@3,2.09,58,'-t 5 77, the differential pressure creited by suction 1)!i.,iip 13 will be applied across piston 41, and a resulting pressure prodticed by the attempted downward moveiiient f)f piston 45 will force back-tip plate 29 and pad 31 outwardly - a-ainst the filter cake lining the wall of the borebole. i@e interior of caisson 100 now will be isolated from 'boro,hole fluids. At the same tinic that vilve 70 is acttjated by opening valve 63 and closin@.- valve 65, the piston and stein of vilve 83 are moved downwardly s6 that conduit 85 is no longer operi to the pressui-e @@,ith,in chambcr 15 tlirou@h the poi,ts of valve 83. When vilve 59 is opencd, bellows 35 will contract to dccreise the prcsslire within spice 109 so. tilit earth fluids will flow igainst the filter cake 3. When valve 97 is opetied., water will be directed igainst filter cake 3 to aid the fluids from earth forinition 28 to waiii away the filter cake. Particles of the filter cake, the wasli water from reservoir 25 and cirth forniation fluids will flow through space 109: llnl]Llit 139, and will be stored in niud chamber 37. Conductivity nicasuriiig cell 140 in condliit 139 is insertcd tO MC.1,SLire the condlictivity Of flllids flowing tlii-otigli condljit 139. Cell 140 niay consist of a pair of insulated electrodes coupled to a poteiitial SOLirce throu.-h suitable current IIICISLiriflg ,ipparittis. The electrical signals prodticed by condL[CtiVity CCII 140 are transmitted t(y the cartli's surface to pi,ovide the offerators with -in indic@tion of.the nature of the fluids pa@sing through conduit 139. As soon a,@ the otitput sionils from cond6ctivity coll 14,10 indicate that formition fluid tre flowin.--freely into nitid chaniber 39, tl]C SL]Ction plfnip 13 n-@,iy be stopped. If the witer in reservoir 25 contains a revbrsa wetting @i,,cnt, re.idings may be made of the resistivity of foriiiitioii 28 ii%, niciins of sititable I-OSiStiVity MC@ISLirinclecti-odes wliicli 7ii,ty be ifTixed to pad 31, pi-efet-ably as close to cais@on 100 is possible. (When resistivity i-eadings are to be made, ciisson 100 and coritainer 104 sliolild either be niade of electi-ic-@illy nonconcilictive @material, of suitably instil,ited fi@om the cirth foriiiition to prevotit ctiri,ent froin flok@,iri- theretliroti-li dtiriii- i resistivity nic,,istii,cnient.) When ilie resistivity rea(ling is completed, valve 95 may be open@@d, L predetermined amount of peichi'ori-c @icid niay be illowed to flow throligh condtiit 99 and porous niedium 103 to-coiitact cirth fomi,,ition 28, and the clian_L,e in temperattire indicited by the cli-,in,C n resistivity of platinLIM wire 111 may be noted. Pad 31 aild backup plate 29 may now be retricted cithcr by de-energizing ifit-, ictbating coil of valve 65 or by ener.-izin.- tfie actliatin.- LOil,,S of vtlves 6.1 ,ind 57. This will remove the pressure on piston@ 107, 119, 129, @ind 135 to reti'act the paci and I)ack-up pi-,ite. Tfie insti-uiiient hOL]sln,- now citlier Diiy be brouglit to the earth's sui-face or may be,repositioned in the borehole foranother measurement. It is possible to estim@te certain of the properties of the earth forthations froni pressure gauge reidings of the pressure in caisson 100. For exiniple, the preSSLIt-o niaintained during the ptimping 6peration aftcr the filter c-,ike is broken will depend oh the punipin.- rate (wliich will be more or less const,,Int) and formation - pernieability. Wlien the ptimp is stopped, the pressure will come to that of the 60 formation. Formation pernicibility will be indicite(i by tlle eqtiilibriui-n presstire ittiined, the rite it wliich the presstire in the c-,iisson rises to foriiiition - pi-esstire, ,ind the r@ite ,it wliicli the v@ii-iolis fltii(ts ni@iy I)C iiijecte(l. I-'[G. 5 ilitintrite@ inollici, cnitio(iiiiient of the itivention (;5 which is adapted for tise wlien the filtcr ctke iS LinLl.$Llllly tliick. When the filter cake is iintisuilly thick,, it may be difficult for porous n-iedium 103 to ' coiitict cii-tli foi,iiiations iftc.r a portion of the filter cakc i(ijicent t[ic niediL]Ill lias been removed. Inner contiiner '104 for poi-otis iiie70 dium 103 is supo orted by guidcs 165 ,ind is ad-,ipted to move to the right ,ind left as viewed in FIG. 5. The con:- tainer is normally bi@sed to the left by coil springs 159 which bear against piston 157. FILiid pressiire fr6ni coiiduit 49 is applied to the space between end plate 153 and 75 6 i);@)foii 157 tbro,@,)Ph port 166. Wliter Iiiie 101 ind acid iiiie 99 are conne-@,ted to_Qether neir end plite 153 and' are iti@octed int-) coiitainer 104 through nipple 151 and tli,., in@erior of contiiner neck 161 Acid va.1ve 95 ,itid water val@,e 97 shOLIld be as close ,.s possible to ti@e jijr,,.:ture of 99 ind 101 and to eni plite 153. 'riie opei-ation of the app,,irittis of FIG. 5 differs from tliit of the enibodiiiieiit of FIGS. 1 throligh 4 ih that fluid pressure ipplied to chamber 155 will force cont,,iiner 104 10 and iiiedium 103 to the right is the filter cake disi.ntegrates. In dlic COURSC, gL]iCICS 165 will strike stop members 163, iiid sprin.-s 159 will be conipletely conipressqd. Note also tliit wisli water will filter througli the porotis mediuiii 103 to.:aid forfliition flllids in wasliin- away the filter ca'ke. Various cliin-es may be @made in the above-described invention, and different eiiibodinients of the invention r@iay be made witholit departing from the spirit atid scop@ thereof. Tbei-efoi-e, it is intcnded tti@it qll of the@ matter cotitained in the' above dqscription a I iid showli I in the ac20 cotiipanying drqwings sliall be coiistrued as illustrative. and not in a Iii-nitin,@ sense. What is cliinied is: 1. AI)pirattis for rcmoving i portion of a filter c,@ke lining the will of a boi-chole and injectiiig formation 25 testin,@ flliids int@ cat-tli fortnitions behind svid filter cake, comprising: a fluid pei-iiicable block@ ali opcn-ended;container for said block inCILiding a fluid impernicable lining for said blo,ck isolating siid block froiii tL@, ititi!rior of s,-,id container, 's,,iid block htving in expose-d poi-tioii at @,o siid open cnd; defbiniable sealing iiicans arotind stid open end of s,,iict coiitiiner idipted to pi-ovide: i litlid-tight se@it between the intcrior of siid conttiner and itlic intet-ior Qf said boi-eliole @@,i@en siid opcn ciid ablits s@iid @ilter .6,ike; iiieins for ibtittin- siid open,cnci @i poi-tioii :,5 or said til',er CIhe; Dl,-@,ITIS li3@(iriLilically coi.ip!cd to the interior of said contaifter for i-educiiig the pi-e,,sLit-- witliin said CODtainer to a presstire less thi n the pressure exerted by cartli fordiation lltiid oii siid portion of said filter cake to I)ct,foi,,,ite siici porlion of @ztid filter @akc; ,in(i means @io for iiijecti@-ig siid tcstin@ JILI!,IS tilFoUgh said lining for s.,iid block so that s@ti(I testing fliiids can filter throligh said block and througli the perforation pi-ocluced by perforating the filtcr cake into the earth formations. 2. Appat-attis for reniovin.- i portion of a lliter cake 45 lining the wall of a borchold and injecting forin-,ition testing fluids into eartli foriiiations behind said filter cake, cchipi-ising: a fluid permeable block; a first fltiid impermeabl6 coiitiiner for sai(i bloc.k; a second fluid impermeible contiiner for said first CODtainer, spaced from s@iid first container; siid first Ind second containers each having an opeii sicle to peiniit siid block to coiitact said filter cike; means for effecting a flliid-tight seal between said filter cake and said second cont,,iiner a@ound said open side of said second container; me,,ins for lowering r),5 the preSSLire in the space betwccn said first and s@cond containers to dt,,,iw earth foriiiition fluids. tjirough said filter cike in sufficient volume to wash away at least a portion of the filter cake throtigh which said formation fluids pass;,and means connected to said first container f6r controllibly injecting, said formation testing .@uids through said fltiid permeable block. 3. Apparatiis for injecting foriiiation tcsting fltiids into ciirtli fOrili,,itions. bcliiii(i ii filtei- c:ike liiiing tlic: will of a I)ot-cliole, coniprising: .i rigi(I-willed cais@on, said c@lissoii li@iviiio itl open cii(i i(l@ipted to I)c @ositioned ag.-tilist said filtcr cike; niciii,@ connected to slliid caiison for effecting a fltiid-tiglit seal between said ctisson -nd siiid filtcr'cike to pievcnt entry-into siid ciisson Of flllids witliin siid borehole; means connected io s,,iid ciisson for 10wering the pressilre within said c,,iisson relitive to borehole pressure to produce a (littei-ential pressure across said filter cake to effect a flow of formation flliids into said ciisson of sufficient fiiagnitude to wash away it least a portion of the filter. cake through which said earth formation fluids flow; and means connected to said caisson
foi- k:otitj-oll.-,tbly, injecting stid testiflg f]Llid, thi-otitl) siid c,-ii:@-,on into said eai-th formati6ns. 4. Appfiritus for testing eirth formations trave@rsr@d by a bachole, coniprisin.-: a fii@st cont,,iiner baving -,in ol)@li: end; a porotis block; a second open-endect container within 5 li@ld fivst coritainer, s-,iid second- co ntaificr bein& ,idapted to F,,irtl,,illy enclose said porous block so that Ln cxi)ose(I f-,ice of siid porous block proti-udes t,@roti2,h said open end of said. fit-st coiit,-iiner; fii-st and second flexible fluid rcsc,.-v@)irs exposcd to boi-chole prcSSLII-e: a suction pun-lp h,- i@,ing .in inlet ind in olitlet, tnd acliptell to . woi4k L,g@iinst . boi-chole pressure it its outict; a i-igid-w,,illed flliid conduit means liyciraulically COIlDling said rigi(I-w,-Llled chaniber with the interior of sqid first container; first clecti-ically actliated valve means; a bellows withi,i said cliamber, and fluid condLIit means. couplitig the interior of said bellows to said pump inlet throiigh said first electrically actuated valve nicans upon actuation of @.,Iid valve means; coupling means including second electrically actuated 'Valve mc,,ins hydrililic-,illy - coupling -0 the interior of said first fliiid reservoir' to the interior of S.,Ii(! @econd,contaitier; cotipling means incltiding thii-d clectric,illy ,ictiiatc(i v-,ilve means hydi-aulically cotipling the intcrior of s-,iid second fluid reservoir to s,,iid second cont@tiner; a (leform-.ible pad affixed to s.-tict fii-st cotit,,iiner ,irotinci s:iid open end thei-cof ici,,iptcct to pi-ovicle a fltii,,Iti@--ht seil i-ainst enti-y of fltiids fi-ojii s-,iid boreliole in!, iirst ,ind' second cont@iiners; @i liydratilic-,iII3, ictiitble r,,iiii for, foi-cin- s,,lid pid. said fii-st coiitiinei-, -,iid .@ii(I porotis block i_giin-@t s@iid filter cike; Ind preSSLII'e TC','Ci-s;ng nieins and fotirth electricilly ,ictLiible v,,ilve ni(@;iiis cotil)ling siid PLIIIIP inlet to slid i-am foi@ipplicition (,f a ppsiti,,-e pres@;tire to said ram i,(@litivd to borcl)olc pt'Is @ @,-, to ,ictii,,ite siid rini Nvhen s-,iid fourtli vilve me-,ins j,,, icL@i;ttcd; siid first, secoiid, thii-d, itid fourth vilve Ieing in(lividti@illy 11-tLl'lble by clectricil coincctioiis @ to the eartli's stirface; @ind means for tutomitic,,illy byp, issing said folirtli @,alve mclins and said suctioh ptimp me.i ns iipon cle-energizition of electrical co nnections to saill f,,-Lirth v,-ilve xiic,,ins. I t) 5. Appar,-itiis for testin,l e,,ii-th fbrm,.itions ti-aversed by a borehole, comprisiti-: a fii-st cont,,iiner havina an op @n I --,ncl; a porous block; ',i second open-ended container withi n said first cont,,iiner, siid sec.ojid cintainer being ,ida pted to it least pirtially enclose said porous block so that ,n exposed face of said porous block protrlides thro uoh said open end of stid first container; first -,"Id sec on! flexible fluid reservoirs exposed to I)orchole presstire ; a suction pump having in iiiiet and outlet, ad,,ipted to work a-,,iinst boi-chole prcsstii-c it its otitlet; a rigidwall ed clianiber; fltiid concluit' iiieins hy(li-@itilically cotiplin g ,aid ri.Rid-willed chaniber with the iiiterior of said first container; first electric-,illy acttiite4.1 valve niciiis; a bell ows within s,,iid ch.-iiiibcr, ,ind flllid conduit nie,,ins coti pling the interior of siid bellows to s,,iid piiii)p iiilet thro ugh said first electrically actli,,ited valve means tipon actti ation of said valve nicins; cotipling nicans includin.@ sec ond electrically actliited valve means bydi-aulically cou pling the intbrior of said first fliiid reservoir to the inter i6r of said second container; coiipling nicins incitid- 60 in.- tliir(.i electric,,illy a'tttiate(I v,,ilve nicins li@dr,,itilically coti pling the interior of said sccoii(i fluij res.-rvoir to sii(i second contiiner: a deforniable p,,ld -ifflxed to s,,iid first container arOLind siicl open en'd thereof ,idapted to pioN,i(i& a flLiid-ti.-lit se@il .,,i-.iinst cilti-y of fltiids withill, 6;-) siid borehole intoi siid first in(I second containers; a by(ir .,itilic,-illy actti,,ible r,-ini for forcing sai(i p.,tcl, slid fir.st cont.,iincr, in(i s,,iid poroiis .z:ii(i filter C,,tkc, ,in(I pi-esstire rcvci-sin,@ iiic,,iiis iiici foiji-tll vilvc efcctric@illy icttiable nicans coupling said punip inlet to said 70 ram for application of a positive pressure to said ram re],- itive to borehole presstire to.,ictuate aid ram when said fOLirth valve nicans is ictLiited; s,,iid rirst, s.econd, third, and f6urth valve meins being indivilually actuable b I y electrical connections to the eatth's surface.' 75 C). i%l)p@l;atL]'@ fk)i- i(@@,iin2 c@tilli liy a coiiilii-i,;ing: a fii-st i:oiit,,liiier liaving in, cpen eid; a poro-,is a ol)eii-eii(led contiiiier Nv:itliii-i ,,t@d rii@si. coiitain,-,i-, secoiici contain,,r b,@iiig -,i@tapte'l to It ].,-,ast 1)@17,t@,111Y oil el@)so @,i'd noi-ous b'@)c!, so ttiit exposed f-,tce of stid poi-olis block protru<.!cs thi-otigli s,,iid opc@n end of siid fii-st cont,,iin-,r; sl; d s@:concl contaiiier bein.- further adaptcd to i-,-ciproc,,ibly move wilhiii -,-,i(i first container at lcast i Iii-nited distince throtigli the opcn end of s,-iid f,@i-sL contiiner; first @ind secoild flexible flliid i-cservc)ii-s cxlioseki to boi-chole ilressure; i SL]ction pump liiviii,, an @iiiet and OLItICt, idapted tc) work ag,@inst bQrchoIe pressurc -,it its outlet; a ri.-idw,-illed cli,,in@ber; fluid concILiit nic,-itis hydratilically coupling said rioid-i@@,alled chaniber witli Lhe interior of said first coiittiner; first electrically actuated valve means; a bellows within said chamber, ,,ind fluid conduit me@@ns coliplin- the intei-ior of s-,iid bellows to said punip int'et tliroligh first clecti-ically actuated valve means tipon Icttiition of s,,tid v,,ilve meins; coupling means incltidin.sccoiid '.electrically aCtLlited valve niiians liydraulic,,llly couplinl- thb intcrior of said fii -st fltiict i-eservoir to the interior of said second cont,,iinei-; coupliiia ineans inclti Iin,- th.ir(I clecti-ically tctuited vtl@,e iiic,-ins hydritilicilly coi,,plin,, tli(, iiitci-:Ior of secoii(i fliii(i i-esci-voir to s,-iid second contaiiicr; -@ defoi-iiiible pid .iflixe(I to s,,iid fii-st conta'iner IrOL[iid stid cpc-.i ciid tlicreof id,,intcd to @I)i-ovide i fli.iid-tiglit se@il ig.,iinst ciitry of flui(,Is i,li,,@i:ii boi-cliole into sii(i fii-st iii(i sccon@i coqtiinci,,.,,: a liy('ii-,,itilic,-illy ictii@il)le j;.iiii foi- foi@citi, i I p, @id firq cot'itiitici- ,ind sai(I porOLIS I)lc)ck riter ci@-("; liycl -.,illlic i rot- foi-ciii_Q slid sccoii(i cinl@tiner s@i;(l ol-,,-,i c-,id of sl-ii@l First colitl;ner @o iiiit si;(.I.poi-oL!s blocl@ iF, :it 111 tiiiies in conl@ict ,n@id lilior ctkc; anc.] ti-@Ll @oui-tl) clecti-ically lCtL],Iblc v,,tlve. I)IC@IIIS COL]Illillg SIid PLIIIIP inict to said riiii for ippliczttion of a positiv presslire to said rini 1-el,-Itive to bot-cholepreSSLII'C to -,6tLiate said i-aiii when s,,iid foiirth v@ilve nicans i,-, I"f:Liated; s,,iid first, @,%,cond, tli;rcl, tncl fOLli-th v,,il%,c iiie@i)is being individtially act@iable by clecti-ical --onnections to the cirtli's slirfac--. 7. Apparatus for perforatiii.- the Jill-@r cake lining the ivill of a borehole, cojiiptisin-: a i,i,@id-walled ciiis!;on id,-iptefl to isolite ,i poi-tioii of the stirfice of said filter c,,ike; derormible scaliii- iiicqns affix,-(] to said caisson for providin- a illiid-tight se,-il between the edge of s-,iid c,,,iisson and the filter c,,ike i@lain@t whi,-h @,aid cdgc ,ibitts; rii-,,ins hydra6lically connected to ttic interior of said c,.iisson for reducing the pi-essure witliin said caisson I)clow the pi-esslii-c of the foi-iii,,itioii fltiid iii the earth fbriii,,ition I@lj@iceilt siicl poi-tioil of s@ii(i filter c,,i'@,c slirface to procluce llow 6f forniation filiids tliroii-h@siid filter c,,ike into siid c-,iisson suITicient to wasb -,iw-,iy a sectioii of sii(i filter ciike; iiict nic.- ins for ginitilt@incously injecting w-,isliing flijid tlirougli said c,,iissoii a-ainst said poi-tioil of said filter cake sui-face. B. Apparitu's for injecting fluids into eartli forniations tbrough a borehole filter cale wbile said borehole is subject to a pressure of precieterminable m,,igiiitude, comprising: an clon-ated housing niembe'r housing a first flexible - resci@voir for said fluids, ,i second reservoir for receiving c,,irtli forin,,ition flliid, a tfiii-d flexible reservoir eiiclosin-, s-,iid first flexible reservoir ink] a predetcrniined qtiantity of w.,.iter, a 4ilcforniable pad surroiinding i metallie caisson meins adapted to -,ibtit -,igainst a portion o the surfice of sii(I filter cake to isol,,ite said portion and the spice eiiclose(i by s,-iiti c,-iissoti iiie.,ins froiii s.,iid I)ol-c-. liole, .lnd hy(ii-atilic,,illy ;icttj,,ite(i iiie.,ins for riiiiiiiiiniz @.ii(i p,,id agiiiist the wall of slid boreliole to pron'ide 1 fluidtig t sea r sai portion of sa d fi.iter cake surface; suction pump means adapted to produce a pressure less than borehole pi'essure in tiie vicinity of siid hotising nioniber-I nicaiis, including first noriiiilly closed clect@ically actuable valve meins and said second reservoir, coupled to said pump means and io the interior of said
9 c,iisson, adapted upon actuation, of said valve means to lower the pressure witwn said caisson relative to said borehole pressure for the purpose of drawing earth foj-mation fluid through said filter cake; means inclu(iing second, normally closed electrically actuable valve means, hydraulically coupling said first teservoir to the interior of said caisson adapted to inject fluid withiii said first reservoir into said caisson means; means including thi@d electrically actuable, normally closed valve mean ' s, hydraulically coupling said third reservoir to the interior of said caisson adap'ted to inject fluid. witliin. said thir(I reservoir into said caisson; and,means -inc]Liding fotirth normally closed electrically actu.,.ible valve means and pressure revcrsing aDd amplifying means coupling said pump to said hydraulically actuable means adapted, upon acttiation of said valve medns, to apply. a pressure to said hydraulically actuable means that is greater than borehole pressure to actuate said hydratilically actuable means; all of said valve means being selectively actuable from a remote location. 9. Apparatus for determining the nature of fluids in earth formations surrounding a borehole having a filter cake. on the wall tliereof, comprising: a first housing rneans adapted to be lowered into sdid borehole-, an ,innular, deformable pad. having a central opening affixed, t(i said first housing means; hydraulically actuated jacking rheans carried by said Erst housing means, adapted when actuated to ram said pad against said filter cake to form a fluid-tit4t seal between 8aid pad and s@id filter cake; caisson means affixed to said pad adapted to isolate the portion of said filter cake defined by said pad froiii said I-lorchole; tension spriiig riieans iffixed' to said hotising -ind to said pad and said jacking iiieans ad,,ipted to not-- a -,ially constrain said jacking means nd said@pad a@vay fi-om the sides of said borehole; a porolis solid witliin said second housi'ng means positioncd to abut against said portion of said filter cake and stipported by a fluidtight container affixcd to said caisson; s,,iid caisson means -Ind s, tid container defining a generally annul,@r space opening igainst said portion of said filter cake, ttirougli @vhich fluids from said porous solid and formation flllids may flow; a first fluid reservoir carried by said first housing and subject to boreholeprcssure; a second fluid reservoir within said first fluid reservoir; means ineltiding electrically actuated valve means coupling said second fluid reservoir to said container to perniit the fl6w of flllid from s-,iid second fILlid reservoir throu.-h said porotis solid to said central opening; iiieans, including electrically aCtLl,,ible valve nieans, coupling said first fltiid reservoir to sii(i container to, permit the flow of flllid froin said first flliid reservoi@ into said central opening; suction puni@ means supported by s@id first housi ng means and adapted to produce a pressure lower tfian borehole pressure; means, including third electrically actuated Vilve nic,,ins, for coiipling siid ptinip to said generally anniiiat space to lower the pressure at ' said central opening of said pad relative to borehole pressui-c around siid pad;. means, including presstire reversing,and amplifying nicins and fourth electrically actuated valve means, coupling said pump means to said jatking means for actuating said jacking means by subjecting said jackiiig means to pressure greater than borehole pressure upon actuation of said fourth valve means; said hydraulic coupling inearts ftirthe@ including a fluid-tiglit container hydraulically coupled to siid generally anniiiai space and a flui(I-filled bellows fluidly coupled to said suction ptimp means Lipon acttiation -of said thi@@ valve iiican's; iiie-,ins fornicastiring the electrical conductivity of liqui(Is entei-ing said generally an nular spice; and meins for electi-ic,,illy measuring physical changes produced by fluids froiii said second fluid reservoir when said fluids contact earth formations adjacent said portion of said filter cake. 10. Apparatus for injecting forniaiion testing fluids int,o cart@ formations behind @i filter cake lining the wal,l of a borehole, comprising: a housing adapted to be passed 3,209,58b 10 thi@oiigh the boreliole tiid positioijed opposite iii carlh foriii,-ttion uiidcr investigatioii; isolating nieai)s carried by said housinl, and ipcluding -i rigid hol'@Ow portion open.ing towird and havin- ed es adapted to en-,i-e qn eartli forniation utider investig,,ition; means. for selectintely urging said edges of said hollow portion of said isoliting mdans into scaling engagement witli said borehole w@ill so as to isolate the portion of said boreliole wall included witbin said edges; means connected to s,,iid isolating means for 10. selectively loweri.ng the press,ure within said hollow portion rcl4,,itive to boi-ch,ole pi-c-3sLire t@o pi-o(itice ,i diffei-eiitiql prcsstirc ,ici,oss said filtei- c,,ike to cffcct @i flc)w of @oi-niation flLli'CIS into s@iid 'liollow poi-tioti of stiflicicii! iii@i-giiitude to N@ash i"iay aL le.,ist -i pot-tion of the filtei- clke 15 thi@(Yiigh which said earth foi-ni,-ttion flliids flow; aiid means connected to said isolating iiieafis for conti-ollably inj@e-_tin- testing fl I Llids througli siid hollow portion iiito 3aid earth formitioji. 11. A metho'd for the exploration of ni,,itei-i@ils eai-tli 20 formdtions traversed by ,t borehole on the sides of which mudcake has formed, comprising the steps of: isola-ting an area,of the borehq]e wall includiiig @any mudcake adjacent thereto, selectively producing a pressuxe on the isolated area of the borehole wall that is less than the pres25 slire of fluids in the e@irth formations adjacent @aid area to ctuse the fluids present iii the earth formations @,idjaceiit the isolat-cd area to flu.@h the nitidct@-;@ a@.\,,,y fi@oiii said isolated area of the borebole wall iiid ;@nto in are@ removed from said isolited ai-ea, inti-qduc-,ing @ifter re30 moval of said mu(icake an a--.ent cap@ible of' -ifl'@.,ctina., a charactei-istic ol the niatei-i@ils in the cirtli f@)riii@itions into t space conti@Liotis @N,itli exposed pbrti 'iis of s,,iid 0 et@th foriiiations in the isolated o'L the boi-eliole wall - tji,2 f at a presstire at loast eqtiil to the pi-esslii-c o@' luid 35 pi,esent in the eaj-tli foriiiitions, and detectiii., @,tid cbaracteristic of said materials after exposure to saili a@ nt. 12. A method for detecting the presence of oxidizable materials in @arth foi-niations traversed by a borehole on I g the the -sides of wliich niudc,,ike I qs fornied, compris'n 40 steps of: isolating an arca of the borefiole wall including any mud,cake adj;acent thereto; seleetively establishin.- in a space contin@,,iiotis witli said isolated area a pressure substantially less than 4,5 the pressure of fILlids preqent in the earth formations adj-,tcent the isolated area so as to cau,se siid huids tO flLlSh the niudcake out of tnd aw,,iy from s,,iid isolatcd afea of the :bot-ehole wali and iyito ,in area i-emoved from s,,iid isoi;ited irei; sijbsecILictitly 'inti@ociticiiia @if(er reiiiov.11 of, the niii(lcake in oxi(lizing a.-ejit c.-ipable of i-e@icliiig witli oxidizab-le materials in the earth formations into said space at a presstire at least cqtial to the pressiire of tho fluid present in thb carlh foi-mations so as to 55 cause a detectable reaction between said oxidizing igent and ,iny oxidizable iiia'tei-iils prewnt in siid foi-iiiitioil; ,ind -detecting an increise ill tciii;p&i-@iture of a point witliin ttie are-,t of influence of said detect-able i-eaction r ep60 resentative of the occurrcnce of such a react:6n'. :13. A in,ethod for detecting the prcsence of oxid,iz@ble -inaterials in. earth foriiiations traversed by a @borchole on the sides of jwhich mudcake has formed; coniprising the steps of: 65 isolating an arei of the borehole wall including any mudcake adiicent tileteto; selectively ci-eating a presstire witliin a sp,,ice c(@ntiggotis witli siid isolated ,irea of a niagnitticle stifli-'. ciently less thin the pressure of fluids p-resent in the 70 6arth formatiojis adjacent the isolated area to cause said fluids to flu h out and aivay. the mqdcake from said isolate'd area of the bor@hole wall and into an -area removed from said isolated area; niaintaining the flow of fluids from said formation f.or 75 a period of time sufficient to reniove enough mud-
c@ike fi-orn @@,,iid isoliit,,@ct @ire@t to expo,;,2. at least so;tl@,@ 1)oi-tions of said adjacent earth formations to contict with substances iiitroduced into said space; SL]Iisequently.introdLicin.- after removal of the ,-t predetet-i-nined quantity of an oxidizing a.-ent cap,ible of readtin- with oxidizable materials iii tti@ earth formatioiis into said space conti.-uous with the exposed portions of s,,iid c,,irth formations in the isolatell area of the borehole wall at a pi-esstire it leist 10 ,:qtial to the presslire of the filiids present in the eartli form,itions so as to cause a, detectable reictioil between said oxidizin@ a,-ent and any oxidizable materials pre-sent in said formationcletecting an increase in temperature it a point within tli4@ irifltience or ,@iid i-e@iclik)n fi,@ni; and i-esulting flici-epro,,i,.Iing in :n(lication of said tenipeiattire increase Terli-esentative of the presence of oxidizable materi,,ils in the pai-ticul,@ir ca@tli formations under investigation. References Cited by the Exiiiiiner @UNITED STATES IIATENTS 21338 372 1144 Wriglit ---------------- 166--44 2,696,262 12/54 llclwcrs ------------- 166-43 X 2,983,586 5/61 Bl;inch,-ir(i ------------- 23-230 RICHARD@C. QUEISSER, Pi-ii?iary E.,raiiiiiier. ROBERT L. EVANS, JOSEPH P. STRIZAK, Exai?iiiiei-s.
