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You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
       [0001]    The present disclosure relates to a system for navigating past obstacles in a wellbore. More specifically, the present disclosure relates to selectively reorienting a shaped guide member to negotiate past irregular sections in a wellbore. 
       2. Description of Prior Art 
       [0002]    Downhole operations in hydrocarbon producing wellbore often involve deploying a tool or a string in the wellbore to a designated depth. Advances in hydrocarbon exploration and production have led to wells with more deviations, thereby introducing curves and bends in the wellbores that introduce obstacles to navigating tools or strings through the wellbore. Further, wellbore systems have been developed that include lateral wellbores that branch from a primary wellbore. Negotiating a tool or string across the angle between a primary wellbore and a lateral wellbore introduces additional difficulties. Further, a tool or string sometimes becomes lodged against washouts or other discontinuities in the wellbore wall when being lowered in an uncased wellbore. 
       SUMMARY OF THE INVENTION 
       [0003]    Disclosed herein is an example of a downhole system for use in a wellbore and which includes a downhole tool having an axis, and that is deployed on wireline and a guide assembly. Here the guide as is made up of a connector coupled to the downhole tool, a sleeve with an end coupled to the connector and another end distal from the connector so that a portion of the circumference of the another end lies in a plane substantially perpendicular with the axis, and another portion that lies in a plane that is oblique with the axis, a pedestal having an outer periphery, and a ledge on the outer periphery that faces the sleeve, and that is profiled generally complementarily with the another end of the sleeve, so that when the ledge is axially urged against me another end t the sleeve, the pedestal rotates relative to the sleeve, a tip member having a curved surface and that is coupled to the pedestal. The downhole system can also a spring in the sleeve that is coupled to the sleeve and to the pedestal, and becomes rotationally tensioned with relative rotation of the sleeve and pedestal. In one example the tip member is an elongated member, and having a curved surface along an elongate lateral side. Optionally, the tip member can have a substantially planar surface along an elongate lateral side that is angularly spaced away from the curved surface. In an embodiment, the planar surface projects along a path that is oblique with the axis. The portions each optionally extend about 180 degrees around a circumference of the end of the sleeve. A standoff can be included on the sleeve. 
         [0004]    Another example of a downhole system for use in a wellbore is described herein and which includes downhole tool that is selectively disposed in the wellbore, a wireline connected to an end of the downhole tool, and a guide assembly connected to an end of the downhole tool opposite the wireline, and that includes a downwardly projecting tip member and a means for orienting the tip member in a designated orientation for navigating past obstacles in the wellbore. The means for orienting the tip member can include a sleeve having an end that terminates at varying axial positions along a circumference of the sleeve, and a pedestal having a ledge on an outer periphery of the pedestal, where the ledge faces the sleeve and is profiled complementarily with the end of the sleeve, so that the pedestal rotates with respect to the sleeve when the ledge is put into abutting contact with the end of the sleeve. In an embodiment, the sleeve is coupled to the downhole tool, and the pedestal is coupled to the tip member, so that relative rotation of the pedestal and sleeve rotates the tip member with respect to the downhole tool. The tip member can be an elongate member having a curved elongate surface, and a planar elongate surface on a side opposite the curved elongate surface, and wherein the planar elongate surface is oblique to an axis of the guide system. 
         [0005]    Also described herein is an example of a method of wellbore operations and which includes deploying a downhole string in a wellbore and on a wireline, where the downhole string includes a downhole tool equipped with a guide assembly having an obliquely angled tip member, lading the tip member on an obstacle in the wellbore, lifting the downhole string from the obstacle, reorienting the tip member along a path directed away from the obstacle, and lowering the downhole string so that the tip member slides past the obstacle. The obstacle can be a discontinuity along a sidewall of the wellbore, such as a washout, a ledge, a curved portion of the wellbore, or an entrance to a lateral wellbore. The method can include repeating the steps of lifting the downhole string and reorienting the tip member. In an alternative, the tip member is reoriented at an angle of around 120 degrees. The method can also include sensing when the tip member lands on the obstacle in the wellbore and lifting the downhole string from the obstacle in response to the step of sensing. An optional step of sensing can include receiving a signal with a controller on surface from as proximity sensor disposed in the guide assembly. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0006]    Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
           [0007]      FIG. 1  is a side sectional view of a tool string landing on an obstruction in a wellbore, where an example of a guide system is mounted to the tool string. 
           [0008]      FIG. 2  is as side sectional view of the tool string of  FIG. 1  being raised upward from the obstruction, and where the guide system is reorienting a tip member. 
           [0009]      FIG. 3  is a side sectional view of the tool string of  FIG. 2  being lowered in the wellbore for navigating past the obstacle. 
           [0010]      FIGS. 4A and 4B  are side perspective views of examples of the guide system of  FIG. 1 . 
       
    
    
       [0011]    While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF INVENTION 
       [0012]    The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term “about” includes +/−5% of the cited magnitude. In an embodiment, usage of the term “substantially” includes +/−5% of the cited magnitude. 
         [0013]    It is to be further understood that the scope. of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. 
         [0014]    Shown in side sectional view in  FIG. 1  is an example of a downhole system  10  being lowered within a wellbore  12 , wherein well bore  12  is formed through a formation  14 . As shown, the downhole system  10  is approaching a deviated section  16  of wellbore  12  while being lowered on wireline  18 . The downhole system  10  includes a downhole tool  20 , which can be for example a perforating gun, an imaging or logging tool, or other tubular being set downhole. A guide system  22  is shown mounted to a lower end of downhole tool  20  opposite its connection to wireline  18 . The guide system  22  includes art orientation assembly  24  with a tip member  26  that depends downward from orientation assembly  24  and is a generally elongate member. One elongate side of tip member  26  is shown having a curved surface  28 , wherein an opposite side of tip member  26  has a generally planar surface  29 . Further illustrated in  FIG. 1  is a surface truck  30  shown mounted on surface  32 . Wireline  18  connects to a reel (not shown) within surface truck  30  and spools over sheaves and into a wellhead assembly  34 , shown mounted over an opening of wellbore  12 . Further shown in  FIG. 1  is a controller  36 , shown in dashed outline within surface truck  30 , can be used for sending and receiving data and control signals to and from downhole system  10 . 
         [0015]    Tip member  26  of  FIG. 1  is shown having landed against an obstacle  38  on the sidewall of wellbore  12 . In the example, the obstacle  38  is the angled sidewall of the wellbore  12  in the deviated section  16 . Other examples of obstacles include washouts, ledges, and entrances into lateral wellbores from a primary wellbore. Referring now to  FIG. 2 , one example of navigating past the obstacle  38  is demonstrated by lifting the downhole system  10  upwards within wellbore  12  and from obstacle  38 . As will be described in more detail below, the guide system  22  automatically reorients tip member  26  as shown so that the curved surface  28  is now facing the direction of obstacle in wellbore  12 . Shown in  FIG. 3  is a subsequent step of an example of navigating past the obstacle  38  where the downhole system  10  is lowered on wireline so that tip member  26  is proximate obstacle  38 . As shown, the strategic positioning of tip member  26  orients the curved surface  28  so it faces obstacle  38 , which enables the downhole system  10  to slide past obstacle  38  and make its way deeper into wellbore  12  and past the deviated section  16 . 
         [0016]    In side perspective views in  FIGS. 4A and 4B  are example embodiments of the guide system  22 . A connector  40  is shown on one end of guide system  22  which is a generally annular member with an open end revealing a hollow portion, inside of hollow portion is an inner surface. Threads  42  are depicted formed within the inner surface of connector  40  and for connecting to the downhole tool  20  ( FIG. 1 ). An end of connector  40  opposite its open end connects to an annular sleeve  44 , shown having an axial bore  45  extending therethrough. Sleeve  44  has an end  46  distal from its connection to connector  40 , and wherein end  46  has a beveled profile such that the end  46  terminates at different axial locations with respect to a circumference of sleeve  44 . More specifically, a portion  48  of the circumference of end  46  lies in a plane that is substantially perpendicular with an axis A of guide assembly  22 . Another portion  50  of the circumference of end  46  projects along a varying axial location and thus lies in a plane that is substantially oblique with axis A y . The portions  48 ,  50  define a Shane that is sometimes referred to “mule shoe”. Also included with guide assembly  22  is a standoff  52 , which is made up of a collar  54  that is shown circumscribing a portion of sleeve  44 . Ridges  56  are mounted on collar  54  at angular locations around collar  54 , and are elongate members that project along the axial length of collar  54 . 
         [0017]    A generally cylindrical pedestal  58  is shown disposed adjacent end  46  of sleeve  44 . The diameter of pedestal  58  transitions radially outward proximate to sleeve  44 , and which defines a ledge  62  that faces sleeve  44 . Similar to the end  46 , ledge  62  has a portion  64  that extends along a part of the circumference of ledge  62 , and which is lies in a plane generally perpendicular with axis A y . Another portion  66  of ledge  62  extends along another part of the circumference of lodge  62 , and which is complementarily formed to portion  50 . Thus portion  66  extends along a plane that is generally oblique with axis A y . Examples exist wherein each of the portions  48 ,  50 ,  64 ,  66  extend about 180 degrees around the respective circumferences of the end  46  and the ledge  62 . Optionally, multiple portions  48 ,  50 ,  64 ,  66  can be formed on the end  46  and ledge  62 , wherein the angular lengths of each of the portions  48 ,  50 ,  64 ,  66  is less than 180 degrees. Optionally, embodiments having multiple portions  48 ,  50 ,  64 ,  66  can give the end  46  and ledge generally castellated appearance. When assembled, the smaller diameter section of pedestal  58  between ledge  62  and sleeve  44  inserts into bore  45  of sleeve  44 . As shown in  FIG. 4A , a bore  68  is formed within pedestal  58  and sized to receive a post  70  mounted on an end of tip member  26 . As depicted in  FIGS. 4A and 4B , an axis A TM  of tip member  26  is generally oblique with axis A y . 
         [0018]    In one example of operation of the guide system  22 , applying a force F against end of tip member  26  as shown in  FIG. 4A , urges pedestal  58  against sleeve  44  so that ledge  62  is in close contact with end  46  of sleeve.  44 . An example of force F can occur when tip member  26  lands on obstacle  38  ( FIG. 1 ). As the ledge  62  is profiled complementary to end  46 , the pedestal  58  will rotate with respect to sleeve  44  until the portions  48 ,  64  are aligned, and portions  50 ,  66  are aligned. A spring  72  which is coupled to both the pedestal  58  and sleeve  44  is torqued into compression and stores energy while the sleeve  44  and pedestal  58  are abutted against one another. When the force F is removed, such as the step illustrated in  FIG. 2  so that the tip member  26  is freely suspended and not landed n a solid surface, the compressed torsion in spring  72  is released and causes rotation of pedestal  58  and tip member  26  relative to sleeve  44  and downhole tool  20  ( FIG. 1 ). As such, the curved surface  28  can be strategically reoriented so that when the downhole system  10  of  FIG. 1  is relowered, the curved surface  28  (and thus smoother surface) of the tip member  26  can engage obstacle  38  with less resistance than when in other orientations, so that the downhole system  10  can be urged further within wellbore  12 . Moreover, orientating tip member  26  so that its axis A TM  is oblique to the axis A y  provides an increased offset angle with respect to obstacle  38  thereby enhancing the ability of the guide system  22  to direct the downhole system  10  past the obstacle  38 . 
         [0019]    Referring back to  FIG. 1 , a proximity sensor  74  is shown within guide system  22  and which ran sense when the pedestal  58  and sleeve  44  are in close contact, thereby indicating the tip member  26  has landed on an obstacle  38  or other solid mass that blocks passage of downhole system  10 . Sensor  74  can he in contact with controller  36  via wireline, so that operations personnel on surface  32  can detect when the downhole system  10  lands on an obstacle  38 . Upon detection of landing, operations personnel can commence the actions of lifting the downhole system  10  and then relowering as illustrated in  FIGS. 2 and 3 , Other ways of sensing may be included, such as monitoring tension in the wireline  18 . 
         [0020]    The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.

Summary:
A downhole system is deployed on wireline and includes a tool and a guide system on it a lower end of the tool for navigating past obstacles within a wellbore. A selectively rotatable tip member projects downward from the guide system. A side of the tip member is curved, so when the tool encounters cm obstacle downhole, the tip member rotates so the curved side faces the obstacle and the downhole system can be urged past the obstacle. The guide system includes a sleeve and pedestal that abut one another on opposing ends that are complementarily profiled. When the sleeve and pedestal axially contact one another, the profiled ends produce relative rotation of the sleeve and pedestal. The pedestal is coupled with the tip member and the sleeve is coupled to the tool, so that the relative rotation of the sleeve and pedestal causes the tip member to rotate relative to the tool.