Patent Application
20130126187
The present invention relates to the field of downhole tools, and in particular to an entry tube system for use in a gravel pack.
The invention generally relates to shunt tubes used in subsurface well completions, and particularly to systems that provide improved fluid entry into shunt tubes.
Conduits providing alternate or secondary pathways (sometimes referred to as shunt tubes) for fluid flow are commonly used in well completions. The shunt tubes allow fluid to flow past and emerge beyond a blockage in a primary passageway. In some prior art embodiments, the single entrance to a shunt tube could be covered, blocked, or otherwise become inaccessible to the fluid, thereby preventing the shunt tube from performing its intended function. Such blockage could occur, for example, when the shunt tube happened to be positioned on the bottom wall of a horizontal bore. Other prior art embodiments provided multiple pathways by which fluid can enter alternate pathway conduits, spacing entrance tubes to prevent all of them from being simultaneously obstructed, covered, or otherwise blocked, but spaced entrance tubes limit the available open area to flow. Therefore, there is a continuing need for improved entrance mechanisms to provide improved access to the shunt tubes.
Full or nearly full circumference fluid flow is provided into an entry tube, allowing fluid to enter a chamber and flow to one or more shunt tubes connected to a downhole end of the entry tube. The fluid can enter the opening in any orientation of the entry tube system, and flow through the chamber to be directed into the shunt tubes.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of apparatus and methods consistent with the present invention and, together with the detailed description, serve to explain advantages and principles consistent with the invention. In the drawings,
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without these specific details. References to numbers without subscripts or suffixes are understood to reference all instance of subscripts and suffixes corresponding to the referenced number. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment.
As used herein uphole generally means towards the surface of the well, while downhole means away from the surface of the well, regardless of the physical orientation of the wellbore. In a horizontally drilled well, for example, uphole may indicate a horizontal direction or a vertical direction, depending on the position at which the indication is made.
The entry tube system 100 may be manufactured at any desired diameter and length.
As illustrated in
The guide member 120 may extend from any first position along the inner mandrel 110 to the downhole end of the chamber 170.
One or more shunt tubes 130 are disposed through the downhole end section 150, with the end of the shunt tubes 130 opening into the chamber 170. The shunt tubes 130 serve as exit tubes for the entry tube system 100. Although two shunt tubes 130 are illustrated in
The uphole end section 160 is preferably formed with a rounded, beveled, or otherwise angled configuration in an uphole direction, to minimize the possibility of damaging or blocking the uphole end section 160 by contact with irregularities in the wellbore when the entry tube system is moved in an uphole direction. Similarly, the downhole end section 150 is preferably formed with a rounded, beveled, or otherwise angled configuration in a downhole direction, to minimize the possibility of damaging or blocking the downhole end section 150 by contact with irregularities in the wellbore when the entry tube system is moved in an downhole direction. The shapes of the uphole end section 160 and downhole end section 150 as illustrated in
The outer diameter of the uphole end section 160, the downhole end section 150, and the cover section 140 may be substantially equal. As best illustrated in
Although illustrated in
The inner mandrel 110 is illustrated in
The inner mandrel 110 may extend through or to an opening (not shown) in the downhole end section 150, allowing fluid flow through the inner mandrel 110 to other regions of the completion string as desired. In one embodiment, the inner mandrel 110 may be sized to slip over a tubular of a completion string (not shown), allowing the entry tube system 100 to be positioned at any desired position on the completion string. In another embodiment, the downhole end section 150, the uphole end section 160, and the guide member 120 may be movably positionable relative to a longitudinal axis of the inner mandrel. In an alternate embodiment, connectors (not shown) may be formed in the uphole end section 160 and the downhole end section 150 for threadedly or otherwise connecting the uphole end section 160 and the downhole end section 150 to portions of the completion string. In yet another alternate embodiment, connectors (not shown) may be formed on either end of the inner mandrel 110 for connecting the inner mandrel 110 to other portions of the completion string. Where connectors are used to connect the entry tube system 100 to other portions of the completion string, any desired type of connector known to the art may be used. In one embodiment, the inner mandrel 110 may be a portion of base pipe onto which the other elements may be positioned, as described in more detail in the discussion of
The guide member 120 is formed with a leading surface 124 that is generally tapered from the bottom of the inner mandrel 110 at the uphole end of the inner mandrel 110 to the top of the inner mandrel 110 at the downhole end of the inner mandrel 110. The taper of the leading surface 124 may be straight or curved as desired, such as a helical taper. The tapered leading surface 124 directs fluid entering through the uphole end section 160 into the chamber 170 around the inner mandrel 110 towards the ends of the shunt tubes 130, regardless of the orientation of the entry tube system 100, as illustrated by example paths 300 in
In one embodiment, the guide member 120 may be formed of a material harder than the inner mandrel 110, to reduce erosion from the fluid guided into the shunt tubes 130 by the tapered surface 124.
The taper of the tapered surface 124 may be as steep as desired, although a gradual taper is preferred to prevent fluid flow problems.
In one embodiment, channels 122 may be formed in the guide member 120 at a proximal to the shunt tubes 130 to further direct the flow of fluid through the channels 122 into the shunt tubes 130. In such an embodiment, an equal number of channels 122 and shunt tubes 130 may be used.
In one embodiment, a nose element 126 of the guide member 120 may extend beyond the uphole edge of the inner mandrel 110 towards an uphole end of the uphole end section 160, to allow welding or otherwise affixing the guide member 120 to the uphole end section 160. In one embodiment, the inner mandrel 110 is welded or otherwise affixed to the guide member 120, but is not welded or otherwise affixed to the uphole end section 160. In one embodiment, the guide member 120 may be welded or otherwise affixed to the downhole end section 150.
In one embodiment, the uphole end of the inner mandrel 110 may be configured to key the inner mandrel 110 to the downhole end of the uphole end section 160, providing additional support.
In another embodiment, the guide member 120 may be omitted. In such an embodiment, the fluid would simply flow into the chamber 170 around the inner mandrel 110 into the shunt tubes 130, but would not be guided toward the shunt tubes as illustrated in
In yet another embodiment, the inner mandrel 110 may be omitted. In such an embodiment, the chamber 170 is formed by the cover section 140, and the uphole end section 160 and downhole end section 150 may be connected to other portions of the completion string using any connection technique known to the art. In a further embodiment, the guide member 120 may be positioned in the chamber 170 without the inner mandrel 110, wherein the tapered surface 124 is a solid tapered surface, instead of being formed around the circumference of the inner mandrel 110 as illustrated in
In another embodiment, instead of extending into the chamber 170 as illustrated in
In one embodiment, the nose element 126 may be omitted and the inner mandrel 110 may be sealed to the inner diameter of the uphole end section 160 along a portion of the circumference of the inner mandrel 110. In another embodiment, the inner mandrel 110 may be welded or otherwise affixed along that portion of the circumference of the inner mandrel 110 to provide additional support.
Because shunt tubes 130 are alternate pathway conduits, used to convey fluid past a blockage, the entry tube system 100 may include one or more elements to restrict fluid from entering the entry tube system 100 through the uphole end section 160 into the chamber 170 until shunt tubes 130 are needed. In one embodiment, restriction members (not shown) such as valves or rupture discs may be placed across the uphole opening of the uphole end section 160, configured to allow fluid flow only if the pressure exceeds a predetermined threshold pressure. By using rupture discs, for example, fluid flow through the entry tube system 100 into the shunt tubes 130 would be prevented under normal operating pressures. However, if a blockage (bridging) occurred, pressure in the annular region could be increased until one or more discs burst at a predetermined pressure, allowing fluid to pass.
In operation, a fluid such as a gravel slurry or fracturing fluid is pumped into an annular region between a production zone of the well and the completion string. In some embodiments, the fluid may be initially pumped through a work string down to a crossover mechanism which diverts the flow into the annular region some distance below the well surface. When the fluid encounters the entrance tube system 100, in the absence of restrictor devices the fluid flows through the inlet 200 and through the chamber 170 into the shunt tubes 130. Because the inner mandrel 110 is of a smaller diameter than the internal diameter of the uphole end section 160, there is a fluid path through inlet 200 into chamber 170, and a guided fluid path in chamber 170 into the shunt tubes 130. That insures the fluid can pass into shunt tubes 130 regardless of the orientation of the entry tube system 100 in the wellbore. In those embodiments employing restrictor devices, the fluid may be restricted from passing into the chamber 170 until the restriction devices are defeated.
The relative size of the outer diameter of inner mandrel 110 to the inner diameter of the uphole end section 160 may be determined as desired, to vary the size of the inlet around the inner mandrel 110 into the chamber 170.
In one embodiment, channels or ribs may be formed longitudinally on the inner mandrel 110 to further guide the fluid toward the shunt tubes 130.
As illustrated in
In this embodiment, multiple inlets 920 into the chamber 170 are formed by the placement of the integral support members 915 of the uphole end section 910. The integral support members 915 are preferably sloped in a downhole direction where they extend radially inward from the circumference of the uphole end section 910. Although as best illustrated in
As best illustrated by
In this embodiment, a stop ring 1320 is disposed on the inner mandrel 110 at a predetermined location, and is affixed by welding or other techniques to the inner mandrel 110. The downhole end section 1330 is configured to mate with the stop ring 1320, allowing the entry tube system 1300 to be slid along the inner mandrel 110 to the stop ring 1320, then welded or otherwise affixed to the stop ring 1320. Affixing the downhole end section 1330 to the stop ring 1320 provides support to keep the uphole end section 1310 and cover section 140 spaced away from the inner mandrel 110, forming a single full-circumference inlet 1410 about the inner mandrel 110 into the chamber 170, as best illustrated in
Although as illustrated in
As best illustrated in
In this embodiment, the keyed member 1720 provides additional support, but is sized and configured to minimize interference with fluid flowing through the single inlet 1810 into the chamber 170 formed between the uphole end section 1710 and the inner mandrel 110, as best illustrated in
As best illustrated in
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments may be used in combination with each other and elements of one embodiment may be combined with elements of other embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention therefore should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.”
