Patent Publication Number: US-2013233620-A1

Title: Stabilizer with Drilling Fluid Diverting Ports

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of co-pending U.S. Provisional Application 61/608,755, filed Mar. 9, 2012. This application also claims priority to and the benefit of co-pending U.S. application Ser. No. 13/341,991, filed Dec. 30, 2011, which claims priority to U.S. Provisional Application 61/430,877, filed Jan. 7, 2011. The full disclosure of each of these applications is hereby incorporated by reference herein for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This application relates to earth boring operations, and in particular to upward and outward pointing drilling fluid diverting nozzles located in a drill string above a drill bit. 
     2. Description of the Related Art 
     Oil and gas wells are typically drilled with a drill string having a drill bit on bottom that is rotated. One type of drill bit is a drag bit having blades with cutting disks that scrape against and cut the formation. Mud pumps on a drilling rig pump drilling fluid down the drill string and out nozzles on the bit face to sweep formation cuttings from the bit face. The drilling fluid entrains the cuttings and returns up an annulus surrounding the drill string. Particularly for horizontal wells, a mud motor may be provided in the drill string to rotate the drill bit. Drilling fluid pressure powers the mud motor to rotate the drill bit independently of the drill string rotation. The mud motor requires a considerable pressure and flow rate of drilling fluid in order to be able to apply the desired torque to the drill bit. 
     If the cuttings are not readily removed, the rate of penetration of the drill bit into the earth declines. Drill bits may also plug and ball up while drilling sticky shale formations. If the mud motor is not able to rotate the drill bit at a desired rotational speed, the rate of penetration may decline. Many variations in the bit nozzle diameters, orientation and placement are used in order to more effectively remove cuttings. 
     SUMMARY OF THE INVENTION 
     Described herein are methods and apparatuses for reducing and/or preventing the accumulation of cuttings or other debris on a drill string during drilling operations. Drilling subs are provided in a drill string that include diverting fluid passages extending between an interior and exterior thereof. A portion of the drilling fluid being pumped downward through the interior of the drill string is diverted through the passages such that additional turbulence is produced in the flow of the drilling fluid returning upward in the annulus around the drill string. The additional turbulence may dislodge accumulated sediments, e.g., from between stabilizer blades, or prevent the sediment from precipitating from the drilling fluid. 
     According to one aspect of the disclosure, an apparatus for facilitating the return of drilling fluid through an annulus surrounding a drill string includes a longitudinal body defining an upper end, a lower end and a longitudinal axis extending therebetween. The upper and lower ends include connectors for connecting the longitudinal body into the drill string. An interior axial passage extends between the upper and lower ends of the longitudinal body for conveying drilling fluid through the longitudinal body. A plurality radially spaced blades are provided that protrude from an exterior surface of the longitudinal body and define open exterior flow channels therebetween. A plurality of radially spaced diverting nozzle passages extends between the inner axial passage and the exterior surface of the longitudinal body. The diverting nozzle passages terminate in nozzle openings exhibiting a radial spacing corresponding to a radial spacing of the exterior flow channels. Drilling fluid discharged from the diverting nozzle passages is directed toward the exterior flow channels. 
     According to another aspect of the disclosure, a wed drilling apparatus includes a body defining a longitudinal body axis, and having a threaded upper end for connection into a drill string and a threaded lower end for connection and rogation with an earth boring bit. An axial passage is provided in the body for conveying drilling fluid to an outlet in the earth boring bit. A plurality of blades extend radially outward from an exterior surface of the body, and are radially spaced to define exterior flow channels therebetween. The plurality of blades is configured for engaging a wall of a borehole formed by the earth boring bit. A plurality of nozzles outlets is defined on the exterior surface of the body and in fluidic communication with the axial passage. Each of the nozzle outlets has a longitudinal position along the body between upper and lower ends of the radially spaced blades. 
     According to another aspect of the disclosure, a method of drilling a well includes the steps of: (a) providing a drill string having an earth boring device at a lower end thereof, wherein the drill string has a body coupled therein, and wherein the body defines a longitudinal axis and includes a plurality of blades extending radially outward from an exterior surface of the body, and wherein the body further includes a plurality of nozzle outlets defined on the exterior surface of the body between the blades, and an axial passage extending through the body and in fluidic communication with each of the nozzle outlets; (b) lowering the drill string into the well and rotating the earth boring device; (c) pumping drilling fluid down the drill string into the axial passage of the body, and conveying a first portion of the drilling fluid through the axial passage and discharging the first portion of the drilling fluid through an outlet defined in the earth boring device into an annulus surrounding the drill string; and (d) diverting and discharging a second portion of the drilling fluid from the axial passage in the body through plurality of nozzle outlets into the annulus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational and partly sectioned view of a drill string having a drilling fluid diverting sub in accordance with this disclosure. 
         FIG. 2  is a vertical sectional view of the drilling fluid diverting sub of  FIG. 1 . 
         FIG. 3  is a horizontal sectional view of the drilling fluid diverting sub of  FIG. 1 , taken along the line  3 - 3  of  FIG. 1 . 
         FIG. 4  is a perspective view of one of the nozzles of the drilling fluid diverting sub of  FIG. 1 . 
         FIG. 5  is a perspective view of the nozzle of  FIG. 4 , as seen from a different view point. 
         FIG. 6  is a sectional view of the nozzle of  FIGS. 4 and 5 . 
         FIG. 7  is a perspective view of an alternate embodiment of the drilling fluid diverting sub of  FIG. 1 . 
         FIG. 8  is an exploded side view of a stabilizer with a fluid diverting sub. 
         FIG. 9  is a side view of the stabilizer of  FIG. 8  secured to the fluid diverting sub. 
         FIG. 10  is a side view of the stabilizer and sub of  FIG. 9  connected into a drill string. 
         FIG. 11  is a side view of a stabilizer having integral fluid diverting nozzles. 
         FIG. 12  is a side view of three of the stabilizers of  FIG. 11  connected into a drill string. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS  
     Referring to  FIG. 1 , a well bore  11  is illustrated being drilled by a drill string  13 . Although well bore  11  is shown as being vertical, often it will have a horizontal portion. In this example, drill string  13  includes a mud motor  15 , which is a conventional component. Mud motor  15  typically has blades or stabilizers  17  extending from its outer side. A drilling fluid or drilling mud diverting sub  19  is secured to the lower end of mud motor  15 . Sub  19  has diverting nozzles  21  in its side wall that have outlets pointing outward and upward. Sub  19  may be joined to an upper end  23  of a conventional earth boring device or bit  25 . 
     In this example, bit  25  is a drag bit having cutting blades  27  extending from a circumference to a lower side or face. Blades  27  have cutting elements  29  mounted thereto for scraping the earth formation as bit  25  rotates. Cutting elements  29  may be formed of a polycrystalline diamond or other materials. Bit  25  also has at least one, and normally several outlets or bit nozzles  31  on its face. Bit outlets  31  receive drilling fluid pumped into a central cavity of bit  25  and discharge the drilling fluid at various angles relative to the face of bit  25 . The discharged drilling fluid entrains cuttings of the earth formation and flows up an annulus surrounding drill string  13 . 
     Drilling fluid diverting nozzles  21  in sub  19  discharge a portion of the drilling fluid being pumped down drill string  13  before the drilling fluid reaches bit  25 . The flow from nozzles  21  joins the fluid stream of drilling fluid being pumped out of bit nozzles  31 . In this embodiment, there are three fluid diverting nozzles  21 , these being nozzle  21   a , nozzle  21   b , and nozzle  21   c . Nozzles  21   a ,  21   b  and  21   c  are equally spaced around the side wall of sub  19 , 120 degrees apart front each other. More or fewer nozzles  21  is feasible. 
     Referring to  FIG. 2 , sub  19  has a tubular body  35  with a threaded upper end  37  for securing to a threaded lower end of mud motor  15  ( FIG. 1 ). Sub  19  may also have a threaded lower end  39  for securing to threaded upper end  23  of bit  25 . Alternately, sub  19  could be integrally formed with and be a part of bit upper end  23 . An interior axial passage  41  extends through sub body  35  along a longitudinal axis  43 . For each nozzle  21 , a diverting nozzle passage  45  joins axial passage  41  and extends upward and outward along a nozzle axis  47  to the exterior of sub body  35 . In this example, nozzle axis  47  is oriented upward about 45 degrees, but different angles are feasible. 
     Referring to  FIG. 3 , an axial or vertical plane  49  is illustrated as emanating from and containing longitudinal axis  43  and also passing through the center of the outlet of each nozzle  21 . In this embodiment nozzle axis  47  is not located within axial plane  49 , rather it intersects axial plane  49  at the outlet of nozzle  21 . The angular difference between nozzle axis  47  and axial plane  49  is referred to herein as an oblique angle and indicated by the numerals  51 ,  53  and  55  for nozzles  21   a ,  21   b  and  21   c , respectively. Unlike axial plane  49 , a vertical plane containing nozzle axis  47  would not be normal to the cylindrical exterior of body  35 . Nozzle axis  47  thus is oblique to the cylindrical exterior of body  35 , in addition to pointing upward and outward. Considering the direction of rotation, which is clockwise looking down as shown by the arrow, each nozzle axis  47  lags axial plane  49 . 
     In this embodiment, oblique angle  51  for nozzle  21   a  is less than oblique angle  53  for nozzle  21   b , which in turn may be less than oblique angle  55  for nozzle  21   c . In one example, oblique angle  51  is 10 degrees, oblique  53  is 20 degrees, and oblique angle  55  is 30 degrees. Different oblique angles may be employed. Further, it is not essential that each oblique angle differ; rather one oblique angle could differ from only one other oblique angle or all of the oblique angles may be the same. 
     Also, in this embodiment, each nozzle  21  is at a different elevation than the others. For example, as shown in  FIG. 1 , nozzle  21   a  is the lowest, or closest to drill bit  25 . Nozzle  21   b  is farther from drill bit  25  than nozzle  21   a . Nozzle  21   c  is farther from drill bit  25  than nozzle  21   c . The difference is distance to drill bit  25  can vary. In one example, the difference is about ⅜ inch from nozzle  21   a  to nozzle  21   b  and the same amount form nozzle  21   b  to nozzle  21   c . The lowest nozzle, which is nozzle  21   a , may have the smallest oblique angle  51 , as shown in  FIG. 3 . It is not essential that the elevations for each nozzle  21  differ. For example, the distance to bit  25  may differ between only two of the nozzles  21 , or all of the elevations could be the same. 
     Referring again to  FIG. 2 , a check valve  57  may optionally be inserted into an upper portion of axial passage  41 . Check valve  57  may be of various types. In this example, a check valve element is biased by a spring  59  against a seat in a cartridge  61 . Cartridge  61  rests on a shoulder in the upper portion of axial passage  41 , which is slightly larger in diameter than the central portion that is intersected by nozzle passages  45 . Check valve  57  allows down flow of fluid in axial passage  41 , but blocks upward blow. When running drill string  13  into the well bore  11 , check valve  53  resists silt and cuttings from passing upward through bit outlets  31  to mud motor  15 , where damage may occur. 
     Referring to  FIGS. 4-6 , each nozzle  21  may have helical grooves  63  formed in its bore or outlet  64 . Grooves  63  spiral from one end to the other of outlet  64 . The helical angle may vary. Also,  FIG. 4  shows that the outer end of each nozzle  21  may have a conical recess  65  that diverges outward. Each nozzle  21  has an O-ring seal groove  67  on its outer diameter for sealing within nozzle passage  45  ( FIG. 2 ). Nozzles  21  may be retained in various conventional manners. A retainer ring shoulder  69  receives a snap ring to retain nozzle  21  in this example. 
     Referring to  FIG. 7 , substantially the entire exterior of fluid diverting sub  19 ′ may have protrusions or dimples  71  formed therein. Dimples  71  serve to enhance turbulence of drilling fluid flowing past sub  19 ′. 
     In operation, fluid diverting sub  19  is secured into drill string  13  between drill bit  25  and mud motor  15 . Alternately, fluid diverting sub  19  may form an upper part of drill bit  25 . If the operator wishes to test mud motor  15  before lowering the string into well bore  11 , and if fluid diverting sub  19  is connected between mud motor  15  and drill bit  25 , the operator will install blank plugs in nozzle passages  45  in place of nozzles  21 . The blank plugs allow the operator to pump drilling fluid through mud motor  15  and out bit outlets  31  to test whether mud motor  15  properly rotates drill bit  25 . 
     After testing, the operator installs nozzles  21  in fluid diverting sub  19 . The operator can select different diameters for the bores of diverting nozzles  21  so as to create a desired flow area ratio to the bit nozzles or outlets  31 . The total flow areas of the diverting nozzles  21  will be fairly small relative to the total flow areas of the bit outlets  31 . Typically, the cumulative diverting nozzle flow area will be only 10 to 20 percent of the cumulative flow area of bit outlets  31 . 
     Once the nozzles  21  are installed, the operator lowers the drill string  13  into well bore  11 . When reaching the bottom of well bore  11 , the operator rotates drill bit  25  to begin drilling while also pumping drilling fluid down drill string  13 . Blades or stabilizers  17  engage a wall of the well bore  11  to stabilize the drill string  13 . The operator can rotate drill bit  25  by rotating drill string  13  from the drilling rig. The operator can also hold drill string  13  stationary, and the drilling fluid flowing through mud motor  15  will rotate drill bit  25  and fluid diverting sub  19  in unison with each other. When drilling horizontal wells, the operator may use both procedures at various times. Mud motor  15  is optional for certain drilling operations, such as vertical portions of the well. In those instances, mud motor  15  may be eliminated and fluid diverting sub  19  may connect to a lower end of drill string  13 , such as the drill collars. 
     The drilling fluid flows into bit cavity  33  and out bit outlets  31 . The drilling fluid returns back up the annulus surrounding drill string  13 , bringing earth formation cuttings. A portion of the drilling fluid is diverted out through diverting nozzles  21 . The upward and outward directed drilling fluid mixes with the returning drilling fluid discharged from bit outlets  31 , creating turbulence and enhancing the retention of cuttings in the flow stream. The jets of drilling fluid exiting fluid diverting nozzles  21  will swirl due to the helical grooves  63  ( FIG. 4 ). 
     Referring to the alternate embodiment of  FIG. 8 , stabilizer sub  73  has a tubular body  75  for connection into a drill string. Tabular body  75  defines a longitudinal axis  76  that extends through an interior axial passage (see  FIG. 2 ) provided for conveying drilling fluid through the tubular body  75 . 
     Several blades  77  are secured of formed on the exterior of body  75  for engaging a borehole wall for stabilizing a drill string. Blades  77  are radially spaced and protrude radially form an exterior surface of body  75  such that open exterior flow channels  77 ′ are defined between the blades  77 . Blades  77  may be inclined relative to the axis  76 , as shown in  FIGS. 8-10 , or they may be parallel to the axis  76 , as illustrated in  FIG. 1 . Blades  77  may be straight or curved. Stabilizer sub  73  has an internally threaded box or upper end  78  for connection to a drill string member. In this embodiment, stabilizer sub  73  also has an internally threaded box or lower end  79  that is located a short distance from the lower ends of blades  77 . The lower ends of blades  77  are all located the same distance above the lower end  79  of body  75  in this example. The upper ends of blades  77  are all located the same distance below upper end  78 . The distance from lower end  79  to the lower ends of blades  77  is shown much smaller than the distance from the upper ends of blades  77  to upper end  78 , but the distances could be the same. 
     A fluid diverting sub  81  has a tubular body  83  with a plurality of fluid diverting ports or nozzle outlets  85 . Tubular body  83  defines a longitudinal axis  84  that extends through an interior axial passage (see  FIG. 2 ) provided for conveying drilling fluid through the tubular body  83 . Nozzle outlets  85  are in fluid communication with the interior axial passage through a Respective fluid diverting nozzle passage (see  FIG. 2 ) and point upward and outward to discharge a portion of the drilling fluid being pumped down the drill string. Nozzle outlets  85  may be constructed and oriented the same as nozzles  21   a ,  21   b  and  21   c  in  FIG. 1 . Three or more nozzle outlets  85  are preferably used in sub body  83 . 
     Sub body  83  has an upper externally threaded pin  87  that secures to the internally threaded lower end  79  of stabilizer sub  73 . Sub body  83  has a lower externally threaded pin  89  that secures to another component of the drill string. Flats  91  may be formed on the exterior of sub body  83  for engagement by a wrench to apply torque to secure sub  81  to stabilizer sub  73 . When secured as assembly  92  shown in  FIG. 9 , the axial distance from the uppermost nozzle outlet  85  to the lower ends of blades  77  is quite small, such as three to five inches. 
     Commercially available stabilizers typically have an externally threaded pin on the lower end, rather than an internally threaded end. Since the externally threaded pin of a commercially available stabilizer would protrude some distance into a sub coupled below the commercially available stabilizer, nozzle outlets  85  provided the sub coupled below the commercially available stabilizer would typically need to be provided at a location below the threaded pin of the commercially available stabilizer. Also, the distance from the upper end of the threaded pin to the lower ends of the blades is farther normally than the distance from internally threaded lower end  79  to the lower ends of the blades  73 . Stabilizer sub  73  may be formed by cutting off the lower threaded pin of a commercially available stabilizer and machining an internally threaded lower end  79 . Alternately, assembly  92  of  FIG. 9  could be integrally formed from a single tubular body. 
     A radially spacing of the nozzle outlets  85  and corresponding diverting nozzle passages may correspond the radial spacing exhibited by the exterior flow channels  77 ′ such that drilling fluid discharged from the nozzle outlets  85  is directed toward the exterior flow channels  77 ′ in some embodiments. Discharging drilling fluid from the nozzle outlets  85  and directing the discharged drilling fluid through the exterior flow channels  77 ′ facilitates the return of drilling fluid at least by dislodging debris or sediments that accumulates between the blades  77 . In some embodiments, each of the nozzle outlets  85  defines a nozzle axis that points upward and outward and also at an oblique angle relative to a vertical plane of the body axis that intersects the nozzle axis at the nozzle outlet in a manner similar to nozzles  21  described above with reference to  FIGS. 2 and 3 . The plurality of blades  77  are inclined, in some embodiments with respect to the longitudinal axes  76 ,  84  in the direction of the oblique angle of the nozzle outlets  85 . 
     One manner of utilizing assembly  92  is illustrated in  FIG. 10 . Drill bit  93  is secured to a fluid diverting sub  95  having nozzles  96  that may be the same as fluid diverting sub  19  of  FIG. 1 . A mud motor  97 , which may the same as mud motor  15 , except it may lack stabilizer blades, may be secured to the upper end of fluid diverting sub  95 . Fluid diverting sub  95  may have a float or check valve similar to valve  37  ( FIG. 2 ) to impede debris from flowing into mud motor  97  when the drill string is being lowered into the borehole. Other tubular members such as a drill pipe or drill collar may be provided in addition to or as an alternative to mud motor  97  in some embodiments. During drilling, some of the drilling fluid being pumped down the drill string diverts out stabilizer sub nozzle outlets  85  to enhance flow of fluid and cuttings between blades  77 . The discharged fluid retards cuttings and debris packing between blades  77  keeping the exterior flow channels  77 ′ relatively clear. The proximity of the nozzle outlets  85  to the flow channels  77 ′ allows the fluid discharged from the nozzle outlets to retain sufficient energy to clean the channels  77 ′. The velocity and force of the fluid discharged from the nozzles  85  facilitates cleaning of the channels  77 ′ by generating turbulence in the annular flow of drilling fluid returning to the surface. The proximity of the nozzle outlets  85  to the flow channels  77 ′ ensures that the turbulence is maintained as the drilling fluid passes the through the flow channels  77 ′, and thereby facilitates cleaning the flow channels  77 ′. Additional drilling fluid is also diverted through fluid diverter nozzles  96  just above bit  93  in the same manner as discussed in connection with fluid diverter  21  in  FIG. 1 . 
     Referring to  FIG. 11 , stabilizer  99  has a tubular body  101  defining a longitudinal axis  102 . An interior axial passage (see  FIG. 2 ) extends through the tubular body  101  for conveying drilling fluid therethrough. The stabilizer  99  includes blades  103  that may be the same as blades  77  of  FIG. 8 . Exterior flow channels  103 ′ are defined between the blades  103 . In this example, the axial lengths of blades  103  are much closer to the overall length of body  101  than the lengths of blades  77  relative to body  75  of  FIG. 8 . A number of ports or nozzle outlets  105  are formed in an exterior surface of body  101 . The nozzle outlets  105  are in fluid communication with the interior axial passage through a respective fluid diverting nozzle passage (see  FIG. 2 ). Nozzle outlets  105  may be constructed and positioned relative to each other in the same manner as nozzles  21  of  FIG. 1 . Each of the nozzle outlets  105  is longitudinally positioned between upper and lower ends of blades  103 . Optionally a nozzle outlet  105  may be located between each of the blades  103 . As illustrated in  FIG. 12 , a lowermost nozzle outlet  105   a  may be disposed between two blades  103  near the lower ends of blades  103 . A next upward nozzle outlet  105   b  may be located between two blades  103  about midway along the longitudinal lengths of blades  103 . An uppermost nozzle outlet  105   c  may be located between two of the blades  103  near the upper ends of blades  103 . More than three nozzles  105  may be employed. 
     Stabilizer  99  is illustrated as having an internally threaded lower end or box  107 . Stabilizer  99  may have an externally threaded upper end or pin  109 . The upper ends of blades  103  are quite close to the base of upper threaded end  109 , such as less than two inches. The Lower ends of blades  103  may also be less than two inches from internally threaded lower end  107 . 
       FIG. 12  illustrates one arrangement where stabilizers  99  may be utilized in a drill string. Internally threaded lower end  107  of a lowermost stabilizer  99   a  is secured to the external threaded pin of a bit  111 . One or more drill collars  113  extend upward from lowermost stabilizer  99   b . Drill collars  113  are sections of drill pipe with a greater weight and wall thickness than the remaining sections of drill pipe. A next upward stabilizer  99   b  secures to the upper end of the drill collar or collars  113  connected to stabilizer  99   a . An adapter can connect between lower internally threaded end  107  ( FIG. 11 ) and the upper box end of drill collars  113 . Alternately, stabilizer  99  could be manufactured with an integral threaded pin on the lower end, similar to pin  89  of diverter sub  81  ( FIG. 8 ).  FIG. 12  also shows another stabilizer  99   c  mounted to drill collars  113  extending upward from stabilizer  99   b . Stabilizer  99   c  may be constructed the same as stabilizers  99   a  and  99   b . Fewer or more stabilizers  99  than three may be used. In  FIG. 12 , a mud motor isn&#39;t used, but it could be. For example, a mud motor may be provided in the drill string tin the place of one of the drill collars  113 . 
     While the disclosure has been shown in only a few of its forms, it should be apparent to those skilled In the art that it is not so limited but is susceptible to various changes without departing from the scope of the disclosure.