!eld of uverdion This invention Sates to the provision of a method of providing a combined running and retrieval tool ( Rotary Disconnect Tool) tbr pressure testing subsea HOP in a single run fbr use in stbsea exploration and production drilling.
in deep water drilling for oil and gas there is a requirement to pressure test the weilbead.
connections and the HOP stack while in position on the sea bed. This is nornaily taMed out by umning a test assembly test plug attached to drill pipe which locates in the well head sealing of the lower part of the well bore in eater to enable the testing of the various rams within the HOP stack, the annular pcventex nonnally located at the top of the HOP stack, (1) as well as the ynives on the stack such as choke and kill lines isolation valves, r C?) Most of the testing can be carried out with the drill pipe and test tool connected However O the testing of the blind shear rams require the drill pipe and upper portion of test assembly N-20 to be disconnected front the lower portion of the test assembly and pulled back to ensure o that no tubithes straddic the area of closure of the blind shear rain This is achieved currently by having a low torque cosme pitch left hand threaded connection within the test tool assembly above the test plug which is located below the blind thear rams when the test plug is seated in the weliheal When the test assembly including the test plug is landed or seated in the welihead and within the SOP stack, tight hand rotation of the drill string will back out this left hand threaded. connection and thereby allow the drill pipe and a portion of the test assembly to be pulled. back in order to clear the area of closure of the blind shear coats. Thus allowing the blind shear rants to be tested betrnen pressure applied down the thoke or kill line pressuring up between the closed blind shear rams and the lower pan. of the test assembly located in the well head.
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Having completed the HOP testing in this way the loar test assembly must be retrieved and pulled back to suthco. However the use of left hand rotation of the drill string to reconnect the left band thread in a long section of marine riser i considered to be undesirable due to the possible risk of backing out of the tool joint contraction elsewhere in the nmning string in the seveml thousands of ihet of till pipe that would exist within, the riser between the subsea HOP and the rig floor, Therefore the drill pipe is pulled oat of the rises back to the drill floor and a right hand threaded retrieval thread in Stalled in place of the left hand threaded pj which was previously disconnect from the lower portion of the teat assembly. This might hand retsiev& conneetkm thread is ma back down the riser to the point of diseormectiors and reconnaoted to the lower portion of the assembly by means of a box cormection whkh is smaller in diameter than the left hand threaded box of the top of the test tool assembly or test plug and located within it. This right hand pin and box connection may be a standard API connect or may be a proprietary cormectioa This process of pulling out the running string to change from the left hand hack off thread (Y) to the right hand retrieval thread takes up considerable rig time which in deep water drilling operton represents considerable. additional cost The invention described below sets out (Y) to mitigate this problem by providing a method of combining the left hand back ofF thread O and a deployable right hand retrieval thread within the single tool to enable the ranting, N-20 discon3rection and retrieval of a HOP test tool assembly in a single runs. this saving many O hours of costly rig time.
flea of the ivction This invention consists of a running and retrieval tool for deploying HOP and well, test tools and assemblies where there is a rqairenent to disconnect end reconncct the nmttg string or drilling tuhuhrrs with right hand. rotation only.
The invention comprises a top sub with a tbreadable connection. means for attachment to a nmning string or drilling tubulars at the upper end which is attached. to a splined housing at the lower end. This splined. housing has a left hand threaded. sealable pin connection at its lower end which connects to a orating loft threaded sealable box. connection located in the top of the bottom sub. The bottom sub having thtea&d connections at it's lower end. for connection to a. test assembly and or test plug. Within and below this bft handed threaded
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box connection at the top of the bottom sub is a second right banded threaded connection dndgned to acconrmodate the deployable tight hand retrieval thread, This deployable right hand. retrieval thread being installed at the lower end of a. splined shaft and piston arrangemen located within the splined housing.
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After the test assembly and test plug have been deployed and landed otti in the subsea well head testing of the RaP's can proceed. Before the blind shear anus are tested however the rotry disconnect tool must be operated to disconnected the upper portion of the test assembly from the lower portion of the test assembly and pull it and the running string back 0 clear cite area of openaion of the blind shear rnrs.
This is achieved by simply rotating from surface the running string and upper portion of the test assembly to the right which backs out the left hand thread and disconnects the rotary disconnect tool Slowing the running string end. upper portion of the test assembly to be pulled clear of the area of operation of the blind shear rams.
Now the testing of the blind shear as can take place by applying pressure via the choke or CO kill line to apply pressure between the test ping located in the welihead and the closed blind o shear nun N-20 0 Having completed testing and opened the blind shear rams the rotary diaccumect tool can be reconnected to retrieve the test assembly to surface by carrying out the following sequence of operations.
1. Circulate from sur&ce at sdUd eat flow rate to cause a pressure drop though the tool.
2. Increase the flow and pressure nutil a significant pressure drop is observed. This indicates that the piston shear pins have sheared. and the piston has moved down to the locked position deploying The right hand retrieval thread longitudinally and rotationally locked in posItion beyond and below the left hand release thread.
3. Stop circulation and lower the running string and upper portion of the test assembly so that the right hand retrieval pin engages in the right hand retrieval hex connection and a small weight loss is seen on swface.
4. Rotate the running swing from surface the pre<requisite number of turns to fhliy engage the tight hand retrieval thread and continue rotating until required. make up torque is observed.
5. ensure all pipe rains are in the open position and the pick up to retrieve the test S assembly and test plug from the weJTh.ead 6. Then retrieve to surface.
The present invention will now he described by way of nori4imiting example only with reference to the following of which: Iig 1. Shows the thily assembkd tool in the running position.
Fig 2. Shows the tool in the backed off position with the lower sub separated from the upper sub and. spiked housing.
(Y) Fig 3. Shows the tool wIth the right hand retrieval thread deployed and locked out Fig 4. shows the tool with the locked out right hand thread engaged in the right handed (Y) threaded section of the]ower sub ready for retrieval of the test tools below it (not shown) O by means of the drilling tuhilars above it (not shown). N2o
o ddflflawithflthed Now referring to the drawings: Referring to Fig 1 The invention consists of an. upper assembly consisting of nub I connected to a spihied housing 2 corrncctrthle to lower subS by means of a left hand threaded oonnection 4. This threaded connection 4a&b being sealable by mesas of the clastomeric seals 5 sealing in the polished bore 6 when the left hand threaded connection 4 is made up. This assembly is provIded with a through bare 7 to permit flow through the tool snd an upper fr connection and kr threaded connections & 9 respectively to permit connection to the running string/ drilling tubulars (not shown) and the test assembly (not shown).
R&ntg to Fig 2 Within the splined housing 2 is contained an activation piston 10 mounted on a splitS S shaft!! wbIch engages in the plines 12 of the splined hcrusing 2, This activation piston 10 is provided with a shear pin groove 13 to enable it to he locked in position prior to actuation. Piston seal. groove 14 fbr itadlation of elastornerk or polymer seal (not shown) which seals in the polished, cylinder bore 1 of the spUmed houtg 2. Located below the seal groove 14 Is a snap rIng 16 located in a snap ring groove 1.6* designed to hitch into the snap ring landing groove 17 in order to lock the piston 10 and aplined shaft 11 in the locked down position after acti:vatioa At the lower end of the splined shaft section 11 there is a right band threaded pin connection 18 designed to be connected to the mating right hand threaded box connection 19 siroated below the left handed threaded connection 4b in the bottom sub 3, At the upper end of the spUmed section 11 and piston 10 is a flow tel' device 20 designed to (Y) provide a positive pressure drop indication at surface when the piston has moved down to the locked position and right hand retrieval pin thread ISis fully deployed and locked out.
O Riuutg npcnee for the too! N2.o 0 deployed the rotaty disconnect tool shown in figi. disconnection is achieved by rotating the drill string to the tight from surface which simply disconnects the left haM disconnect connection 4a and 4b thus allowing the upper and lower portions of the rotary disconnect tool to be sepanded and pulled dear of each other, Reeonnection is achieved by circulating from surface at a sufficIently high rate to cause a pressure drop across the piston 10 to shear the shear pins in the shear pin groove 13 to shear allowiig the piston 10 to move down. As the piston 10 moves down and the top of the piston 10 clears the flow tell device 20 a pressure drop is observed at surface, This indicates that the piston 10 has moved down far enough to allow the snap ring 16 to engage in the snap ring landing groove 17 locking the piston in the fully down position as shown in fig 3.
in this configuration it is now poih1e to lower the upper portion of the rotary disconnect tool back down to n%connect with the lower portion of the rotary disconnect tool as shown in fig 4. This is achiew by owering until the rIght hand retrieval connection pin 9 is engaged in the right band retrieval box connection 19. RotatIon from surface screwing the S two threads together with applied weight being carried by the snap rIng 16 and the applied torque being carried by the splined shaft H engaging in the splines 12 of the splined housing 2. Now having reconnected the rotary disconnect tool the test assembly can he retileved to surthce I 5 r