US3155175A

US3155175A - Wellhead cementing assembly with by-pass

Info

Publication number: US3155175A
Application number: US200717A
Authority: US
Inventors: Glenn D Johnson
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1962-06-07
Filing date: 1962-06-07
Publication date: 1964-11-03
Anticipated expiration: 1981-11-03

Description

Nov. 3, 1964 G. D. JOHNSON 3,155,175

WELLHEAD CEMENTING ASSEMBLY WITH BY-PASS Filed June '7, 1962 2 Sheets-Sheet 1 I I anna INVENTORZ GLENN D. JOHNSON fi, HTL Qvfi HIS AGENT FIG. I

Nov. 3, 1964 .G. D. JOHNSON 3,155,175

WELLHEAD CEMENTING ASSEMBLY WITH BY-PASS Filed June 7, 1962 2 Sheets-Sheet 2 INVENTOR:

GLENN D. JOHNSON Q. Hmf a HIS AGENT United States Patent 3,155,175 WELLHEAD CEMENTiNG ASSEMBLY WITH BY-PASS Glenn D. Johnson, Downey, Calif., assignor to Shell Oil Company, New York, N.Y., a corporation of Delawme Filed June 7, 1962, Ser. No. 290,717 12. Claims. (Cl. 175--7) This invention relates to a wellhead assembly for use in drilling oil and gas wells and pertains more particularly to a wellhead cementing assembly especially adapted to be employed underwater at the top of a well at offshore locations.

A recent development in the oil industry is the drilling and producing of offshore wells wherein the wellhead assembly and the production flow lines are positioned below the surface of the water, preferably on or near the ocean floor so as not to be subjected to the major wind and wave forces and to be out of the way of boats that may navigate in the area. Most offshore well drilling operations of this type are conducted from a platform or anchored barge from which the various pieces of equipment, used in or on the well, are lowered through the water from the barge to their position near the ocean floor. When operating at water depths or at locations where a diver cannot be employed to assemble the equipment on the ocean floor, it is necessary to provide apparatus that may be lowered through the water from a remote station, and then remotely operated or manipulated in order to carry out the necessary drilling operations.

When cementing the innermost casing string of a pair of easing strings depending from a casinghead of an underwater wellhead assembly, normal cementing methods and apparatus employed in cementing land wells cannot be employed at offshore locations due to the fact that the operational platform mounted on the drilling platform or barge from which drilling operations are being carried out, is subject much of the time to rise and fall due to the motion of the sea. Thus, it is difficult if not impossible most of the time to suspend the innermost casing hanger a slight distance off its seat within the casinghead during cementing operations without the hanger becoming damaged by beating itself against the casinghead or seat due to the rise and fall of the vessel.

It is therefore a primary object to provide wellhead cementing apparatus for an underwater well whereby cement slurry may be pumped down the innermost of two well casings and a portion of the cement slurry circulated up the annular space between the two casings while the fiuid in the annular space between the casings is circulated up through the wellhead cementing assembly and thence upwardly through a marine conductor pipe to the drilling platform or vessel.

A further object of the present invention is to provide a wellhead cementing assembly wherein the fluid between a pair of well casings is displaced out of the well casinghead and past one or more blowout preventers during well cementing operations.

Another object of the present invention is to provide apparatus adapted to be remotely manipulated for closing the conduit at a wellhead assembly through which fluid is circulated to a drilling platform or vessel at the surface of the water. p

These and other objects of this invention will be understood from the following description taken with reference to the drawing, wherein:

FIGURE 1 is a diagrammatic view taken in longitudinal projection of the well cementing assembly of the present invention; 7

FIGURE 2 is a diagrammatic view taken in longitudinal projection illustrating a'drilling wellhead assembly being 3,155,175 Patented Nov. 3, 1964 ice raised from an underwater wellhead assembly positioned on the ocean floor; and,

FIGURE 3 is a diagrammatic view of the wellhead cementing assembly of the present invention shown in partial longitudinal cross section.

Referring to FIGURES 1 and 2 of the drawing, a drilling vessel 101, of any suitable floating or floatable type is illustrated as floating on the surface of the water 162 and fixedly positioned over a preselected drilling location by being anchored to the ocean floor 103 by

anchor lines

104 and 105 running to anchors (not shown). Equipment of this type may be used when carrying on well drilling and cementing operations in water varying from about 100 feet to 1500 feet or more. The drilling vessel is equipped with a suitable derrick 106 containing a fall line system and the other associated equipment normally used during this well drilling operation. During much of the well drilling operation a large-diameter pipe known as a marine conductor pipe 167 extends from the drilling vessel 101 to the wellhead assembly positioned underwater. The underwater wellhead assembly may com prise a base plate 108 having secured thereto and extending upwardly therefrom a foundation pile 110 with a casinghead 12 mounted thereon. During drilling operations the top of the casinghead 12 is closed by a drilling bonnet 112 which in turn is mounted in coaxial alignment with one or

more blowout preventers

113 and 114. A wellhead connector 115 of any suitable type is employed to connect the lower end of the marine conductor pipe 107 to a landing mandrel 116 which extends upwardly from the uppermost blowout preventer 114. During drilling operations a string of drill pipe 117 is positioned and rotates within the marine conductor pipe 107 while during cementing operations this string of pipe becomes a cementing string.

in FIGURE 3 of the drawing, numeral 11 represents a surface casing or conductor pipe which has been installed in a well in the ground and preferably cemented therein in a conventional manner. At the time the surface casing is positioned in place, a Welhead or casinghead has been fixedly secured to the top of the surface casing in any suitable manner such as by welding or by a threaded connection. In the particular arrangement of the wellhead shown in the drawing, the wellhead comprises lower, intermediate and

top sections

12, 13 and 14, respectively, of a housing which forms the wellhead of the present invention. The lower section 12 of the housing is preferably provided with a support base 15 which is fixedly secured to or formed on the lower section. The support base 15 in turn may rest on a foundation pile 110 or any other suitable foundation or base placed around the well.

The lower section 12 of the housing of the wellhead is provided with a sloping shoulder 16 adapted to seat and receive thereon a cooperating portion of a casing hanger 17 which is normally provided with suitable seals 18L The casing hanger 17 is employed to support a string of well casing 21 within the surface casing 11. The exterior wall of the casing hanger 17 is provided with suitable means, for example, a left-hand thread 22 by which the casing hanger 17 can be attached to the lower end of a pipe string (not shown) for lowering this element 17 and its depending casing string 21 into the well from a suitable operational platform 101 (FIGURE 1) positioned above the well. 7

The lower and intermediate sections of the

housing

12 and 13, respectively (FIGURE 3), are provided with sloping

seating surfaces

23 and 24, respectively, on the outer surfaces near the upper ends thereof which are adapted to seat thereon cooperating sloping self-aligning seating surfaces 25 and'Zd formed onthe inner surfaces near thelow'enends of the intermediate andu'pper housing sections 13 and 14, respectively. Seals 27 and 23 are provided between the cooperating seating faces.

Lower locking screws or bolts 31 are horizontally positioned in a threaded manner within the lower end of the intermediate section of the housing 13 and arranged to extend through the walls thereof and into cooperating recesses 32 formed in the wall of the lower housing section 12 near the top thereof. In a like manner, the top section 14 of the housing is provided with upper lock screws 33 adapted to seat in recesses 34 in the wall of the intermediate section 13 of the housing near the top thereof. If desired or necessary, the

lock screws

31 and 33 may be provided with

fluidtight seals

35 and 36. While it is preferred in accordance with the present invention to employ a wellhead having lower and intermediate sections of a

housing

12 and 13, respectively, it is quite apparent that the intermediate and

lower sections

13 and 12 could be formed as a single element in which case the lower locking screws 31 could be eliminated. However, as a safety precaution in underwater wellhead structures, the housing employs lower and

intermediate sections

12 and 13 secured together by means of the lower locking screws 31 which are preferably made of an alloy carbon steel or other suitable material so that theycan be drilled out in the event that the upper lock screws 33 become wedged or corroded in a manner so that they cannot be withdrawn from their seating position in order to remove the top section 14- of the housing from the wellhead.

Formed on the inner wall of the intermediate section 13 near the top thereof is a landing surface 37 adapted to receive and seat thereon a casing or tubing hanger 38. The outer surface of the casing hanger 38 at the lower end thereof is provided with a tapered seating surface 41, preferably provided with seal means 42, such for example as any suitable type of packing or O-rings. The casing hanger 38 is adapted to be secured at its lower end to the top of a string of casing 43, for example, by screw threads. The casing string 43 depending from the casing hanger 35 is concentrically arranged within the well casing string 21.

During drilling operations the drilling bonnet 112 which is attached to the lower end of the blowout preventer 113 in any suitable manner as by bolts 39, is provided with a sloping seating surface 40 adapted to seat on a cooperating sloping self-aligning seating surface 41 formed on the upper end of the top section 14 of the wellhead. Seals 42 and 43 may be provided between the cooperating elements. The drilling bonnets 112 may be secured to the top section 14 of the wellhead in any suitable manner and by any suitable connector device but it is preferred to provide locking screws 44 which seat in cooperating recesses 45 formed in the outer wall of the upper end of the top section 14 of the wellhead.

The wellhead assembly of the present invention, in this case the intermediate section 13 of the wellhead, is provided with a fluid outlet port through the wall thereof which is adapted to be closed by a valve member 47. In this embodiment of the invention the valve member 47 is in the form of a plug valve provided with a wrench head 43 whereby the plug valve 47 can be run to a closed position on a threaded pin 51 which is fixedly secured to the valve housing 51. The outlet port 52 from the housing 51 may have formed therearound an upwardly extending nipple 53 into which the lower end of a bypass conduit 54 may be positioned in a fluidtight manner. At the same time the lower end of the bypass conduit 54 is preferably readily disconnectible from the valve housing 51 upon an upward pull of the bypass conduit 54. Thus, a stab-type connector is preferably employed at the bottom of the bypass conduit 54. The bypass conduit extends vertically past the top section 14 of the wellhead and is in communication with the interior 'of the drilling wellhead assembly at some point above the top section 14.

In FIGURE 3, the upper end of the bypass conduit 54 v is shown as screw-threaded, as at 55, into a port 56 which enters the blowout preventer 113 preferably below the rams therein. Alternatively, the top of the bypass conduit 54 could be in communication through the wall of the drilling bonnet 112, as shown in FIGURE 2, with the bore 57 therein. Since the valve member 47 is employed during cementing operations as a uni-directional valve, it is quite apparent that the valve member 47 need only be a check valve. Additionally, while the stab-type connection has been illustrated in FIGURE 3 as being provided at the lower end of the bypass conduit 54 it is to be understood that it could be arranged at the top of the bypass conduit instead so that the bypass conduit 54 would be left on the wellhead at the time the drilling bonnet 112 and the blowout preventer 113 were raised off of the wellhead. From the above-described arrangerent it may be seen that the fluid bypass conduit 54 on the outside of the drilling assembly and the wellhead assembly is in communication through the walls thereof with the vertical bore of the drilling assembly and the interior of the wellhead or casinghead at a point intermediate the landing surfaces 16 and 37 in the casinghead from which the casing hangers 17 and 38 are hung, respectively. Although only one bolt or lock

screw

31, 33 and 44 has been shown at each level of the assembly, it is to be understood that a plurality of these radially extending lock screws are positioned around the circumference of each section of the assembly.

The lower and intermediate sections of the

wellhead

12 and 13, respectively, are provided with control or hold-down screws 61 and 151 which extend through the wall thereof to cooperate with

annular grooves

62 and 63 in the hangers 17 and 33, respectively.

In carrying out drilling and cementing operations with the equipment of the present invention, a well is first drilled in the ocean floor and the conductor pipe 11 lowered thereinto in a manner well known to the art after which cement is pumped down the conductor pipe 11 and up the outside thereof with the surplus cement being discharged on the ocean floor. Well drilling operations are then continued with a smaller size bit down through the conductor pipe 11 until it is time to set the next string of casing 21. This string of casing 21 is run down into the well with its casing hanger 17 which is hung on the seating surface 16 of the casinghead. In cementing it in place cement is pumped down through the string of casing in a conventional manner, preferably with the use of a cementing pipe string of small diameter with the fluid in the annular space between the conductor pipe 11 and the casing string 21, passing out a side outlet or conduit 63 which is in communication with the annular space 62 with the other end of the conduit 63 normally extending to the barge or vessel 101 on the surface of the water.

Drilling operations are then continued through the cas ing string 21 with a smaller size bit until it is time to set the innermost casing string 43 which is hung from its hanger 33 on the landing surface 37. Normally it would be impossible to seat the hanger 38 on its landing surface in the casing'head prior to cementing the innermost casing string 43 as thererwould be no means for the fluid trapped in the annular space d4- between the casing strings 21 and 43 to escape from the well. By use of the apparatus of the present invention with the valve member 47 in the bypass conduit 54 open, when cement is pumped down through the innermost casing string 43 the fluid trapped in thc? annular space between the casings 21 and 43 passes out the port 46 past the valve member 37 and up the bypass conduit 54 and thence through port 56 into the bottom of the blowout preventer113. From here the fluid passes up the conductor pipe 137 outside the cementing string 117 (FIGURE 1). After-the cementing of the casing string 43 has been completed,'the valve member 47 is closed and at er the performance of other subsequent well operations the drilling assembly (FIGURE 2) comprising the drilling bonnet 112,

blowout preventers

113 and 114, wellhead connector 115 and marine conductor pipe 187 are withdrawn upwardly to the vessel 101. During this action the lower end of the bypass conduit 54 pulls out of the valve housing 51. The bolts, screws and valve member 47 of the present apparatus are operated in any suitable manner, preferably by means of an underwater manipulator device shown and described in copending patent application, Serial No. 118,849, filed June 22, 1961.

I claim as my invention:

1. Apparatus for drilling and cementing an underwater well from an operational base positioned above the surface of a body of water, said apparatus comprising (a) a wellhead assembly fixedly positioned below the surface of a body of water,

(b) said wellhead assembly including a casinghead having landing surface means for suspending therefrom a pair of concentric pipe strings with the upper ends in axial spaced relationship,

(0) a drilling assembly having a vertical bore therethrough in communication between said operational base and the interior of said wellhead assembly with the lower end of said drilling assembly being fixedly secured to the upper end of said wellhead assembly in a fluidtight manner, and

(d) fluid bypass conduit means outside and connected between said drilling assembly and said wellhead assembly and in communication through the walls thereof with the vertical bore of said drilling assembly and the interior of said casinghead at a point intermediate the landing surface means in said casinghead for said pair of pipe strings.

2. The apparatus of claim 1 including valve means in said fluid bypass conduit means.

3. The apparatus of claim 1 wherein said landing surface means comprises first and second landing surfaces in said casinghead above and below the point at which the interior of the casinghead is in communication with said fluid bypass conduit means.

4. The apparatus of claim 3 wherein said first and second landing surfaces are in the form of landing shoulders formed on the inner wall of said casinghead.

5. The apparatus of claim 3 including first and second pipe hanger means supported by said casinghead at said first and second landing surfaces, and f rst and second concentric pipe strings depending from said first and second pipe hanger means, said concentric pipe strings forming an annular space therebetween, said annular space being in communication with one end of said fluid conduit bypass means.

6. The apparatus of claim 1 including connector means in said fluid bypass conduit means.

7. The apparatus of claim 6 wherein said connector means are stab-type connector means having first and second telescoping portions adapted to mate in slidable fluid tight engagement.

8. The apparatus of claim 2 including connector means in said fluid bypass conduit means on the side of said valve means adjacent said drilling assembly.

9. The apparatus of claim 8 wherein said fluid bypass conduit means above said valve means is fixedly secured to said drilling assembly and removable above said connector means on raising said drilling assembly from said wellhead assembly.

10. The apparatus of claim 2 wherein said drilling assembly comprises wellhead connector means connected to the top of said wellhead assembly, blowout preventer means mounted coaxially on said wellhead connector means, and a marine conductor in fluid communication between said blowout preventer means and an operational platform on the surface of the body of Water.

11. The apparatus of claim 10 wherein the upper end of said fluid bypass conduit means is in communication with the vertical bore of said drilling assembly through the wall of said blowout preventer means near the lower end thereof.

12. The apparatus of claim 10 wherein the upper end of said fluid bypass conduit means is in communication with the vertical bore of said drilling assembly below said blowout preventer means.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. APPARATUS FOR DRILLING AND CEMENTING AN UNDERWATER WELL FROM AN OPERATIONAL BASE POSITIONED ABOVE THE SURFACE OF A BODY OF WATER, SAID APPARATUS COMPRISING (A) A WELLHEAD ASSEMBLY FIXEDLY POSITIONED BELOW THE SURFACE OF A BODY OF WATER, (B) SAID WELLHEAD ASSEMBLY INCLUDING A CASINGHEAD HAVING LANDING SURFACE MEANS FOR SUSPENDING THEREFROM A PAIR OF CONCENTRIC PIPE STRINGS WITH THE UPPER ENDS IN AXIAL SPACED RELATIONSHIP, (C) A DRILLING ASSEMBLY HAVING A VERTICAL BORE THERETHROUGH IN COMMUNICATION BETWEEN SAID OPERATIONAL BASE AND THE INTERIOR OF SAID WELLHEAD ASSEMBLY THE LOWER END OF SAID DRILLING ASSEMBLY BEING FIXEDLY SECURED TO THE UPPER END OF SAID WELLHEAD ASSEMBLY IN A FLUIDTIGHT MANNER, AND (D) FLUID BYPASS CONDUIT MEANS OUTSIDE AND CONNECTED BETWEEN SAID DRILLING ASSEMBLY AND SAID WELLHEAD ASSEMBLY AND IN COMMUNICATION THROUGH THE WALLS THEREOF WITH THE VERTICAL BORE OF SAID DRILLING ASSEM BLY AND THE INTERIOR OF SAID CASINGHEAD AT A POINT INTERMEDIATE THE LANDING SURFACE MEANS IN SAID CASINGHEAD FOR SAID PAIR OF PIPE STRINGS.