US3730267A - Subsea well stage cementing system - Google Patents

Abstract

A system for cementing plural cement stages in subsea wells having a well casing string connected to drill pipe and suspended from a casing hanger in a well bore below a subsea well head, the casing including a float collar; a lower first stage cementing plug releasably mounted above the float collar and below a stage cementing valve collar incorporated in the casing string, and an upper second stage cementing plug releasably mounted within the casing string above the stage cementing valve collar with actuating members of successively larger diameters which are adapted to pass through the drill pipe into the casing string and to successively: (a) release the first stage cementing plug, (b) close off the casing string below the stage cementing valve collar and open the cementing ports of the collar, and (c) release the second stage cementing plug which is adapted to close the cementing ports of the collar. Further cement staging may be provided with the casing string above the foregoing and below the casing hanger by providing appropriate additional components of the kind disclosed.

Description

United States Patent 119'] Scott "1541 SUBSEA WELL STAGE CEMENTING Primary Examiner-Marvin A. Champion Assistant Examiner- Richard E. Favre'au Attorney-Donald W. Banner, William S. McCurry and John W. Butcher 1 I 1 111 I} 3,730,267 I [451 May 1,1973

't 'vi" imam A system for cementing plural cement stages in subsea wells having a well casing stringconnected to'drill pipe and Suspended from a casing hanger in a well bore below a subsea well head, the casing including a float collar; a lower first stage cementing plug releasably mounted above the float collar and below a stage cementing valve collar incorporated in the easing string, and an upper second stage cementing plug releasably mounted within the casing string above the stage cementing valve collar with actuating members of successively larger diameters which are adapted to pass through the drill pipe into the casing string and to successively: (a) release the first stage cementing plug,

( b) close off the casing string below the stage cement ing valve collar and open the cementing ports of the collar, and (c) release'the second stage cementing plug which is adapted to close. the cementing ports of the collar. Further cement staging may be provided with the casing string above the foregoing and below the casing hanger by providing appropriate additional components of the kind disclosed.

l 1 Claims, 6 Drawing Figures Patented May 1, 1973 3 Sheets-Sheet 2 iT QVE NTO R 65 46 5- SCOTT Patented May 1, 1973 5 Sheets-Sheet 5 '7 INV ENTOli LVQE 15. $6077- 1 SUBSEA WELL STAGE CEMENTING SYSTEM BACKGROUND OF THE INVENTION ,as disclosed herein, the well casing string to be ccmented within the well is lowered and suspended within the well bore from the subsea well head and connected with drill pipe from the well head upwardly to the drilling rig floor.

Well casing is generally of relatively thin wall construction and large diameter and equipped with threaded pipe type connecting couplings primarily designed for permanent connection when installed. In contrast, well drill pipe is of generally smaller diameter with sturdy wall construction for withstanding the torque and tension imposed during the drilling of a well. Drill pipe is equipped with machined tool joints having tapered machined threads for rapid and repeated connection and disconnection.

In offshore locations where drilling operations are performed from a floating vessel, it is very desirable to use drill pipe principally because it is always available on board the float. The distances between the subsea well head and the surface of the water may be as much as 2000 feet or more. If casing were used, as much as 2000 feet would have to be transported to this vessel which may be miles off shore; and when the job has been completed,this same amount would have to be transported back to shore, as there would be no further use for casing of that size and there is no room on board for superfluous material. Furthermore, due to the type of threads and thin wall construction of casing, it isinot easily assembled and disassembled. Another important advantage of using drill pipe is that, even if the floating drilling vessel is usually well secured, it still is subject to much sea motion. Telescoping bumper subs or joints are readily available and are used to absorb this movement for drill pipe but are unavailable for well casing.

Stage cementing methods are presently in use for land based well installations in which the lower portion of the well only is cemented in one operation, and the upper portion is cemented in subsequent operation. This type of operation requires a special type of equipment, such as bypassing cementing plugs and shut-off plugs and a stage cementing collar that is usually placed above a lower zone to be cemented in a previous cementing stage. As known, the cementing plugs used in stage cementing operations differ from cementing plugs used in conventional cementing operations. Since a stage cementing collar is designed with restrictions in its bore, the cementing plugs must be very flexible to pass through these restrictions. The added flexibility of these plugs is detrimental to their wiping qualities. This invention pertains to incorporating subsea stage cementing apparatus to be used in combination with subsea equipment from drill pipe, and at the same time i provide a system that permits the use of conventional type cementing plugs with such subsea stage cementing equipment.

DESCRIPTION OF THE PRIOR'ART Previous methods and apparatus available for subsea cementing operations are disclosed in U.S. Pats. No.

head and connected through drill 3,507,325 and No. 3,545,542. Well cementing plugs and floating equipment are disclosed in U.S. Pat. No. 3,159,219 and No. 3,437,137. Also, for example, floating and stage cementing equipment and methods are disclosed on pages 582-590 of the 1970-71 edition of the COMPOSITE CATALOG of Oil Field Equipment and Services, published by Gulf Publishing Company, Houston, Texas, U.S.A., hereinafter referred to as the COMPOSITE CATALOG.

SUMMARY OF THE INVENTION The present invention provides means to cement a subsea well in stages through drill pipe where the subsea well head may be several thousand feet under water.

The present invention also provides means to reduce the time and expense of separate concentric strings of well casing being cemented in a subterranean well where stage cementing may be utilized in lieu thereof.

The present invention further provides utilization of a maximum adaptation of commercially available and proven components with minimum requirements for relatively expensive specially manufactured components.

The foregoing and other accomplishments and advantages are attained in a system for cementing plural cement stages in subsea wells including a well casing string to be cemented into position which is suspended below a subsurface well head and from a casing hanger mounted within the well head; the casing hanger is connected through a removable installation tool, which tool is in turn connected to the lower end of a string of drill pipe suspended from equipment at the water surface. The casing string may include a float collar,- a float guide shoe and/or a guide shoe. The casing string will include a lower first stage cementing plug releasably mounted below a stage cementing collar, which cementing collar is incorporated at a predetermined position in the casing string, and an upper second stage top cementing plug releasably mounted at a predetermined position within the casing string above the stage cementing collar. Respective actuating members of successively larger diameters are adapted to passthrough the small drill pipe into the larger casing string and to successively: (a) actuate the first stage cementing plug, (b) close off the casing string below the stage cementing collar and open the cementing ports of the stage cementing collar, and (c) actuate the second stage cementing plug, which in turn is adapted to close the ports of the stage cementing collar. Further cement staging may be provided for a casing string above the foregoing apparatus and below the casing hanger, by providing additional apparatus of the kind herein disclosed.

BRIEF DESCRIPTION OF THE DRAWING Referring to the drawing:

FIG. 1 is an elevational and partly sectional view of the apparatus of the present invention as installed in suspension from a schematically shown subsea well pipe to a floating drilling rig above (not shown);

FIG. 2 is a detailed sectional view of the lower first stage cementing plug, the stage cementing collar and the upper second stage cementing plug;

FIG. 3 is an elevational sectional view of the apparatus during the first stage cementing phase wherein the cement has been pumped to below the first stage plug and the first stage plug actuating member is seated;

FIG. 4 is an elevational and sectional view of the apparatus after the first stage of cement has been pumped out of the casing string and with the stage cementing collar actuating member shown at the completion of the opening of the stage collar cementing ports;

FIG. 5 is an elevational sectional view of the apparatus during the second stage cementing phase wherein the cement has been pumped to below the upper second stage cementing plug and the second stage plug actuating member is seated; and

FIG. -6 is an elevational sectional view of the ap paratus after the second stage of cement has been pumped out of the casing string through the stage cementing ports, the upper second stage plug having completed the closure of the stage collar cementing ports.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 there is shown acasing string combination 10 disposed in awell bore 12 which extends below a sea floor l4. CAsingstring 10 is suspended from a hanger body 16 which in turn is supported by a larger hanger body 18. Hanger body 18 is connected to a larger and shorter casing string (not shown) which, for illustration, would be previously installed and cemented into position. Hanger body 18 is connected within a subseawell head assembly 20, schematically shown.Casing string 10 is connected upwardly through an installation tool 22 and a string ofdrill pipe 24 into appropriate hoisting and cementing equipment (not shown) located at the surface of the water. Supplemental information concerning subsea well head installations and prior art features of this invention are shown in U.S. Pat. No. 3,545,542, specifically incorporated herein by reference.

Thecasing string combination 10 is comprised of aconventional guide shoe 26 connected through an upwardly disposedcasing 28 of selected length into connection with afloat collar 30.Float collar 30 is connected through an upwardly disposedcasing 32 of selected length into connection with a first stagecementing plug combination 34 which in turn is threadedly connected to the lower end of astage cementing collar 36.Cementing collar 36 is connected through an upwardly disposedcasing 38 of selected length into connection with hanger body 16 whereby the entire casing string combination I0 is suspended from the hanger body.

Asecond stage 1cementing plug assembly 40 is disposed at a selected position withinupper casing 38 and threadedly connected through aswivel 42 and an operating mandrel 44 into the bottom of installation tool 22.Cementing plug assembly 40 is preferably provided to fit very tightly withincasing 38 to ensure a good wiping action as later described and the principal purpose ofswivel 42 is to permit threaded connection and assembly of the components as shown without rotation of the tightly fittedplug assembly 40 withincasing 38. It is to be noted that installation tool 22 and hanger 16 are provided with cooperating threads to form a reverse or lefthand threaded connection 46. As later mentioned, connection 46 is disengaged when desired by right hand rotation of installation tool 22 bydrill pipe 24 relative to hanger 16.

Float collar 30 may be of conventional and commercially available construction such as shown at page 588 of the 1970-71 COMPOSITE CATALOG, for example. For illustration,float collar 30 is shown in include acheck valve ball 48 retained in acage assembly 50 and adapted to close against aseat 52. Valveball 48 is disposed to permit fluids to be pumped downwardly throughcasing 32 and 28 and to seat againstseat 52 to prevent upward fluid flow intocasing 32 as shown in FIGS. 3-6.

Referring to FIG. 2, the first stagecementing plug assembly 34 is shown to comprise a flangedsupport sleeve 54 mounted in threaded relation within a threadedcasing collar 55.Casing collar 55 also serves to threadedly connectcasing 32 to the lower end ofstage cementing collar 36. Rotatably mounted withinsupport sleeve 54 is a shoulderedswivel sleeve 56 which together with the support sleeve comprise aswivel structure 57. A retainer bushing 58 is threadedly connected to the lower end ofswivel sleeve 56 to retain the sleeve in rotatable relation withinsupport sleeve 54. Bushing 58 is fitted in nested relation within a counterbore formed in a hollowcylindrical body 60 of a cementingplug 62 and releasably retained in position by holding means such asshear pin 64. Thebody 60 of cementingplug 62 is encased in arubber wiper structure 66 having a plurality of sturdy annular wiper lips as is conventional with full casing size cementing plugs of this kind. Cementingplug 62 is preferably provided as an adaptation of the structure taught by US. Pat. No. 3,437,137. Cementingplug 62 is provided to fit very tightly withincasing 32 to ensure a good wiping action and theswivel structure 57 is provided to permit rotating connection of the threaded members during assembly of the structure as shown without incurring the difficulty of rotating cementingplug 62 withincasing 32.Body 60 is provided with a second counterbore which defines aretainer seat 68. Thepurposeof seat 68 is to retain an actuating member such as a ball 70 (shown in FIGS. 3-6) which is utilized in later described steps of operation of the invention.

Stage cementingcollar 36 is best shown in FIG. 2. Thecollar 36 may be of conventional types available from several sources and, as shown for illustration, is a modification ofa stage cementing collar such as shown on page 588 of the 1970-71 COMPOSITE CATALOG. Generally described,collar 36 is provided with acylindrical body 72 adapted for threaded connection tocollar 36 andcasing 38. A plurality of cementingports 74 are defined through and around the walls of body ,72 and is selectively closed off by anopening sleeve 76 slidably mounted within the bore ofbody 72. Slidably mounted within the bore ofbody 72 above openingsleeve 76 is aninitial closing sleeve 78.Sleeves 76 and 78 are retained in initial position as shown by holding means such as shear pins 80 and 82. Fitted in slidable relation aroundbody 72 is a sealingsleeve 84 which is retained in the upper open position as shown by means such as shear pins 86. .Sealingsleeve 84 serves to permanently close off cementingports 74 when moved to a lower position. Sealingsleeve 84 is also equipped with aninner ratchet ring 88 which is adapted to engage accommodating ratchet grooves defined aroundbody 72 and retain the sealing sleeve in the lower closed position. Aprotector sleeve 90 is mounted about sealingsleeve 84.Protector sleeve 90 is provided with ports which are in registry withports 74. Aport 92 inbody 72 provides pressure communication from withinbody 72 to the chamber defined by the upper end of sealingsleeve 84,body 72 andprotector sleeve 90.

To the extent described above,stage cementing collar 36 is conventional in design and commercially available. The modifications tocollar 36 for its adaption to the present invention are the provision of a portopening retainer seat 94 mounted within openingsleeve 76 and a port closingretainer seat 96 mounted within closingsleeve 78.

The purpose of openingretainer seat 94 is to retain an actuating member such as an opening ball 98 (shown in FIGS. 4-6) which is utilized in later described steps of operation of the invention. The purpose of closingretainer seat 96 is to retain the second stage cementing plug 40 (shown in FIGS. 3-6) in the operation of the invention.

Second stage cementingplug structure 40 is best shown in FIG. 2.Structure 40 is seen to include a hollowcylindrical body member 100 encased by arubber wiper structure 102 having a plurality of sturdy annular wiper lips. A threadedretainer bushing 104 is nested within a counterbore defined in the upper end ofbody 100 and releasably fixed therein by means such as ashear pin 106. A latchinggroove 108 is defined within the bore ofbody 100 to receive the latching snap ring of an actuating means such as a wiping launching dart 110 (shown in FIGS. 5 and 6). As withplug structure 34, plugstructure 40 is preferably provided as an adaptation of the structure taught in US. Pat. No. 3,437,137. Each of the annular lips, except the bottom lip, ofplug structure 40 is ported or slightly vented as shown in FIG. 2 to permit fluid pressure to be transmitted across the plug structure as later mentioned.

Retainer bushing 104 is threadedly connected through a ventilated nipple intoswivel 42. As previously mentioned, plugstructure 40 is tightly fitted intocasing 38 and the purpose ofswivel 42 is to permit rotation of the various threaded connections of hanger body 18, operating mandrel 44 and installation tool 22 to assemble the structure as shown without the attendant difficulty ofrotating plug structure 40 withincasing 38.

DESCRIPTION OF METHOD AND OPERATION shown,drill pipe 24 is connected at the surface through a conventional cementing manifold to a pump (not shown). Such cementing manifolds are for the purpose of introducing actuating elements such as ball 70,ball 98 and launching dart l into the pump discharge and thereon throughdrill pipe 24 intocasing string 10 for purposes hereinafter described.

When positioned as shown in FIG. 1, fluid under pressure, generallydrilling fluid or possibly seawater, is pumped through drill pipe24, casingstring 10, out throughguide shoe 26, up through the annulus betweencasing string 10 and well bore 12, and out between hanger body 16 and hanger body 18 to establish fluid circulation through the system.

Referring now to FIGS. 3-6, afirst stageof cement 112 is introduced into drill pipe .24 and displaced with pumped fluid through and out ofcasingstring 10 into the annulus within well bore 12. The actuating ball is introduced intodrill pipe 24 at or near the juncture ofcement 112 and the displacing fluid and followscement 112 intocasing string 10 as shown in FIG. 3. The

respective size of ball 70 andretainer seats 68, 94 and 96 are such that the ball passes throughseats 94 and 96 and seats into sealing engagement withseat 68, thereby blocking fluid flow through the first stagecement plug structure 34. Further application of pump pressure causespin 64 to shear, releasing the plug fromsupport assembly 57. Ball 70 is preferably provided of density comparable to the fluids being pumped, hard rubber or plastic for example, in order to be conveniently moved along with thecement 112.Plug 34 and the fluid above the plug thereon displacecement 112 out ofcasing string 10 up into the annulus of well bore 12. Such displacement is continued, leaving thecasing 32 free of cement, until plug 34 lands in supporting abutment onfloat structure 30 as shown in FIG. 4. As shown 'in FIGS. 5 and 6, no further flow of first stage cement I 12 or the displacing fluid is permitted in either direction by the opposing check valve action ofballs 48 and 70.First stage cement 112 is then in position to set as shown in FIG. 5.

At some selected time before or aftercement 112 has set or has been even fully displaced, the openingball 98 is introduced into thedrill pipe 24 and thereafter allowed to drop or sink through the fluid in the drill pipe, casingstring 10 andclosingretainer seat 96 into sealing engagement with openingretainer seat 94.Ball 98 is provided of a high density material, such as a lead alloy for example, to hasten its rate of descent. Application of fluid pump pressure againstball 98 andretainer seat 94 causes pin to shear and openingsleeve 76 to slide to its lower position, permitting fluid passage through cementing ports I 74 and preventing fluid flow to belowcasing collar 36 as shown in FIG. 4. Pumping is thereon continued to establish fluid circulation through the cementingports 74 and upwardly through the annulus.

Whencement 112 has had a sufficient time period to set (generally a minimum of four hours)second stage cement 114 is introduced intodrill pipe 24 and thereon intocasing string 10.Cement 114 is displaced through.

drill pipe 24 by a launching dart followed by pumped fluids to a position in casing 38 as shown in FIG. 5, whereupon launchingdart 110 entersplug structure 40 and latches into thegrooves 108. Additional pumping causespin 106 to shear and thedart 110 and plugstructure 40 to move down jointly throughcasing 38, displacingcement 114.Dart 110 serves to wipe the drill pipe clean of cement during its passage through the drill pipe and plugstructure 40 combined withdart 110 serves to wipecasing 38 clean of cement during passage down throughcasing 38.

Continued pumping forces cement 114 down throughcasing 38, out throughports 74 and upwardly in the annulus between well bore 12 andcasing string 10, as shown in FlGS. and 6, untilplug structure 40 engages closingretainer seat 96. The fluid pressure aboveplug structure 40 thereupon causespin 82 to shear and closingsleeve 78 to move to its lower position to close offports 74. Closure ofports 74 causes an increase in pump pressure at the surface, indicating such closure, and also causes pressure to be transmitted through the vented wiping lips ofplug structure 40 and throughport 92 to be imposed on sealingsleeve 84, causing the sealing sleeve to move down acrossports 74 and to be locked into closed position byratchet ring 88 as shown in FIG. 6. Installation tool 22 then may be rotated out of hanger 16 and the entire assembly attached to drillpipe 24 withdrawn to the surface.

Cement 112 andcement 114 are then given time to set properly as determined by the operator (several hours to several days) after which time drilling may be resumed through casing string to removeplug structure 40,retainer seats 94 and 96,sleeves 76 and 78,

I plugstructure 34, the drillable interior portions of float spirit of the invention as herein set forth.

That being claimed is:

1. A subsea well installation comprising:

a. a composite string of well casing suspended within a subsea well bore from a casing hanger supported by a subsea well head, said casing being adapted to be connected through an installation means and a string of drill pipe to hoisting and cementing equipment disposed at the water surface above the well head;

b. a stage cementing collar having cementing ports which can be opened and closed incorporated at a selected intermediate position within said casing;

c. a hollow first stage casing cementing plug means mounted in swiveled and releasable relation within said casing below said cementing collar;

d. a valved casing floating means mounted within said casing below said first stage cementing plug means, and

e. a hollow second stage casing cementing plug means mounted in swiveled and releasable relation within said casing above said cementing collar.

2. The subsea installation ofclaim 1 further comprisa. a first actuating means adapted to pass through drill pipe, said second stage cementing plug means and said cementing collar to engage said first stage,

cementing plug means and move said first stage cementing plug means to a lower portion of said casing in response to fluid flow through said drill pipe and said casing;

b. a second actuating means adapted to pass through drill pipe and said second stage cementing plug means to open said cementing ports and close off fluid flow through said casing to below said cementing collar, and

c. a third actuating means adapted to pass through drill pipe to engage said second stage cementing plug means and move said second stage cementing plug means downwardly in said casing to close said cementing ports.

3. The subsea well installation ofclaim 1 wherein one of said casing cementing plugs comprises:

a. a circular flanged swivel support member defining an axially disposed cylindrical bore and adapted for mounting within a casing collar to be included in a well casing;

b. a shouldered swivel sleeve rotatably mounted within and extending below said support member;

-c. a cylindrical cementing plug means including a cylindrical plug body member defining an axially disposed cylindrical bore having retainer means therein adapted to receive an actuating member passing through drill pipe; said body member being encircled by a resilient sealing and wiping structure having annular wiping lips and adapted for a tight sealing fit within a well casing, and

d. releasable connection means releasably connecting said cementing plug means to the lower end of said swivel sleeve to be released from said swivel sleeve by force applied between said swivel sleeve and said plug body member. The subsea installation of claim 2 further comprising:

a. a first actuating means adapted to pass through drill pipe, said second stage cementing plug means and said cementing collar to engage said first stage cementing plug means and move said first stage cementing plug means to a lower portion of said casing in response to fluid flow through said drill pipe and said casing;

b. a second actuating means adapted to pass through drill pipe and said second stage cementing plug means to open said cementing ports and close off fluid flow through said casing to below said cementing collar; and

c. a third actuating means adapted to pass through drill pipe to engage said second stage cementing plug means and move said second stage cementing plug means downwardly in said casing to close said cementing ports.

5. An improved cementing plug means comprising:

a. a circular flanged swivel support member defining an axially disposed cylindrical bore and adapted for mounting within a casing collar to be included in a well casing;

b. a shouldered swivel sleeve rotatably mounted within and extending below said support member;

c. a cylindrical cementing plug means including a cylindrical plug body member defining an axially disposed cylindrical bore having a retainer seat thereon adapted to receive an actuating member passing through drill pipe; said body member being encircled by a resilient sealing and wiping structure having annular wiping lips and adapted for a tight sealing fit within a well casing;

d. releasable connection means releasably connecting said cementing plug means to the lower end of said swivel sleeve to be released from said swivel sleeve by force applied between said swivel member and said plug body.

6..Apparatus adapted to be suspended from a subsea well head within a subsea well bore and cemented in stages within the well bore, comprising:

a. a composite string of well casing adapted to be suspended from a casing hanger supported by a subsea well head, said casing being adapted to be connected through an installation means and a string of drill pipe to hoisting and cementing equipment disposed at the water surface above the well head;

b. a stage cementing collar having cementing ports which can be opened and closed mounted at a selected intermediate position within said casing;

c. a hollow first stage casing cementing plug means mounted in releasable relation within said casing below said cementing collar; and

d. a second stage casing cementing plug means mounted in releasable relation within said casing above said cementing collar.

7. The apparatus of claim 6 wherein at least one of said casing cementing plug means comprises:

a. a circular flanged swivel support member defining an axially disposed cylindrical bore and adapted for mounting within a casing collar to be included in a well casing;

b. a shouldered swivel sleeve rotatably mounted within and extending below said support member;

0. a cylindrical cementing plug means including a cylindrical plug body member defining an axially disposed cylindrical bore having a retainer seat thereon adapted to receive an actuating member passing through drill pipe; said body member being encircled by a resilient sealing and wiping structure having annular wiping lips and adapted for a tight sealing fit within a well casing;

d. releasable connection means releasably connecting said cementing plug means to the lower end of said swivel sleeve to be released from said swivel sleeve by force applied between said swivel sleeve and said plug body member.

. The apparatus of claim 7 further comprising:

a first actuating means adapted to pass through drill pipe, said second stage cementing plug means and said cementing collar to engage said first stage cementing plug means and force said first stage cementing plug means to a lower portion of said cas ing in response to fluid flow through said drill pipe and said casing; g

. a second actuating means adapted to pass through drill pipe and said second stage cementing plug means to open said cementing ports and close off fluid flow through said casing to below said cementing collar, and

c. a third actuating means adapted to pass through drill pipe to engage said second stage cementing plug means and force said second stage cementing plug means downwardly in said casing to close said cementing ports.

9. A method of cementing a composite string of well casing in stages within a subsea well bore, said casing string including a stage cementing collar having cementing ports which can be opened and closed and which is incorporated at an intermediate position a hollow second stage casing cementing plug mounted in swiveled and releasable relation within said casing above said cementing collar, the steps comprising:

a. suspending said well casing within a well bore from a casing hanger supported by a subsea well head;

b. connecting said casing through an installation means and a string of drill pipe to cementing equipment at the water surface above the well head:

c. passing a first stage of cement followed by a first actuating means through said drill pipe, said second stage casing cementing plug means, said cementing collar and said first stage cementing plug means, whereupon said first actuating means engages and forces said first stage cementing plug to a lower portion of said casing to displace said first stage cement out of said casing into said well bore;

d. passing a second actuating means through said drill pipe and said second stage cementing plug means to open said cementing portsand to close off fluid flow through said casing to below said cementing collar, and

e. passing a second stage of cement followed by a third actuating means through said drill pipe and said second stage cementing plug whereupon said third actuating means engages and forces said second stage cementing plug down through said casing to displace said second stage cement out of said ports and into said well bore and to close said ports following displacement of said second stage cement.

10. A method of cementing a composite string of well casing in stages within a subsea well bore, said casing string including a stage cementing collar having cementing ports which can be opened and closed and which is incorporated at an intermediate position within said casing, a hollow first stage casing cementing plug means mounted in releasable relation within said casing below said cementing collar, a valve casing floating means mounted with said casing below said first stage cementing plug means, and a second stage casing cementing plug mounted in releasable relation within said casing above said cementing collar, the steps comprising: V g v a. suspending said well casing within a well bore from a casing hanger supported by a subsea well head;

b. connecting said casing through an installation means and a string of drill pipe to cementing equipment at the water surface above the well head; passing a first stage of cement followed by a first actuating means through said drill pipe, said second stage casing cementing plug means, said cementing collar and said first stage cementing plug means, whereupon said first actuating means engages and forces said first stage cementing plug downwardly into engagement with said casing floating means to displace said first stage cement out of said casing into said well'bore;

d. passing a second actuating means through said drill pipe and said second stage cementing plug means to open said cementing ports and to close off fluid flow through said casing to below said cementing collar, and e. passing a second stage of cement followed by a third actuating means through said drill pipe and said second stage cementing plug means whereupon said third actuating means engages and forces said second stage cementing plug down through said casing to displace said second stage cement out of said ports and into said well bore and to close said ports following displacement of said second stage cement. 11. A method of cementing a composite string of well casing in stages within a subsea well bore, said casing string including a stage cementing collar having ceequipment at the water surface above the well head;

. passing a first stage of cement followed by a first actuating means through said drill pipe, said second stage casing cementing plug means, said cementing collar and said first stage cementing plug means, whereupon said first actuating means engages and forces said first stage cementing plug to a lower portion of said casing to displace said first stage cement out of said casing into said well bore;

d. passing a second actuating means through said drill pipe and said second stage cementing plug means to open said cementing ports and to close off fluid flow through said casing to below said cementing collar;

. passing a second stage of cement followed by a f. retaining said first stage of cement and said second stage of cement in displaced position until set, and

g. drilling out obstructions within said casing.

Claims (11)

1. A subsea well installation comprising: a. a composite string of well casing suspended within a subsea well bore from a casing hanger supported by a subsea well head, said casing being adapted to be connected through an installation means and a string of drill pipe to hoisting and cementing equipment disposed at the water surface above the well head; b. a stage cementing collar having cementing ports which can be opened and closed incorporated at a selected intermediate position within said casing; c. a hollow first stage casing cementing plug means mounted in swiveled and releasable relation within said casing below said cementing collar; d. a valved casiNg floating means mounted within said casing below said first stage cementing plug means, and e. a hollow second stage casing cementing plug means mounted in swiveled and releasable relation within said casing above said cementing collar.

2. The subsea installation of claim 1 further comprising: a. a first actuating means adapted to pass through drill pipe, said second stage cementing plug means and said cementing collar to engage said first stage cementing plug means and move said first stage cementing plug means to a lower portion of said casing in response to fluid flow through said drill pipe and said casing; b. a second actuating means adapted to pass through drill pipe and said second stage cementing plug means to open said cementing ports and close off fluid flow through said casing to below said cementing collar, and c. a third actuating means adapted to pass through drill pipe to engage said second stage cementing plug means and move said second stage cementing plug means downwardly in said casing to close said cementing ports.

3. The subsea well installation of claim 1 wherein one of said casing cementing plugs comprises: a. a circular flanged swivel support member defining an axially disposed cylindrical bore and adapted for mounting within a casing collar to be included in a well casing; b. a shouldered swivel sleeve rotatably mounted within and extending below said support member; c. a cylindrical cementing plug means including a cylindrical plug body member defining an axially disposed cylindrical bore having retainer means therein adapted to receive an actuating member passing through drill pipe; said body member being encircled by a resilient sealing and wiping structure having annular wiping lips and adapted for a tight sealing fit within a well casing, and d. releasable connection means releasably connecting said cementing plug means to the lower end of said swivel sleeve to be released from said swivel sleeve by force applied between said swivel sleeve and said plug body member.

4. The subsea installation of claim 2 further comprising: a. a first actuating means adapted to pass through drill pipe, said second stage cementing plug means and said cementing collar to engage said first stage cementing plug means and move said first stage cementing plug means to a lower portion of said casing in response to fluid flow through said drill pipe and said casing; b. a second actuating means adapted to pass through drill pipe and said second stage cementing plug means to open said cementing ports and close off fluid flow through said casing to below said cementing collar; and c. a third actuating means adapted to pass through drill pipe to engage said second stage cementing plug means and move said second stage cementing plug means downwardly in said casing to close said cementing ports.

5. An improved cementing plug means comprising: a. a circular flanged swivel support member defining an axially disposed cylindrical bore and adapted for mounting within a casing collar to be included in a well casing; b. a shouldered swivel sleeve rotatably mounted within and extending below said support member; c. a cylindrical cementing plug means including a cylindrical plug body member defining an axially disposed cylindrical bore having a retainer seat thereon adapted to receive an actuating member passing through drill pipe; said body member being encircled by a resilient sealing and wiping structure having annular wiping lips and adapted for a tight sealing fit within a well casing; d. releasable connection means releasably connecting said cementing plug means to the lower end of said swivel sleeve to be released from said swivel sleeve by force applied between said swivel member and said plug body.

6. Apparatus adapted to be suspended from a subsea well head within a subsea well bore and cemented in stages within the well bore, comprising: a. a composite string of well casing adaptEd to be suspended from a casing hanger supported by a subsea well head, said casing being adapted to be connected through an installation means and a string of drill pipe to hoisting and cementing equipment disposed at the water surface above the well head; b. a stage cementing collar having cementing ports which can be opened and closed mounted at a selected intermediate position within said casing; c. a hollow first stage casing cementing plug means mounted in releasable relation within said casing below said cementing collar; and d. a second stage casing cementing plug means mounted in releasable relation within said casing above said cementing collar.

7. The apparatus of claim 6 wherein at least one of said casing cementing plug means comprises: a. a circular flanged swivel support member defining an axially disposed cylindrical bore and adapted for mounting within a casing collar to be included in a well casing; b. a shouldered swivel sleeve rotatably mounted within and extending below said support member; c. a cylindrical cementing plug means including a cylindrical plug body member defining an axially disposed cylindrical bore having a retainer seat thereon adapted to receive an actuating member passing through drill pipe; said body member being encircled by a resilient sealing and wiping structure having annular wiping lips and adapted for a tight sealing fit within a well casing; d. releasable connection means releasably connecting said cementing plug means to the lower end of said swivel sleeve to be released from said swivel sleeve by force applied between said swivel sleeve and said plug body member.

8. The apparatus of claim 7 further comprising: a. a first actuating means adapted to pass through drill pipe, said second stage cementing plug means and said cementing collar to engage said first stage cementing plug means and force said first stage cementing plug means to a lower portion of said casing in response to fluid flow through said drill pipe and said casing; b. a second actuating means adapted to pass through drill pipe and said second stage cementing plug means to open said cementing ports and close off fluid flow through said casing to below said cementing collar, and c. a third actuating means adapted to pass through drill pipe to engage said second stage cementing plug means and force said second stage cementing plug means downwardly in said casing to close said cementing ports.

9. A method of cementing a composite string of well casing in stages within a subsea well bore, said casing string including a stage cementing collar having cementing ports which can be opened and closed and which is incorporated at an intermediate position within said casing, a hollow first stage casing cementing plug means mounted in swiveled and releasable relation within said casing below said cementing collar, and a hollow second stage casing cementing plug mounted in swiveled and releasable relation within said casing above said cementing collar, the steps comprising: a. suspending said well casing within a well bore from a casing hanger supported by a subsea well head; b. connecting said casing through an installation means and a string of drill pipe to cementing equipment at the water surface above the well head: c. passing a first stage of cement followed by a first actuating means through said drill pipe, said second stage casing cementing plug means, said cementing collar and said first stage cementing plug means, whereupon said first actuating means engages and forces said first stage cementing plug to a lower portion of said casing to displace said first stage cement out of said casing into said well bore; d. passing a second actuating means through said drill pipe and said second stage cementing plug means to open said cementing ports and to close off fluid flow through said casing to below said cementing collar, and e. passing a second stage of cement followed by a third actuatiNg means through said drill pipe and said second stage cementing plug whereupon said third actuating means engages and forces said second stage cementing plug down through said casing to displace said second stage cement out of said ports and into said well bore and to close said ports following displacement of said second stage cement.

10. A method of cementing a composite string of well casing in stages within a subsea well bore, said casing string including a stage cementing collar having cementing ports which can be opened and closed and which is incorporated at an intermediate position within said casing, a hollow first stage casing cementing plug means mounted in releasable relation within said casing below said cementing collar, a valve casing floating means mounted with said casing below said first stage cementing plug means, and a second stage casing cementing plug mounted in releasable relation within said casing above said cementing collar, the steps comprising: a. suspending said well casing within a well bore from a casing hanger supported by a subsea well head; b. connecting said casing through an installation means and a string of drill pipe to cementing equipment at the water surface above the well head; c. passing a first stage of cement followed by a first actuating means through said drill pipe, said second stage casing cementing plug means, said cementing collar and said first stage cementing plug means, whereupon said first actuating means engages and forces said first stage cementing plug downwardly into engagement with said casing floating means to displace said first stage cement out of said casing into said well bore; d. passing a second actuating means through said drill pipe and said second stage cementing plug means to open said cementing ports and to close off fluid flow through said casing to below said cementing collar, and e. passing a second stage of cement followed by a third actuating means through said drill pipe and said second stage cementing plug means whereupon said third actuating means engages and forces said second stage cementing plug down through said casing to displace said second stage cement out of said ports and into said well bore and to close said ports following displacement of said second stage cement.

11. A method of cementing a composite string of well casing in stages within a subsea well bore, said casing string including a stage cementing collar having cementing ports which can be opened and closed and which is incorporated at an intermediate position within said casing, a hollow first stage casing cementing plug means mounted in releasable relation within said casing below said cementing collar, and hollow second stage casing cementing plug mounted in releasable relation within said casing above said cementing collar, the steps comprising: a. suspending said well casing within a well bore from a casing hanger supported by a subsea well head; b. connecting said casing through an installation means and a string of drill pipe to cementing equipment at the water surface above the well head; c. passing a first stage of cement followed by a first actuating means through said drill pipe, said second stage casing cementing plug means, said cementing collar and said first stage cementing plug means, whereupon said first actuating means engages and forces said first stage cementing plug to a lower portion of said casing to displace said first stage cement out of said casing into said well bore; d. passing a second actuating means through said drill pipe and said second stage cementing plug means to open said cementing ports and to close off fluid flow through said casing to below said cementing collar; e. passing a second stage of cement followed by a third actuating means through said drill pipe and said second stage cementing plug means whereupon said third actuating means engages and forces said second stage cementing plug down through said casing to displace said secoNd stage cement out of said ports and into said well bore and to close said ports following displacement of said second stage cement; f. retaining said first stage of cement and said second stage of cement in displaced position until set, and g. drilling out obstructions within said casing.

Images