Patent Publication Number: US-6220361-B1

Title: Circulating nipple and method for setting well casing

Description:
RELATED U.S. APPLICATION DATA 
     This is a divisional of application Ser. No. 09/079,321 filed on May 14, 1998, now pending. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to circulating nipples used for filling well casing and for circulating fluid through well casing while setting or running the casing in a well, and more particularly, to a circulating nipple having an extended neck portion adapted for receiving a pipe wrench thereon and having holes therein adapted for receiving a handle or operating bar therethrough to facilitate installation and removal of the nipple. 
     2. Description of the Prior Art 
     It is conventional practice to drill a well to a desired depth and set casing in the well by running a casing string and then cementing the casing in place. The casing string is made up by connecting a plurality of casing sections or joints as the string is lowered into the well. The casing string is held stationary while each section of the casing is connected to the top of the existing casing string. The casing string is then lowered until the top of the string approaches the level of the rig floor. The next section of casing is assembled on the casing string, and the casing is again lowered. As each length of casing or casing section is connected, a circulating nipple, sometimes referred to as a circulating swage, is made up on the upper end of the casing string. The nipple is designed with a casing or tubing pin thread at the bottom and a smaller connection at the top for engagement with fluid flow lines. This top connection is typically a two-inch FIG. 1502 female connection. 
     Since the sections of the pipe forming the casing are relatively long, the top of the casing may be as high as thirty to forty feet above the rig floor which requires that the nipple be made up on the upper section of casing that far above the rig floor. This necessitates that the nipple be made up on the casing by hand and tightened with the use of hand-held chain tongs. Prior art circulating nipples are relatively long and heavy, and the outer surface of the nipple is usually a smooth, machined finish. This finish makes it difficult for the chain tongs to “bite” into the surface. As a result, the chain tongs frequently slip which can cause loss of balance of the person trying to make up the nipple as well as increasing the time required to complete the task. In addition, the weight and length of the nipple adds to the problem of maneuvering it into position on the casing. 
     Therefore, there is a need for a circulating nipple which is easier to handle and position on the casing string and which is also more easily made up on the casing string. The present invention addresses this need in several ways. Because-the nipple is designed so that it does not need to be made up with chain tongs, the length and weight of the nipple are approximately thirty to thirty-five percent less than prior art nipples. The lighter weight and shorter length combine to make the nipple easier to handle, especially when making up the casing string a large distance above the rig floor. A neck portion of the nipple has been lengthened compared to the prior art, allowing the use of a pipe wrench thereon if desired to make the nipple up in the casing. Further, holes have been provided on the circulating nipple which allow the use of a handle or operating bar to tighten the nipple. The operating bar is the same as, or similar to, the type used to open and close plug valves, such as Halliburton Lo-Torc® plug valves. Because the bar is inserted into a hole, there is extremely little chance that the bar will slip, thereby minimizing the dangers that are present with the use of chain tongs on prior art nipples. Thus, the circulating nipple of the present invention may be made up more quickly and in a manner which is relatively safer for the person making up the nipple and other personnel on the rig floor. 
     SUMMARY OF THE INVENTION 
     The present invention includes a circulating nipple-for use in running well casing into a well while pumping fluid into the casing string. The invention also includes methods of running casing into a well using the new circulating nipple. 
     The invention may be described as a casing nipple comprising a body portion having a casing thread thereon adapted for engagement with a casing connector and also comprising a neck portion extending from the body portion and having a union connection thereon. The body portion preferably defines a transversely extending hole therethrough adapted for engagement by a handle or operating bar. The neck portion preferably has a sufficient length such that a pipe wrench may be grippingly engaged with an outer surface of the neck portion. By using either or both the operating bar and/or pipe wrench, the circulating nipple may be easily threadingly engaged with the casing connector and made up on the casing string. 
     In one embodiment, the body portion further defines a slot thereon to facilitate drilling the hole. The slot has a radiused surface having a radius slightly larger than a radius of the hole. In one embodiment, the slot is one of a plurality of spaced slots on opposite ends of the hole. A central axis of the hole forms a chord with respect to an outside-diameter of the body portion. 
     A plurality of such holes may be spaced substantially evenly around the body portion. The hole central axes of each of the holes are substantially coplanar, and the plane in which the hole central axes lie is substantially perpendicular to a nipple central axis of the nipple. 
     Preferably, the body and neck portions are integrally formed. This may be accomplished by machining the nipple from a single piece of bar stock or by permanently attaching a plurality of elements to form the nipple, such as by welding. 
     Stated in another way, the invention includes an apparatus for use in a well comprising a length of well casing, a casing connector on the length of casing, a circulating nipple defining a central opening therethrough, and a fluid line. The circulating nipple comprises a body connected to an end of the connector and a neck extending from the body. The fluid line is connected to the neck. The fluid line may be further connectable to a fluid source such that fluid may be pumped when and as desired into the casing through the nipple as the casing is being run into the well. The neck may have a wrenching surface thereon of sufficient length for engagement by a pipe wrench, and the body portion may define a hole therethrough adapted for engagement by a handle or operating bar. 
     The present invention also includes a method of running casing into a well comprising the steps of providing a casing section or length of casing with a casing connector at an upper end thereof, positioning the casing adjacent to and aligned with an upper opening of the well, engaging a body of a casing nipple with an upper end of the casing connector, lowering the casing section into the well, disengaging the nipple from the casing connector, engaging an additional casing section with the casing connector, and engaging the body of the nipple with a casing connector at an upper end of the additional casing coupling. The method may also comprise the step of engaging a fluid line with the neck of the nipple. The step of lowering the casing may comprise pumping fluid through the fluid line and nipple into the casing section. The operator can pump liquid to fill the new section or sections of pipe and/or circulate fluid therethrough. The operator may do this after each section or after a plurality of sections is connected. 
     The step of providing the casing with a casing connector may comprise connecting a casing coupling to an upper end of the casing section or length of casing or may comprise simply providing an integral casing section with the casing connector forming an integral portion thereof, such as a female thread. 
     The step of engaging the body of the casing nipple may comprise using a pipe wrench on an elongated neck of the nipple and/or using a handle or operating bar extending through a hole defined in the nipple. 
     The steps may be repeated as desired to run additional casing sections or lengths of casing into the well. 
     Numerous objects and advantages of the invention will become apparent as the following detailed description of the preferred embodiments is read in conjunction with the drawings which illustrate such embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a partial schematic of a drilling rig utilizing the circulating nipple for setting or running well casing of the present invention. 
     FIG. 2 shows a cross section prior art circulating nipple made up onto a casing string with a fluid line connected thereto as used in setting casing. 
     FIG. 3 shows a cross section of a first embodiment of the circulating nipple of the present invention as made up on a casing string with a fluid line connected thereto. 
     FIG. 4 is a vertical cross section of a first embodiment of the circulating nipple. 
     FIG. 5 is a cross-sectional view taken along lines  5 — 5  in FIG.  4 . 
     FIG. 6 is a side elevation of the first embodiment of the circulating nipple, such as seen from lines  6 — 6  in FIG.  5 . 
     FIG. 7 is a partial cross section taken along lines  7 — 7  in FIG.  5 . 
     FIG. 8 is a plan view of a second embodiment of the circulating nipple of the present invention. 
     FIG. 9 is a vertical cross section of the second embodiment taken along lines  9 — 9  in FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, and more particularly to FIG. 1, a first embodiment of the circulating nipple for setting well casing of the present invention is shown in use and generally designated by the numeral  10 . A second embodiment generally designated by the numeral  100  will be further described herein. The following description of FIG. 1 also applies to second embodiment circulating nipple  100 . 
     FIG. 1 also illustrates a conventional drilling rig  12  having a derrick  14  and a rig floor  16 . Below rig floor  16  is a wellhead  18  with a wellbore  20  therethrough. A length of surface casing  22  is shown set in wellbore  20 . A blowout preventer  24  is provided at the top of surface casing  22 , and a discharge line  26 , which is connected with surface casing  22 , conducts drilling fluid to a pond or ditch (not shown) adjacent to drilling rig  12 . 
     Surface casing  22  extends downwardly only a portion of the depth of wellbore  20 , and a production casing string  28  is lowered through surface casing  22  and into open wellbore  20  below the surface casing in a manner hereinafter described. There may also be one or more strings of intermediate casing (not shown) below surface casing  22 . Surface casing  22  and any intermediate casing are progressively smaller in diameter with the depth of the wellbore. 
     While the running of casing string  28  into wellbore  20  is described herein, the same procedure may also be employed for running surface casing  22  and intermediate casing into the wellbore. The only difference is the size of circulating nipple  10  or  100  depending upon the size of the particular casing string that is being run. 
     Casing string  28  is made up of a plurality of casing sections  30 . Casing sections  30  are lengths of pipe which are generally about twenty to forty feet long. Adjacent casing sections  30  may be secured together by a casing coupling or collar  32  which is threaded onto the ends of the casing sections. Alternatively, adjacent casing sections  30  may be integral casing sections (not shown) with a male connector of one casing section engaged with a female connector or an adjacent section. 
     First embodiment circulating nipple  10  or second embodiment nipple  100  is attached to the uppermost casing section  30  by a casing coupling  32  as will be further described herein. Connected to the upper end of circulating nipple  10  is a wing union  34 , as will also be further described. Wing union  34  is attached to a hose  36  connected to a mud pump (not shown) of a kind known in the art. 
     Casing string  28  is lowered into wellbore  20  by means of elevators  38  connected to bails  40  which are in turn connected to a traveling block  42  in a conventional manner. 
     Referring now to FIG. 2, a prior art circulating nipple is shown and generally designated by the numeral  44 . Prior art nipple  44  has a threaded lower end  46  attached to a casing coupling  32  at threaded connection  48 . Prior art nipple  44  defines a central opening  47  therethrough. Casing coupling  32  may be attached to a casing section  30  of casing string  28  at a threaded connection  50  or may form an integral enlarged end of the casing section. FIG. 1 also applies to prior art circulating nipple  44  with regard to the connection of the prior art nipple with the other components associated with drilling rig  12  and casing string  28 . 
     Prior art nipple  44  has an elongated body portion  52  which forms lower end  46  and a relatively short neck portion  54 . Body portion  52  has a generally conical transition area  56  connected to neck portion  54 . 
     Body portion  52  must be sufficiently long that chain tongs (not shown) can be engaged with a substantially cylindrical outer surface  57  thereof. The chain tongs are not engaged with neck portion  54  or transition area  56  of body portion  52 . Outer surface  57  of body portion  52  is usually a smooth, machined finish, and this makes it difficult for the chain tongs to “bite” into the surface. The result is that the chain tongs frequently slip as previously described. 
     Neck portion  54  defines a typical female connection  58  therein, such as a two-inch FIG. 1502 female connection, and also has an external thread  60  thereon. Female connection  58  and external thread  60  are adapted for engagement by wing union  34 . Wing union  34  includes a male sub  62  which fits into female connection  58 . A seal  64  provides sealing engagement between male sub  62  and neck portion  54  of prior art nipple  44 . A wing nut  66  of wing union  34  is engaged with external thread  60  to hold male sub  62  in place. 
     The casing coupling  32  which connects prior art nipple  44  with uppermost casing section  30  of casing string  28  has a downwardly facing shoulder  70  thereon which may be supported on elevators  38  so that casing string  28  with nipple  44  thereon may be lowered into wellbore  20 . Alternatively, elevators  38  may be slip-type elevators having a plurality of teeth  68  thereon which may be used to grippingly engage the outside diameter of the corresponding casing section  30 . The important aspect is that in any embodiment, casing section  30  is supported below casing coupling  32 . It should also be noted that elevators  38  may be used in the same manner on an integral casing section or joint (not shown) of a kind known in the art which has a shoulder formed by an enlarged end with a female thread therein. Basically, an integral casing section is substantially similar to casing section  30  with casing coupling  32  thereon except that it is integrally formed rather than made using two pieces. Any description herein of connecting to casing coupling  32  should be understood to be equivalent to connecting to the female end of an integral casing section. In fact, casing sections  30  are usually supplied at the well site with a casing coupling  32  already attached to one end of the casing section. 
     Fluid may be circulated through hose  36 , wing union  34  and central opening  47  of prior art nipple  44  while lowering casing string  28 . 
     Referring now to FIGS. 3-7, a first embodiment of circulating nipple  10  is shown. Looking first at FIG. 4, nipple  10  defines a central opening  71  therethrough and has a body portion  72  with an outer surface  73  and a threaded lower end  74 . Body portion  72  is relatively shorter than body portion  52  of prior art circulating nipple  44 . Circulating nipple  10  is not designed to be used with chain tongs and rarely would there be an attempt to make up nipple  10  on casing string  28  by use of such chain tongs. Therefore, the length of outer surface  73  of body portion  72  is relatively shorter to reduce the overall length of circulating nipple  10  as compared to prior art circulating nipple  44 . Of course, this results in a decrease in weight as well, making nipple  10  easier to handle than prior art nipple  44 . In the preferred embodiment, this decrease in size between circulating nipple  10  of the present invention and nipple  44  of the prior art is approximately a thirty to thirty-five percent reduction. It is only necessary to have body portion  72  of circulating nipple  10  long enough above threaded lower end  74  to allow for a few thread recuts as the threads wear. 
     Circulating nipple  10  has an elongated neck portion  76  extending from body portion  72 . Neck portion  76  is relatively longer than neck portion  54  of prior art circulating nipple  44  because new neck portion  76  is preferably sufficiently long that a pipe wrench  77  may be engaged with outer wrenching surface  78  thereof to tighten circulating nipple  10  into casing coupling  32  on casing section  30  or into a female end of an integral casing connection. Pipe wrench  77  is much easier to use than chain tongs. 
     Neck portion  76  defines a female connection  80  therein, such as a known two-inch FIG. 1502 female connection, and has an external thread  82  thereon. Female connection  80  and external thread  82  are substantially identical to female connection  58  and external thread  60  on neck portion  54  of prior art circulating nipple  44 . 
     The upper end of body portion  72  has a relatively thicker transition area  84 . 
     Referring now to FIG. 3, circulating nipple  10  is shown made up to an upper casing section  30  of casing string  28  in a manner similar to that shown in FIG. 2 for prior art circulating nipple  44 . That is, lower end  74  of body portion  72  of nipple  10  is attached to casing coupling  32  at threaded connection  86 . An integral casing section (not shown) may be used rather than a casing section with a separate casing coupling  32 . Either forms a casing connector for engagement by circulating nipple  10  or by an adjacent casing section. 
     A male sub  62  of wing union  34  is disposed in female connection  80 , and a seal  64  provides sealing engagement between male sub  62  and female connection  80 . Male sub  62  is held in place by a wing nut  66  threadingly engaged with external thread  82  of neck portion  76 . 
     As with prior art circulating nipple  44 , shoulder  70  on casing coupling  32  or a similar shoulder on an integral casing section is engaged by elevators  38  extending from bails  40  by which casing string  28  with circulating nipple  10  thereon may be lowered. Also in a manner similar to the prior art, elevators  38  alternatively may have teeth  68  thereon for grippingly engaging the outside diameter of the corresponding casing section  30 , rather than supporting the casing section by shoulder  70 . 
     Referring again to FIGS. 4-7, additional details of the circulating nipple  10  will be discussed. Referring particularly to FIG. 5, transition area  84  of body portion  72  defines a plurality of holes  88  therein, each of the holes defining a hole central axis  90 . Hole central axes  90  are preferably substantially coplanar and each hole central axis forms a chord with respect to outside diameter  92  of outer surface  73 . The plane in which central axes  90  lie will be seen to be substantially perpendicular to a nipple central axis  91  of nipple  10 . 
     Central axes  90  of holes  88  are spaced substantially equally radially outwardly from nipple central axis  91 , and thus, it will be seen by those skilled in the art that central axes  90  are all tangential to a single imaginary circle. Also, holes  88  are substantially equally spaced circumferentially around circulating nipple  10 . However, precise location of holes  88  is not particularly necessary and other arrangements of the holes may work just as well. 
     A slot  94  is formed in circulating nipple  10  on opposite ends of each hole  88 . That is, there are a pair of spaced slots  94  associated with each hole  88 . Slots  94  are provided as a relief in body portion  72  to facilitate drilling of holes  88  therein. As best seen in FIG. 7, but also shown in FIG. 4, each slot  94  has a radiused inner surface  96  which is approximately concentric with hole  88  and has a slightly larger radius so that a slight relief is formed between slots  94  and holes  88 . 
     Holes  88  are adapted for receiving a handle or operating bar  98  therethrough which may be positioned in any of the holes and used as a lever to tighten circulating nipple  10  into casing coupling  32  on casing section  30  or into a female end of an integral casing section. Such an operating bar is a primarily cylindrical rod having a taper on one end to facilitate insertion into the hole and a knurled surface on the other end to facilitate being gripped by the operator. Preferably, but not by way of limitation, the holes are large enough to receive a one-inch diameter operating bar  98 , such as used to open and close Halliburton Lo-Torc® plug valves. This use of operating bar  98  in holes  88  may be used as an alternative to, or in addition to, tightening circulating nipple  10  with the previously mentioned pipe wrench  77  engaged on outside wrenching surface  78  of neck portion  76 . 
     Referring now to FIGS. 8 and 9, an alternate embodiment circulating nipple for setting well casing of the present invention is shown and generally designated by the numeral  100 . Unlike first embodiment circulating nipple  10  which may be machined from a single piece of bar stock, second embodiment circulating nipple  100  is designed for use with relatively larger casing, for example, surface casing  22 . Accordingly, the embodiment shown may be made of several separate pieces which are welded into an integral unit, although nipple  100  could be formed as a single piece such as by casting, forging, etc. 
     Second embodiment nipple  100  has a central opening  101  therethrough and has a body portion  102  with a threaded lower end  104 . Forming an upper end of body portion  102  is a transition area or member  106  which is generally dome shaped. A neck portion  108  extends from transition area  106  of body portion  102  and has a relatively long outer wrenching surface  110  adapted for engagement by pipe wrench  77 . Neck portion  108  of second embodiment nipple  100  is similar to neck portion  76  of first embodiment nipple  10  in that it defines a female connection  112  and an external thread  114  which are adapted for engagement to wing union  34  in a manner previously described. 
     A plurality of bosses or lugs  116  extend from body portion  102  adjacent to transition area  106 . Each boss  116  defines a hole  118  therethrough. Each hole  118  has a hole central axis  120 . Hole central axes  120  are preferably substantially coplanar. This plane is substantially perpendicular to a nipple central axis of nipple  100 . Also, central axes  120  will be seen to be tangential to a single imaginary circle. 
     Holes  118 , like holes  88  in first embodiment circulating nipple  10 , are adapted for receiving operating bar  98  there through for tightening the circulating nipple  100  to casing string  28 . 
     OPERATION OF THE INVENTION 
     In using first embodiment circulating nipple  10  or second embodiment circulating nipple  100 , the method of running well casing  28  into wellbore  20  is substantially the same. As already mentioned, casing sections  30  are normally provided at the well site with a casing coupling  32  already attached to one end thereof. An integral casing section (not shown) with an enlarged end having a female thread therein may also be used. Again, such an integral casing section looks substantially the same as a casing section  30  with a casing coupling  32  thereon except that the integral casing section is a single piece. As is well known in the art, an assembly formed with a casing section  30  and a casing coupling  32  thereon is interchangeable with an integral casing section. 
     In some cases, casing section  30  may not have a casing coupling  32  already engaged therewith. In such cases, casing coupling  32  is threadingly engaged with an upper end of a casing section  30  in the process of running casing. Bails  40  and elevators  38  are positioned as shown in FIG. 1 to engage shoulder  70  on casing coupling  32  or to use teeth  68  to engage casing section  30 . Circulating nipple  10  or  100  is threadingly engaged with casing coupling  32  by use of pipe wrench  77  engaging outer wrenching surface  78  of neck portion  76  of nipple  10  or outer wrenching surface  110  of neck portion  108  of nipple  100 . Alternatively, or in addition to this use of pipe wrench  77 , operating bar  98  may be inserted into one of holes  88  in nipple  10  or one of holes  118  in nipple  100  to make up the threaded connection between the nipple and casing coupling  32 . 
     Wing union  34  is then engaged with neck portion  76  of nipple  10  or neck portion  108  of nipple  100 , thus placing central opening  71  of nipple  10  or central opening  101  of nipple  100  in communication with the mud pump through hose  36 . Traveling block  42  is lowered so that casing section  30  with attached nipple  10  or  100  is lowered into wellbore  20 . When nipple  10  or  100  is near rig floor  16 , the nipple is disengaged from casing coupling  32 , and another length of casing  30  is engaged with that particular casing coupling  32 . Nipple  10  or  100  is then connected to another casing coupling  32  at the top of the new casing section  30  in the same manner previously described. 
     This procedure is repeated for as many casing sections  30  as necessary for the well. While thus running casing string  28  into wellbore  20 , the casing string may be filled when desired by the mud pump through hose  36 , well union  34  and nipple  10  or  100 . Also, the fluid may be further pumped down casing string  28  to circulate the fluid if desired as the casing string is run into wellbore  20  with the circulated fluid returning through the annulus between the casing string and wellbore. This filling or circulating process may be carried out for each casing section  30  or may be done after a plurality of casing sections has been run depending upon the desires of the operator and the well conditions. 
     With either nipple  10  or  100 , the use of chain tongs is not necessary, and the problems associated with the slippage of such chain tongs on prior art nipples, such as nipple  44 , are eliminated. The reduced length and weight of either nipple  10  or  100  compared to the prior art nipple  44  makes it easier to make up nipple  10  or  100  on casing string  28 . Manipulating a lighter and smaller nipple and eliminating the slipping problem with the chain tongs thus helps reduce or eliminate some dangers associated with the prior art nipples and methods of installing them. 
     It will be seen, therefore, that the circulating nipple for setting casing in a wellbore and method of use are well adapted to carry out the ends and advantages mentioned. While presently preferred embodiments of the apparatus and steps in the method have been shown and described for the purposes of this disclosure, numerous changes in the arrangement and construction of parts in the apparatus and steps in the method may be made by those skilled in the art. All such changes are encompassed within the scope and spirit of the appended claims.