Abstract:
The present invention generally provides apparatuses and methods for an improved shunt nozzle which is part of an alternative pathway for a slurry to by-pass an obstruction such as a sand bridge during gravel packing. In one embodiment, the nozzle has a hardened insert that lines a surface of a hole in the shunt and seats on a surface of a wall proximate the hole, thereby restraining movement of the insert relative to the shunt for welding an outer jacket to the shunt.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 10/876,249, filed Jun. 23, 2004, now abandoned which is herein incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   Embodiments of the present invention generally relate to methods and apparatuses for providing a more uniform gravel pack in a wellbore. More particularly, the invention relates to methods and apparatuses for providing an improved nozzle for a shunt tube. 
   2. Description of the Related Art 
   Hydrocarbon wells, especially those having horizontal wellbores, typically have sections of wellscreen comprising a perforated inner tube surrounded by a screen portion. The purpose of the screen is to block the flow of unwanted materials into the wellbore. Despite the wellscreen, some contaminants and other unwanted materials like sand, still enter the production tubing. The contaminants occur naturally and are also formed as part of the drilling process. As production fluids are recovered, the contaminants are also pumped out of the wellbore and retrieved at the surface of the well. By controlling and reducing the amount of contaminants that are pumped up to the surface, the production costs and valuable time associated with operating a hydrocarbon well will likewise be reduced. 
   One method of reducing the inflow of unwanted contaminants is through gravel packing. Normally, gravel packing involves the placement of gravel in an annular area formed between the screen portion of the wellscreen and the wellbore. In a gravel packing operation, a slurry of liquid, sand and gravel (“slurry”) is pumped down the wellbore where it is redirected into the annular area with a cross-over tool. As the gravel fills the annulus, it becomes tightly packed and acts as an additional filtering layer along with the wellscreen to prevent collapse of the wellbore and to prevent the contaminants from entering the stream of production fluids pumped to the surface. Ideally, the gravel will be uniformly packed around the entire length of the wellscreen, completely filling the annulus. However, during gravel packing, the slurry may become less viscous due to loss of fluid into the surrounding formations or into the wellscreen. The loss of fluid causes sand bridges to form. Sand bridges are a wall bridging the annulus and interrupting the flow of the slurry, thereby preventing the annulus from completely filling with gravel. 
   The problem of sand bridges is illustrated in  FIG. 1 , which is a side view, partially in section of a horizontal wellbore with a wellscreen therein. The wellscreen  30  is positioned in the wellbore  14  adjacent a hydrocarbon bearing formation therearound. An annulus  16  is formed between the wellscreen  30  and the wellbore  14 . The Figure illustrates the path of gravel  13  as it is pumped down the production tubing  11  in a slurry and into the annulus  16  through a crossover tool  33 . 
   Also illustrated in  FIG. 1  is a formation including an area of highly permeable material  15 . The highly permeable area  15  can draw liquid from the slurry, thereby dehydrating the slurry. As the slurry dehydrates in the permeable area  15  of the formation, the remaining solid particles form a sand bridge  20  and prevent further filling of the annulus  16  with gravel. As a result of the sand bridge, particles entering the wellbore from the formation are more likely to enter the production string and travel to the surface of the well. The particles may also travel at a high velocity, and therefore more likely to damage and abrade the wellscreen components. 
   In response to the sand-bridging problem, shunt tubes have been developed creating an alternative path for gravel around a sand bridge. According to this conventional solution, when a slurry of sand encounters a sand bridge, the slurry enters an apparatus and travels in a tube, thereby bypassing the sand bridge to reenter the annulus downstream. 
     FIG. 2  is a sectional view of a prior art nozzle assembly  50  disposed on a shunt tube  55 . The construction for an exit point from the shunt tube  55  involves drilling a hole  80  in the side of the tube, typically with an angled aspect, in approximate alignment with the slurry flow path  75 , to facilitate streamlined flow. The nozzle assembly  50 , having a tubular outer jacket  65 , and a tubular carbide insert  60 , is held in alignment with the drilled hole  80 , and the outer jacket is attached to the tube with a weld  70 , trapping the carbide insert  60  against the tube  55 , in alignment with the drilled hole  80 . The nozzle assembly  50  also has an angled aspect, pointing downward and outward, away from the tube  55 . Sand slurry exiting the tube  55  through the nozzle  50  is routed through the carbide insert  60 , which is resistant to damage from the highly abrasive slurry. 
   Both the method of constructing the nozzle  50  and the nozzle itself suffer from significant drawbacks. Holding the nozzle assembly  50  in correct alignment while welding is cumbersome. A piece of rod (not shown) must be inserted through the nozzle assembly  50 , into the drilled hole  80 , to maintain alignment. This requires time, and a certain level of skill and experience. During welding, the nozzle assembly  50  can shift out of exact alignment with the drilled hole in the tube due to either translational or rotational motion. After welding, exact alignment between the nozzle  50  and the drilled hole  80  is not assured. Because the carbide insert  60  actually sits on the surface of the tube  55 , the hole  80  in the tube wall is part of the exit flow path  75 . Abrasive slurry, passing through the hole, may cut through the relatively soft tube  55  material, and bypass the carbide insert  60  entirely, causing tube failure. 
   Therefore, there exists a need for an improved nozzle assembly for a shunt tube and a method for attaching the nozzle to the shunt tube. 
   SUMMARY OF THE INVENTION 
   The present invention generally provides apparatuses and methods for an improved shunt nozzle which is part of an alternative pathway for a slurry to by-pass an obstruction such as a sand bridge during gravel packing. 
   In one aspect of the invention, a nozzle assembly is provided for use in a tool having a hole through a wall of the tool, comprising: an insert configured to at least partially line the hole and seat on a surface of the wall proximate the hole, thereby restraining movement of the insert relative to the tool. 
   Preferably, the insert comprises a first portion; and a shoulder portion between the first portion and a lip portion, wherein the shoulder portion is configured to seat on the surface of the wall proximate the hole. Further, the lip portion may be configured to at least partially line the hole and comprise a tapered portion that is configured to form an interference fit with a surface of the wall defining the hole. The nozzle assembly may further comprise a jacket having a bore therethrough and a recessed portion for receiving the first portion of the insert. The nozzle may be constructed from a relatively hard material, such as a carbide material. The insert may have a bore therethrough and may be configured so that a center of the bore will be substantially aligned with a center of the hole when the insert is seated on the wall of the tool. 
   In another aspect, a nozzle assembly is provided for use in a tool having a hole through the wall of the tool, comprising: an insert having a bore therethrough, wherein the insert is configured to mate with the tool so that a center of the bore is held in substantial alignment with a center of the hole. 
   In another aspect, a method is provided for attaching a nozzle assembly to a tool, comprising: inserting an insert into a hole in a wall of the tool until the insert seats on a surface of the wall proximate the hole, thereby lining at least a portion of the hole with the insert and restraining movement of the insert relative to the tool. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted; however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
       FIG. 1  is a side view, partially in section of a horizontal wellbore with a wellscreen therein. 
       FIG. 2  is a sectional view of a prior art flow nozzle configuration. 
       FIG. 3  is a top end view of a gravel pack apparatus, according to one embodiment of the present invention, positioned within a wellbore.  FIG. 3A  is a sectional view, taken along line  3 A- 3 A of  FIG. 3 , of the gravel pack apparatus positioned within wellbore adjacent a highly permeable area of a formation.  FIG. 3B  is a schematic of one of the shunts showing the placement of nozzles along the shunt. 
       FIG. 4  is a sectional view of a nozzle assembly, according to one embodiment of the present invention, disposed on one of the shunts.  FIG. 4A  is an enlargement of a portion of  FIG. 4  indicated by the dotted oval labeled  4 A. 
       FIG. 5  is a sectional view of a nozzle assembly, according to another embodiment of the present invention, disposed on one of the shunts. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 3  is a top end view of a gravel pack apparatus  100 , according to one embodiment of the present invention, positioned within wellbore  14 .  FIG. 3A  is a sectional view, taken along line  3 A- 3 A of  FIG. 3 , of the gravel pack apparatus  100  positioned within wellbore  14  adjacent the highly permeable area  15  of a formation. Although apparatus  100  is shown in a horizontal wellbore, it can be utilized in any wellbore. Apparatus  100  may have a “cross-over” sub  33  (see  FIG. 1 ) connected to its upper end which, in turn, is suspended from the surface on a tubing or work string (not shown). Apparatus  100  can be of one continuous length or it may consist of sections (e.g. 20 foot sections) connected together by subs or blanks (not shown). Preferably, all components of the apparatus  100  are constructed from a low carbon or a chrome steel unless otherwise specified; however, the material choice is not essential to the invention. 
   Apparatus  100  includes a wellscreen assembly  105 . As shown, wellscreen assembly  105  comprises a base pipe  110  having perforations  120  through a wall thereof. Wound around an outer side of the base pipe  110  is a wire wrap  125  configured to permit the flow of fluids therethrough while blocking the flow of particulates. Alternatively, wellscreen assembly  105  may be any structure commonly used by the industry in gravel pack operations which permit flow of fluids therethrough while blocking the flow of particulates (e.g. commercially-available screens, slotted or perforated liners or pipes, screened pipes, prepacked screens and/or liners, or combinations thereof). 
   Also disposed on the outside of the base pipe  110  are two shunts  145 . The number and configuration of shunts  145  is not essential to the invention. The shunts  145  may be secured to the base pipe  110  by rings (not shown). At an upper end (not shown) of the apparatus  100 , each shunt  145  is open to the annulus. Each one of the shunts  145  is rectangular with a flow bore therethrough; however, the shape of the shunts is not essential to the invention. Disposed on a sidewall of each shunt is a nozzle  150 . 
     FIG. 3B  is a schematic of one of the shunts  145  showing the placement of nozzles  150  along the shunt  145 . As shown, a plurality of nozzles  150  are disposed axially along each shunt  145 . Each nozzle  150  provides slurry fluid communication between one of the shunts  145  and an annulus  16  between the wellscreen  105  and the wellbore  14 . As shown, the nozzles  150  are oriented to face an end of the wellbore  14  distal from the surface (not shown) to facilitate streamlined flow of the slurry  13  therethrough. 
   Disposed on the outside of the base pipe  110  are a plurality of centralizers  130  that can be longitudinally separated from a length of the base pipe  110  that has the perforations  120  and the wire wrap  125 . Additionally, a tubular shroud  135  having perforations  140  through the wall thereof can protect shunts  145  and wellscreen  105  from damage during insertion of the apparatus  100  into the wellbore. The perforations  140  are configured to allow the flow of slurry  13  therethrough. 
   In operation, apparatus  100  is lowered into wellbore  14  on a workstring and is positioned adjacent a formation. A packer  18  (see  FIG. 1 ) is set as will be understood by those skilled in the art. Gravel slurry  13  is then pumped down the workstring and out the outlet ports in cross-over sub  33  to fill the annulus  16  between the wellscreen  105  and the wellbore  14 . Since the shunts  145  are open at their upper ends, the slurry  13  will flow into both the shunts and the annulus  16 . As the slurry  13  loses liquid to the high permeability portion  15  of the formation, the gravel carried by the slurry  13  is deposited and collects in the annulus  16  to form the gravel pack. If the liquid is lost to a permeable stratum  15  in the formation before the annulus  16  is filled, the sand bridge  20  is likely to form which will block flow through the annulus  16  and prevent further filling below the bridge. If this occurs, the gravel slurry will continue flowing through the shunts  145 , bypassing the sand bridge  20 , and exiting the various nozzles  150  to finish filling annulus  16 . The flow of slurry  13  through one of the shunts  145  is represented by arrow  102 . 
     FIG. 4  is a sectional view of a nozzle assembly  150 , according to one embodiment of the present invention, disposed on one of the shunts  145 .  FIG. 4A  is an enlargement of a portion of  FIG. 4  indicated by the dotted oval labeled  4 A. The nozzle assembly  150  comprises an insert  160  with a flow bore therethrough, that features a lip  160   a  that extends into a drilled hole  170  in a wall of the shunt  145 , thereby lining a surface  145   a  of the shunt wall that defines the hole  170 . Preferably, the insert is made from a hard material, e.g., carbide, relative to the material of the shunt  145 . As shown, the length of the lip  160   a  is substantially the same as the wall thickness of the shunt  145 . However, the lip  160   a  may be substantially longer or shorter than the wall thickness of the shunt  145 . Preferably, the lip  160   a  features a slight taper on an outer surface  160   c  for seating on the surface  145   a  of the shunt wall, thereby providing a slight interference fit; however, the taper is not essential to the invention. The insert  160  also features a shoulder  160   b  which seats with a surface  145   b  of the shunt wall proximate the hole  170 , thereby providing a rigid stop limiting the depth to which lip  160   a  can penetrate the shunt  145 . An outer jacket  155  having a flow bore therethrough and a recess configured to receive a portion of the insert  160  may then be easily slipped on and secured to the shunt  145  with a weld  165 . Preferably, the outer jacket  155  and insert  160  are tubular members; however, their shape is not essential to the invention. Preferably, the hole  170  is not perpendicular to the surface  145   b  of the shunt proximate the hole; however, the hole may be perpendicular to the surface of the shunt proximate the hole. 
   Assembly of the nozzle assembly  150  is as follows. The insert  160  is inserted into the hole  170  until the taper of the outer surface  160   c  of the hard insert  160  is press fit with the shunt surface  145   a  defining the hole  170  and the shoulder  160   b  is seated on the shunt surface  145   b  proximate the hole  170 , so that the lip  160   a  lines the surface  145   a  and the insert  160  is secured to the shunt  145 . In other words, the smallest end of the taper is inserted into the hole  170  first, and the tapered surface of the insert  160  self-centers until it becomes snugly seated against the side of the hole  170  at the surface  145   a . This contact occurs in the approximate area of surface  160   c  on the carbide insert. The outer jacket  155  can be disposed over an outer surface of the insert  160  and securely welded with minimal handling. Assembly time is greatly reduced, as is the required skill level of the assembler. Once seated, the nozzle assembly  150  is restrained from translating or rotating relative to the shunt  145 . Alignment of the insert bore and the jacket bore with the drilled hole  170  in the shunt  145  is assured. Sand slurry  13  exiting the tube, represented by arrows  175 , passes through the lip  160   a  of the hard insert, not the surface  145   a  of the hole  170 . The possibility of flow cutting the surface  145   a  of the hole  170  is greatly diminished. 
     FIG. 5  is a sectional view of a nozzle assembly  250 , according to another embodiment of the present invention, disposed on one of the shunts  145 . The nozzle assembly  250  comprises an insert  260  with a flow bore therethrough. Preferably, the insert  260  is made from a hard material, e.g., carbide, relative to the material of the shunt  145 . A proximal lip  260   a  of the insert  260  extends into an aperture  270  in a wall of the shunt  145 , thereby lining a surface  245   a  of the shunt wall that defines the aperture  270 . The proximal lip  260   a  can include any of the features described above with respect to the lip  160   a  of the nozzle assembly  150  illustrated in  FIG. 4  such that the nozzle assembly  250  is assembled in the same manner with the proximal lip  260   a  serving the same functions. 
   An outer jacket  255  of the nozzle assembly  250  includes a bore therethrough configured to receive the insert  260 . Specifically, a recess  256  along an inner diameter of the outer jacket  255  proximate the aperture  270  accommodates an outer diameter of a medial length of the insert  260 . A distal extension  260   d  extends from an opposite end of the insert  260  than the proximal lip  260   a  and has a reduced outer diameter with respect to the medial length of the insert  260  to form an outward shoulder  261 . Accordingly, the outer jacket  255  easily slips over the insert  260  and secures to the shunt  145  with a weld  265 . Once welded, an inward shoulder  258  defined by the recess  256  of the outer jacket  255  mates with the outward shoulder  261  of the insert  260  to prevent outward movement of the insert  260  with respect to the aperture  270 . 
   The insert  260  and the outer jacket  255  preferably share a common terminus due to a sufficiently sized length of the distal extension  260   d  of the insert  260 . In other words, the insert  260  concentrically disposed within the outer jacket  255  lines substantially the entire length of the inner diameter of the outer jacket  255 . Threads  259  on an outside end of the outer jacket  255  can replace inner threads to enable securing of a cap (not shown) to the nozzle assembly  250  if desired. 
   Preferably, the outer jacket  255  and insert  260  are tubular members; however, their shape is not essential to the invention. As with other embodiments described herein, sand slurry  13  exiting the shunt  145 , represented by arrows  275 , passes through the proximal lip  260   a  of the insert in order to reduce wear on the surface  245   a  of the aperture  270 . In addition, sand slurry  13  exiting the nozzle assembly  250  passes through the distal extension  260   d  of the insert  260  without flowing through and contacting an end of the outer jacket  255 , which may be made of a softer material similar to the shunt  145 . In this manner, the distal extension  260   d  protects the shoulders  258 ,  261  that cooperate to keep the insert  260  from escaping and causing failure at the nozzle assembly  250 . Thus, the insert  260  can provide a carbide conduit that protects all other portions of the nozzle assembly  250  from flow cutting since sand slurry exiting the shunt  145  passes substantially entirely through the carbide conduit. The possibility of flow cutting the surface  245   a  of the aperture  270  or the end of the outer jacket  255  is greatly diminished. 
   As shown, the nozzle assemblies  150 ,  250  are used with a shunt of a gravel pack apparatus; however, the nozzle assemblies described herein may be used with various other apparatuses. 
   While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.