US2644523A - Method and apparatus for connecting well casings to liners - Google Patents

Description

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2 Sheets-Sheet 2 Filed March 12, 1949 INVENTolAz. '6.6. Brown v Patented July 7, 1953 U'NrrEof STATES PATE-NrfoFF-ICE` METHOD AND APPARATUS FOR coNNEcT- ING WELL cAsINGs 'ro -LINERs v Cicero C. Brown, Houston, Tex. Application March 12, 1949, Serial No. 81,0754 Y 4 Claims.

Y This inventio-n relates to a method and apparatus for connecting Well casing's to liners.

In the drilling and completion of Wells by the rotary method, the Well bore is normally drilled to a selected depth Without lining the bore with a metal casing, except for the usual surface pipe, the drilling fluid being employed to form a plastic lining to support the Wall of the lbore during the drilling. When a formation is encountered which it is desired to test for production possibilities, various conventional methods may be employed to prepare the portion of the Well bore traversing that formation for testing the lat- A ter. In accordance with one of the more com- -mon of these methods, a string of casing of sufficient length to extend all the way from the surface to or through the formation to be test-` tion isfoundto benon-productive, a quite frequent occurrence, it then becomes necessary to cut the casing at so-me point above the cemented portion and Withdraw it from the Well 'in order to salvage it. This generally results Vin the loss of a substantial section of the casing and in considerable expense-of cutting and salvaging the severed portion. v

In-accordance with another generally conventional method, a relatively short section of casing, commonly termed a linerfis run into the Well -bore and cemented at an appropriate depth in the Well. Such liners may be of variable length, but being in every case less than the full length of the Well bore. Such liners are run into the wellbore on a releasable liner setting tool which is released from the liner'and withdrawn from the well, leaving the liner in place for subsequent testing of the surrounding for- 1 mations. If the latter prove to be dry or commercially non-productive, the liner Vmay be left in the Well and abandoned. This type of testing is favored because'of the saving in casing andA other costs if the well is found to be unproductive. IOn the other hand, if the formations are found to be productive, then a full string, of casing must be set in the well. Becausethe liner is already in place and cemented, it has heretofore been deemed necessary to setthe production string through the liner and cement it in place, after Which both the casing and liner and the surrounding and interven- 2 ing cement bodies must be perforated to provide `comr'nunication between the formation :and the interior of the casing string. This operation necessarilyrequires the use of a casing string and :apparatus by which a casing may be connected directly to the upper end of a pre-set liner so as to form the liner and lcasing into one continuous string which may be of uniform internal diameter from top to bottom of the Well. 'By means of this invention, the advantage of the use of relatively short liners for testing purposes is retained and when production is f o-und, a full diameter casing may4 then be set in the Well, and substantial savings in casing :and operating costs may be effected.

Still another important advantage of this invention is that since the produ-ction casing does not have to be set inside and through the liner, the expense and diiiiculties of re-cementing between the liner and casing and re-perforating both strings to bring the Well into production is avoided.

Various other objects and advantages of Vthis invention will become apparent from the following detailed description when read in conjunction. with the accompanying drawings Which-i1- lustrate useful embodiments in accordance with this invention.

In the drawings:

Figs. 1, 2, 3, and illustrate apparatus used in performing the method, in accordance with one embodiment ofvthis invention, for connecting a casing to a liner, the several gures illustrating several stages of operation; Y

Fig. 5 is a longitudinal quarter-sectional viewof the aligning or guide member employed in effectingthe connection between ,the casing and a liner; and

Figs. 6, 'I and 8 illustrate a slightly modified form of apparatus, showing relative positions thereof at several stages of Operatollr Referring first to Fig. 1, Athere is shown a WW1 bore I0, provided with the usual Surface casing Il, fitted at its upper end with a conventional Well head l2, havingY a valved outlet connection I3 communicating therethrough with the Well bore. A liner l5 is shown installed in the Well lbore at some previously determined depth, the

.for connection to collar 23.

liner being cemented in place by a body of cement C lling theV annular space between the liner and the wall of the well bore to a suitable height along the exterior of the liner. These liners may ordinarily vary in length from less than 100 feet to even several thousand feet but, in any event, are shorter than the full length of the well bore, as previously noted. It will be understood that liner I will -previously have been put in place and cemented in accordance with conventional procedures. The bore of the liner will have been cleared of cement preparatory to testing of the surrounding formations and may be filled with well fluid, drilling mud or other fluid at the time of initiation of the operations which are to be performed in accordance with the method of this invention.

The upper end of liner I5 will ordinarily be fitted with the usual screw collar It to 4which is connected a conventional liner setting sleeve I'I having a tubular skirt I8 screwed down over its upper end. Liner setting sleeve Il and skirt I8 are parts which are conventionally employed for releasably connecting a conventional setting tool (not shown) employed in setting the liner in the well and will normally remain in the well when the setting tool has been withdrawn following cementing of the liner. In accordance with usual practice, the bore of setting sleeve I? will have the same diameter as that. of liner I5 so as to be flush therewith. Skirt I8 will ordinarily have a bore of somewhat larger diameter than that of sleeve I'I and liner I5 and the upper end of sleeve II will be inserted into the bore of skirt I8 and threadedly connected thereto, as illustrated. The upper end of sleeve I'I will thus form an internal shoulder I9 in the bore of skirt I8 which may be employed in the subsequent casing-connecting operations, but is not essential thereto, as will be evident from the subsequent description. For the purposes of this description, liner I5, setting sleeve II and skirt I8 is termed the liner string.

Astring of casing 2t! is shown inserted into well bore IB through well head I2 and connected at its upper end to the usual hollow swivel 2i adapted to be suspended from the conventional hoisting mechanism of a derrick (not shown), whereby the casing string may be raised or lowered in the well bore, as required. Swivel 2I is provided with a hose connection 22 through which cement slurry, drilling mud, or other fluid may be introduced into the interior of casing 23 by means of conventional slush pumps (not shown).

Casing 23 will preferably, although not necessarily, be of the same internal and external diameter as liner I5 and will ordinarily be provided at its lower end with the usual screw collar 23, forming an enlargement thereon to provide an abutment 23a which is adapted to engage and rest on the upper end of skirt I8 when the casing is lowered into the well bore sufficiently to bring the lower edge of collar 23 into contact with the upper end of the skirt.

Connected to collar 23 and forming an extension of casing 20, is an aligning or guide member, indicated generally by the numeral 24, which is adapted to enter the bore of skirt I3 and effect axial alignment of casing 2U with liner I5. Guide member 24 (see Fig. 5) includes a tubular body 25, externally threaded at its upper end Body 25 will ordinarily have the same external and internal diameters as casingZ and liner I5, its external diameter being, therefore, slightly smaller than the internal diameter of skirt I8 whereby body 25 will be slidable inside skirt I8 in accordance with the movements of casing 20. Connected to the lower end of body 25 is a tubular extension 25 of substantially smaller external diameter than body 25. Extension 26 may be connected, as shown, to the lower end of body 25 by means of a tubular bushing 2'I externally threaded about its upper end at 28 for threaded insertion into the bore of body 25 and provided with a laterally extending flange 29 forming a shoulder against which the lower end of body 25 is seated. The outer diameter of flange 29 is made flush with the exterior of body 25. The bore of bushing 21 is internally threaded at 3B to receive the upper end of extension 26.

The lower end of extension 26 is provided with cap 3I adap-ted to form a closure for the end of the extension. An annular packer or sealing ring 32, constructed of compressible, resilient material such as rubber or the like, is mounted about the lower end portion of extension 23 and provided with an upwardly and outwardly flaring flexible lip 33 adapted to form a fluidtight seal for the annular space between the exterior of extension 26 and the bores of liner I5, sleeve I'I and skirt I8, as the case may be, exible lip 33 being adapted to accommodate the sealing ring to any of the diameters of these elements. A plurality of radial openings 34 is provided in the wall of extension 26 somewhat above sealing ring 32 to provide communication between the bore of extension 26 and the exterior thereof. A pair of axially spaced sealing rings 35 are seated in circumferential grooves in the exterior of body 25 below its point of connection to casing 20 and may be of any suitable or conventional form adapted to form a fluidtight seal between body 25 and skirt I8 when the former is inserted into the latter.

The above-described apparatus may be employed for connecting casing 20 to liner I 5 in the following manner, reference being had particularly to Figs. l to 4, inclusive:

Guide member 24 will be connected to the lower end of casing 23 and lowered thereon into well bore I0 as the casing string is made up to the length necessary toy extend from the surface to the upper end of the liner string. When the casing string has been made up to the proper length, it will be lowered from the surface sufciently to cause guide member 24 to enter skirt I8 (Fig. 1). The casing string will then be further lowered until either flange 29 contacts shoulder I9 or abutment 23a contacts the upper end of skirt I8, either conta/ct serving to stop the further downward movement of the casing and guide member relative to the liner string (Fig. 2). At this stage of operations, body 25 will be enclosed within skirt I8 and spaced seals will be Vformed between the exterior of guide member 24 and the adjacent portions of the liner string by means of sealingrings 32 and 35. At this stage of operations, the pumps at the surface will be started pumping a suitable hydraulic fluid, which may be mud, water, or cement slurry, through the interior of casing 20, thence through the registering bores of body 25 and extension 23, the iluid passing out of opening 34 into the annular space between guide member 2d and the the pumps and will be yevidencedj bystoppage of the pumps ora-sharp increase in gauge pressure on .the pumpfdischa'rge.AIneither'event, this back pressure'willfserve as Lan-indication to .the operator that` `guide member 24 has been properly ,inserted in the liner string and. that the casing string isproperly aligned with the liner string. The casing string will then behliited at thesurface a suiiicient distance to raise-body 25 outfof the upper end of skirt I8 and thereby open communication between'the guide member .the distancewhich vthestring'."should be raised forthis purpose, while keeping thelower end of extension 26 and packingsring :32 within the bore of skirt I8, maybe readilydeterminedefrom the known length of guide member 2.4. .This-position of the parts of the apparatus is illustrated' liner string and the wall of the well bore above the previously placed body of cement C. A suf- Viicient quantity of cement slurry will be thus introduced into the well bore to ll the annular space between the wall oi the well bore and the exterior of casing string 20 to the desired height, conventional cementing methods being used for this'purpose. When the cement slurry has all been introduced and displaced in the usual manner from the interior of the casing string, the latter will again be'lowered until shoulder 23a again rests on the upper end of skirt I8, or flange 29 contacts shoulder I9, as the case may be, this position of the parts of the apparatus again corresponding to that shown in Fig. 2. The cement will now be allowed-to harden, thus firmly cementing the casing in the well bore and joining it with the liner string, both by the continuous cement body formed with cement C and by the telescopic connection through member 24. After the cement has hardened, a conventional drill will be run through the bore ofcasing 20 and will be employed to drill out cap 3|v and all metal parts or cement inside guide member 24 to a diameter whichy will be ush with the bores of casing 20 and liner I5, as illustrated particularly in Fig. 4. In this illustrative embodiment, it will be evident that the drill will be required to remove only extension 26 and the portion of bushing 21 which extends inwardly from the inner wall of body 25. It will be understood that the metal parts to be removed will preferably be Y out, a flushbore will be provided throughout the liner and casing string. The wall of body 25 Aforms with the enclosing skirt I8 a double walled withut the `inter',Ventron vof elements sushis-1s setting sleeve I'I kand skirt v1 8; `ofc 4v,theprevidusly described embodiment.` In this'. instance, a guide member 24a has therupper end ofi its bodyf25a connected into the end of vcasing 200,.;by means of a bushing 21a, similarin construction to, bushing 21, which. is inserted into the .end of. casing 28a, body 25a beingdimensioned to slideinsid'e the bore of liner Ia. VInrall other respects the vand; the wel-l bore;V Itv willbe'. understood; that section which will substantially strengthen the inter-connected portions of the liner and casing' strings. Also sealing rings 35 will remain in place between the body 25 and skirt I8 and thereby prevent leakage of iluids between these memconstruction of `guide member .24a issidentical with guide member 24v.l f' The :aligningandfcon- `necting operations are also conducted Lin .the

same manner as previously.` described. Fig v6 shows the guide member partially inserted in liner I:5a.at a stage preparatory to the introduction .of cement slurry. Fig; 7 shows the casing and liner connected following theintroduction .of :the cement, andv Fig. 8 shows the casing and liner connected with the entire guide member 24a bored Aout to provide the flush bore through the casing .and liner. v In accordance Iwit'h the foregoing, it will be evident that methods and apparatus .are provided for readily connecting'well casings toz'liners which are already in place in a well and to-thereby provide a continuous well lining of uniform bore which includes the liner as a part thereof. It will be understood, of course, that casing strings of. smaller or larger diameter than the liner may be connected thereto by suitable modification of the inter-connecting parts.

The herein described method and apparatus may beV employed to provide full length cemented casings for Very deep wells by connecting together a series of liners which are adapted to forma continuous casing of the desired length. By this method, the undesirable high hydrostatic pressures commonly occurring in conventional full string cementing in deep wells may rbe avoided without the relatively complicated apparatus and procedures of conventional stage cementing.

Various alterations and changes may be made in the details of the illustrative embodiments within the scope of the appended claims but without departing from the spirit of this invention. Y

What I claim and desire to secure by Letters Patent is:

1. The method of connecting a well casing to a .liner previously installed in a well bore, comprising, lowering a casing into the well bore into axial alignment with said liner and axially spaced from the upper end thereof, sealing the upper end of the bore of said liner against the entrance of uids, introducing cement slurry into the well bore surrounding the adjacent ends of said liner and casingl lowering said casing into end-abutting engagement with said liner, allowing said cement slurry to'harden to form a continuous cement sheath about the engaged ends of said liner and casing, and removing said seal to provide a continuous bore connecting said liner and casing.

2. Apparatus for connecting a well casing to a liner which is in place in a well bore,'comprising, an upwardly facing internal annular shoulder in the bore of said liner below the upper end of said liner, a tubular connection member closed at its lower end and connected to the lower end of said casing and insertible into said liner, a downwardly facing external annular shoulder on said connection member intermediate its ends adapted to seat on said internal shoulder, a sealing elementV mounted on said connection member below said external shoulder and adapted to form a. uid-tght seal between said member and said liner below said internal shoulder, and openings in the wall of said member between said sealing element and said external shoulder.

3. Apparatus for connecting a well casing to a liner which is in place in a well bore, comprising, an upwardly facing internal annular shoulder in the bore of saidy liner below the upper end of said liner, a tubular connection member closed at its lower end connected to the lower end of said casing and insertible into said liner, a downwardly facing annular external shoulder on said connection member intermediate its ends adapted to seat on said internal shoulder, a pair of circumferential sealing elements mounted at spaced points along said connection member above and below said external shoulder adapted to form axially spaced fluid-tight seals between said connection member and said liner above and below said internal shoulder, and openings in the wall of said member between the lower one of said sealing elements and said external shoulder.

4. Apparatus for connecting a well casing to a liner which is in place in a well bore,k comprising, an upwardly facing internal annular shoulder in the bore of said liner below the upper end of said liner, a tubular connection member connected to the lower end of said casing, said connection member being insertible into said liner and including an upper portion adapted to form a close sliding t in the bore of said liner and a lower portion of reduced diameter closed at its lower end, the juncture of said portions forming a downwardly facing annular external shoulder adapted to seat on said internal shoulder, circumferential sealing elements mounted on said upper and lower portions of said mem--Y ber adapted to form axially spaced fluid-tight seals between said portions and said liner above and below said internal shoulder, .and openings in the wall of said lower portion between the lower one of said sealing elements and said external shoulder.

CICERO C. BROWN.

References Cited in the le of this patent UNITED STATES PATENTS Smith Jan. 24, 1950

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