg/L, and preferably greater than 1.20 kg/L. In some embodiments, the self-lubricating polymer has a density of suitably between about 1.00 kg/L to about 1.50 kg/L, more suitably between about 1.10 kg/L to about 1.3 kg/L, preferably between about 1.20 kg/L to about 1.25 kg/L, and most preferably about 1.24 kg/L.

[0041] The self-lubricating polymer has a tensile strength of suitably greater than 5000 psi, more suitably greater than 8000 psi, and preferably greater than 9000 psi. In some embodiments, the self-lubricating polymer has a tensile strength of suitably between about 7000 psi to about 12000psi, more suitably between about 8000 psi to about 11000 psi, preferably between about 9000 psi to about 10000 psi, and most preferably about 9250 psi.

[0042] The self-lubricating polymer has a flexural modulus of suitably greater than 150000 psi, more suitably greater than 200000 psi, and preferably greater than 240000 psi. In some embodiments, the self-lubricating polymer has a flexural modulus of suitably between about 200000 psi to about 300000psi, more suitably between about 220000 psi to about 250000 psi, preferably between about 240000 psi to about 250000 psi, and most preferably about 242000 psi.

[0043] The self-lubricating polymer has a flexible strength of suitably greater than 5000 psi, more suitably greater than 8000 psi, and preferably greater than 9000 psi. In some embodiments, the self-lubricating polymer has a flexible strength of suitably between about 7000 psi to about 12000psi, more suitably between about 8000 psi to about 11000 psi, preferably between about 9000 psi to about 10000 psi, and most preferably about 9250 psi. [0044] The self-lubricating polymer has a notched izod impact 0.125” of suitably greater than 2 Ibs/in, more suitably greater than 3 Ibs/in, and preferably greater than 3.5 Ibs/in. In some embodiments, the self-lubricating polymer has a notched izod impact 0.0125” of suitably between about 2 Ibs/in to about 5lbs/in, more suitably between about 3 Ibs/in to about 4 Ibs/in, preferably between about 3.5 Ibs/in to about 4 Ibs/in, and most preferably about 3.7 Ibs/in.

[0045] The self-lubricating polymer has a Rockwell Hardness of suitably greater than 10, more suitably greater than 30, preferably greater than 50 psi, more preferably greater than 70, and even more preferably greater than 100.

[0046] The self-lubricating polymer has a Shore D hardness of suitably between than about 50 and about 200, more suitably between about 60 and about 150, preferably between about 70 and about 120, more preferably between about 75 and 110, and most preferably between about 95 and about 110.

[0047] Preferably, the self-lubricating polymer comprises one or more lubricants at suitably between about 0.1% to about 10%, more suitably between about 1% to about 5%, preferably between about 1% and about 4%, and most preferably between about 1 % to about 3% by weight of the polymer.

[0048] The present guide has enhanced anti-friction properties for use in pumping applications such as downhole pumping operations. Suitably, the guide is used in sucker rods, couplers between sucker rods, roller couplings, progressive cavity pumps and other pumping devices.

[0049] In one embodiment, the guide is for use in a sucker rod. In this regard, in an embodiment, the invention resides in a sucker rod comprising a guide that comprises a centralizer that is formed of a self-lubricating polymer.

[0050] In certain embodiments, the guide is for use in a coupler. Preferably, the coupler is for coupling sucker rods. In this regard, in an embodiment, the invention resides in a coupler comprising a guide that comprises a centralizer that is formed of a self-lubricating polymer.

[0051] In one embodiment, the guide further comprises one or more detectable components. [0052] The detectable component is suitably disposed within the guide and/or centralizer. The detectable component may be located in a cavity within the guide and/or centralizer. The detectable component may be located at different depths of the guide and/or centralizer so that different components are released at different levels of wear.

[0053] In one embodiment, the guide comprises one, two three, four or more detectable components located in different cavities at different depths of the guide and/or centralizer.

[0054] During a pumping operation in a downhole, the pumped fluid is moved from the base of the downhole to the surface, and flows past the guide and centralizer. When the guide and/or centralizer is worn down to the cavity, the detectable component is released and is taken to the surface. The detectable component can then be detected by a detector on the surface. The detectable component thus provides useful information regarding the degree of wear of each component. This provides an indication as to the wear level of the well components (e.g., sucker rods or coupler).

[0055] In one embodiment, the detectable component(s) are located towards the top of the centralizer towards the surface of the well (near the exit flare; mentioned in hereinafter) as this area of the centralizer typically experiences greater wear than the lower end of the centralizer.

[0056] Furthermore, the detectable component may provide information regarding the location of the impending failure and this assists in efficient servicing and replacement, and alleviates the problem of loss of production. There should be sufficient detectable component such that it is in a detectable amount at the surface.

[0057] The detectable components may be a compound that is not detectable until it is released. In this regard, the detectable components may react with the fluid being pumped to form a detectable compound.

[0058] Furthermore, each guide or centralizer may be provided with a different detectable component that are distinguishable from one another. This allows the wear levels of different components to be monitored. Once a detectable component is detected by the detector, this can be correlated to a specific component and information regarding its location in the assembly. This will be useful when replacing the component.

[0059] Non-limiting examples of the detectable component includes dyes, RFID chips, fluorescent compounds, or magnetic components. Non-limiting examples of the detectable property include RFID signals, fluorescence and magnetism.

[0060] Referring to FIG. 1, there is a shown a guide 100 integrally molded and compressed on a sucker rod 150. The guide 100 comprises a centralizer 110 that is formed of a self-lubricating polymer. As can be seen in FIG. 1, the centralizer 110 radially extends outwardly from the sucker rod 150. As such, during operation, the centralizer 110 contacts the walls or tubing of a downhole operation such that the sucker rod 150 is centralized and the sucker rod 150 itself does not contact the walls or tubing. This alleviates the problem of the sucker rod 150 being worn by friction.

[0061] In use, the centralizer 110 contacts the downhole wall and releases the one or more lubricants. Although the centralizer 110 will gradually degrade through friction, this issue is alleviated by the constant release of the one or more lubricants uniformly dispersed through the self-lubricating polymer.

[0062] The guide 100 and centralizer 110 are suitably injection molded or extruded onto the sucker rod 150. Suitably, prefabrication, the sucker rod 150 may be formed with a recess such that the guide 100 can be formed thereon. This recess alleviates the problem of the guide 100 becoming loose and sliding on the sucker rod 150. The recess, such as a machined recess, may be provided with a rough surface to assist with adhesion of the self-lubricating polymer thereto. It will be appreciated that a recess is not a necessity in a sucker rod. It will be appreciated that the sucker rod 150 can be formed of any typical sucker rod material known to the person skilled in the art. Non-limiting examples of the sucker rod material include steel, heat treated steel, alloys (e.g., nickel- chromium molybdenum alloys) and fiberglass. Preferably, the sucker rod is formed of steel. [0063] The centralizer 110 suitably comprises a passageway that facilitates pumping of a fluid from the downhole. As shown in FIG. 1, the centralizer may have a spiral formation 115 which facilitates movement of fluid from the downhole to the surface. It will be appreciated that centralizer 110 can be formed in any structure that allows the pumped fluid to flow therethrough. The sucker rod 150 comprises attachment portions (not shown) on each longitudinal end thereof. The attachment portions facilitate attachment to a coupler (mentioned in more detail hereinafter).

[0064] A sucker rod may be provided with one or more guides to centralize the sucker rod 150 during operation. In one embodiment, a sucker rod comprises one or more guides.

[0065] Referring to FIG. 2, there is shown an alternate guide 200 integrally molded and compressed on a coupler 250. The coupler 200 is suitably for connecting sucker rods (such as those shown in FIG. 1).

[0066] The guide 200 comprises a centralizer 210 that extends radially outwardly from the coupler 250. During operation, the centralizer 210 may contact the walls of the downhole tubing such that the coupler 250 itself, and also an attached sucker rod, does not contact the walls of the downhole tube. This alleviates the problem of the coupler 250 and sucker rod 150 being worn and causing premature downhole tubing failure through friction.

[0067] The guide 200 and centralizer 210 are suitably injection molded or extruded onto the coupler 250. Suitably, prefabrication, the coupler 250 may be formed with a recess shaped therein such that the guide 200 can be formed thereon. The recess may be provided with a rough surface to assist with adhesion of the guide 200 thereto. This recess, such as a machined recess, alleviates the problem of the guide 200 becoming loose and sliding on the coupler 250. It will be appreciated that the coupler 200 can be formed of any typical coupler material known to the person skilled in the art. Non-limiting examples of the coupler material include steel, stainless steel and alloys (e.g., nickel-chromium molybdenum alloys), austenitic stainless steel with high levels of nickel and titanium and/or copper/nickel/tin alloys. Preferably, the coupler material is formed of quenched and tempered micro alloyed steels. [0068] The centralizer 210 comprises a passageway 220 that is defined by a plurality of ribs 225. The passageway 220 is angularly disposed in relation to the longitudinal axis of the coupler 250 and guide 200. The coupler will have a top end and a bottom end in relation to its use in a downhole. The passageway 220 comprises a flared opening 221 at the bottom end and flared exit 222 at the top end. The flared opening 211 is suitably larger than the flared exit 222. Alternatively, the flared opening can have the same dimension as the flared exit. The passageway 220 facilitates flow of a fluid from the downhole pump to the surface. In one embodiment, the opening and exit may be tapered.

[0069] The coupler 250 comprises attachment portions 230a, 230b on each longitudinal end thereof. The attachment portions facilitate attachment to sucker rods.

[0070] FIG. 3 shows the coupler 250 comprising guide 200 (shown in FIG. 2) attached to sucker rods 150 (guide 110 not shown), and the surface dynamics of the coupler 250. As shown in FIG. 3, the flared opening 221 facilitates entry of a fluid being pumped and this is pushed through the passageway 220 and out the flared exit 222. This structure is postulated to assist in fluid flow therebetween.

[0071] Shown in FIG 4 is a simplified cross-section of a sucker rod comprising a guide in relation to production tubing. Please note that the dimensions of the polymer matrix and pores are not to scale, and are only represented as such for illustrative purposes. It will be appreciated that the pores in the polymer matrix are significantly smaller.

[0072] Guide 400 is molded on sucker rod 450. The guide 400 comprises matrix 405 comprising polymer 410, and pores 420 which contain lubricant. In a downhole operation, the guide 400 and sucker rod 450 are rotated. As shown in FIG 4, the guide 400 contacts a production tubing 480, and zone 490 experiences friction. As the guide 400 experiences friction, the lubricant in the pores 420 is released to the surface to cause a lubricating effect.

[0073] Furthermore, it is postulated that the self-lubricating polymer may be utilized in production tubing. In this regard, the invention further resides in production tubing that comprises an inner lining formed of the self-lubricating polymer. The advantages of utilizing the self-lubricating polymer are similar to those mentioned hereinabove. However, in this case, it is the lining that provides the lubricating effect. This production tubing may be utilized with the above guides.

[0074] The production tubing may be formed by lining the internal surface thereof with self-lubricating polymer. The production tubing is utilized in the oil and gas industry. In particular, the production tubing is for use in, or when used in, downhole operations or well operations.

[0075] In addition to downhole operations, it is also postulated that a self- lubricated polymer can be utilized in a number of similar circumstances. For instance, it is postulated that a self-lubricating polymer could be utilized in machines where manual lubrication is difficult to practice because the part to be lubricated is difficult to reach (i.e. , 1-2 km below the surface) or in an area that is inaccessible.

[0076] It is postulated that a self-lubricated polymer can be utilized in a progressive cavity pump. In this regard, progressive cavity pumps can suffer significant wear when they run dry because the stator to steel rotating shaft contact area requires the pump fluid for lubrication. The use of a self-lubricating polymer alleviates this problem by virtue of the self-lubricating properties.

[0077] The invention also resides in a method of manufacturing a guide comprising the steps of: a. providing a polymer; b. mixing the polymer with one or more lubricants to form a compounded mixture; and c. forming a guide comprising a centralizer from the compounded mixture, to thereby form a guide comprising a centralizer that is formed of a self-lubricating polymer.

[0078] The guide, centralizer, self-lubricating polymer and components thereof are as substantially described herein.

[0079] In one embodiment, step c) is formed by extrusion or injection molding.

[0080] In an embodiment, the method further includes the step of compressing to form the guide.

[0081] In one embodiment, the method further includes the step of provide a sucker rod. In this embodiment, step c) further includes the step of forming one or more guides on the sucker rod.

[0082] In a certain embodiment, the method further includes the step of providing a coupler. In this embodiment step c) further includes the step of forming one or more guides on the coupler.

[0083] In one embodiment, the method may further include the step of providing a coupler comprising one or more recesses. In this embodiment, step c) further includes the step of forming a guide on a respective recess of the coupler. Preferably, the coupler comprises a single recess.

[0084] The invention also resides in a method of extracting fluid from a downhole including the step of: a. connecting a reciprocating pumping unit to a sucker rod; b. connecting a coupler to the sucker rod; c. connecting a further sucker rod to the coupler; d. repeating steps b) and c); and e. connecting a bottom sucker rod to the downhole pump assembly, wherein at least one coupler and/or sucker rod comprises the guide of the first aspect, to extract fluid from a downhole.

Examples

Example properties of the self-lubricating polymer

[0085] The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. Accordingly, this invention is intended to embrace all alternatives, modifications and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.