CA2052308A1 - Bore-hole packer - Google Patents

Abstract

Abstract of the Disclosure Title: BOREHOLE PACKER

The packer (4) is for use in isolating long lengths (ie heights) of a borehole (2), eg between sampling points. The packer includes bentonite (23) which is activated by the natural groundwater in the borehole. The water is admitted into the bentonite through narrow portholes (21), which delays the flow of water into the packer. The water is distributed evenly throughout the bentonite by means of blotting paper (14,16), which soaks up the incoming water and prevents the water passing to the bentonite until the blotting paper is all saturated. Alternatives to the use of blotting paper, to transmit the water evenly over and through the whole body of bentonite, include perforated corrugated plastic, corrugated cardboard, and perforated plastic pipes.

(Fig 1)

Description

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BOREHOLE P~CK~R

Thi~ ~nvention relates to borehol~ Packers. Paokers ar~
used in boreholes ~or ~uoh aotivitie~ a~ isolatin~
instrument~ that ~asure aqui~er conditions.

Use o~ the paoker~ en~bles ground~ater to be eon~in0d to particular levels in th~ borehole and ~nable~ th~ ground-water to be oonstra~ned a~ainst ~oving vertically up or down the bor~hole.

Borehole packer~ have hitherto been seen as ~xpensive items.
As a rosult, the d~si~ner o~ a borchole syste~ has speci~ied paokers only at u~ paoed locat~ons alon~ the depth o~ the borehol0. In the known sy~e~s, the paoker~ aotually oooupy only a tiny proportion o~ khe total depth o~ the borehole, the paoker~ belng so arranged, along the len~th or depth o~
the bore-hole, as to aohievo th~ ~axi~um atrate~lo ~a~p~in~
e~ect; and one o~ the ~kills required oP the hor~holo de~i~n~r has been in aohivvin~ good i~olation o~ the sampline zonos while usin~ a ~ini~u~ nu~b~ and ~ize o~
~aoker~.

As ~n altornative to a pr~-manu~aetured exp~ndable packer, ~t i8 kno~n ~or a de~i~n~r to ~p~¢i~y that water-expandabl0 ~at~rial be poured into th~ borehol~, a~t~r th~ instru~ent-ation has been put in plaoe, to seal up the "dead" ~pty ~pace~ in th~ borehole. Thi~ can b~ done progr~ssively as

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instru~entation is built up in the bo~hol~. How0ver, the proce~ o~ pouring in ~oo~o dry partlele~, or powder, or granulo~, o~ b~ntonit~ or other exp~nd~ble ~aterial has rarely proved sat~s~a4tory: the pa~ticles ~atoh on the walls ~tc and absorb wetness or ~oi~ture, and tend to swell pra~aturely, and in the ~ron~ places.

Thus, while thD exp~nse o~ pre-~anuPaokured packe~6 o~n be tolerated ~or the purpo~e o~ i~olatin~ the actual ~ampling zones, th~ nesd i8 cl~ar ~or an insxpensiv0 paoker th~t will prevent verticQl move~ent oP water in the dead portion of the borehole that lie~ bet~e~n the sa~pling zone~ thi~
inexpen~ive packer oan be d~si~n~d ~o bo ~o s00ure that the inexpensive paoker can it8~1~ bs usod to ~ 801ato the ~a~plin~ zones, th~n B0 ~uoh the better; but th0 r0al need ~8 that the lnexpensive paok~r wlll prev0nt gro~s ~low up and down the doad portion~ o~ the borehol~, in th~ areas bet~een the ~a~pling zone~, Minor leaka~e or seepa~ in the dead port~on i8 not so imporkant.

The invention i8 ai~ed a~ providin~ a pre-~anu~aotured paoker that i~ so in~x~onsiv~ to ~anu~aotuP~ and use that the on~ineer wil} consi~r it economioal to ~it the paok~rs ov~r the ~hol~ depth o~ th~ bor0hol~. This i~ likoly to lead to a ~rcatcr aoouracy o~ æa~plin~ result~, booause a ~ully paGk~d bor~hole i8 more nsarly r~pr~ntative o~ ~h~
ground ~8 lt ~a~ be~or~ it wa~ di~urbed than ia a borehol~
which p8r~it8 a ~ubstantial u~/down circulation or ~J~3~3~

tran~eranoe o~ ~roundwat~r.

The pressure o~ ~hs groundwak~r in a borehole ~ hard to pr~dict and to ~asure. In ~ot, a borehole ~ltht ~ drY
~hen packer~ are inst~lled, but ~iBht lat0r oontain wat~rJ
and th~ natural borehole wat~r pre83ure ~i~ht vary naturallY
with ri5~8 and ~alls in the local wat~r table. It h~o b~en known ~or the ~a~e borshole on one oooasion to ~e dry and on another oooas~on to oontain artesian pr~s~ure.

To en~ure a good seal in a packer o~ ths ~ur~ace-activated kind, the ~E~ssure o~ the wa~0~ ~ed ~ro~ the ~ur~ac~ ~u~t be high anough to oater Por the~a vari~tion~. So~eti~e~, therefore, it ~ay happen that the pre~æure ~ithin ~ sur~ace-aotivated packer is very ~u¢h hi~her than the pres~ure o~
the groundwater ~urrounding the ~ck~r, ~ith ~h~ r~oult that the pack0r would kend ko ~allo~n ou~ into suoh ~io~ures 0to as ~ay be pre6~nt, i~ prooautiono wer0 not t~ken. A
~urPao0-~otivated packer ~u9t th~re~oro inoorpora~o ~o~
~ean~ ~or prev~ntin~ balloon~n~, and ~uoh ~eano aro invarlably ~xp~n B ive.

An oxaapl~ o~ a ~ur~aoe-activated paok~r with an anti-balloonin~ ~an~ i8 sho~n in W0-88/03597 (~LSHAW, ~ay 8~3.

Th~ tend~n~y has there~or~ be~n~ hitherto, ~or th~ ~nEin~er to 8pe~i~y the expensiv0 sur~ao~-aotivated pack~r~
iD~diately above and bolow th~ s~mplin~ æon0, to prov~de

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the reguired ~ood ~eal, bu'c to leave cl0ar th0 da~d ~rea be'cwe~n the sa~plin~ zon0s. Thi~ has ~eant that groundwat0r could pas~ ~re~ly up and down khe dead ar~a o~ tho bor~holeJ
~ith the r~sult th~t wat~r ~ro~ a oonaiderabl~ distanos ;llight ea~ily be present very close to a 8a~nplin~t zone. ~he engine~r c:annot rsly upon such w~ter not to ~eo~ through the surroundinll aqui~r ~atsrial into tho ~a~plin~ æone. But it has b~en ~oo exE~en~iv~ ~or the sngine0r ~o provide eur~ace-activated paokar~, with theil~ ~xp~nsive anti-balloonin~
8y~te~18, throughout the ~hole samplinlg ~ang~ o~ tha borohole .

GLNEP~AL FEATURES OF THE I~ lITIOI~

I~ the pa~ker oan bs aotiv~ted by the ~roun~walter tha~ i8 naturally pres0nk ~n th0 borehol~, or at 10a~t by wat~3r whose ~ressure i~ no ~reater th~n that oP tho groundwat0r, the proble~ o~ th~ packor balloonin8 out inko ~ urc~
beoo~es no lon~er a proble~. A di~lculty with a ~round water-aotivakod pack~r lic~ in how the oxpandabl~ ~at~rial i~ to bo introduo~d into i~ corroot lo~ation in kh~ boro-hole, and aanipulat~d into posltion, without ~xpandin~
pr~aturely; once th~ ~roundwater touohs~ the paoker material, 'ch~ packer ~at~rial starts to exp~nd. Another di~iculty liqs ln ho~ ths ~xpandable materlal, in dry Por3l, 18 to b~ ~ont~ined with1n thc pa~ker.

.

2~3rj~3~8 Y~t anoth0r diPPiculty lie9 in th0 Paok that ~xpandable paok~r ~aterial, ~uch aOE bon~on~te, kend~ ko ~e40m~
i~pormeablo whon wet. Ther~ore, th~ do~i~n0r ~hould 0n~ur0 that tha ~round~atcr i8 not call~d upon to p~nRtrate throu~h already wettsd bentonlte in ordor to reAch th0 re~aining dry bentonite. There would be little point in a paok~r that ~xpanded iully at tho point where water was admitt~dJ iP the re~t o~ ths paok~r were to r~ain un~xp~nded.

A ~urther di~rioulty aris~ ~rom the shape 4~ the packer.
Insvitably, the pa~k~r i~ rolativoly long and sl~nder~ Its ~tructure lncludes an inner tube whioh oont~in~ ths conduits ~tc ~or the down-holc in~tru~entation. Whilst th~ inne~
tubR o~ ~ourso is s~allor than the boxehole, n~v0rth~1~s~
th~ annulnr ~pao~ availabl~ betwe~n th~ inn~r tube and the borehols, io tho 8p~1C8 into whioh the ~ontonil;~ or other paoker mat~rial i~ to ~it, i~ very ll~itod. The ~entonits thererore oompri~e~ only a thin annul~r layer~ and th~
manne~ 01 loca'cin~ th~ bentonit~ within khe ~laokHr ~u~t be suoh that th~ khin annular l~yor Or dry b~nl~nite Branul~s r~in~ inta~t and in 20~ition until the packer i~ installed irl its 2inal looation in tho bor~hol~.

A ~uantity Q 02 wat0r i~ the ~auantity o~ ~roundNater 3~rom the borehole that i~ resauired to be ad~itted into the body o~ ~xp~ndabl~ ~tarial in th~ pack~r, in ordor to ~ully expand the body o~ ~xpandabls ~aterial. ln the invontiorl, the packzr include~ a port or port~ ~or ad~ittinlig the ~2~

guantity Q. The in~entlon provld0~ al80 ~ di~tri~ution ~ean~, ~or distribukin~ the ~eoeiv~d water Q throu~hout substantlally the wholo body o~ expandable ~aterial. Tho invontion provides al80 ~ delay ~ansJ ~or del~ying the ~aid dist~ibution o~ w~ter.

The trans~is~ion ~ans ~ay oo~pPi~e, ~or exa~plcJ a ~h0et o~
u~tor-ab~orb0nt ~aterial, whi~h i~ wrapp~d around the inner tub~ og the packer. Th~ ab~o~bent ~aterial ~hould be o~ th~
kind which r~ains p~r~eable even when wet. An ~xampl~ o~ a suitabl~ water-ab~orbont ~a~erial whioh re~ain~ ~sr~able i~
blottin~ paper.

Wat~r ~nters throu~h the portE ~ ~nd i~ ~bæorbed lnto th~
absorbent ~atsrlal. The nature o~ the absorbent ~aterial æhould b8 ~uch that the ~ater pre~r~ to kra~el through th~
absorb0nt ~atorial, by progros~ivo ab~or~tion, r~ther than to pa~ ~ro~ th~ abeorbent ~ater~al into the ~x~and~bl0 ~t~rial. In other word~, th0 ab~orbent ~ateri~l ~hould pre~er~bly be ~uoh that the exoo~o water do~ not ~tart to pa6~ tro~ th~ ab~orbent ~at~rial into the ox~andable ~aterial, until a~t3r the whola body o~ ~b~orb~nt ~ak~r~al ha~ beco~ thorou~hly saturated. The absorbsnt ~atorial pre~orably ooeuPie~ ths ~ull l~n~th ~i~ the ~ull Yertical hei~ht) o2 the pa~kor, with th~ r~oult th~t ~atsr i~
trans~itted and distribut~d and i~ ~rescnt throu~hout ~he ~ull length or h~i~ht o~ the pack~r bo~oro ~he w~t~r 8tart8 to entor th0 ~x~and~ble ~t~rial.

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Thi~ i~ not to 8ay that the whoï~ body o~ bentonit~ ro~ain~
co~pl~toly dry until the wholo body o~ a~orbent ~t~ial b~co~e~ ~aturat~d, but rathor thliLt 'che bentonite n~ar to khe ~ort does not ia~medi~t~ly soak up all ~he water ent~rin~ -throu~h th~ port, and that 80~0 oP tho ;~t~r i8 ~low~d to pass throu~h the ab~orbont matorial to tho ro~t o~ the ~ody oP bentonits.

In plaee o~ th~ absorbent mat~rial iust desoribed, the tran8~io8ion ~ean~; ~ay co~prise oth~r suitabl~ ~chanis~
~or 3X~!Unpl0, the trans~i~sion ~e~n~ ~ay co~prise a she~t el ~ov~n g80t8xtil~ mat~rial. Thc points not~d above, regarding the ~act that the matsrial should oontinu~ to tralle~lit wat~r even thou~h the bontonite iæ becoDing i1nper~eableJ apply, what~ver the ~at~ial.

Tho trans~iæ~ion ~0ans Day oo~pri~e ~ean~ other than ~bric materi~ or cxdmpl0~ a ~ri~ o~ kran~oi~ior pipe8, wi1;h ~aoillty to di~tributa tho water, ~y al~o b~
u~cd. Tho variou~ alternak~voo arb do~orib~d in ~ore~ do~
bolow .

The delay ~an~ may co~rise a re~triotion in the ~ro~s-s~ctional are~ o~ thfl port or ports. A typio1l1 paok~r ~i~ht cont~in 3 li1;a~e~8 oP expandable ~ack~r ~atsrial, and by the tiloe ths packer ha~s oxpanded suP~ioiontly ko ~ill the borehole, will contain a s~antltY ~ o~ water o~, typically, ....

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10 litres or ~o. I~ porto ars provided one at eaoh 0nd o~
th~ pa4k~r, ~nd i~ ~oth port~ are re~trloted ~e a~out Z sq cro~s-~eckional ar3~, than it will tak~ soveral hours, or e~n a dRy vr t~o, Por tho guantity Q to be ~d~itted into ths paok~r, and Por the packer to Pully expand. Th~ aotu~l rate depends on a nu~ber o~ ~actors, includln~ th~ pr~sur0, te~peratur~, salinity, et¢, o~ the groundwat~r in th~
borehole.

Othar delay mean~ will be d0scribed be~ow.

~he port~ ~hould be ~o sized and arranBed that the particles o~ bentonite cannot ent~r, or Pall out through, the port~
dur~ng oanu~acturs, tran~port~ and installation o~ the packcr. It i8 pr~erable, ~or th~ purpo~ 4P tak~ng evldencs in a pollution oase, ~or exa~pl0~ i~ the ~n~ineer in char~e o~ the s~mpling op~r~tion can declaro th*t the bentonite its~1~ oannot pC~8~itlly have besn th~ ~ouro~ o~ any oonta~inantæ that Zai~ht be pro~ent in tho borehol~. Th~
small-area ~orto, ~ de~orlbed, w:lll ,~en~rallsr bo ~oo~3~ted by a tribunal ~lo ~rovldin~ e~otiv~ i~olation ~or tbe benton ite .

The packer o~ the invontion U1~3e8 ~roundwat~r ~ro~ the borohole itselI a~ ths water which expands the paoker. In contra2i~t to the ty~e o~ p~ckor whlch iE~ aotivatsd by ~ater ~ed down ~ro~ th~ sur~ace, the paoker o~ th~ ~nv~nt~on i~
not prone to ballooninl2 out into ~ u~e~ eto in the ~ ,~3 ~

bor~hol~ ~all.

The p~ok0r Or the invontion i~ o~ono~i¢~l to prov~de ln lo~B
lon~thQ, ~ith the r38ult that tho whole depth o~ a borehol~
~ay b~ ~acked prop~rly aQd e~otlvoly. Th0 inv~ntion o~n thero~ore h~lp in cr~atin~ down-holo oonditions whioh ar~ a~
clo~o as po~sible to th~ condik~on~ whioh obtain~d bo~or~
the ground wa~ di~turbed.

Hitherto, a~ ~ntion~d> b~ntonite has siapl~ ba~n poured straight into th~ ho}~ in an atte~pt to pack the ~ol~. In that case, not th~ 18~8t 0~ the proble~ thc sn~ine~r facss i8 that h~ cannot t~ or ~ure ~hether th~ hol~ is packed or not. ~ith th~ pack~r o~ the invention, th~ ~n~ine~r at least can be sur~ that the paoker i~ pr~sent in the holo, and at ~hat depth.

As will be doecribcd la~0r, the lnvention al90 addr~ t.ho probl~ of how th~ dry xranul~r 0xpandablo ~ateri~l lo to be ~s3~bled into, and oon~in~d w~thin, tho ~truotur~ oP th~
paoker.

One o~ ~ha pre~err~d u~es o~ the pack~ o~ the inv~ntion i~
in oo~bination with pack0rs o~ tho sur~o~-aetivated typs.
Pack~rs which are activat~d by pr~ssuro ~rom th0 ~ur~a~e can b~ ~ad~ to ~al rery ti~btly to the ~all~ o~ the borehole, and this o~ ¢ourBo i8 a u~ul attribute, ~arti¢ularly in i~olatin~ a 8~all zone o$ the bor~hole Pro~ which an aotu~l . . .

C~ 8 ~nDple i8 to b~ tak~n. Thu~, a ~air oP ~urP~oo-aativat~d paoker~ ~ay bs provid~d in respeot 4~ oach sa~plin~ zon0, ons above and ono below ~ho sa~plin~ zono, whilst tho relati~ely lon~ "dsad" hei~ht o~ the boxehol0 between the ~a~plin8 zon~8 i8 occu~i~d by the ~ckor o~ tho lnvention.

The pack~r o~ the invontion ~ay be ~anu~actured in standard len~ths, sueh ~8 1.5 or 2 ~etro~ J which arJ ~asy to h~ndle.
Sevoral packors could be fittad in s~ri~ ~or deoP
boreholc~.

D~IL~D DESCRIPTI~ OP PREF~RRED ~BODIME~T

By way of furthor explanRtion o~ tho inv~ntion, an ~xe~plary ~bodi~nt o~ the invontion wlll now be ds~crlbod with ref~renoe to tho acoompanyin~ drawin~, in ~hioh:

F~ cro~ actlon o~ a paokflr whioh inoor~orat~ th~
inv~ntion, ~hown in~tall~d in a boroholc;
Fi~ a OrO881-8e~0tiOn ~howin~ ~ olo~-u~ o~ ~o~ o~ tho oonponents oP the ~aokor oP ~
Fi~ 3 is a vie~ o~ a borohol~, ~how~n~ a nu~b~r 4~ paCk~rB
in~tallcd in oer~0s;
Pig 4 is a cro~s-~ec~ion o~ tho ~ok~r o~ ~ig 1, ~hown at a sta~ in th~ ~anu~aotur~ o~ th~ paok~r;
~ie 5 i~ a Vi8W correspondin~ to PiB 2~ o~ anoth~r packer;
~g ~ is ~ view oorr~pondin~ to Pi~ 2, o~ yet anothcr pack~r.;

~ r3 ~ ~ 3 ~ ~

Th~ apparatu~ shown in th0 aeoompanyin~ dr~win~o ancl de~cribod b~low ar~ oxaJnple~ which ~mbody tho invontion. It should be notod th~t th~ ~oope oP the invention i~ de~in~d by ths accoinpanyin~ olai~s, and not ns4~ss~rily by sp~oiPio ~eatur~s s~ ~xeDplary embodi~snts.

A3 ~hown in Fi,~ 1, a borehole 2, prepared by drillinfi~, i8 suitable ~or th~ taking oP aleasuromon~s reslating to bolow-8round pa~amater~. A central tube 3~ olade o~ thick, ri~id, plastio, ext~3nds down Pro~ the ~ur~ac~ nd tha vnricus s~rvicog (not ~hown) ~or th~ ~ea~uring in~tru~nt~ ar~
hous3d with~n tho tub~ 3.

A packor 4 provid~s a ~oal betwe~n the tube 3 and th0 borehole 2.

In tho ln~tRll~tion ~hown in l~i~a 1, th~ ~unotion o~ tho pa4ker 4 i9 to pr~vent tho Plow oP s2roundwat~r vortic411~ up and down th~ boroholo, and thu~ to i~olak~ tho æon0~ wher~
~o~wur0~0nts D.ro aotually boirl~ tak~n. Th0 zonc~ tho~s~lvos are not ~hown in Pig 1.

Th~ paol~er 4 utili~s the tub~ 3 a~3 a ~igid lnnsr tubs o`f th~ pack~r. An outer tubc or ~leeve 5 i~ o~ thin rubber.
Th0 rubber i8 plain ~UD rubber, which contain~ no r~inr~orc0al0nt~, and is v~y ~l~xiblo and strotchable.

2 ~

Upper and lo~er ~nd-pieces ~,7 are included at the end~ o~
the paoker 4. ~ach ond-pi00e oompri~0~ a pla~tio ~ouldin~
8. Th~ noulding 8 i~ prov~d~d internally with an O-rin~
which seals the end-pieoe onto th~ innor tube 3. The ooulding 8 i8 ~;uitable, 118 to its outer diam~ter, to rec~ive the outer tube 5, aLnd a tubs-¢la~p lO.

The mouldin~ 8 ~l~o $nclud~s a ~¢~ 12. Po~itioned in th~
r~ce~s, and ~xtendin~ inko the packer alon~ the lengkh o~
the inn~r tube 3, i~ a ~heet 14 o~ watsr-ab~orbent mat0rial:
~n th$s ca~e, blottin~ paper. The æheet o~ blottinla pape~
encirclss the inner kube 3, and ths sheet 14 ~3xtends almost to halrway alon~ th0 len~2th o~ ths pack~r. A correspondin~
shoet 16 2xtsnd3 f rom the other end-pi~3ce 7 . The sheet~
14,16 do not ~eet or ov~rlap, a~d in ~act a ~ap 18 i~ lePt bet~oen tho ~heato.

The loouldin~ ~ al80 lnolud~s a port ~O, in the iorla oP a through-hole whioh oo~unioato~ the roce~3s 12 with tho out~id~, ~nd thus ~7ith ~ny wakor which m~y b~ pr~ont in tha borehole out~ide the paokar.

A body 23 or~ expandabl~ packer material oocupis~ th~ annular spac~ 25 betweerl the inner and outer tubos. The expandable ~aterial in thi~ caao i~ bentonit~, which sxpand~ and ~;W~ 8 oonsiderably ~hen wa'c. The bentonite i8 inserted, dry, into the packer ln granular or powder ~or~.

-~ 2 3 ~ ~

Wh~n the paoker i9 in~erted inko ~he bo~shol~, the dia~0ter oY the out~r tub~ S 1~ oon~id~rably le~ than the di~et~
o~ the borehole, ~nd 80 the paoker pa~0~ ~a~ily down the borehole. Durin~ insertion o~ ths paoker, any water present in th~ hol~ oan ea~ily pa~ up and down th~ hole, ouk~id3 th~ outer tub~.

On~0 th~ packer is b~low th~ lev~l o~ water in tha bor~hol~, ~at~r start~ to ~nt~r throu~h th~ ports 20. Th~ hole 21 is o~ ~uch ~ s~all diao~ter that water ontor~ only very slo~ly.
The water cont~cts ths blotting paper 14,16 and gradually ~oaks th~ whol~ shoet o~ blottin~ pap~r. Blottine p~per i a very absorbent ~aterial, 50 that wat~r t~nd~ to per~at~
throu~hout th~ blotting p~p~r rath~r than ~low out o~ th~
blotting paper into the b~ntonite.

~ventually, how~v~r, a~ ~oro wat~r 0ntor~ throu~h th0 port~
20, the blottin~ papor b000~ a~urated, and th~ w~t0r ~tart~ to ~oak ~nto th~ b~ntonlto. BlottinB pap~r hu~ u tond0n4y to so~k up the w~k~r into it6~1~, and not allow the water to ~nter th~ bentonito until tho whol~ oP the sheet oP
blotting paper ha~ booo~e ~aturated; this tendoney i~
u~e~ul, in th~ inv~ntion, inso~ar a~ it ~ns~r~s that ths whole o~ ths body o~ bsntonit~ at ~ir~t ro~ins dry, or ~ubstantially dry, and tho~, onc3 ~etting ~tarts, the ~hol~
o~ the body oP b~ntonit~ baco~es w~tt~d to~th~r. Thus, the blottin~ paper acts to w~t all the bentonits 8imulta~0u~1y~
~oothly, a~d ~v~nly.

. . .

~5~

A~ the b~ntonike 23 becom~ ~7ct, it ~w~ , and ~ontinu~ to swell until lth~ outer tube 5 h~ 0xp~nded suP~ioi~ltly to ~111 the borehol~s 2. The pr~sæure ~hich the expandinl2 bentonite exerts i8 su~f ioient to ~tret¢h th~ rubber oP ths out~r tub~ 5, and to Porc~s the tubf3 to confor~ to any minor irro~ulariti~ in the sur~aoe o~ th~ borehole. Ho~7~ver, ~h~
e~acc~3s8 oi~ pre6sure or~ated within ~ body oP b3ntonit~ upon beco~ing wet i~ only a littl~ greater than th~ prss~ure o~
the water. Therefor~, the outer tube 5J whila it ~ill expand to fill the bor~hol~ 2, doos not tend to ballr~on out~ard~ into f is~ur~s ~tc lthat ~ay ~ pre~ent .

Whatev~sr the pr~s~uro or~ th0 ~roundwat~r (within limit~) th~
packer will pr~ against the side~ o~ the borchol0 with a slightly ~reater prossure.

~h0n bentonit0 beco~s w~t~ it un~ortunately ~nd~ o ko becoa~ i~p~rm0ablo, in khat w0Lter oEln p~n0trato only a ~mall d~st~nce into w~t bentonite 0ven i~ thor~ i6 dry bontonit~
boyond tho wet. It wlll be noted khat thQ blottin~ paper co~rl~e~ ~ tr~nsD~ ion ~naan~3, through whioh ~7at0r oan be tran~oitted evenly throughout th~ body o~ bentonite ~ without the ~at~r hav~n~ to ba ~ran~itt~d throulth th~ b~ntonit~
its~ h~ armular spaca 25 i~ typic:ally about 10 ~ wide, radi~lly, so that the water i~ ~alled llpon to penotrat~ only this ~mall dist~no~ throu~h b~ntonit~.

. . , 6~%~
-- ~5 --Nithout th~ blottin~ papor to act a~; a tran~mi~sion ~ean~, the ben~onitc ad~aoent to the port~ Zl~ would ~oll, and would then become impsr~no~ble, ~o th~t th~ r~t ~ th~ ~ody o~ bentonit~ would r~ain dry, and would not ~xpand.

A~ a ~att~3r o~ d~sign, the~ holo 21 should ns~t be lar~, Qnd the blotting pap~r æhould not b~ too quick to soak up water.
Th~ intention i~ that it ~;hould tak~ ~everal hour~, or even a day or two, a~ter th0 paoker 4 i8 lo~rad into ths wator be~or0 th~ l?aoker b~oe~s~ fully s~Ied into the bor~hol~.
Th~s period per~it~ tho l?ack~r 4 to be manipulatcd into its corr~¢t position, and p~r~its o$her expanda~ls paokl3rE;, which ~ht be~ activatod Irom th~ ~ur~aoei, to bo also s~t in place b~3fore the pack0r 4 beco~oe~ i~movabl~.

Th~ pack~r 4 as dcocribsd i8 a¢tivAt~d by the ~roundwat~r in~ide the borehol0 2, out~$de th0 packer. A8 mentioned, the pro~sur~ ~xort~d b~ th~ outer tube 5 aBain~t the sido0 o~ tho borehol~ i~ not ouoh ~0v.tor ths.n the prws-lre o~ tho 6~rountwakor. In ~any installakions, thoro~ore, tho paekur oannot be relied upon to bo a oo~plote æoal in tho borohole:
rathor, tho pre~enee o~ tho paeker 4 ~hould, in tho~e oa~o~;, be re~aLrdod ~eroly ~ preventln~2 a gro~ Plow o~ ~ater up and down th6 borl3hole, a~ dlstinoit ~ro~ ~Peotin~ a ~oliab~o and ~er~ot soal.

Fi~ 3 shows ~n installsit~on whiGh includos a ~roundwator sampling zono 30, Pro~ whieh water i8 dra~n oP~ ~or to~t . .

3 ~ ~

purposes throu~h a sa~pl~n~ ~ort 32. Paoker~ 34,3B i~olate the ~pling zon~ 30 ~ro~ tho re~t oP th~ b~rehole. The pack~rs 34,3B aro oP th~ kind that are aotlvat~d ~io ~xpanded) by ~eans o~ a water pressure ~sd do~n the inner tubs 3 fro~ th~ sur~ace. ~ith thi~ kind o~ packer, the engineer eenerallY ~ust ensure th~t the actuation pressuro o~ th~ water ~ro~ th~ surfac~ i5 u8Ually C0118iderAbly greater than ~h~ pres~ure o~ ~he down-hole ground~at~r, in ordcr to cnsure that the packer ~re~s~s v~ry tightly a~ain~t th~ sides o~ th~ bor0hol~.

To en~uro a ~ood s~al in a pac~er o~ th~ sur~ace-activatsd kind, the pr~ssure oP ths watsr P~d ~rom th~ sur~ac~ ~ust be hi~h enough to cator for t~esa variations. So~eti~e~J
ther~fore, it ~ay happen that the pr0ssuro within a sur~ace-a¢tivated packer i8 very ~nuch hi~h~r than the pre~sur~ e~
the ~roundwater surroundin~ lt, r~ith t;h0 resulk that thH
p~cker would tend to b~lloon out lnto ~uch ~is~ure~ 0to a~
uay bo pre~0nt, iP pr~oautlon~ ~ere not ~ak~n. A ~urPao0-~otivatod paok~r mu~t ~here~ore inoorporat~ ~oo0 ~ean~ Por preventin~ balloonin~, and suoh ~an~ are ~nvariablY
expsnsivs.

Th~ tend~ncy ha~ thero~ore boen, hitherto, ~or ~he sn~ineer to spoci~y the expen~iYe sur~a~e-aotivated paokzr~
~ diat~ly above ~nd belo~ tho ~a~pling zon~, to provido the r~quired good seal, but to l~e ol~ar the ar~a bet~en the saa~ling zonos. This has ~sant that groundwatcr c3n 2 ~

paS8 ~reely upr and down th~ boroholo, with the r0sult th~t water $rom a oonsid~rabl~ distanc~ can aa~ily b~ ~r~;erlt very 0108~ to a sa~plin~ zono, and the an~ino0r c~nnot r~ly upon such water not to seep through the ~urroundin~ ~qui~cr ~aterial into tho ~a~pling zon~. But it ha~ be~n t~o expen~iv~ ~or the ~ngin~or go provide ~ur~ac~-aotiv~ted packor~, with th~ir exp~nslYe anti-balloonin~ ~y~t~o.~, throughout th~ whol~ 2~an~plin~ ranl2~ of the bore~hole.

Fi61 4 illustrate~; th~ ~anner in which th~ pack~r oP ~ig 1 may b~ asæ~bl~d. Ths rubb~r Guter tub~3 5 i9 ~la~sd within a vacuu~ uni~ 40. The upp~3r and lowar end~ o~ the tub~ 5 ar~ strotched ov~r,and ~e~led tn, suitabl~ æpi~ots in ths vaouum unlt. Nhen the spaoo 43 in th~ vaou~o unit i~
evacuat0d, the tube~ 8 i~ sueked outw~rds, and ~xp~nd~ into oon~ormity with thn wall 45.

Th~ upEI~r and low~r ~h~et~s 14416 O:e blottinl2 papor aro wrappod around tho inn~r tube 3, and ll htly h~ld ln plao0 with, ~or example, ~dh~ive ta~. The 14~er ond-pi~oe 7 i~
~lipped ovex thc low~r cnd o~ the tube 3, wh~re it i~ hold ~n pla~ls by the ~riction o~ thz 0-rinl;t 3. DurinB as~bly, the tel~hnician takes oare that th~ blotting paper ent~ræ thc reeeæs 12 in tho mouldin~ 8 o~ tho low~3r snd~ ce 7. ~`ho sub-asss~bly oompri~in~ the tub~ 3, th~ lower ond-pi~3c~ 7, and both shoet~ 14,1~3 o~ blottinb~ p~l3r, i~ plac~d inside tho stretchsd-out rubbe~ tubo 5, th~ condition aæ ~hown ir Pi~

- 18~ $

Tho top o~ th~ spac~ 25 04nStitUtl36 an annular op~n mouth 47. l~xpandable paeksr ~aterial, in (dry) powder or ~ranular ~or3l, is pour~d into this ~outh. Su~ici~nt ~ate~
poured in to Pill up th~ annular spacc 25.

I~hen the æpac~7 25 i6 ~ull, th~ upper end-pi~ce ~ i8 ~li};~ped over th~ inn~r tube 3~ a~2ain taking cars that th0 blotting pap~r ~4 properly enter~i: th~ reoe:s 1~. Th~ vacuusl can th~n be rslea~ed, which oauses the rubber tube 5 to ~hrink s~nto the bentonite ~rains, thu~ containing and support~ng th~ -~rains. ~inally, the top ~nd oP tha out~r tub~ 5 i$ clipped or Glaaped around the upper end piac~ IB. Tho dim~n~ions o~
thc comeonent~ ar~ such thak the tubs 5, wh~n the v~cuum i~
rolca~sd, ~rips the grains o~ bsntonite ~;o ti~htly th~t the ~rains will not movo, ~svsn khough th~ pack0r may be sub~0ck to tho usual knook~ and oth~r abuso durin~2 tran~port and in3tallation. Th0 oorr~ot de~zr~ oP ti~hkn4~ o2 kh~ rubbor out~r tube 5 i~ genortlly aohi~rod enly wh~n kho nomintll, un~trotohed, d~a~kor o~ tho rubber t~be ~ tha~n the etsr o~ th~ inner tub~ 3.

FiB S show~ a ~odi~ioation to the paoker ~u~t dl0~;crib~d. In Fi~ 5, the blotting p~per i~ replac~d by ~ sori~ o~ 8111~1~
pla tio Pip~8 50. The pipel5 51~ hav3 an intern~l bor~ o~ 2 or 80, and th0 w~118 0~ ~he pip~8 aro por~ors.t~d 0vory 2 cm or ~o. Wat~r anter~ the plpe2it 50 via tll0 port~ 20, a~
with ths blotting paper~ and pas8e8 along th~ pip~ nd .

.~ ~J~32 thenoo into oontaot with th~ b~ntonite ~3. The pip~ 50 lie along the inn~r tub~ 3 ~nd oxt~nd righk around kh~
circu~rono~ o~ the inncr tube.

The pipes 50 ar~ prsPerrad ov~r blottin~ pap~r Por ths long~r len~ths o~ pa~k~r, ie ~or packer~ o~ 2 ~tre3 axial l~ngth or aore, a~ provi~ing a more ~08itiV~, ~V011, trans~ ;on o~ the w~tsr over long diotancss. On the othor hand, tho pi~es are ~ora expensi~ and tricky to a se~ble.
Pipe~ al80 occupy more r~diu~: the pipe5 t~ke up æpao~ that could otherwiso b~ ocoupi~d with ~or~ bentonita.

As a ~urthsr altcrnative, the pipe~ 50 ~aY be replaocd by corrugat~d ~lastic shset, suitably p~rPorat~d. A~ y~t another alternative, oorru~atsd oardb4ard ~ay be sub~tikut~d althou~h the ~at~r-trans~ission pa~a~c~ in oorrug~tod oardbo~d can 80~ti~0~ bo olo~ed oPP by the 6a~11in~
b~ntonitc.

Good rooult~ havo al~o be~n obtain~d by ~akin~ the ~h~t,~
14,1~, not ~ro~ blotting pap0rJ but ~ro~ ~eo-t0xtile Daterial. Gee-textile ~aterial i8 a ~enePie ter~ ~or many typa~ o~ woven poly~ropylene ~te ~abri~. Th~ ~abric ~old under th~ T~adena~s HIRA~IJ o~ 1.5 ~ thiekn~s, i8 on~ that ha~ boen ~oun ~uitabl~ ~or u~ in tho invsntion.

Ths geot~xtilo ~nbrio i8 wrapP~d around the ~nner tube 3 in the sa~e ~nner a~ dss¢ribed in relation ~o the blotting 2 3 ~ 8 pap~r. The ~brio i~ eP~0e~e at tran~mittin~ ~Ater ~venly and thoroughly over th~ wh~ls she~t o~ ~abrio. The ~ak~r in ~act trav~ls alon~ the 3~aa~ b~twoon the woYen ~lbre~:
$ibre~ o~ polypropyl0ne~ the~ v0~ do not r~adlly ab~orb ~nd tran~it ~ater.

Th~ lnteraction o~ thc ports 2G and the wat~r transmi~ion ~ean3 will now be desorib~d. The intention i~ th~t ~roundwatcr Pro~ th~ borehole enters only v~ry 6~0wly throu~h th~ port~ 20, but that onc~ the water i~ through the port 20 the water can ~pr~ad qu~okly an~ ev~nly throul3hout the tran~ission ~eans, and into th~ body o~ ~xpandable ~aterial. Th~ inten~ion i~ that the packer i~ 810~ to ~tart to ~xpand, bain delayad pre~erably ~or ~evHral hour~ a~ter th~ ~acker iæ lowor~d into the hol~, but th~t ev0ntually, when the paoker doea sxpand, it does so evanly and oo~pl~toly. It ha~ bs0n ~ound that a go4d do~rea o~ deluy i~ aohieved when the hol~ 21 in the port 20 iB 1 . 5 ~ or ~o in diameto~.

An advantag0 that arl~ wh~n th~ port~ 20 ~re oP tho Por~
a~ de~orib~d is that the op~ration o~ th~ port~ i~ cntir~ly pa~ivo, i~ ~h~ ~n~ineer 8i~1y lo~ors th~ paoker dow~ the boroholo, ~nd th0 groundwat3r ~n the borehol0 auto~atically ~lo~ into the port~ and ~ctivat~ th~ expandabl~ ~terial.
As dsscribed, it has prov~d to b~ possible to delay the 0xpansion o~ the packcr ~a~erial ~or a convenient poriod o~
ti~e, and yet to snsur~ that kh~ p~ok~r oventually does . . , 2 31D ~

.
oxp~nd ~ully and evenly. Tho ports ~0 ar~ o~ oourse very inexp~ns~ve to providoJ and no oonneotion with the sur$aoe lo r~quircd in ord~r to acti~at* the ~aok0r.

On the other hand, it is contemplated in ths invention that the ports 20 ~ight be o~ th~ kind that ars operat~d ~o~ tho sur~aoa. an exa~pl0 is shown in Fi~ 6. H~re, a line 52 ext~nd~ up the insid~ o~ the inner tube 3 to the sur~ace.
The inner tube has ~ hole 54 throu~h it3 wall, aith whioh the lo~er end of the line conn~ctE. A piston 5~ i~ h~ld out~ard~ by (e~ nitrogsn~ prs~ure ~n kh~ line, in which cond~tlon th~ piston 5B blocks ~he hol~ 58 (corresponding to holc 21) oonnecting th~ recess 12 ~ith khe ~roundwater in th~ borehole. Whon th~ sn~in0~r wish~ to ackivat~ the paoker, he rel~es kho pre~ure in the lino 5~, wh~reby th0 piston 5B ~OVeB cloar o~ the pa~age 58.
.
Apart ~roo tho 0xtra oxpen~o o~ providing the oo~onent~
~hown in ~l~ B, thc addition oP an extra lino ln0ide th~
inner ~ubo 3 i~po~e~ a ~paoo pen~lty. Tho lnner tub0 ls ~snorally paoked with ~iPeS and oonduits ~or ~orv~cing th~
various 9a~1in~ ports~ and th~r~ is littI0 roo~ ~or ~or~.
How~ver, th~ paoker can, in the right circu~tano~s, b2 a¢tivat~d Pro~ th~ sur~acs in the ~anner d~cribed.

It i~ ~180 ¢onte~plated that the dslay ~eans oould b~
oo~prised by a bo~y o~ ~lo~-to-di~solve oat~rial. This ~at~rial would be in~rt3d prePerably into thc port or . . .

3 ~ 8 -- 2~. --port~. Wh~n tho pack~r i9 10~70red into th~ borehol~, th~
6~roundwat~r contaot~ tho di~solvable mat~rial, which then start~ slo~ly to E~ in~o solution. When the ~aterial has all dissolved, wa~er enters through th~ port and into th~
trans~i~slon ~eans. One oP the bene~its o~ thia ~ran~e~ent i8 that the ports can bs quite unrestricted ~o that the watsr, whan it ~inally does enterJ oan ~low in strongl~.

The dissolvabl~ ~at~rial ~ust be s~lected ~o as not to ~
its~ susp~cted o~ contributing to any contamination which Dieht b~ pres~nt in the borshole.

Ths ~ap 18, as pr~viou31y ref~rred to, i8 iDportant for th~
~ollowing rsason. A desired $un¢tion o~ the paok~r i~ to isolate tho saopling points in the borehole; and in ~act to return ~ach sa~plin~ ~oint as ~uch as possibl~ to ths condition it wa~ in b~ore ths 12round wa~ di~turbed.
~ithout the ga~ 1~ in the tr~n~ ion m~n~ (blottlng pa~r or oth~r) thero would bQ a lpa8~ga~0, or at l~a~t a notion~l pa~aBe, vertioally ri~ht throul2h tho whol~ h~i~h~ o~ tho paoker. ~lator oould, ~t leask thooretloally, 8~3ep Pro~ the ~a~plin~ Eloint abov~ tho p~Lck~r right through to tho ~alapling point b~low the packer. The gap 18 ~nsure~ that there i~ no throusth-Pa~sa~

Tho ~ap lô ~hould be wide enou~h thaS ~ator oannot cross the g~p: on the other hand, th~ ~2ap should not be 80 ~ide that ~ome o~ the b~ntoniLt~ ~ight rsmain dry. Bentonite beoo~es jS~5~

al~oot i~perme~ble whon w~t, ~o th~t ~tsr sub5tanki~11Y
cannot penetrate v~ry Par through ~aturated, swelled, bentonite to the dry b~ntonit~ b~yond.

~R sho~n, the packer is ~ed with water sy~metrically ~ro~
~oth ends, and the g~p 18 i~ in th~ ~entre o~ ~hc height oP
the packer and is about 2 ca wide.

In the case o~ a v~ry long packor, th~ oentral portion o~
ths body o~ bentonite ~ay be ¢on~id~red to b~ very r0~0ta ~ro~ the ~nds. IP so, an sxtra ~upply port ~ay be incorpor~tod at th~ upper or lo~er end o~ the pack0r, and a ~largs) trans~er pip8 ~ay b~ providsd to trans~er groundwater ~ro~ the port directlr w~thout resist~noe to th~
central portion. Only on* ~ap 18 neod b~ ~rovidod.

A~ de80rib~d, the b~dy 23 o~ ~entonito pro~0ra~1y i~ in powder or ~ranular ~or~. Bentonite i~ 0~0y ~nou~h ko proo~o into other shapes, ~uoh ~ ball~J whioh also oan ~e poured. It i~ al~o oont~mpl~ted khat the bentonito Dlay be ~oulded in~o tube~, or hal~-tube3, Nhioh oan b~ ins0rtod, rath~r than poured, into the molJth 47, although l~rge ~oulding~ in bentonits tend to be ~ra~ Oth~r wat~r-0xE~andabl~ paoker ~terial~ ar~ ~vailabl0~ ~0~13 oP
which, thou~h ~or~ ~xpen$iv0, ~r3 sa~i0r to handle in olould~d-tub~ ~or~.

The inv~ntion ~hould not be ~on~tru~d as bsing li~ited to a ~7J ~

partioular ~orm oi ~xpandabl0 Rlat~ri~l. Tho l~portant as~oct oP th~ inventi~n io tho provi~ion oP thc ~ ns ~or reo~iv~n~ ~round~aker ~rom the bor~hol0, not water Prozll the ouriaoe, and ~or tran~Ditt~ng the r~300ived ~round~ater ~venly over the whole body oP expandable material, and in en~uring a delay 80 that ~h~ packcr can be movod ~nd adju~t0d and ~anipulat~d ~or at loas~ 3~veral hours a~ter in~rtion into the borshole.

Claims (7)

1. CLAIM 1. Borehole packer assembly, wherein:
   
   the assembly includes an inner tube, and an outer tube of elastomeric material that is flexible and stretchable;
   
   the inner and outer tubes are so dimensioned and arranged as to create an elongate annular chamber therebetween;
   
   the assembly includes means for closing off the upper and lower ends of the annular chamber;
   
   the assembly includes a body of expandable packer material, the material being of the kind which expands considerably when wet, and which becomes impermeable when wet;
   
   the body of expandable packer material is located in, and substantially fills, the elongate annular chamber;
   
   the assembly includes an activation port or ports, so disposed as to provide passage between the said chamber and natural groundwater present in the borehole;
   
   the nature and dimensions of the body of expandable packer material are such that a quantity Q of the groundwater is required to be introduced into the body of material in order for the body to expand sufficiently to fully seal off the borehole;
   
   the assembly includes a distribution means, which is effective to distribute the quantity Q of the groundwater received via the port or ports throughout the whole body of expandable packer material;
   
   and the assembly includes a delay means which is effective to delay for a substantial period of time, passage of the full quantity Q of the groundwater from the port or ports, through the distribution means and into the body of expandable packer material.
2. CLAIM 2. Assembly of claim 1, wherein the delay means comprises a restriction in the cross-sectional area of the port or ports, whereby the groundwater can pass only very slowly from the port or ports, through the distribution means, and into the body of packer material.
3. CLAIM 3. Assembly of claim 2, wherein the diameter of the port or ports is 1.5 mm.
4. CLAIM 4. Assembly of claim 1, wherein the distribution means comprises a body of permeable, absorbent material, the absorbent nature of which is such that groundwater supplied to one area of the body of absorbent material spreads throughout the whole of the body.
5. CLAIM 5. Assembly of claim 4, wherein the permeable, absorbent material is blotting paper.
6. CLAIM 6. Assembly of claim 4, wherein the body of absorbent material is so disposed wihin the annular chamber that substantially all of the expandable packer material is so closely adjacent to the absorbent material that substantially all of the packer material is wettable by water present in the absorbent material.
7. CLAIM 7. Procedure for manufacturing a borehole packer, wherein:
   
   the procedure includes the step of providing an outer tube of stretchable elastomeric material, and an inner tube of rigid material, the tubes being co-axial and vertical;
   
   the procedure includes the step of expanding the diameter of the outer tube by stretching the elastomeric material, to a sufficient degree that an annular space or chamber is created between the inner and outer tubes;
   
   the unstretched diameter of the outer tube is such that such an annular space or chamber does not, in substance, exist until the diameter of the outer tube is expanded by stretching;
   
   the procedure includes the step of closing off the bottom axial end of the said annular chamber, and of arranging the top axial end of the annular chamber as an open mouth;
   
   the procedure includes the step of admitting expandable packer material into the said mouth, and thereby into the annular chamber;
   
   the expandable packer material is in granular or particulate form;
   
   the procedure includes the step of admitting a sufficient quantity of the packer material to substantially fill the chamber;
   
   the procedure includes the step of closing off the top end of the annular chamber;
   
   the procedure includes the step of releasing the stretch or expansion of the outer tube, whereupon the outer tube contracts and thereby acts to compress the material contained within the annular chamber.