Patent Grant
10907420
The present invention generally relates to oil pumps and couplings used therein and, more specifically, to a roller coupling apparatus and related method therefor.
In general terms, an oil well pumping system begins with an above-ground pumping unit, which creates the up and down pumping action that moves the oil (or other substance being pumped) out of the ground and into a flow line, from which the oil is taken to a storage tank or other such structure.
Below ground, a shaft or “wellbore” is lined with piping known as “casing.” Into the casing is inserted piping known as “tubing.” A string of sucker rods is inserted into the tubing. The string of sucker rods typically includes multiple individual sucker rods, which are typically 25-28 feet in length each. In addition, the rod string can include pony rods (also known as shooter rods, pups, and rod subs), which are sucker rods that are less than 25 feet in length. Pony rods can be of different lengths, such as two, four, six, or eight feet in length. The individual sucker rods are joined together with couplings to form the sucker rod string. According to American Petroleum Institute (API) specifications, such couplings are 4.5 to 5 inches in length. Standard couplings may typically be 4-6 inches in length. The sucker rod string can be up to or more than one mile in length and is ultimately, indirectly coupled at its north end to the above-ground pumping unit. The string of sucker rods is coupled at its south end indirectly to the subsurface oil pump itself, which is also located within the tubing, which is sealed at its base to the tubing. The sucker rod string couples to the oil pump at a coupling known as a 3-wing cage. A sinker bar, which is heavily-weighted to help maintain the tension in the sucker rod string particularly on the downstroke, can be positioned directly above the subsurface oil pump.
The subsurface oil pump has a number of basic components, including a barrel and a plunger. The plunger operates within the barrel, and the barrel, in turn, is positioned within the tubing. The north end of the plunger is typically connected to a valve rod or hollow valve rod, which moves up and down to actuate the pump plunger. The valve rod or hollow valve rod typically passes through a valve rod guide.
Beginning at the south end, subsurface oil pumps generally include a standing valve, which has a ball therein, the purpose of which is to regulate the passage of oil (or other substance being pumped) from downhole into the pump, allowing the pumped matter to be moved northward out of the system and into the flow line, while preventing the pumped matter from dropping back southward into the hole. Oil is permitted to pass through the standing valve and into the pump by the movement of the ball off of its seat, and oil is prevented from dropping back into the hole by the seating of the ball.
North of the standing valve, coupled to the sucker rod, is a traveling valve. The purpose of a conventional traveling valve is to regulate the passage of oil from within the pump northward in the direction of the flow line, while preventing the pumped oil from slipping back down in the direction of the standing valve and hole.
In use, oil is pumped from a hole through a series of “downstrokes” and “upstrokes” of the oil pump, wherein these motions are imparted by the above-ground pumping unit. During the upstroke, formation pressure causes the ball in the standing valve to move upward, allowing the oil to pass through the standing valve and into the barrel of the oil pump. This oil will be held in place between the standing valve and the traveling valve. In the conventional traveling valve, the ball is located in the seated position. It is held there by the pressure from the oil that has been previously pumped. The oil located above the traveling valve is moved northward in the direction of the 3-wing cage at the end of the oil pump.
During the downstroke, the ball in the conventional traveling valve unseats, permitting the oil that has passed through the standing valve to pass therethrough. Also during the downstroke, the ball in the standing valve seats, preventing the pumped oil from slipping back down into the hole.
The process repeats itself again and again, with oil essentially being moved in stages from the hole, to above the standing valve and in the oil pump, to above the traveling valve and out of the oil pump. As the oil pump fills, the oil passes through the 3-wing cage and into the tubing. As the tubing is filled, the oil passes into the flow line, from which the oil is taken to a storage tank or other such structure.
Unlike typical wellbores of the past, which are typically drilled in relatively straight vertical lines, a current drilling trend is for wellbores to be drilled vertically in part and then horizontally in part, resulting in wellbores that have some curvature or “deviation.” Such wells may commonly be referred to as “deviated” wells. When drilling deviated wells, drillers typically drill vertically for some distance (e.g. one mile), through the upper zone and down to the bedrock, and then transition to drilling horizontally. One advantage to drilling wellbores in this configuration is that the horizontal area of the well typically has many more perforations in the casing, which allows for more well fluid to enter the wellbore than with typical vertical casing wells. This, in turn, allows for more well fluid to be pumped to the surface. It should be understood that while conventional wells are typically drilled vertically, conventional wells can also have some moderate curvature or deviation in the wellbore.
Horizontal wells may typically be drilled at an angle of roughly ten to twelve degrees over roughly 1000 feet to allow for a gradual slope. This results in approximately one degree of deviation for every 100 feet. A problem that occurs when drilling such wells, particularly when they are drilled relatively fast, is that the wells are not drilled perfectly, resulting in crooked wellbores. Such wells may have many slight to extreme deviations in the drill hole, which would create a non-linear configuration. When the deviated well is completed to depth, the drill pattern is positioned horizontally to drill. The pump, coupled to the sucker rod string, then must be lowered from the surface through all of the deviations of the wellbore down to the horizontal section of the well where it would be placed in service.
There are a number of problems that are regularly encountered during oil pumping operations. Oil that is pumped from the ground is generally impure, and includes water, gas, and solid impurities such as sand and other debris. The presence of solids can cause major damage to the pump components, thus reducing the run cycle of the pump, reducing revenue to the operator, and increasing expenses. For example, during pumping operations, scale, paraffin, or other solids buildup can accumulate in various areas of the tubing. This can create a very narrow tolerance between the pumping system's various subsurface components (including, for example, rods, rod couplings, and sinker bars) and the tubing which, in turn, can cause wear and damage to these subsurface components and tubing during pumping operations, especially when they are dragged across the interior diameter surface of the tubing. Further, particularly where deviations are present (whether in conventional or horizontal wells), the rod couplings can make contact with the tubing, also causing wear and damage to the couplings and tubing during pumping operations. In such situations, the rod couplings and tubing must then be repaired or replaced, which is both time consuming and expensive and, further, can result in loss of revenue to the well operators while the well is non-operational.
One solution to address these problems has been to provide wheeled couplings/rod guides. However, presently known wheeled couplings/rod guides suffer from several shortcomings in various areas of the design. For example, such wheeled couplings/rod guides are typically around 28 inches in length, which falls outside of the API specification range for rod couplings. Such wheeled couplings/rod guides require manual installation with hand wrenches or other hand tools. This method of installation is time consuming and can result in inconsistent torque application during coupling installation. This can cause loosening of the couplings and rod parts during pumping operations, leading to coupling failure and expensive well downtime. As a further example, the wheels of presently known wheeled couplings/rod guides are typically fitted through openings in the body of the coupling/rod guide and centered vertically in the body, such that portions of each wheel protrude from opposing sides of the body. This configuration can be problematic. For example, in the event that the wheel encounters a high spot in the tubing due to scale or paraffin or other solids buildup, the wheel will seize and drag through the high spot, causing damage to the wheel by flattening its protruding portions.
The present invention addresses these problems encountered in prior art pumping systems, and provides other, related, advantages.
In accordance with one embodiment of the present invention, a roller coupling apparatus is disclosed. The roller coupling apparatus comprises, in combination: a body having a threaded north end and a threaded south end; and a plurality of wheels rotatably coupled to the body; wherein the wheels are positioned radially around the body; and wherein the wheels are spaced-apart equidistantly from each other.
In accordance with another embodiment of the present invention, a roller coupling apparatus is disclosed. The roller coupling apparatus comprises, in combination: a body comprising: a threaded north end; a threaded south end; a plurality of wheel wells positioned between the north end and the south end; and a plurality of aligned pairs of openings; a plurality of wheels rotatably coupled to the body, a plurality of inserts, each insert having an opening configured to receive an axle, and wherein each insert is configured to be positioned in an opening in one of the plurality of wheels; a plurality of axles, wherein each axle is configured to be positioned through one of the plurality of aligned pairs of openings in the body and in one of the plurality of inserts; wherein each wheel well of the plurality of wheel wells is configured to receive one of the plurality of wheels; wherein the wheels are positioned radially around the body; and wherein the wheels are spaced-apart equidistantly from each other.
In accordance with another embodiment of the present invention, a method for protecting pumping system components from wear during pumping operations is disclosed. The method comprises the steps of: providing a pumping unit; providing a roller coupling apparatus comprising, in combination: a body having a threaded north end and a threaded south end; and a plurality of wheels rotatably coupled to the body; wherein the wheels are positioned radially around the body; and wherein the wheels are spaced-apart equidistantly from each other, providing a first threaded component; providing a second threaded component; securing together the first and second threaded components by threadably coupling the north end of the roller coupling apparatus to a south end of the first threaded component and threadably coupling the south end of the roller coupling apparatus to a north end of the second threaded component to form an assembly; positioning the assembly within tubing of a wellbore; causing the assembly to move up with an upstroke of the pumping unit and down with a downstroke of the pumping unit; and during the movement with the upstroke and the downstroke, causing the wheels of the roller coupling apparatus to contact and roll along an interior diameter surface of the tubing.
The present application is further detailed with respect to the following drawings. These figures are not intended to limit the scope of the present application, but rather, illustrate certain attributes thereof.
The description set forth below in connection with the appended drawings is intended as a description of presently preferred embodiments of the disclosure and is not intended to represent the only forms in which the present disclosure may be constructed and/or utilized. The drawing figures are not necessarily drawn to scale and certain figures can be shown in exaggerated or generalized form in the interest of clarity and conciseness. The description sets forth the functions and the sequence of steps for constructing and operating the disclosure in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and sequences may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of this disclosure.
Referring first to
Beginning at the top portion of
Continuing southward in the drawing figures, as seen in this embodiment, the body 12 further includes a plurality of wheel wells 20, each of which is configured to house one of a plurality of wheels 30, as described further herein. Each wheel well 20 can be substantially semi-circularly shaped and can comprise a concave wall configured to correspond to the shape of each wheel 30. With this configuration, a portion of each wheel 30 can be positioned within each wheel well 20. This configuration helps to protect the wheels 30 from damage that could otherwise be caused by the narrow tolerance between the roller coupling apparatus 10 exterior and tubing interior due to buildup of scale, paraffin or other solids, since the wheels 30 will continue to roll in such solids buildup areas. This is in contrast to presently known wheeled couplings/rod guides, in that the wheels of such couplings/rod guides can seize and become dragged through areas of the tubing having solids buildup, flattening the wheels. Each wheel well 20 can have an overall diameter that is greater than an exterior diameter of each wheel 30. In this way, each wheel 30 can be suspended when positioned in each wheel well 20 without contacting the interior surface of the wheel well 20. As best seen in
Referring now to
Referring again to
In one embodiment, the body 12 can be approximately five inches in length. However, it should be understood that the length of the body 12 may deviate from this dimension, as desired. For example, the roller coupling apparatus 10 could have a length longer than five inches, in order to accommodate additional sets of three wheels 30 each, as described further herein, or as may be required for heavier rod loads, severe deviation of the wellbore configuration, and the like. As another example, the roller coupling apparatus 10 could have a length slightly less than five inches.
Referring now to
Referring now to
Referring now to
Each wheel 30 is rotatably coupled to the body 12 by axle 50, which is inserted through aligned openings 28 and 42 in the body 12 and insert 40, respectively. Referring now to
As best seen in
Referring now to
In this embodiment, the body 12 includes six wheel wells 20, corresponding to six wheels 30 (see
As seen from a review of
While non-grooved wheels 30 are shown in the embodiment in
As described herein, each roller coupling apparatus 10 and 100 is configured to be coupled at its north end 14 to the south end of a rod, and at its south end 22 to the north end of another rod or to a sinker bar, thereby connecting the two rods together, or connecting a rod and a sinker bar together, to form an assembly. Multiple roller coupling apparatuses 10 and 100 may be utilized to connect multiple rods together, thereby forming a rod string of various lengths, as may be needed depending on the depth of the well and length of the wellbore in which the roller coupling apparatuses 10 and 100 are employed.
The roller coupling apparatus 10 can be installed in the same manner as a conventional rod coupling. In this regard, the roller coupling apparatus 10 can be installed with hydraulic power tongs on the pulling unit. Such tongs can be set so that an equal amount of torque is applied to each roller coupling apparatus 10 utilized in a given pumping operation, which can include multiple roller coupling apparatuses 10 as may be needed. This method of installation is economical, efficient, and provides torque consistency among the rod couplings. Compared to manual installation, this method of installation is faster in that it can require a few seconds to install rod couplings with hydraulic power tongs, as opposed to the minutes that may be required for manual installation.
Unlike the roller coupling apparatus 10, the roller coupling apparatus 100, with its multiple sets of wheels 30, is not suited for installation with hydraulic power tongs on the pulling unit, due to its longer body length. Instead, the roller coupling apparatus 100 can be installed manually with hand wrenches or other hand tools.
In operation, the roller coupling apparatus 10 or 100, being part of the rod string, will move up with the upstroke of the pumping unit and down with the downstroke of the pumping unit. As the roller coupling apparatus 10 or 100 moves within in the wellbore, wheels 30 make contact with and roll along the interior diameter surface of the tubing. This prevents the body 12 exterior from contacting the tubing interior, preventing surface-to-surface wear of the body 12 exterior and tubing interior, including in deviated areas of the wellbore. In turn, with the wheels 30 contacting the tubing, this helps to keep the rods from contacting the tubing. This prolongs the life of the rod assembly and tubing.
The roller coupling apparatus 10 or 100 that includes one or more wear grooves 35 on wheels 30 provides further advantages. In this regard, wear grooves 35 allow the operator to determine the wear undergone by the wheels 30 and provide an indication of when the roller coupling apparatus(es) 10 or 100 should be repaired or replaced. The operator can inspect the wheels 30 for wear when the well experiences down-time and the downhole pumping system components are retrieved for repair. This will enable the operator to determine the location of the most severe wear areas in the wellbore, by reviewing the wear patterns on the wheels 30 including where the grooves 35 have become worn. The operator can then make an informed decision, based on quantitative data, to place additional roller coupling apparatuses 10 or 100 in the severe wear areas, by replacing single sucker rods with multiple, shorter, pony rods, which would allow for more roller coupling apparatuses 10 or 100 to be installed in wellbore locations experiencing severe wear. Such wear may occur due to such reasons as rod loading in deviated areas of the wellbore or rod buckling due to fluid pounding caused by the pump barrel not completely filling with fluid in between pump strokes. This causes the rods to buckle in the tubing, particularly when the traveling valve passes through an empty space in the barrel and then slams into the fluid area. This results in a large shock throughout the rod assembly, causing damage to the rods and tubing. Utilizing the roller coupling apparatus 10 or 100 in the rod assembly lessens the damage to the rod assembly and tubing.
The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. While embodiments of the disclosure have been described in terms of various specific embodiments, those skilled in the art will recognize that the embodiments of the disclosure may be practiced with modifications without departing from the spirit and scope of the invention.
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| UPC Global, “Wheeled Rod Guides (R),” https://www.upcoglobal.com/images/brochures/Brochure_OFI_v2.pdf, accessed Jul. 8, 2019, 6 pages. |
