Patent Application
20120175131
The present invention relates to systems useful for centralizing a pump or downhole tool within tubing or piping.
Drilling and completing well bores in subterranean formations using tubular strings can be accomplished easier if the tubular string is prevented from fully eccentering and generally contacting or lying against the borehole wall. Devices, which are frequently referred to as centralizers, are used to reduce eccentricity or centralize the tubular string within the borehole. Centralizing devices are configured to economically meet a variety of drilling and completion applications.
Several types of devices have been used to centralize a tubular string in casing. For example, a bow spring has been used that includes a metal strip shaped like a hunting bow and can be attached to a tool or to the outside of casing. Bow-spring outer diameter (OD) centralizers are typically used to keep tubing in the center of a well bore or casing (i.e., centralized) prior to and during a cement job.
Although many centralizer devices are currently available, many of the centralizers have a minimum compressed diameter that limits the environments in which they can be deployed in. In particular, when equipment is contained within tubing, and has to pass through constricted diameters, it is difficult to find centralizers that can centralize the equipment within the tubing due to the compressed diameter of the tubing.
A need exists for a centralizer that can be used in applications in which a typical centralizer cannot be used. More specifically, a need exists for a centralizer that can be used for equipment that has to be passed through tubing that has a reduced diameter or constricted area.
In view of the foregoing, an apparatus and methods of spacing a downhole tool from walls of pipe or tubing are provided as embodiments of the present invention. Methods of centralizing a downhole tool within a string of well pipe are also provided as embodiments of the present invention.
For example, as an embodiment, a centralizing apparatus for spacing a pump from walls of tubing is provided. In this embodiment, the apparatus includes a plurality of casing pipe sections making up a casing pipe string; a tubing contained with the casing pipe string; a seating ring positioned on an inner wall of the tubing; a pump positioned within the tubing; and a centralizer having inwardly arched sides or inwardly arched bow springs so that an inner diameter of the centralizer increases from a longitudinal midpoint to a longitudinal end point of the centralizer. The centralizer has a smaller diameter than the tubing so that it can be positioned inside of the tubing downstream of the seating ring in a relaxed position so that when the seating ring and the pump pass through the centralizer, the inwardly arched sides expand towards an inner wall of the tubing to centralize and inhibit movement of the pump when deployed through the inwardly arched sides of the centralizer.
As another embodiment of the present invention, a method of centralizing a pump from walls of tubing contained within casing pipe string is provided. In this embodiment, the casing pipe string includes tubing that has a centralizer positioned therein. In an aspect, the centralizer can be a cylindrical sleeve. The centralizer has inwardly arched sides. The method embodiment includes the steps of moving the pump through the tubing from a relaxed position to a constricted position so that when the pump passes through the centralizer, the inwardly arched sides of the centralizer expand towards an inner wall of the tubing to centralize and inhibit radial movement of the pump.
So that the manner in which the above-recited features, aspects and advantages of the invention, as well as others that will become apparent, are attained and can be understood in detail, more particular description of the invention briefly summarized above can be had by reference to the embodiments thereof that are illustrated in the drawings that form a part of this specification. It is to be noted, however, that the appended drawings illustrate some embodiments of the invention and are, therefore, not to be considered limiting of the invention's scope, for the invention can admit to other equally effective embodiments.
Embodiments of the present invention relate to a through tubing conveyed application in which the deployed pump hangs off of a seating assembly that is deployed through tubing and set in a seating ring located on the tubing. The seating ring has a constricted diameter that will not allow for a conventional OD centralizer to pass through. The centralizer of the present invention can be used beneath the seating ring on the tubing string. By using the apparatus and methods of the present invention, the pump can pass through the centralizer of the present invention and be centralized and stabilized by it. The centralizer of the present invention can be used in both horizontal and vertical positions.
As indicated previously, centralizing devices exist and various designs are common, most common being the bow spring OD centralizer. A common problem with the OD centralizers is that they all have a minimum compressed diameter limiting the environments they can be deployed in. Embodiments of the present invention can be used to centralize and inhibit the radial motion of a pump or other equipment when deployed through a constricting ID and set in a larger ID than the constricted ID by putting the centralizer in the tubing and passing the pump or equipment through it. Embodiments of the present invention are intended for specific equipment that must pass through tubing that has a reduced diameter, to be stabilized, when a standard OD centralizer cannot be used as it will not pass through the constriction.
Turning to the figures,
In an aspect, the pump assembly 10 comprises a rotary pump. In a preferred embodiment, the rotary pump is a progressing cavity pump with a helical rotor 44 and a stator 42 contained within a housing 46, as shown in
As shown in
In an embodiment, the inner diameter centralizer 6 includes a formed cylindrical sleeve having a curved hourglass shape in cross-section, as shown in
In an embodiment, the inner diameter centralizer 6 includes a plurality of inwardly arched bow springs 35, as shown in
The inner diameter centralizer 6 can be constructed from an alloy metal that is flexible enough to yield or give when the pump or equipment is inserted therein. In an aspect, the alloy metal is flexible. Suitable alloy metals that can be used in embodiments of the present invention can include AISI 4340, spring-tempered 301 stainless steel, ASTM 1074/75, or combinations thereof. Other suitable construction materials for the inner diameter centralizer 6 will be apparent to those of skill in the art and are to be considered within the scope of the present invention.
In an aspect, the centralizer 6 can be used with various types of equipment. For example, the centralizer 6 can be used with various types of pumps, such as a rod-driven progressive cavity pump as shown in
As an embodiment of the present invention, a string of well pipe into which a downhole tool is lowered in a well is provided. In this embodiment, an improvement includes a centralizer 6 mounted in the well pipe to centralize the downhole tool. In an aspect, the centralizer 6 has inwardly arched sides defining a minimum inner diameter at a longitudinal midpoint while in an initial position. The inwardly arched sides can be flexed outward at the longitudinal midpoint to centralize the downhole tool as the downhole tool enters the centralizer 6.
In an aspect, the minimum inner diameter of the tubing 15 in the initial position is smaller than a maximum outer diameter of the downhole tool. In another aspect, the centralizer 6 has at least one end that is free to slide axially in the pipe and the tool flexes the arched sides outward.
Another embodiment that includes having a string of well pipe into which a downhole tool is lowered in a well is provided. In this embodiment, an improvement includes a centralizer 6 that is mounted in the well pipe to centralize the downhole tool. The centralizer 6 includes end rings that are connected by inwardly arched bow springs 35 defining an inner diameter at a longitudinal midpoint while in an initial position, as shown in
In an aspect, the minimum inner diameter of the tubing 15 in the initial position is smaller than a maximum outer diameter of the downhole tool.
In an aspect, the centralizer 6 has at least one end that is free to slide axially in the pipe and the tool flexes the arched sides outward. In an aspect, the centralizer 6 elongates as the tool moves into the centralizer.
As yet another embodiment of the present invention, an apparatus for pumping well fluid up well tubing is provided. In this embodiment, a rotary pump and a centralizer are included. The rotary pump has a maximum outer diameter small enough to lower the pump down the well tubing. The centralizer has inwardly arched bow springs defining a minimum inner diameter at a longitudinal midpoint. The centralizer has a maximum diameter that is small enough to mount the centralizer within the tubing so that when the pump passes into the centralizer, the inwardly arched bow springs flex outward to centralize the pump.
A method of centralizing a downhole tool within a string of well pipe is provided as an embodiment of the present invention. In this embodiment, a centralizer 6 is mounted within the well pipe. As with other embodiments, the centralizer 6 has inwardly arched sides. The tool is then lowered in the pipe and into the centralizer 6. The tool causes the inwardly arched sides to flex outward to centralize the tool.
Embodiments of the present invention can also include the step of landing the pump 10 within a seat while the pump 10 is at least partially within the centralizer 6. In an aspect, the tool or pump 10 is passed completely through the centralizer 6.
As yet another embodiment of the present invention, a method of centralizing a downhole tool within a string of well pipe is provided. In this embodiment, a centralizer 6 is mounted within the well pipe. The centralizer 6 has inwardly arched bow springs. The tool is then lowered in the pipe and into the centralizer 6. The pump causes the inwardly arched bow springs 35 to flex outward to centralize the tool.
Besides being contained within an inner diameter of the tubing 15, the inner diameter centralizer 6 can be part of a packer or other type of device, as will be understood by those of skill in the art. Other types of devices in which the inner diameter centralizer 6 can be used will be apparent to those of skill in the art and are to be considered within the scope of the present invention.
As an embodiment of the present invention, a centralizing apparatus for spacing a pump from walls of tubing 15 is provided. In this embodiment, the apparatus includes a plurality of casing pipe sections making up a casing pipe string; a tubing 15 contained with the casing pipe string; a seating ring positioned on an inner wall of the tubing 15; a pump positioned within the tubing 15; and a centralizer 6 having inwardly arched sides so that an inner diameter of the centralizer 6 increases from a longitudinal midpoint to a longitudinal end point of the centralizer 6. The centralizer 6 is an inner diameter centralizer. The centralizer 6 has a smaller diameter than the tubing 15 so that it can be positioned inside of the tubing 15 downstream of the seating ring in a relaxed position so that when the seating ring and the pump 10 pass through the centralizer 6, the inwardly arched sides expand towards an inner wall of the tubing 15 to centralize and inhibit radial movement of the pump 10 when deployed through the inwardly arched sides of the centralizer 6.
As another embodiment of the present invention, a method of centralizing a pump 10 from walls of tubing 15 contained within casing pipe string is provided. In this embodiment, the casing pipe string includes tubing 15 that has a centralizer positioned therein. The centralizer 6 has inwardly arched sides. The method embodiment includes the steps of moving the pump 10 through the tubing 15 from a relaxed position to a constricted position so that when the pump 10 passes through the centralizer 6, the inwardly arched sides of the centralizer 6 expand towards an inner wall of the tubing 15 to centralize and inhibit radial movement of the pump 10.
In an aspect, the centralizer 6 can be inserted within tubing 15. In another aspect, the centralizer 6 is not attached to the tubing 15.
To limit the movement of the centralizer in the tubing 15 a first upper stop collar 45 configured to be affixed to an inner surface of the tubing 15 and a second lower stop collar 50 spaced apart from the first stop collar 45 and configured to be affixed to an inner surface of the tubing 15 can also be included in embodiments of the present invention, as shown in
The centralizer 6 or cylindrical sleeve can be constructed of various types of materials. In an aspect, the centralizer comprises an alloy that is AISI 4340, spring-tempered 301 stainless steel, ASTM 1074/75, or combinations thereof. Other suitable materials of construction for the centralizer will be apparent to those of skill in the art and are to be considered within the scope of the present invention.
The shape of the centralizer 6 can be any shape that allows the centralizer to function as intended. For example, the centralizer 6 can be hour-glass shaped in cross-section, as shown in
Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.
Throughout this application, where patents or publications are referenced, the disclosures of these references in their entireties are intended to be incorporated by reference into this application, in order to more fully describe the state of the art to which the invention pertains, except when these reference contradict the statements made herein.
