US2870842A - Cementing head - Google Patents

Description

Jan. 27, 1959 J. A. HALL CEMENTING HEAD FiledAug. 4, 1955 nllllvll United States Patent t This invention relates to improvements in a cementing head for use upon the `upper end of the casing of an oil l or gas `well when the well is being cemented.

Therefore, an object of the present invention is to provide a plug containing cementing head having a positive acting mechanical device for moving the cement plug into the casing string from the storage compartment ofthe head, said device operable satisfactorily even if the head is fouled with preset cement or ice from use in cold weather and does not require extra fluid fittings to the head.

Another object is to provide a plug containing cementing head fitting for the well head which permits the un interrupted sequence of operations including mud circulation, cement introduction and the placing of the cement in a well bore by introducing mud behind the cementing plug without the removal ofthe cementing head from the top of the casing or the switching of valves.

Still another object is to provide a cementing head which permits constant reciprocation of the casing string during the steps of mud circulation, introduction of the cement and placing of the cement in the well bore.

Another object of the invention is to be able to use the almost unlimited power of the rig to break loose and force out a plug that is frozen in the head by subzero weather or by prematurely set-up cement.

Another object of the invention is to release the plug or plugs without stopping the circulation cycle whatso- A ever and without switching any valves whatsoever.

Other and further objects of the invention will appear in the course of the following description.

In the accompanying drawings, which form a part of the instant specification and are to be read in conjunction therewith, an embodiment of the invention is shown and, in the various views, like numerals are used to indicate like parts.

Fig. 1 is an enlarged elevational view of a cementing head embodying the instant invention with parts broken away and parts in section. t

Fig. 2 is a view taken along the lines 2-2 inl Fig. 1 in the direction of the arrows.

Fig. 3 is a `View taken along the lines 3-3 of Fig. 1`

cement and the application of mud pressure behind theV plug to force the cement into place in the well bore without the removal of the cementing head from the casing string. 1By performing this sequence of steps with.- out the `removal of the cementing head from the top of the vcasing string, and by not having any valves` on the head to switch, there need be no interruption of thereciprocation of the casing string during the steps of the cementing process.

Referring to Fig. 1, the cementing head consists of a hollow. body portion 10 screw threaded at its bottom end at 10a for attachment to the top of the casing and screw threaded at its top at 10b to receive its upper seal` into an upper plug chamber 10c and a lower chamber 10d. Rod 175 has threaded stem 15a which has key slot 15b therein. Stufling box threads 12a are engaged by the internally `threaded end of hollow shaft 17. Bearing 18 is Welded to shaft 17 at 19, keyed torstein 15a at 20 and has thrust collar groove 21 thereon.. Key 20 prevents rotation of rod 15 around its axis. Bearing 18 does not engage the threads 16. Nut 22 is threaded to stern 15a and has thrust collar groove 23 thereon. Grooves 21 and 23 o-n bearing 18 and nut 22 are engaged by thrust collar 23 to permit rotation of nut 22 relative bearing 18. Nut 22 `is encircled by and is` fxedly attached to wheel or chain sheave 25 which is engaged by endless chain 26. Rotation of wheel 25 will thus back rod 15 off from or insert rod 15 in recess 16, depending on the direction of ro-tation thereof.

Threaded nozzle 27 is connected into lower chamber 10d and to this nozzle may be screwed fitting 28 which, preferably, is connected to a T head into which, preferably, lead suitably valved mud and cement lines from conventional mud and cement sources to permit alternate controlled input of mud or cement into the body portion 10. This latter arrangement is not illustrated as it involves only conventional apparatus.

A cement plug 29 is placed in the upper chamber 10c abovethe rod 15 before the cementing head is mounted on the top of the 4casing string. One or more rods 30 are welded to the inside of body 10 to provide a fluid by-pass past plug 29 (see Fig. 3).

Adaptor shell 31 has threads 32 and `is attached to threaded upper body portion 10b by collar 33. Upper packing box 34, having opening 34a, is welded into the top of adaptor 31 and has packing 35 sealed therein by hollow packing nut 36. O rings 37 are positioned in grooves 38 in packingbox 34. Hollow shaft 39, having opposing slots 40 running essentially the length thereof, is threaded to the outside of packing box 34. Cement plug drive rod 41, having thrust pad 42 at the lower end thereof, extends through packing box 34, nut 36 and shaft 39. Resilient seal 43 is mounted above pad 42. Rod 41 is bifurcated near its upper end to receive pulley 44 mounted on pin 45. Guide plate 46, having an outer diameter slightly less than the inner diameter of shaft 39, is fixed to rod 41 below pulley 44 and has rubber bumper 47 mounted therebelow. Cable 48 isV attached to bracket 11 through hole 11a by eye 49, passes through slots 40 in'shaft. 39, loops over pulley 44 and threads eye 50 on stud 51 welded to body 10. The portion of shaft 39 extending above the top of rod 41 when the latter is in extended position serves to protect the rod from the rig hook and other rig apparatus above the` been drilled to the desired depth land mud has been circulated to thoroughly clean the debris from the well bore.

Contemplating a cementing operation, a cement shoe is attached to the lower'end of the bottom section of well pipe and the casing is run into the well in the usual manner. Along the exterior of the casing are applied scratcher and 'centralizer elements. These yabrading ldevices are arranged at proper intervals to maintain the :casingncentrally iin the "well bore Aand clean the wall of the well when the string is vreciprocated ias hereinafter described. After the-casing has ybeen vrun into-the well, -th`e cementing head, shown in Fig. '1, ismountedfatthe top of thecasing.

A fitting y28 is attached to the horizontal nipple 27 of the bodyl Vportion r10- and the .previously described, `but not-shown, mud and -cement input hose or .apparatus attached thereto. The rod .15 is seatedpin the `recess 16. The cement plug `29A .has been placed in the upper chamber c ofthe cementing :headbefore mounting the head onv the casing.

To begin the operation, mud fluid is :charged through the 'tting 28 into "the -lower compartment V10d of the head through the vnozzle 27. The :mud duid ventering the head below the rod is directed downwardly through the casing string and 'out `of the bottom of the rcasing into the well bore surrounding 'the casing. Themud ffluid also by-passes the plug '29 in the -cementing. head :by means of rods 30, therebyequalizing the'pressure-onv each side of the plug and 'uniformly Idistributing the internal pressure throughout the body portion 10. The-mud -rises in the well -to the ground level and yis returned to the mud pit. During this'circulation, the casingstring is A'reciprocated vertically in the well bore andthe abrading elements yon the exterior of Athe pipe remove adhering mud 'cake from the Well wall and exterior of'the casing, or, the casing may be rotated by means -of "swivel :connection on the head at 10a or by a swivel Iconnection yin the hose, which would have to be held above -the thead, thus allowing -the head to turn with the pipe. When the well bore has been cleaned in this fashion kand the amount of cement-needed hasbeen determined by logging the well or Ymaking a caliper survey, the mud circulation `,is finterrupted. v)immediately thereaftenthe vfluid cement mix is Vcharged into the vnozzle.27 `from the source :of-cement supply, such as a cement truck,-n'ot shown. The-cement mix enters the lowerV compartment 16d of .the head through the nozzle and passes vdownwardlyrthroughfthe casing as -a column vforcing the mud before it. xOnce again, the by-pass rods 301permit equalizationof thepressure within the cementing he'ad'on allsides of theplug 29. When the quantity of cementiigured for the ,particularlcement job has been introduced, the cement`mixingis stopped. The rod 155is Withdrawn from recess 16 below the plug 29 by rotating Wheel or sheave 25 by endless lchain 26 and the cement pump is started to pump cement, water, oil or mud or the mudvpumpis startedto charge .mud into `the -top of -the head through rthe nozzle. Simultaneously, force Yis exerted on`the cable 48 through'a winchor othermeans (not shown) Vwhereby to move plug 29 downwardly in the Vce'menting head under impetus ofthe rod dl. As thepressure is equalizedon all sides ofthe iplug'byy the byepassing ofuids around rod-30, no greatexc'ess of force is required-to move theplug. Sufficient force may be applied, however,

to break any ice, mud or cement bridges between 'fthe plug and body 10. When either the bottom edge of plug 29.has passed below-the bottom edge of nozzle 27, the pressure will travel up on top of the plug-by by-pass rods 30 or when theupper edge of plug 29 'haspassed below the upperedge ofthefnozzle 27,the pressure of theinput mud is exertedonly on the topsurface .of theplu'g .and from .thisYPoint, the plug is i. driven kdownwardly `by .the action of the fluid alone. The dotted linesrin Fig. .1.illustrate the rod 41 -at -its 'lowest extension-with bumper 47 abutting thetop of packingnut 36. Rodflill-is'zpreferablyfof such length that at full extension the top of plug 29 is pushedvjust below the upper edgeofvinput nozzle '27 whereby the iiuidrinput will now-in behind the plug 'to continue `its motion into the casing. The

pressure ofthe fluid also ,tends to return the piston rod 41 to its extended position in the hollow shaft 39 after the plug passes nozzle 27. The mud fluid charged behind the plug forces the plug from the lower compartment 10d of the head into the casing and, acting as a plunger, forces the column of cement downwardly through the casing and into the well bore surrounding the casing. By the time the plug has reached the oat valve, not shown, located a short distance above the cement shoe, the liuid `cement has been properly placed in the well bore, and mud replaced or forced out of thel Well by ythe cement :is returned to the mud pond.

During the initial mud circulationand while the cement is being placed, the casing string is vertically reciprocated to maintain the string centrally in the well bore, to prevent accumulation of mud on the Well wall and outside of the casing, bridging of the mud or cement between Xthe well wall and `the casing, and channeling Aof the cement while it is -being placed.

Thus it will be seen that there has been provided a cementing `head adapted to `be mountedpon Ithe top of the casingstring for use Yduring the .period when thewel'l is .being `prepared for .cementing yand .during :the time that the cement .is being placed. The :construction lof the `head'fis such that fthe `consecutive operations of -mud circulation, introduction .of cement, insertion -of ithe vcement plugand charging ofthe `mud :behind the cement column are performed without the necessity of removing the head. ABy dispensingwith the removal .of `the ,head beforeeachfoperation and vby eliminating valveiswitching at the head :and Athereby yeliminating stopped vcasing ztime, considerable 4'time is saved and difficulties attending the interruption of Vcasing reciprocation are avoided. As previously noted, continuous vertical or rotational movement of the vcasing string in the .well bore, combined with thescraping and .agitating action of the abrading elementsVserve `not only to centralize the pipe :butalso to keep the solids in the mud liuid and the cement mix from setting up prematurely and the cement =miX `from channeling.

From the foregoing it will be seen that this invention is one :well adapted to attain Iall the ends and objects hereinabove set forth, `together with other advantagesV which are obvious and are inherent to the structure.

It will be kkunderstood that certain .features -and subcombinationsrare of utility andmay -be employedwithout reference to other :features vand subcombinations. This is contemplated by and is ywithin the scope of `'the claims.

As many possible embodiments may be made of the invention without departingtfromfthe scope thereof, it is tobe understood that Aall material hereinbefore set forth or shown in the drawings is to be interpreted-as illustrative and not in a limiting sense.

Having described fmy-invention, vI claim:

1. A cementing head comprising Va hollow body portion, the lupper part of saidbody portion adapted tol-receive a cement plug, the lower `portion adapted to be connected to the-casing so as `to substantially align nthe axes of the casing and body portion, removable means for retaining the/plug in the upper body portion positioned adjacent the bottom of the upper body portion, the lowerlportion'of said body portion havingan input opening *for well vfluids and open at its lowerend Afor egress of said fluids therefrom, means cooperating between the upper and lower body parts to permit bypass of'a portion4 of thewellniluids entering the body portion throughfthe input opening pastthe plug into. the-upper body-portion to equalize the-pressure oneach Vside ofthe plug, apiston rod mounted at the upper end of saidbody portion and lextending therethrough, the lower vend-of said piston rod abutting the top of said cement plug, means 'for `applying force axially of said -piston rod mounted lon said Vbody portion lwhereby to `move said plug from the upper body portion at least past the upper edge of the fluid input openingin the lower body portion, said rod of sufcient le'igth to continually contact said plug until it passes the upper edge of said uid input opening, the means cooperating between the upper and lower body portions to permit bypass of well fluids past the plug into the upper body portion comprising at least one rod xedly attached to the inner wall of said body portion and extending between said upper and lower body portions, said rod of greater length than said plug.

2. A cementing head comprising a hollow body portion, the upper part of said body portion adapted to receive a cement plug, the lower portion adapted to be connected to a casing so as to substantially align the axes of the casing and body portion, removable means for retaining said plug in said upper body portion positioned adjacent the bottom of the upper body portion, the lower portion of said body portion having an input opening for well fluids and open at its lower end for egress of said fluids therefrom, means cooperating between the upper and lower body portions to permit bypass of a portion of the well uids entering the body portion through the input opening past the plug into the upper body portion to equalize the pressure on each side of the plug, a piston rod mounted at the upper end of said body portion and extending therethrough, the lower end of said piston rod abutting the top of said cement plug, means for applying force axially of said piston rod mounted on said body portion whereby to move said plug from the upper body portion at least past the upper to exert force on the cable.

3. Apparatus as in claim 2 including a cable guide mounted on the body portion through which said cable passes, said guide mounted at least substantially on the opposite side of the body portion from the cable attachment thereto.

4. Apparatus as in claim 2 wherein a` doubly slotted cable guide surrounds the extension of the `rod from the upper body portion, the cable passing through the slots therein.

5. Apparatus as in claim 4 wherein the upper ends of the slots in the guide are closed whereby to retain the cable within said guide.

References Cited in the le of this patent UNITED STATES PATENTS 759,412 Beane May 10, 1904 1,750,143 Wickersham Mar. 11, 1930 1,763,642 Dievendorif et al. June 17, 1930 1,894,912 Otis Jan. 17, 1933 2,647,582 Brown et al. Aug. 4, 1953

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