US3179178A

US3179178A - Method and apparatus for stripping well pipes

Info

Publication number: US3179178A
Application number: US273005A
Authority: US
Inventors: Jr Vernon F Furry
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1963-04-15
Filing date: 1963-04-15
Publication date: 1965-04-20
Anticipated expiration: 1982-04-20

Description

April 20, 1965 v. F. FURRY, JR

METHOD AND APPARATUS FOR STRIPPING WELL PIPES 3 Sheets-Sheet 1 Filed April 15, 1963 FlG.

INVENTOR'.

ms AGENT April 20, 1965 v. F. FURRY, JR

METHOD AND APPARATUS FOR STRIPPING WELL PIPES 5 Sheets-Sheet 2 Filed April 15, 1963 FIG. 6

lNVENTOR:

V. F. FURRY FIG- 3 HIS AGENT April 20, 1965 v. F. FURRY, JR

METHOD AND APPARATUS FOR STRIPPING WELL PIPES 3 Sheets-Sheet 3 Filed April 15, 1963 FIG. 9

FIG. 7

FIG. ll

FIG. IO

' INVENTORZ V. F. FURRY BY: t

IS AGENT United States Patent 3,179,178 METHGD AND APPARATUS FUR SlTREPPlNG WELL FEES Vernon F. Furry, In, Bakersfield, Cali assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Apr. 15, 1%3, Ser. No. 273,tlll5 15 Claims. (Ql. Ida-49) This invention relatesto a method and apparatus for running pipe in and out of a well and pertains more particularly to a method of inserting into or removing from a well a string of pipe which surrounds a second string of pipe of a smaller diameter or a well tool which must be held in tension in the well to prevent it from dropping to the bottom of the well.

The operation of inserting a pipe into a well or remov ing it therefrom, when the pipe surrounds a second pipe or an elongated object already disposed within the well, is commonly referred to as stripping.

In an attempt to locate new oil fields an increasing amount of well drilling has been conducted at offshore locations, such, for example, as of]? the coasts of Louisiana, Texas, and California. As a general rule, the strings of casing in a well, together with the tubing string or strings, extend to a point well above the surface of the water where they are closed in a conventional mannerthat is used on land wells, with a conventional wellhead assembly being attached to the top of the casing. Attempts have been made recently to provide methods and apparatus for drilling, completing and working over a well wherein both the well casing-head and the various well components secured thereto or suspended therefrom .are' located underwater at a depth suiiicient to allow Ships to pass over them. Preferably, the casinghead and its associated equipment are located close to the ocean door. In order to install equipment of this type underwater in depths greater than the shallow depth at which a diver can easily operate, it has been necessary to design entirely new equipment for this purpose.

In one such method of drilling offshore wells wherein a wellhead base structure is positioned on the ocean iloor, strings of pipe, made up of many sections of pipe fastened together, are stripped in and out of the well by the method and apparatus of the present invention.

It is the primary object ofthe present invention to provide a method and apparatus, the apparatus being simplein design and easy to operate, whereby a larger internal diameter pipe may be stripped into a well over a smaller diameter pipe or a well tool of smallerdiameter.

. A further object of the present invention for stripping pipe into an oifshore well from a platform positioned above the ocean surface, while maintaining a constant tension on an inner pipe string of smaller diameter over which the larger diameter pipe string is being stripped.

Another object of the present invention is to provide simple and safe apparatus adapted to be connected to and FIGURE 2;

locked on an inner string of pipe to be held in constant a tension while an outer string of pipe is stripped over it.

Still another object of the present invention is to provide a method and apparatus for stripping pipe into or out of a well wherein the suspension apparatus for the pipe is positioned substantially along the center line of the pipe at all times.

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 longitudinal diagrammatic View illu trating cutaway sections of a derrick together with the hoist systems mounted in the derrick in accordance with the present invention;

FIGURE 6 is a fragmentary isometric View illustrating the locking sleeve normally carried in the connector base of FIGURE 2; and,

FEGURES 7 through 11 are schematic views illustrating the stepwise operations of carrying out the method of the present invention.

Referring to FIGURE 1 of the drawing, numerals 11 and 12 represent fragments of a well derrick, such for example as the type used in drilling wells, which would extend down to an operational base or fioor 13, which may be the floor of a derrick or a floor of a drilling platform, either stationary or floatable, as used in drilling oilshore wells. The derrick Ill-l2 is provided with a conventional hoist system including a crown block 14, a traveling block 15 provided with a hook 15a and fall lines to running to a hoist lea. Secured to the lower end of the traveling block 15 are elevator links 17 which suspend a conventional pipe-engaging elevator 18. The elevator 18 is designed to clamp around the upper end of a larger-internal diameter pipe string 29, or a section thereof, for raising or lowering the pipe string.

The derrick i112 may be also provided with another hoist system comprising hoist 21, hoist line 23, sheave 25 and connector element 27 carried at the end of the hoist or suspending line 23. In the event that the present hoist system is mounted on a floating drilling barge adapted to move up and down with relation to a wellhead positioned on the ocean floor, the hoist 21 would be preferably constant tension hoist. r I

A second hoist or suspending line or cable 24, having a loop. 24a at the top thereof to fit over the hook 15a and be suspended thereby, is provided at the lower end thereof with a connector element 28 which is similar to connector element 27. The length of the suspending cable 24 is sufficient so that the connector element 28 would be at least below the lower end of a section of pipe 20 hanging in the elevators l8.

Positioned substantially axially within the larger-diameter outer pipe string Zlla is a smaller diameter innerpipe string 3t having a connector base 31 secured to the top thereof which is adapted to be locked to either of the con hector elements 27 or 28., The pipe string Ella is illustrated as extending through a hole 32 in the floor of the derrick, and through a spider or rotary table 33 in which slips 3% are wedged in order to hang the pipe strings 2t? therefrom.

in FIGURE 2,one form of a connector base 31 comprises a body member 35 having an upwardly-extending mandrel section 36 of smaller diameter, with a pair of locking or latching lugs 3'7 and 33 formed on or fixedly secured thereto. The lugs 3'7 and 38 are positioned diametrically opposite each other on the mandrel 36 and extend outwardly therefrom.

The connector element 27 is illustrated as being provided with an opening 40 in the body thereof for receiving and locking therein one lug, in this case lug 37 of the connector base 31. The hoist cable 23 is fixedly secured to the top of the connector element 27 in any suitable manner, as by a split thimble 41 and a lead upset 42. The opening 48 is more clearly shown in the isometric view of FIGURE 4. The upper end of the opening 4% is wider, as at 40a, than the lower portion at dill), the bottom of the connector element 27 isbeing.

closed, as at 43, so as to support a locking lug 37 or 38 g of the mandrel 36. As shown in FIGURE 5 some of the wider portion 37a of the lug 37 is adapted to pass through the wide opening 40a in the connector element 27 while the grooved portion 37b of the locking lug 37 is adapted. to seat within the narrow opening 48b of the connector device 27.

To prevent the connector element 27 (FIGURE 2) from becoming accidentally unlatched from the locking lug 37 of the connector base 31, the connector base 31 is provided with suitable locking means which may take the form of a sleeve 44 mounted in the top of the body memher35 for rotational movement about the mandrel 36. The locking sleeve 44 is retained in the body member 35 by means of a ring 45 or other suitable means. A spring 46 mounted within the body member 35 is adapted to bear against a flange 47 carried at the lower end of the sleeve 44 for pressing the flange 47 downwardly against a positioning ball or orienting element 48. These elements are more clearly shown in the disassembled view of a portion of the connector base as shown in FIGURE 6. Here it is shown that the bottom face of the flange 47 is provided with a pair of diametrically-positioned

grooves

50 and 51 which are aligned with the center line of a slot 52 cut in the side of the locking sleeve 44 which extends downwardly from the top thereof, as illustrated. The sleeve 44 may be provided with one or more holes 53 extending through the wall thereof into which a pin can be positioned for turning the sleeve. The slot 52 in the locking sleeve 44 should be slightly wider than the widest part of either locking

lug

37 or 38 carried at the upper end of the connector base 31. The height of the sleeve would be such that as shown in FIG- URE 2, the sleeve 44 may be rotated under the lower end 43 of the connector element 27 when it is engaged and with the bottom of the locking lug 37 of the mandrel 36 thus locking the connector element to the connector base 31. To unlock the connector device so that the connector element 27 can be detached from the locking lug 37, the locking sleeve 44 would be rotated 180, or until the groove 50 (FIGURE 6) seated on the ball 48, at which time the slot 52 in the locking sleeve 44 would be positioned beneath the closed end 43 of the connector element 27, allowing it to be moved downwardly into the slot 52 at which time the enlarged portion 37a of the locking lug would be opposite the wide portion 40a of the opening 40 so that the connector element 27 could be removed laterally from the locking lug 37.

The lower end of the connector base 3]. is provided with suitable means, such as screw threads 54, whereby the connector base 31 may be removably secured to the top of the smaller-diameter inner pipe string 34) (FIG- URE 1). It is to be understood that any other suitable form of a device for latching onto the inside or the outside of a pipe may be employed for securing the connector base 31 (FIGURE 2) to a smaller diameter tubular pipe string 30 or other elements over which pipe is to be stripped.

In performing an operation in accordance with the present invention of stripping a larger internal diameter pipe into a well over a smaller diameter pipe which is axially movable within the larger pipe, the operation would start as illustrated in FIGURE 7 with the larger internal diameter pipe 28a being held by means of slips 34 in a fixed position within the spider or rotary table 33. At the same time the connector base 31 (FIGURE 2) would be secured to the top of the smaller diameter pipe string 30 (FIGURE 7) with the connector element 27 secured to the lower end of hoist line 23, being connected to one lug of the connector base 31 so that the tension on the cable 23 could hold the connector base 31 above the upper end of the pipe string 28a. With connector element 27 and its hoist cable 23 being employed in this manner, the other connector element 28 and its cable 24 (FIGURE 7) would be run down another section of pipe 28 which is to be added to pipe 20a already suspended from slip 34. The elevator 18 would be connected to one end of the pipe section 28 to be added and it would be hoisted to move into the position shown in FIGURE 8 by means of the main hoist system of the derrick. With the new section 24B of pipe suspended in this position, the connector element 28 extending therethrough would be carried over manually to the locking lug 37 and locked thereon as shown in FIGURE 8. Alternatively, the connector element 28 could be connected to the connector base 31 prior to moving the pipe section 29 to a vertical position over the pipe string 28a. At this time the pipe section 28 and the cable 24 carried substantially concentrically therein would be jointly suspended in substantial longitudinal relationship with the pipe string 29a already in the well, as shown in FIGURE 8. Tension would then be applied to cable 24 and its connector element by means of the hoist 16a, fall lines 16, traveling block and hook 15a (FIGURE 1), at which time the weight of the inner pipe string 30 would be transferred from connector element 27 to connector element 28. Alternatively, the weight of the inner pipe string 38 may be transferred from connector element 27 to connector element 28 by reducing the tension or slacking off slightly on suspending cable 23. With the cable 24 and its connector element 28 now supporting the inner pipe string 31), the other connector element 27 and its cable 23 are disconnected from the locking lug 38 of the connector base 31 and removed therefrom.

The additional section of pipe 28 is then lowered simultaneously together with the cable 24, connector element 28, connector base 51 and inner pipe string 38 moving lower in the pipe string 28a until the threads 82 at the lower end of the pipe section engage the threads in the upper section of the pipe 28a and may be rotated therein, for coupling the two pipe sections together. After the new section 28 (FIGURE 9) was secured to the pipe string 28a, the slips 34 would be removed (FIGURE 10) while the elevator 18 (FIGURE 1) supported the larger internal diameter pipe string 20a and lowered it into the well a distance equal to the added pipe section 28, at which time the slips 34 would again be inserted around the pipe string 20a to suspend it in place. The elevator 13 would then be disconnected from the top of the pipe section 20 and the traveling block 15, hook 15a, suspending cable 24 and connector device 28 would be pulled up until the inner pipe string had been pulled up through the larger internal diameter pipe a distance to bring the connector base 31 above the larger internal diameter pipe string Zita as shown in FIGURE 11. The other connector device 27 at the end of suspending cable 23 would then be secured to the connector base 31 and the weight of the inner pipe string 38 would be transferred thereto by slacking off on cable 24 or hoisting on cable 23 slightly. By repeating the cycle of operation described, the desired amount of pipe may be stripped into a well. It may be seen that since the pipe section 20 must be positioned vertically above the pipe section 20a, the sheave (FIGURE 1) is preferably positioned near the center line of the derrick. Alternatively, the present method may be practiced without use of a hoist 21 for cable 23. Instead a cable 23a may be fixedly secured to a temporary cross beam extending between braces 61 on the derrick, the beam 6'!) being close to the center line of the derrick but out of line of travel of block 15a.

To remove a larger internal diameter pipe from a well and strip it out of a smaller diameter pipe, the abovedescribed procedure would be reversed. After connector element 28 was secured to the connector base, the block 15a and elevator 18 would be lowered and connected to pipe section 20. The upper pipe section 20 would then be raised together with pipe string 20a by means of elevator 18 (FIGURE 1) and unscrewed and elevated from that section 20a, to expose the connector base 31 as shown. The connector device 27 would then be brought into position and latched on the connector base 31 and tension applied to its cable 23 or cable 24 being slacked off to transfer the weight of the inner pipe string 30 to cable 23. Connector 28 would then be detached from the connector base 31, as shown in FIGURE 7, and the connector device 28 and its cable 24 would be pulled out of the pipe section 20, as shown in FIGURE 7, while the other cable 23 and its connector device 27 supported the inner pipe string 30.

I claim as my invention:

1. A method of stripping a larger internal-diameter outer pipe string over a smaller-diameter inner elongated member which is axially movable, said method comprising the sequential steps of (a) temporarily suspending said larger internal-diameter outer pipe string and connecting a first suspending element to said inner member to suspend said inner member within said larger internal-diameter outer pipe string,

(5) running a second suspending element through a section of larger internal-diameter outer pipe to be added to the top of said outer pipe string,

(c) jointly suspending and moving said pipe section to be added and said second suspending element carried therein into substantial longitudinal position above said suspended outer pipe string,

(:1) connecting said second suspending element to said inner member,

(e) transferring the Weight of said inner member from i said first suspending element to said second suspending element,

(1) disconnecting said first suspending element from engagement with said inner member, s

(g) lowening said larger internal-diameter pipe section into engagement with said outer pipe string While lowering said inner member in tension Within said outer pipe string, and

(h) connecting the pipe section to the pipe string.

2. The method of claim 1 wherein the weight of said inner member is transferred to said second suspending element by applying tension to said second suspending element.

3. The method of claim 2 wherein the application of tension to said second suspending element comprises the step of raising said second suspending element.

4. The method of claim 2 wherein tension is applied to said second suspending element by lowering said first suspending element.

5. The method of claim 1 including the subsequent steps of lowering said outer pipe string and said inner member simultaneously a distance substantially equal to the pipe section added, and again suspending the outer pipe. string against further downward movement.

6. The method of claim 5 including the subsequent step of raising the inner member until the top thereof emerges from the top of the outer pipe string.

7. A method of stripping a larger internal-diameter outer pipe string over a smaller diameter inner pipe string having at least the lower end thereof positioned within a well, said method comprising the sequential steps of (a) fixedly suspending said outer pipe string by engaging the outer surface thereof in a supporting manner,

([2) attaching a connector base to the top of the inner pipe string,

(c) connecting a first suspending cable to said connector base to suspend said inner pipe string within said larger internal-diameter pipe string,

(cl) running a second suspending cable through a section of larger internal-diameter outer pipe to be added to the top of said outer pipe string,

(e) jointly suspending and moving said outer pipe section with said second suspending cable positioned substantially concentrically therein into substantial longitudinal position above said suspended outer pipe string, (f) connecting the lower end of said second suspending cable to said connector base,

(g) raising said pipe section and said second suspending cable simultaneously to suspend the inner pipe string from said suspending cable,

(h) disconnecting said first cable from said connector base,

(i) lowering and connecting the larger internal-diameter pipe section into engagement with said suspended outer pipe string,

(j) simultaneously lowering said inner and outer pipe strings a distance substantially equal to the pipe section added, and i (k) again suspending outer larger-diameter pipe string free of said smaller inner pipe string.

8. The method of claim 7 including the subsequent step of raising the inner pipe string in suspension until the connector base thereof is above the top of the outer pipe string.

9. A method of stripping a larger internal-diameter outer pipe string over a smaller-diameter axially-movable inner elongated member, said method comprising the sequential. steps of (a) fixedly suspending said outer pipe string from the outer surface thereof, 7

(b) connecting a first suspending element to said inner elongated member to suspend said inner member therefrom,

(c) loweringsaid first suspending element and said smaller-diameter inner elongated member into said larger internal-diameter outer pipe string a distance substantially equal to the length of a pipe section of said outer pipe string,

(d) engaging in a suspending manner said larger internal-diameter outer pipe string above its suspension point and simultaneously raising said inner elongated member and said outer pipe string until at least one section of the outer pipe string is above its previously-suspended position,

(e) again fixedly suspending said outer pipe string at a point below the uppermost pipe section thereof,

(7) disconnecting at least one pipe section from the top of said outer pipe string,

(g) raising said disconnected pipe section until at least :the top or" the inner member is exposed,

(h) engaging said inner elongated member with a second suspending element positioned outside said disconnected pipe section,

(i) transferring the weight of said inner elongated member from said first suspending element to said second suspending element, and g i (j) disconnecting said first suspending element from said inner elongated member.

10. The method of claim 9 including the subsequent steps of moving said large internal-diameter pipe section to one side of said suspended pipe string, and withdrawing said first suspending element from said pipe section.

11. Apparatus for use in well operations for selectively stripping to or from a Well a larger internal-diameter pipe string over a smaller-diameter inner elongated member held in tension throughout the operation, said apparatus comprising (a) an operational and sup-port base positioned adjacent said pipe string,

(b) hoist means including hoist cable means having a portion arranged for vertical movement above said pipe to be stripped out of the well,

(0) connector means secured to the end of said hoist cable means, said connector means including,

(d) a first connector of a size adapted to connect to the upper end of said larger internal-diameter outer pipe string,

(2) a connector base removably securable to the upper end of said inner elongated member and a second connector of a size to connect to said connector base of said inner elongated member and pass through said outer pipe string and being of a length sufficient '7 to extend beyond said first connector a distance greater than a section of pipe in said outer pipe string,

(f) independent suspension means mounted adjacent said small-diameter inner elongated member and being of a size to engage it selectively and temporan'ly secure it against axial movement relative to said larger internal-diameter outer pipe string, and

(g) slip-type anchoring means for engaging the large internal-diameter outer pipe string to selectively and temporarily secure it relative to said base against axial movement.

12. The apparatus of claim 11 wherein said independent suspension means comprises a cable having a third connector at one end thereof for engaging the upper end of the smaller diameter inner elongated member.

13. The apparatus of claim 12 including a hoist connected to the other end of said cable for raising and lowering said third connector.

14. The apparatus of claim 11 wherein said first connector is a pipe-engaging elevator secured to a traveling block.

15. The apparatus of claim 14 wherein said second connector includes a flexible cable secured to a traveling block of said hoist means and arranged to depend therefrom in concentric arrangement :Within said elevator and having means at the lower end thereof for engaging the upper end of said inner elongated member.

References (Iited by the Examiner UNITED STATES PATENTS CHARLES E. OCONNELL, Primary Examiner.

Claims

1. A METHOD OF STRIPPING A LARGER INTERNAL-DIAMETER OUTER PIPE STRING OVER A SMALLER-DIAMETER INNER ELONGATED MEMBER WHICH IS AXIALLY MOVABLE, SAID METHOD COMPRISING THE SEQUENTIAL STEPS OF (A) TEMPORARILY SUSPENDING SAID LARGER INTERNAL-DIAMETER OUTER PIPE STRING CONNECTING A FIRST SUSPENDING ELEMEMT TO SAID INNER MEMBER TO SUSPEND SAID INNER MEMBER WITHIN SAID LARGER INTERNAL-DIAMETER OUTER PIPE STRING, (B) RUNNING A SECOND SUSPENDING ELEMENT THROUGH SECTION OF LARGER INTERNAL-DIAMETER OUTER PIPE TO BE ADDED TO THE TOP OF SAID OUTER PIPE STRING, (C) JOINTLY SUSPENDING AND MOVING SAID PIPE SECTION TO BE ADDED AND SAID SECOND SUSPENDING ELEMENT CARRIED THEREIN INTO SUBSTANTIAL LONGITUDINAL POSITION ABOVE SAID SUSPENDED OUTER PIPE STRING, (D) CONNECTING SAID SECOND SUSPENDING ELEMENT TO SAID INNER MEMBER,