Patent Publication Number: US-10309175-B2

Title: High flow downhole lock

Description:
BACKGROUND OF THE INVENTION 
     A conventional downhole lock assembly is used to locate and retain various downhole tools in a wellbore. A running tool is removably attached to a top distal end of the lock assembly to run the assembly into the wellbore and a tool is attached to a bottom distal end. Commonly used tools include flow control and safety tools. During trip in, the lock assembly and tool are landed in a conventional landing nipple disposed downhole. Upon reaching the setting depth, the running tool is jarred downward to shear a plurality of setting pins that lock the assembly in the landing nipple in the wellbore. The running tool may then be removed and the lock assembly and tool may provide the flow control or safety function. 
     BRIEF SUMMARY OF THE INVENTION 
     According to one aspect of one or more embodiments of the present invention, a high flow downhole lock assembly includes a mandrel with a plurality of external collet finger detents disposed about an exterior surface and an unobstructed inner diameter configured for flow, an external collet with a plurality of collet fingers disposed about an interior surface, and a dog housing with a plurality of extendable retaining dogs. When transitioning to a set configuration, a portion of the mandrel travels within the external collet, the plurality of collet fingers come to rest in one or more of the external collet finger detents, and the plurality of extendable retaining dogs are extended. 
     Other aspects of the present invention will be apparent from the following description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a cross-sectional view of conventional downhole lock assembly set in a landing nipple. 
         FIG. 2  shows an exploded isometric view of a high flow downhole lock assembly and nose piece attachment in accordance with one or more embodiments of the present invention. 
         FIG. 3A  shows an isometric view of a high flow downhole lock assembly and nose piece attachment in a running configuration in accordance with one or more embodiments of the present invention. 
         FIG. 3B  shows an isometric view of a high flow downhole lock assembly and nose piece attachment in a set configuration in accordance with one or more embodiments of the present invention. 
         FIG. 4A  shows a cross-sectional view of a high flow downhole lock assembly in a running configuration in accordance with one or more embodiments of the present invention. 
         FIG. 4B  shows a cross-sectional view of a landing nipple in accordance with one or more embodiments of the present invention. 
         FIG. 4C  shows a cross-sectional view of a high flow downhole lock assembly in a set configuration in accordance with one or more embodiments of the present invention. 
         FIG. 4D  shows a cross-sectional view of a high flow downhole lock assembly in a set configuration in a landing nipple in accordance with one or more embodiments of the present invention. 
         FIG. 5A  shows a cross-sectional view of a high flow downhole lock assembly in a running configuration with a running tool attached to a first distal end and an orifice tool attached to a second distal end in accordance with one or more embodiments of the present invention. 
         FIG. 5B  shows a cross-sectional view of a high flow downhole lock assembly in a running configuration with a running tool attached to a first distal end and an orifice tool attached to a second distal end being inserted into a landing nipple in accordance with one or more embodiments of the present invention. 
         FIG. 5C  shows a cross-sectional view of a high flow downhole lock assembly in a set configuration with a running tool attached to a first distal end and an orifice tool attached to a second distal end after being inserted into a landing nipple and set in accordance with one or more embodiments of the present invention. 
         FIG. 5D  shows a cross-sectional detail view of a portion of a high flow downhole lock assembly in a running configuration in a landing nipple prior to setting in accordance with one or more embodiments of the present invention. 
         FIG. 5E  shows a cross-sectional detail view of a portion of a high flow downhole lock assembly in a set configuration in a landing nipple after setting in accordance with one or more embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One or more embodiments of the present invention are described in detail with reference to the accompanying figures. For consistency, like elements in the various figures are denoted by like reference numerals. In the following detailed description of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention. In other instances, well-known features to one of ordinary skill in the art are not described to avoid obscuring the description of the present invention. 
     Conventional downhole lock assemblies are primarily used in production applications (flow from the bottom of the wellbore up) such as, for example, to hold back trapped pressure originating from the bottom of the wellbore. In production applications, flow interfaces primarily with the tool disposed at a bottom distal end of the lock assembly and the obstructed inner diameter of the lock assembly is less relevant since there is little to no flow therethrough. However, in injection applications (flow from the surface of the wellbore down), conventional downhole lock assemblies are less effective because of the obstructed inner diameter of the lock assembly. The internal profile of the inner diameter of a conventional downhole lock assembly is not uniform or smooth and includes obstructions that cause erosional turbulence within the lock. The turbulence is caused by the abrupt diametric changes within the inner diameter because at least portions of the locking mechanism are located within the internal profile of the inner diameter of the lock assembly. The non-uniform and obstructed internal profile of the inner diameter of the lock assembly gives rise to erosional turbulence, poor flow characteristics, and lower injection efficiencies. In addition, reliability and operational life is substantially reduced. As such, conventional downhole lock assemblies are not suitable for high flow rate injection applications. 
     Another drawback of conventional downhole lock assemblies is that, because portions of the locking mechanism are disposed within the inner diameter of the lock assembly, when the shear pins or setting screws used to set the lock assembly in a landing nipple are sheared, sheared portions may fall within the inner diameter of the lock assembly, cause damage to the inner diameter of the lock assembly due to turbulence, and ultimately foul the flow control or safety tool, also requiring the removal and replacement of the lock assembly and tool. 
     Accordingly, in one or more embodiments of the present invention, a high flow downhole lock assembly provides all setting components outside the lock assembly such that the inner diameter of the assembly is larger, unobstructed, smooth, and free from encumbrance. Once set, the unobstructed inner diameter allows for higher injection rates, reduced turbulence, improved flow characteristics, reduced erosion, lower internal velocities, lower differential pressures, and lower installed reaction forces than conventional lock assemblies. Advantageously, the high flow downhole lock assembly may be used in both production and injection operations, including high flow rate injection operations. 
       FIG. 1  shows a cross-sectional view of conventional downhole lock assembly  105  and orifice tool  125  set in a landing nipple  110 . Conventional downhole lock assembly  105  may be a conventional DB-6 type lock assembly that is commonly used in industry. As shown in the cross-sectional view, aspects of the locking mechanism may be disposed within an internal profile of the inner diameter  115  of the lock assembly  105 . For example, an internal collet  120  may be disposed, at least partially, within the inner diameter  115 . In addition, inner diameter  115  includes a number of abrupt diametric changes that obstruct flow therethrough. As such, the internal profile of the inner diameter  115  of the lock assembly  105  is not uniform or smooth and includes obstructions that cause erosional turbulence within the lock assembly  105 . The turbulence is caused in part by the abrupt diametric changes within the inner diameter  115  and the portions of the locking mechanism that are located within the internal profile of the inner diameter  115  of the lock assembly  105 . The non-uniform and obstructed internal profile of the inner diameter  115  of the lock assembly  105  gives rise to erosional turbulence, poor flow characteristics, and lower injection efficiencies that render lock assembly  105  unsuitable for high flow rate injection applications. 
       FIG. 2  shows an exploded isometric view of a high flow downhole lock assembly  200  and nose piece attachment in accordance with one or more embodiments of the present invention. A high flow downhole lock assembly  200  may include a mandrel  210 , an external collet  230 , and a dog housing  250 . Mandrel  210  may include an outer mandrel portion  214  having a first outer diameter smaller than a landing nipple inner diameter (not shown), a first inner mandrel portion  216  having a second outer diameter smaller than the first outer diameter of the outer mandrel portion  214 , a second inner mandrel portion  218  having a third outer diameter smaller than the second outer diameter of the first inner mandrel portion  216 , and a third inner mandrel portion  228  having a fourth outer diameter smaller than the third outer diameter of the second inner mandrel portion  218 . A plurality of external collet detents  220  may be disposed about the exterior surface of the second inner mandrel portion  218 . Each external collet detent  220  may be a groove formed about a circumference of an exterior surface of the second inner mandrel portion  218 . Mandrel  210  may include a plurality of retention pin slots  222  disposed along a longitudinal axis about an exterior surface of the second inner mandrel portion  218 , a recovery shear pin groove disposed about the exterior of the second inner mandrel portion  218 , and a sloped interface  227  between the second inner mandrel portion  218  and the third inner mandrel portion  228 . In addition, mandrel  210  may include one or more shear screw spotfaces  224 . A top distal end  212  of outer mandrel portion  214  of mandrel  210  may be configured to connect to a running tool (not shown) during tripping in or a connection (not shown) during operation. Mandrel  210  may include an unobstructed inner diameter (not independently shown) configured for high flow rates. 
     External collet  230  may include a first distal interface portion  232  having a first inner diameter configured to receive a first inner mandrel portion  216  of mandrel  210 , a collet portion  234  having a second inner diameter configured to receive a second inner mandrel portion  218  of mandrel  210 , and a second distal interface portion  242  having the first inner diameter configured to connect to a first distal end of dog housing  250 . External collet  230  may include a plurality of collet fingers  236  disposed about an interior surface of the second inner diameter of collet portion  234 . Second distal interface portion  242  may include a plurality of collet set screw receivers  240  configured to receive collet set screws  238  that secure the second distal interface portion  242  of external collet  230  to a first distal end of dog housing  250 . A garter spring  244  sits on top of the recovery shear pins  256  and drives them down into the recovery shear pin groove  226  once the lock assembly  200  is set in a landing nipple (not shown). 
     Dog housing  250  may include a first dog housing portion  259  having a first outer diameter configured to connect with the first inner diameter of the second distal interface portion  242  of external collet  230 , a second dog housing portion  261  having a second outer diameter larger than the first outer diameter of first dog housing portion  259 , and a third dog housing portion  263  having a third outer diameter smaller than the second outer diameter of the second dog housing portion  261  that is configured to connect to a nose piece attachment  279 . First dog housing portion  259  may include a plurality of retention pin holes  266  configured to receive a plurality of retention pins  254  that may be disposed within the plurality of retention pin slots  222  of mandrel  210 . The retention pins  254  allow the mandrel  210  to translate within the dog housing  250  during setting of the lock assembly  200 . First dog housing portion  259  may also include a plurality of shear screws  252  to be disposed within a plurality of threaded shear screw holes  253  that interface with the shear screw spotface  224  of mandrel  210 . The shear screws  252  provide resistance to the movement of the mandrel  210  during the setting of lock assembly  200  in a landing nipple (not shown). First dog housing portion  259  may also include a plurality of recovery shear pins  256  that are held in place by garter spring  244 . The recovery shear pins  256  ride on the second inner mandrel portion  218  in the running configuration and fall into the recovery shear pin groove  226  of the mandrel  210  in the set configuration. Second dog housing portion  261  may include a plurality of retaining dog ports  260  disposed about a circumference of second dog housing portion  261 . A plurality of extendable retaining dogs  258  may be disposed in the plurality of retaining dog ports  260 . The plurality of extendable retaining dogs  258  may be interchangeable to mate with a particular type of landing nipple (not shown). Third dog housing portion  263  may include a threaded nose interface  264  for securing a nose piece  280 . 
     A nose piece attachment  279  may include a seal stack  270 , a first o-ring  272 , an insert  274 , a second o-ring  276 , a nose piece  280 , and a plurality of nose set screws  282 . Seal stack  270  may slide over a portion of third dog housing portion  263 . First o-ring  272  may then slide over a portion of third dog housing portion  263 , placed on the seal stack  270  side of threaded nose interface  264 . Insert  274  may be inserted with second o-ring  276  into nose piece  280 . Nose piece  280 , with insert  274  and second o-ring  276  disposed therein, may be connected to threaded nose interface  264 . The plurality of nose set screws  282  may be threaded through a plurality of nose set screw receivers  284  of nose piece  280  to further secure nose piece  280  to the third dog housing portion  263 . Nose piece attachment  279  may be a production safety valve, an injection safety valve, an anti-surge valve, a fixed orifice valve, an injection orifice, a storm choke, an isolation plug, a gauge, a cement retainer, or a combination thereof. 
     In certain embodiments, mandrel  210 , external collet  230 , dog housing  250 , and nose piece attachment  279  may be composed of steel. In other embodiments, they may be composed of steel alloys. In still other embodiments, they may be composed of corrosion resistant alloys. One of ordinary skill in the art will recognize that any other suitable material may be used in accordance with one or more embodiments of the present invention. In certain embodiments, seal stack  270 , first o-ring  272 , and second o-ring  276  may be composed of elastomers. In other embodiments, they may be composed of non-elastomers. In still other embodiments, they may be composed of a combination of elastomers and non-elastomers. One of ordinary skill in the art will recognize that any other suitable material may be used in accordance with one or more embodiments of the present invention. In certain embodiments, screws and pins meant to shear, such as, for example, shear screws  252  and recovery shear pins  256  may be composed of brass. 
       FIG. 3A  shows an isometric view of a high flow downhole lock assembly  200  and nose piece attachment  279  in a running configuration in accordance with one or more embodiments of the present invention. In the running configuration, a running tool (not shown) may be attached to the internal running profile ( 292  of  FIG. 4A ) of dog housing  250  to trip in the lock assembly  200  and nose piece attachment  279  downhole. In this running configuration, a plurality of collect fingers  236  may rest in a distal collet finger detent  220  nearest the nose piece attachment  279 . The plurality of extendable retaining dogs  258  may be seated within the plurality of retaining dog ports  260 . In this running configuration, lock assembly  200  and nose piece attachment  279  may be landed in a landing nipple (not shown). Once a sufficient depth is reached, a jarring action may be applied to the running tool (not shown) to force the mandrel  210  downward in the direction of the bottom of the wellbore (not shown). Mandrel  210  travels within external collet  230 , the plurality of collet fingers come to rest in an external collet finger detent  220  nearest the distal end  212  of mandrel  210 , the plurality of extendable retaining dogs  258  are extended outside of the plurality of retaining dog ports  260 , and the recovery shear pins ( 256  of  FIG. 4A ) fall into the recovery shear pin groove  226  of mandrel  210 . When the plurality of extendable retaining dogs  258  are extended outside of the dog housing  250 , they secure the lock assembly  200  in the landing nipple (not shown). Continuing,  FIG. 3B  shows an isometric view of a high flow downhole lock assembly  200  and nose piece attachment  279  in a set configuration in accordance with one or more embodiments of the present invention. In this set configuration, the plurality of collet fingers  236  come to rest in a distal collet finger detent  220  nearest the outer mandrel portion  214  of mandrel  210 . The plurality of extendable retaining dogs  258  are extended outside of the plurality of retaining dog ports  260 , thereby securing lock assembly  200  in the landing nipple (not shown). 
       FIG. 4A  shows a cross-sectional view of a high flow downhole lock assembly  200  in a running configuration in accordance with one or more embodiments of the present invention. In this view, first inner mandrel portion  216  is in contact with, but not fully seated within, the first distal interface portion  232  of external collet  230 . A plurality of collet fingers  236  may be disposed in distal collet finger detent  220  on the right hand side, corresponding to the location nearest the bottom of the wellbore (not shown). A plurality of extendable retaining dogs  258  may be seated within the plurality of retaining dog ports  260 . Outer mandrel portion  214  may include a recovery internal profile  286  configured for removal of lock assembly  200  after use. Outer mandrel portion  214  may also include a smooth flared profile portion  288  that funnels down to an unobstructed and smooth inner diameter  290  of assembly  200 . Inner diameter  290  is unobstructed, smooth, and free from encumbrance and configured for maximum flow. In certain embodiments, the unobstructed inner diameter  290  of assembly  200  may be coated with a corrosion resistant coating to enhance the operational life of assembly  200 . 
     Continuing,  FIG. 4B  shows a cross-sectional view of a landing nipple  300  in accordance with one or more embodiments of the present invention. Landing nipple  300  may include an inner diameter  310  larger than the outer mandrel portion ( 214  of  FIG. 4A ) of the mandrel ( 200  of  FIG. 4A ) and a dog receiver portion  320  configured to receive a plurality of extendable retaining dogs ( 258  of  FIG. 4A ). Landing nipple  300  may be a conventional off-the-shelf landing nipple and may vary from manufacturer to manufacturer. The plurality of extendable retaining dogs ( 258  of  FIG. 4A ) may be interchangeable to fit within and mate to a given landing nipple  300 . Continuing,  FIG. 4C  shows a cross-sectional view of a high flow downhole lock assembly  200  in a set configuration in accordance with one or more embodiments of the present invention. In this view, first inner mandrel portion  216  is in contact with, and seated within, the first distal interface portion  232  of external collet  230 . The plurality of collet fingers  236  may be disposed in distal collet finger detent  220  on the left hand side, corresponding to the location nearest the top of the wellbore (not shown). The plurality of extendable retaining dogs  258  may be extended beyond the plurality of retaining dog ports  260 . Continuing,  FIG. 4D  shows a cross-sectional view of a high flow downhole lock assembly  200  in a set configuration in a landing nipple  300  in accordance with one or more embodiments of the present invention. In this view, the plurality of extendable retaining dogs  258  are extended into dog receiver portion  320  of landing nipple  300 , thereby securing lock assembly  200  in landing nipple  300 . 
       FIG. 5A  shows a cross-sectional view of a high flow downhole lock assembly  200  in a running configuration with a running tool  500  attached to a first distal end and an orifice tool  279  attached to a second distal end in accordance with one or more embodiments of the present invention. One of ordinary skill in the art will recognize that the orifice tool is merely exemplary and any other tool  279  may be used. Continuing,  FIG. 5B  shows a cross-sectional view of a high flow downhole lock assembly  200  in a running configuration with a running tool  500  attached to a first distal end and an orifice tool  279  attached to a second distal end being inserted into a landing nipple  300  in accordance with one or more embodiments of the present invention. In this view, the lock assembly  200  is being lowered into, but has not yet reached the landing depth of, the landing nipple  300 . Continuing,  FIG. 5C  shows a cross-sectional view of a high flow downhole lock assembly  200  in a set configuration with a running tool  500  attached to a first distal end and an orifice tool  279  attached to a second distal end after being inserted into a landing nipple  300  and set in accordance with one or more embodiments of the present invention. In this view, the lock assembly  200  has been landed in the landing nipple  300  and a jarring action has been applied to the running tool  500  to set and secure lock assembly  200  in landing nipple  300 . 
     Continuing,  FIG. 5D  shows a cross-sectional detail view from  FIG. 5B  of a portion of a high flow downhole lock assembly  200  in a running configuration in a landing nipple  300  prior to setting in accordance with one or more embodiments of the present invention. In the running configuration, a sloped interface  227  between the second inner mandrel portion  218  and the third inner mandrel portion  228  may be disposed to the left of the plurality of extendable retaining dogs  258 , leaving the plurality of extendable retaining dogs  258  in the flush position. A plurality of recovery shear pins  256  may be radially biased by garter spring  244  and a plurality of retention pins  254  may be disposed in a distal end of a plurality of retention pin slots  222  closest to the bottom of the wellbore (not shown). 
     Continuing,  FIG. 5E  shows a cross-sectional detail view from  FIG. 5C  of a portion of a high flow downhole lock assembly  200  in a set configuration in a nipple after setting in accordance with one or more embodiments of the present invention. When transitioning to the set configuration, a transition of contact from the third inner mandrel portion  228  to the second inner mandrel portion  218  along the sloped interface  227  with the plurality of extendable retaining dogs  258  causes the plurality of extendable retaining dogs  258  to be extended into the plurality of dog receivers  320  of landing nipple  300 , thereby securing the lock assembly  200  in the landing nipple  300 . The garter spring  244  drives the plurality of retention shear pins  256  to make contact with the recovery shear pin groove  226  as the recovery shear pin groove  226  moves in the downhole direction during setting. The plurality of retention pins  254  travel to an opposing distal end of the plurality of retention pin slots  222  closest to the top of the wellbore (not shown). In the set configuration, as shown in the figure, lock assembly  200  may be secured in place in landing nipple  300 . Importantly, sheared portions of the plurality of recovery shear pins  256  remain outside the unobstructed inner diameter  290  and do not interfere with a nose piece attachment  279  during installation or operation. Because all locking mechanisms used to secure the lock assembly  200  in the landing nipple  300  are disposed outside of the unobstructed inner diameter  290 , the inner diameter  290  allows for high flow rate injection while maintaining the lock assembly  200  secure in place in the landing nipple  300 . 
     Advantages of one or more embodiments of the present invention may include one or more of the following: 
     In one or more embodiments of the present invention, a high flow downhole lock assembly provides all setting components outside the lock assembly such that the inner diameter of the assembly is unobstructed and free from encumbrance. Once set, the unobstructed inner diameter allows for higher injection rates, reduced turbulence, and reduced erosion during production or injection operations. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly has an unobstructed and smooth inner diameter free from encumbrance that allows for high flow rates with improved flow characteristics. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly has all setting components used to secure the assembly in a landing nipple disposed outside of the unobstructed inner diameter. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly may be configured to land in a variety of commercially available landing nipples. Because the extendable retaining dogs are interchangeable, an appropriate type and shape of extendable retaining dog may be used to secure the lock assembly in a particular type of landing nipple. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly has reduced turbulence within the inner diameter because the inner diameter is unobstructed, smooth, and free from encumbrance. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly provides for lower internal velocities than a conventional lock assembly. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly provides for improved flow characteristics than a conventional lock assembly. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly has lower differential flowing pressures within the inner diameter because the inner diameter is unobstructed, smooth, and free from encumbrance. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly has lower installed reaction forces which tends to make the lock assembly more secure when set in a landing nipple than a conventional lock assembly. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly allows for higher injection rates than a conventional lock assembly. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly has a larger inner diameter than a conventional lock assembly. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly provides higher reliability than a conventional lock assembly. There is no potential for a recovery shear pin or set screw from entering the unobstructed inner diameter and fouling the nose piece attachment during installation or operation. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly has a longer operational life than a conventional lock assembly. The inner diameter of the lock assembly may be coated with a protective coating to extend the operational life of the assembly. 
     In one or more embodiments of the present invention, a high flow downhole lock assembly may be used for both injection and production applications whereas conventional lock assemblies are only suitable for production applications where flow is from the bottom of the well to the top. 
     While the present invention has been described with respect to the above-noted embodiments, those skilled in the art, having the benefit of this disclosure, will recognize that other embodiments may be devised that are within the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the appended claims.