GB1480865A - Controlled release apparatus applicable to releasable conduit connections - Google Patents

Abstract

1480865 Releasable couplings HALLIBURTON CO 18 Aug 1975 [11 Oct 1974] 34305/75 Heading F2G [Also in Division E1] A controlled release apparatus 20, e.g. for launching a cementing plug 23 in a well casing 21, which is actuated by a closure member being driven therein and a subsequent internal pressurization thereof, includes a tubular casing 30 (connected to the drill pipe 16) having an internal ledge 56, a collar 50 having a contractible external ledge 51 releasably interlocking with the ledge 56 of the casing 30, a tubular sleeve 60 within the collar 50, the sleeve holding the ledge 51 of the collar 50 in engagement with the ledge 56 of the casing 30, and an adapter 70 (which carries the cementing plug 23) attached to the collar 50, the arrangement being such that when a closure member 9 is driven through the casing 30 to engage and block the sleeve 60 and the casing 30 is subsequently pressurized, the sleeve 60 is moved so that the ledge 51 of the collar 50 can contract and release from engagement with casing 30, thereby releasing the adapter 70 (and cementing plug 23). As described the casing 30 is in two parts screwed together, the ledge being formed by the upper end of the lower part 40 and carrying a bearing race 91 and thrust bearing 92 which permits rotation of the adapter/collar assembly. The collar 50 is a double collet spring having upper fingers 51 which engage the ledge in the casing 30 and lower fingers 55 which engage a groove 77 in the adapter 70 to secure them together. The sleeve 60 has an out-turned upper end 62 which holds the fingers 51 on the casing ledge and is secured to the adapter 70 by shear pin 80. In use a closure member 9 is pumped down the drill pipe 16 until it seats against the sleeve 60 and the drill pipe 16 is pressurized. This causes a downward force on sleeve 60 which shears pin 80 and moves the sleeve 60 downwardly as shown in Fig. 2b so that the fingers 51 can disengage from the casing ledge. The sleeve 60, collar 50 and adapter 70 then move downwardly until the middle portion 53 of the collar 50 engages a shoulder 45 in the casing part 40, thus stopping the collar 50. At this position the lower fingers 55 of the collar are clear of the casing part 40 and can move outwardly from the groove 77 in adapter 70, thus completely releasing the adapter 70 as shown in Fig. 2d. The cementing plug 23 (carrying the adapter 70, sleeve 60 and closure member 9) can then move down the casing 21. The apparatus also includes a second cementing plug 24 secured to the first cementing plug 23 by shear means (not shown) and which can be released prior to the release of the first cementing plug 24 by pumping a ball 12 down the drill pipe 16, which ball 12 engages the second cementing plug 24, subsequent pressurization of the drill pipe 16 then causing the shear means between plugs 23 and 24 to break.