CA2041788A1 - Deployment and recovery of pre-packed screens - Google Patents

Abstract

ABSTRACT Fig. 1 Deployment and Recovery of Pre-Packed Screens A bottom hole assembly (BHA) comprises pre-packed screen 1, washpipe 2 and stinger section 3. The screen has an outer fluid permeable wall 4, an inner permeable wall 5 and an annular layer of pre-packed particulate material 6 therebetween. Fluid can flow radially inwardly through the screen into the annual space 7 between the screen inner wall and the washpipe outer wall. Washpipe sections are coupled by a subsection of pipe 8. The ends of the coupling are joined to respective ends of sections of washpipe by conventional means. Screen sections are joined together by a stinger.
Conventional joining means may be used. The stinger has a portion of its length necked down, and this portion has a polished sealing surface 9 which can provide a contact seal to a pair of appropriately sized pipe rams (not shown).
Internally of the stinger, at the same level as the external sealing surface, there is an internal polished sealing surface. An annular seal 10 carried on a sub-unit 8 forms a contact seal on this internal sealing surface. Thus, fluid from the annular space 7 cannot pass by the seal 10. A method for deployment of a BHA as described above is disclosed. m e BHA may be deployed in an oil/gas well under pressure.

Description

~17~

DeDloYment and Recover~r_of Pre-Dacked Scre~ns The present invention relates to a me~d for deployment (and reco~ery) of pre-packed screerIs in oilJgas ~ells. Pre-padced screens as such are kI~own in the ar~, and are ~nployed dur~r.g pmduction fmm t~e well to preverlt flowback of ex~essive q~antiti~s of paxticulate material (e.g. fracture ~ropant, sand and the like). In effect, ~re-packed screens are ole filters to re~ve partio~late ~atter fmm the flow.

pre-packed screen is in tuhllæ form ~of a suita~le diameter to be able to run in the well~ore) and hAe outer and inner fluid permeable screen WAlls. Fluid flows radially inwardly and passes through packed particulate material in an anollar layer b~tween the screen walls. Filtered fluid passes thrcugh to the central spaoe inside the screen and thence flows back up the welLbore.

It is desirable to remove part~culate ~atter from the flow because of the abrasive effects of particles w~ich are det,riment 1 to surface production facilities s~h as pumps, valves etc.

When it is known, prior tO oompletion of ~he well, that a well is likely to prod~ce sanl is it possible to pack the entire perforation intervAl wi~h ~'gravel pack material" tO act as a filter. Addition21ly or inste , a pre-packed screen can be fitted at the down hole end of the welLbore in the region of the perfor~tion interval. ane ex2mple of sand contr~l using a ccmbination of gravel pack materiAl and a pre-packed screen is disclosed in USP-4,856,590.

Ths kottom hole assembly (3H~) described in the prior patent is to be deployed and rexvered on coiled tubing (kNcwn in t~e 2V4~ 788 art). The assembly has an a~vantage that it includes internally a washpipe which opens at the tip of the P~e~bly and alLows liquid to be flushed through the tip of the assembly. Liquid may be supplied to the washpipe under pressure for flushing usLng ooil tubing connected at the up hwle end of the assembly. Flushing via the washpipe is particularly useful when the ~sembly is to be recovered because it loosens the assemhly in the surmunding material and so eases withdrawal.

However, a severe dis2dvantac,e of the prior method and apparatus is that it can only be employed when the well is shut down ani depressurised. It is both expensive and time oonsuming to "kill" th~ well once it is in product~on, and further cost and delay is incurred on bringing it back to production. FL- -er~ore, i~ long lengths of screening æe required to cover a long perforation interval, it would, using convention 1 _~chnniques, be necessary to mcbilice a rig to work over the well. ~ rig is requirad to handle lengthy rigid bottom hole assemblies. This adds both to cost and delay.

The present invention seeks to provide a meth~d capable of deployL~g and retrieving leng~hy pre-packei screens (e.g. 10 to 100 metres or more). ~hese screens will oQmprise an internal washpipe. The screens and w hpipe can be deployed and retrieved under pressure on pre-existing live wells which only have limited or nD wellhead riser caFability (e.g. 3 to 20 metres riser acc3m~LIation space). ~he invention ~llows pre~packed screens with washpipe to b~ run into pre-existing live wells withcut the need to kill the well with oompletion fluid, brins or mud. The method can be used to run screens on braided line using a convention 1 wireline unit, or the screens c~n be run on coil tubing. Coil bubing has a p~rticular ~dvantago th~t it can accommodate highly deviated, 2 ~

even horizontal, wells by virtue of the ability to use ~he tubing t3 ~'push" -he screen m the well kore. Cbil tubing is used to suDply fluid ta the washpipe under pressure. me inve~t_on can provide a methDd wh~reky r3mote or elevated mou~tir.g of heavy machinery (e.g. a ooiled tubing injector, with its attendant complexity a~d s~ety problems) is avoided.

The present invention ~150 allows pre-packed screens with ~ashpiDe to be run without the use of a cor~ventior~l rig. The problems associated with already-completed wells unexFecte ly producing particulate material can be overocme with the present invention, even though those well-~ were not originally desisned to take gravel packing ani pre~pac~ed screens.
Despite t.~o oonstraints of a) the availability of riser acocm~cdation on the pre-existing well head installation and b) the llmitation on size of object which can be run in a pre-existing wel1 bore, the present invention provides a simple and effective answer to the problen of retro-fitting a fluid filter in the perforation L~terval of a live well. It overcomes the inh~e~ent problems associated with attempting ~o insert into a well under pressure an assembly which is intended to allow fluid flcw, without escape of well fluid during insertion.

The invention also provides an assèmhly inoorporating a pre-pack~d screen, s~litable for use with the method of the invention.

In the following description, the term hottcm hole assembly (B~) will he used to refer to thie assembly of pre-packed screen(s~ washpipe a~d other associated equipment which is intended to be deployed in the well bore in the perforation interval. The perforation interval is scmetImes referred to in the art as the "produ d on zone".

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Hereaf~er the invention will be described with reference to deployment/recovery using coiled tubing, but it is to be unders~ood that the use of wire line techniques migh~ be appli~hle in certain ~ell situat_ons and could be used within the invention. Cl ly, only by us m g coiled tubing can the wash-through capability of the washpipe be utilised.

m e use of coilei tubing for various well treatme~t p m cesses such as fracturin~, acidising and gravel packi~g is well known. The advantages in the use of coild tubing include relatively easy and qulck entry into Lhe well without the necessity of employing complex and costly apparatus such as a wDrk over rig. The use of coiled tubing is preferable to the insertion into the well of a t~bing string which is made up of a plurality of short lengths of tubing which must be indivi~lAlly joine~ gether.

Typic lly, up to seT~ thousands of metres of tubing is coiled onto a arge reel which is mounted on a truck or skid.
A coiled tubing injector head, typically employing chain-t~ack dri~e, is mounted axially ove the well heal d the coiled tubing is fed to the injector for insertion into the well.
The coiled tubing is plactically defor~ed as it is paid out frcm ~he reel and over a goose~eck gulde which positions the coiled tubing along ~lhe A~;C of the well bore an~ the mjec~or drive nYY~ulism.

Tool~ used with coiled tubing senerally comprlse a long rigid elemen~ ha~ m g a central bore which, when attached to the ooiled tubing, allcws fluid comm~nication between the bore of the ooilod tubing through the tool an~ outwardly ~hrough variouC valves and port_ in the tool to the well bore itself.
The tools Also typically inclule one or mDre packer elements .. .. . ... . .. . .. ... ..

2~17~8 which ac- to isolate cer~ain portions of ~he well bore f.~,.
each other. Such tools may be of any le~gth but, for instance, for treatment of a partlcul~r interval in ~he well bore, the tool m~st incorporate packer elements which, when positioned in the well bore, eff~c~ively straddle and isolate that par~ion of the well bore from the r~mair~L~g portions, bo~h a~ove and below th~ zone of interest. If the interval to be treated is particularly long, the treatment t~ol m~st be simil~rly of great length. Thus, tcols of 25 metre~ in length or lonser are not unccmmon. If the particular intervzl for treatment is at the end of the well bore the treatment tool may be locked into the well bore end and extend from the well bore end: in such a case a packer element is only required above the tool.

The injection of such a long-length tool which cannot be plastically defor~d in the manner of coiled tubing and which is typically of a larse~ di~et-r than the coiled tubing itself such that it will not pass through the injector drive mechanism prese~ts so~.e difficulty. In or~er to overoome this difficulty, it has been prior practice to mount the tool in a oonduit which is effec~ively an extension of the well casing above the well head and to position the injec~or drive mechanism on top of this ocnduit. The cond~it and inj or forms a pressurised cyll~drical enclosure for the tcol.
Obviously, this placss the bulky and heavy injector drive mcK~.ulisn at an extreme height above the well head when long tools are to be used. Such weight cannot be supported solely by the cylindrical oon~uit, and th~refore, mus~ be at least partially supForted by a heavy duty crane or derrick Ln position over the well he3d. ~espite employLng guy-wires to steady the positio m ng o~ the top heavy elevated drive mechanism, the uneven and irregul~- lateral foc~s applied to the assembly by unreeling an~ ke~ g of the ooiled tubing 2~78~

makes such positioning difficult at best and an extreme safety hazzard at worst.

In accordance with one aspect of the present invention, a E5 of any length is mounted within a close~-end cylindricAl lubrica~or which is then mounted on the well head. Upon establishment of fluid cammunication between the lubricator ani the well head by openLng of at leaLst one well head val~e, the BH~ is lowered from the lubricator into the r~ell bore with a por~ion of the 3Ha remaining within the well head at the location OI the blow out prevention (aOP) stack, adjacent pipe seal rams located in the well head which are then closed to engage anl seal around the ~H~. The lubricator is then remDved and the injector h~ is positioned above the well head and the coiled tubing i9 extended to engage the captured ~H~ and fluid a~n~ tLsrL lS est2blished between the coiled tubing and EH~ c ,~or drive mec~æ~u~m is then connecced to the w6lL he~d and the pipe se 1 rams capturmg the aH~ are releas3c .-.d fluid comm mication is established between the well bore and the tubing injector drive heed.

The retrieval and removal of the coild tubing and BH~ i5 effected by perform m g the above steps in reverse order.

In another aspect of the invention a ~H~ of any length is mounted wichin a riser extending upwzrdly from the well head.
m e riser l~ill have at its upper end rams for capturing anl sealing tha ~H~, and a bi~nd ram for oompletely sealing the bore. An injector drive h~^1 for coiled tubiQg can be mounted over the rEms above the riser. In other resF#cts deployment of the ~ using a riser is the same as deployment using a lubricator. In certain circumstances where an exceptionally long EH~ is to be deployed, a lubricator may be mDunted above a riser/ram assembly, with the injector on top.

2 0 ~

Once particular advantage of the process in accordance with the present invention in that pressure testing is possible and desirable throuqhout the procedure which greatly ~nhances the sarety of the operation. Thus, the se21ing of the lubricator or riser attachment to the well head can be pressure tested prior to the OpenLng of the blind rams. Similarly, the sealing of the pipe rams against the ~H~ can be tested prior to rem~val or the lubricator or riser ~rom the well heat.
Additionally, the pressure integrity of any connection between the BHA anl coiled tubing (if used) can be tested as well as the press~re testing of the coiled tubing in the injector drive mechanism and its 5~A1 both against the well he~d and against the coiled tubing can be tested ?rior to opemng of the pipe rams. It can also be cl ly seen that pressure te~ti~g of the reverse order of the retriev 1 operation can be effected in like .~anner.

Where the BH~ is re~uired to be of such iength (e.g. 100 metres) that it cannot be acc3mmcdatod at the well head in a single length in a riser or lubricator, it is a particularly advantageous feature of the invention that parts of the ~H~
can be assembled into a string. As each seccion of the 3H~ is completed it can be lowered into the bore hole and another section connected on top. The alre&dy-Acsembled paxt of the EH~ is suspended from tho woll ho&d by a slip ram whic;h supports its weig~t. mO aH~ is seal~d by pipe r2ms in order that the well koro is m~intlined under pressure. Once the string has be~n oompleted the entire EE~ can then be deployed.

Acoording to ths invention the EH~ yrises a pre-packæd sc~een unit with an intern~l washpipe. The BHa ha~ means for locatin~ and locking the ~sembly iA the well bore at a predetermlned position.

....... , . . . . _ .. .... . . .. . . .

2~7g8 At leas~ a part of the outer sur~ace of the BH~ provides a sealing surface onto ~hich an appropriately sized pair of pipe rams can ,^orm a contact seal. The seali~g surface is located at a por~ion of the EH~ which is r~di~lly Lmpermeable to ~ell fluid. In some cases, the sealing surface (e.g. a polished outer cylin~rical surface) may be formed .~s an integral part of the ~ylir~rical body of the pre-packed screen.
~lternati~ely, it is preferred that the sealirg sur~ace may be provided on a section of pipe in the form Ot a bar or a "stinger" which is detachably connected in axial alignment with the screen. Where a string EH~ is to be deployed sections of screen may be Lnterposed by stinger sec~ions. The string may ~e gripped at various positions by suitable slip rams and sealed by suitable pipe rams beariny on the sealing surfaces. With stingers spaced at intervals along the length of the string, there is the possibility of gripping and sealing at chosen locations along the string. For example a string could be built sequentially by ad~ing a pre-pa~kad screen ar~ a stinger section, lowering the cGmbinet~ se~ctions in~o the well bore, sealing ^e bore against the pipe rams and adding arDther screen and stinger ~,bLnation above the previous sections.

When a pre-packed screen is to be deployed (or recovered) in a live well uner pressure it is essential to prevent escape of well fluid up the internal bore o~ the screen. Otherwise, when the 3H~ is held in t~e pipe ram of the 30P stack well fluid under pressure will by-pa99 the 9e~1 on the outer su2face of the stinger by passage radially throu~h the screen walls anl up the bore. The washpipe which is carried inside the internal bore of the screen can be sealed internally at the top end with a suitable v~lve. Also (or instead) the tcp end of the washpipe can be connecteld to the coil~d tubins 2 ~ g under pressure to prevent fluld ~ack-flow therethrough.
Furthermore, the wash~ipe bottom end may be provided with one or more non return valves such as flap valves, ball valves or rupture disc valves. According to the present invent_on there is addltionally provided in the EH~ at least one se lir~ m~ans to prevent well ~luid ~lcw in the annLlar space def~ned between the external surface of the washpipe and the internal sur~ace of the bore LnsLde the screen/stinser, ~he se ling means is located at a portion of the wall of the screen/stLnser which L radLally ~mpermc~ble to well f_uid; ir is par~lcularly prererre1 to make the seal at the same level as the external seal whLch is ~ate by the pipe ram. ~ost preferably, the sealing means is a subsection of pipe rormung a coupling pipe connectable between washpipe sections and capable of making a contact seal between its external surface and the surrcun~iDg internal surface of a stinger section.
The seal may be mA~e using, for exa~ple, one or more O-rings, or alternatively usLng for example chevron seals. 1.~.~ se 1 -self is generally carried on one of the parts in order to -.~ure its oorrect location and it makes con~act with a sealing surface on the other part: it is presently preferred to C~LTy the seal on the washpipe (or on a sub-unit attach~d thereto) ar~ to have a se ling surface (e.g. a polished surface) on th~ inside surface of the wall of ~he stir.ger.

The preferred ocmbinRtion is a 3H~ using pre-packed screen sections c~upled toc3et..er by interFosed stinger sections a~d including washptpe sections coupled together by sealing subsections. Formi~g both the screen anl washpipe Ln sections advantageo~sly facilitates the assembly of a ~ in the form of a str~ng. An m~odi=enc showing this arransement will now be described ky way of example with reference to the accx~any mg drawLn~s, in which:

_ ~ _ .. . , .. . ... _ . ... . .

2~ 7~

Figure 1 is a sche~atic section o~ part or a 3H~ in string form; ar~

Figure 2 is a scheTa~ic section of the bott~m end of the 8 of figure 1.

As shown in fisure 1 the ~H~ oo~prises pre-packed screen 1, washDipe 2 and stinser seccion 3.

~he screen hæ an outer ~luid permeable wall 4, an inner permeable wall S and an annular layer of pre-packe particulate materi~l 6 therebetween. Fluid can flcw radially inwardly through the screen into the annual space 7 between the screen inner wall and the washpipe outer wall.

The washpipe has an external diameter smaller than the m m imum internal diameter of the annLlar space. IWD washpipe sections are shown coupled by a subsection of pipe 8. The ends of the coupling are joined to respective ends of sections of washpipe by conventional means.

Two screen sections are shown joined together by a stinser.
Conventional joinL~g means may be used. m e stinger has a portion of its length necked down, and this portion has a polished sealing surface 9 which can provide a contact seal to a pair or ap,Dropriately sized pipe rams (not 3hcwn).

Interr~LLly of tho stinger, at the same level as the external senling surfaoe, there i9 an interruLL poLish~d se~ling surface. An annul æ se~L 10 carried on a sub~unit 8 forms a oontact se~LL on this inten~L sealing surface. ThLs, fluid frcm the an~Lar space 7 cannot pas~ ~y the seal 10. Provided the pipe rams senl the outer surface of the stinger and provided the internal bore 11 of the washpipe is closed (e.g.

.. .. . . ..

2 ~ g by a ~alve, not shown) the 3H~ provides a ocmplete seal for the well bor~ and prevents escape of ~ell f1uid~ ur~er pressure.

In the e~tc~1unelt of figure 1 an extra section is illustrated.
For practi d purposes, especially when deploying a aH~ in a severly deviated well, it is advantaseous to guide the passage of the ass~mbly in the well bore. In this e~bcdime4t a sub-unit is coupled into the str m g and carries a bow spring centraliser 12 which is collapsible to conform to the intern~
diameter Ot th~ well bore and which tends to hold the assembiy cen~rally in the bore as it is deployed. F~wever, use of a guide is t essential to the present invention.

As shown in figure 2, the bottom end to the BH~ may carry a washpipe end assemly 21. ~he assembly is mounted on the e~d of the washpipe by means of a slip joint 22 which allows SGme relative movement between -~he assembly 21 ani t e remair~er of the 2H~ - this has the fiunct_on of preventing eni-loRd stresses being transmitted up the washpipe during deployment.

The assembly 21 carries a shear pin 23 or collet type arrangement which holds the washpipe tip during deployment but which cAn release the washpipe when it is to be recovered fm m the ~H~ once t~e ~H~ is in place.

The tip of the assembly 21 can be clo9ed b~y means of a bot~om flapper t:ype assembly 24; this can be opened in situ by pumping fluid dcwn the washpipe.

As shGwn, the internal bore 11 of the washpipe is closeable against flow up the bore by means of a non-return spring-and-ball check v~lve 25. ~lternative types of check valves are for ex2mple flapper type valves and rupcure disc 2 ~ 8 3 valves ~known in the art but not sh~wn). Ideally, at least two sets of valves should be present to assure the safety of the washpipe against blow out.

A ccmplete 3E~ according to this invention would have at its uppermost end a locking de~ice ~oz locki~g the 2H~ into the welLbore at the preselected point in the bore. Also, t~e BH~
would have means at its uppermost end for engaging a recovery tool for recovering the EH~ an~or recGvering the washpipe.
It is hereagain stressed that the actual deployment and recovery of the ~H~ may equally well ~e made using wire line techniques or coiled tubing db~x3~ing on the circumstances.

The presence of the washpipe is only of significant v~lue during deployment and/or retrieval an~ recovery of the washpipe (leaving the pre-packed scr~en assembly in place) is contemplated. Clearly, if wire line techniques are usei for the whole deployment and reoovery operation the wash-through potential provided ~y the washpLpe cannot 'be utilised.
~onetheless the use of a wire line technique is not outside the scope of this invention.

Claims (14)

1. A bottom hole assembly (BHA) which comprises:
a) a pre-packed screen having an internal bore, b) an internal washpipe in the bore sealable against axial fluid flow, and c) means for locating and locking the assembly in a wellbore at a predetermined position, characterised in that:

at least a part of the outer surface of the BHA provides a sealing surface onto which an appropriately sized pair of pipe seal rams can form a contact seal, the sealing surface being located at a portion of the BHA which is radially impermeable to well fluid, and further characterised in that there is a sealing means located at a portion of the BHA which is radially impermeable to well fluid, which sealing means is located in the annular space defined between the external surface of the washpipe ant the internal surface of the pre-packed screen bore and which prevents axial fluid flow.

2. A BHA according to claim 1, wherein the external sealing surface is provided on a section of pipe in the form of a bar or "stinger" which is detachably connected in axial alignment with the pre-packed screen.

3. A BHA according to claim 2, wherein the stinger has a portion of its length necked down and this portion has a polished outer sealing surface.

4. A BHA according to any one of claims 1 to 3, wherein the sealing means is at the same level as the external sealing surface.

5. A BHA according to any one of claims 1 to 4, wherein the sealing means is a sub-section of pipe forming a coupling pipe connectable between washpipe sections and which is capable of making a contact seal between its external surface and the surrounding internal surface of the pre-packed screen bore.

6. A BHA according to any one of claims 1 to 5, wherein a seal is carried on the washpipe or coupling pipe sub-section and forms a contact seal against a polished internal surface of the pre-packed screen bore.

7. A BHA as defined in any preceding claim, comprising a plurality of sections in an axially aligned string.

8. A BHA as defined in claim 7, comprising a plurality of pre-packed screen sections joined by interposed stinger sections.

9. A BHA as defined in claim 7 or 8, comprising a plurality of washpipe sections interposed by coupling pipe sub-sections providing sealing means.

10. A BHA substantially as hereinbefore described with reference to figure 1 or figure 2.

11. A method for deployment of a BHA as defined in any one of claims 1 to 10 in an oil/gas well under pressure which method is characterised by the steps of:

a) mounting the BHA in a closed-end cylindrical lubricator, b) making a sealed connection between the lubricator and well head, c) establishing fluid connection between the lubricator and well head by opening at least one well head valve thereby pressurising the internal space of the lubricator, d) lowering the BHA from the lubricator into the wellbore with a portion of the BHA remaining within the well head at the location of the blow out prevention (BOP) stack adjacent pipe seal rams located in the well head which are then closed to engage and seal around the BHA, e) removing the lubricator and positioning a coiled tube injector or wire line unit above the well head, f) sealing the connection between the injector/wire line unit and the well head, g) releasing the seal rams capturing the BHA and, h) deploying the BHA in the wellbore.

12. A method for deployment of a BHA as defined in any one of claims 1 to 10 in an oil/gas well under pressure which method is characterised by the steps of:
a) mounting the BHA in a riser, b) mounting a blow out prevention (BOP) stack at the upper end of the riser to seal the riser and making a sealed connection between the riser and the well head, c) establishing fluid connection between the riser and the well head by opening at least one well head valve thereby pressurising the internal space of the riser, d) lowering the BHA from the riser into the wellbore with a portion of the BHA remaining within the well head at the location of the well head blow out prevention (BOP) stack adjacent pipe seal rams located in the well head which are then closed to engage and seal arount the BHA, e) mounting an injector drive head for coiled tubing or a wire line unit over the BOP at the upper end of the riser, f) sealing the connection between the injector/wire line unit and the riser, g) releasing the seal rams capturing the BHA, and h) deploying the BHA in the wellbore.

13. A method according to either of claims 11 or 12, modified in that the steps are carried out in reverse order in order to retrieve the BHA from a wellbore.

14. A method substantially as hereinbefore described with reference to the deployment (or recovery) of a BHA as hereinbefore defined in an oil/gas well under pressure.