CA1195491A - Core orientation instrument - Google Patents

Abstract

ABSTRACT
"CORE ORIENTATION INSTRUMENT"

An instrument for determining the orientation of [the]
a borehole or core sample utilizing a plumbed compass ball which is held in a gellable liquid within a container passed [down the borehole. The] through a wireline drill spring.
Once the instrument is positioned as desired, the liquid is gelled [thus fixing the position of the compass ball relative to the instrument once it is positioned as desired. The liquid is gelled] by the forced injection of a catalyst normally held in a piston/cylinder reservoir and separated from the liquid by a spring loaded one way valve.
Injection is caused by [hydraulic] pressure applied to a portion of the piston by drill fluid. [The hydraulic]
Application of the pressure is controlled by a sleeve and port valve which is opened by telescopic movement of two cylindrical partially co-extensive coaxial members.

Description

:~~

The present invention relates to borehole survey/core orientation instrumellts ~or use with wireline drilling equipment ~o survey boreholes ~nd ob~ain the orientation of core samples.
The disadvan~ages of known exi.sting e~uipment for these purposes were outlined on page 2 of Australian Patent No. 420553, and its corresponding U.S.A. Patent 3rsla~22 Canadian Patent g01974 and South ~frican Patent 69/0260.
The device disclosed in these paten~s attempted ~o overcome ~hese defieiencies. I~ relied on an injection mechanism ~o ir.ject a catalyst into a gel tube holding a gellable liquid. When the lig~id gelled it secured into place a magnetic compass ball, from which the orien~a~ion of the bore and the core sample c~uld be ob~ained.
Operation of the ins~rument depended on the generation of a fluid impulse or ne~ative pressu~e wave which momentarily destressed drilling fluid circula~ing in ~he drill string and borehole~ The sudden reduc~ion in pressure allowed air entrapped wi.thin the instrument and compressed by the combined pressure of ~he static head and the circulating fluid pumped ~hrough the drill string to expand ~nd thereby activate the injection mechanism. Generation of ~he negative pres~ur2 w~ve was aceomplished by ~apidly collapsing ~he pressure in the drilling fluid pumped through the drill string by opening a fast-ac~ing by-pass valve fitted in the pump delivery circuit.
The prior art device suffered from ~he disadvan~age that in deep bores where the static head pressure was high the entrapped air pocket leng~h was small and a~ter generation of the negative pressure wave ~he expansion of the air pocket was insufficien~ to acti~ate ~he injection mechanism. This deficiency wa~ compounded by the need for-additional seals in ~he in~rument a~ greater depths which in ~urn increased ~he friction on sliding par~s and crea~ed the need for extra force to operate the injector~
one further di&advantage o this pri.or ar~ device is that it can not be used in horizontal or near ~orizontal bores ~s Lhe entrapped air, vital to its operatiorl, could esca~e.
It is an object of the present invention to provide a .3~
bore~lole ~,urvey/core o~ielltaLlon înstrurnent whic3~ ~vercuTrles or subs~:antially ameliorates the abo~re mentioneà
disadvantages. This applies particularly ~o ~he harrlPssirlg of an adequate force to ensure operat;sn of the ins~rurnents at depth.
~ rherefore, acc:ording to one broa~ asp2c~ t-E ~he present invention there ;s provided a borehole surveyJcore orien~ation ins~rument suitable for use with wireline dr;lli~g eguipmen~, ~aid instrument comprisin~ a co~DpGsite cylinder having ~ fir~t member telescoplcally lin};ed ~o a second member, said flrs~ member being biased away flom sa;d ~econd member ~ said second member includlny a ~ransparen~
~ressel co~taining a plumbed ma~netlc compass ball ~ubmerged in a gellable first liguid, a leservoir containinq a catalyst for gelling ~aid first liguid a~d an injection ~nechanism fs: r in jec~ g ~ai~ catalyst in~o said ~res~el V1~ a normally closed communication mearls l~etween s~id reservoi~
and saia vessel, said communication means being su~h ~ha~
compress;ve movement of said first member relati~e ~o ~iaid ~e~ond member allows said injecti.on mecllanlsm ~to be activated causing ~aid communioation means ~o i~pen and ~aid ca~alys~ to en~er said vessel.
One emb~diment of the present irlventlon ~ill n~w be descr;bed with reference to the drawlngs in whic2~
Fig~ 1 is a sect;onal view of an upper p~rt30n o an embodimen~ of th~ ~resent invention;
E'ig. 2 i~ a ~ectional view of a lo~er porti.on o~ ~he apparatus of Fig. 1 and The de~ignation~ ~upper" and Wlower~ refer go ~e posi~ion the components would assume in a ~elt.lcal or near vertical bore All components, ~;th the except;on o~ ~he compass, ar~ made from non-magnetic material As illustrated in Fig~ nd 2~ the ins~rumen~ 1, ~ornprises the tubes 2 and 3 ~hich are ~elescopically llrl,ced together. The upper tube 2 is bia~ed ay~ins~ cornpression r~lative to t~e lower tube ~, by mearls of ~he oompr~ss-L~n sprin~ he sprln(J ~ is located w;t~;n ~he ~ube 3 by means of the rela.iv~ly stationary spring sea~ nd movable seat ~b.
The tube 2 is fitted with a w~sh~r or pump packiny 44 for the pumping of the instrument 1 through ~he wlreline drill string and for increasing the effectiverless o~ the force which can be applied to tube 2 to telescope it relative ~o tube ~ when the instrument 1 engages with the core barrel spearhead 42.
The tube 2 is provided with a spear head 5 for ret.rieval of ~he instrument 1 and core sampling barrel once the downhole orientation p.rocedure has been completed. The combination guide/stops 6 are a~tac~ed to the tube 2 and are adapted to slide within ~he groove 7 in tube 3. The surface 8 at ~he bottom of the groove 7 prevents over compression o th~ telescopically linked barrels 2 and 3.
Extending downwardly from the base 3 of the tube 2, is a cylindrical hollow spigot 10, which engages a sliding valve member 11 within sliding ~alve subassembly llb. The slidinq valve member 11 i5 biased to keep por~ 12 closed by means of the compression spring 13. Seals lla within the sliding valve member 11 prevent fluid ingress to ~he port 12 when the valve member 11 is in its elosed position. The spigot 10 is located over the centre of the valve member 11 by sitting over and around a circular stop 14 which al~o prevents the valve member 11 from disengaging the valve guide rod 15. There is furthef provided in the spigot 10 a series of hole6 16 which allow the pas~age of water or fluid (not illustrated) under pressure.
As illustrat.ed in Fig. 2, ~he port 12 (Fig. 1) in the valve guide rod 15 communicates, by means of passage 17 and outlet 18. with an inner chamber 19 of an injector sub-assemhly 20. Within the chamber 19 i~ an injec~or pin 21 which s ~ealably slidable ~hrough it~ guide bore 21a by mean~ of the s~al 22 and gland nut 23. A~ the ba~e of ~he ~uide bore 21a i~ an injection chamber 24 ~orin~ the gelliny cataly6t 25.
The cataly~t 25 remain~ in the chamber 24 by mean~ of ~he normally closed non return valve 26. The non-re~urn valve 26 i~ bia~ed closed again~ valve ~ea~ 27 by means of spring 28. The injec~ion chamber 24 communicate~ wi~h a tran~paren~ ve~sel or gel tube 29 a gel tube subas~embly 29a via annular spring re~ainer 30.
The transparent gel tube 29 comprises a hemispherical base 31 and is filled with a gellable liquid 32. It i~
sealably mounted on a spigot 43 on the lower end of the injec~or subas~embly 20 and is covered by a wa~ertight gel tube cover 29b. Beneath ~he surface of the liguid 32 is a magnetic compass ball 33 having a meridianal line 34 to indicate direc~ion i.e. magnetic north, and a di~inguished upper hemisphere 35 to indicate the horizontal plane. The compass ball 33 also h~s a weighted pivot 36 which allows the compass ball 33 to ~pin freely in a plumbed position.
The plumbing effect of ~he pivo~ 36 allows the compass ball 33 ~o indicate the horizon~al plane by mean~ of the junction line of the lower hemisphere of the ~ompass ball 33 and the distinguished upper hemisphere 35, due to ~he influence of gravity on the weighted pivot 36. Wh~n ~he gel ~ube 29 i5 fitted to the instrument 1 a longitudinally ~cribed mark (not illus~rated) on the ex~erior of the gel tube ~ is plac~d in regi~er with a Da~um line lnot illus~ra~ed) on the exterior of the injector sub-assembly 20.
The tube 3 is al~o provided with hole~ 39 which allow fluid under preszure to surround the whole instrument The lower portion of the tu~e 3 has a thread end 37 which connect~ wi~h ~he threaded upper end of the injector sub-assembly 20. The lower end 37a of the injector sub-assembly 20 is al~o threaded and connect~ with a tube 38 which allows the connection of the instrument 1 to the core barrel (containing the core ~ample to be orientated) by m~ans of jaws 40 and spearhead 42 on the core barrel. This connection, by m~an~ of toothed portions 41 on both ~he jaws 40 a~d ~pearhead 42, pre~ents rota~ion o~ the core barrel relative to the in~trument 1. Retrieval o~ the core barrel together with the coupled ins~rument 1 i8 achiQved by means of the spear head 5 and a grappling device on a wire line ~not illustrated) which i~ lowered through the drill ~tring.
PREPARING INSTRUMENT FOR OPERATION IN A V~RTICAL OR NEAR
VERTICAL BORE.
The ~liding valve ~ub~a~embly llb. in~ection ~ub-assembly 20, ~nd gel ~u~e ~ub-assembly 29a are removed as a ~ingle unit from the i~trument 1. The g~l tube cover 29b, the gel -tube ~9. and ~he non return valve 26 are detached and a rod in~erted into ~.he injection chamber 2~ to push the injector pin 21 back to the top of its strcke pOSitiOII. The injection chamber 2~ i5 filled with a solution of ammonium persulpha~e or other suitable initiator catalyst ~hrough ~he counterbore in the bot~om of ~he injec~ion sub assembly 20 where the non return valve 26 fits. When the injection chamber 2~ i~ full the non return valve ~6 i~ refitted and ~he out~ide of ~he injection ~ub assembly 20 wiped clean.
The gel tube 29 is partially fille~d with a ~ui~able gellable xolution. One such solution i~ AM~, a chemic~l ~rout which has been marketed by Cyanamid Aust Pty Ltd. It i~ a mixrure of two organic monomers, acrylamide and ~,N7 --methylenebisacrylamide ln propor~ions which produce ~ f gels ~rom dilute aqueous solu~ion~ when properly cata1ysed.
An activator catalyst is needed in addition ~o the initiator cataly~t which is injected from the injec~ion chamber ~9. A
~uitable activator cataly~t is B-dimethylaminopropionitrile whieh is included with ~he ~M9 ~olu~ion in the gel tube 29.
The gel tube 29 is focced o~er a seal on the 8pigo~ 4 at the bottom of the injection ~ub-as~embly 20 and is held in place by the pressure of the seal on ~he in~ide wall of the ~el tube 29. When :Eitting the gel tube 29 the datum line scribed on ~he tube (not illustrated) i~ placed in register with ~he datum line (not illustra~ed) on ~he injection ~ub a~embly 20. The gel tube co~rer 29b is replaced on the injectioll ~ub a~sembly 20 to maintain the posi~ion of the gel tube 29 and 62al it in a waterl:ight compar~.ment . The combined slidirlg valve sub-~s~embly 1~ b~
injection sub-a~sembly 20 and gel ~cube ~ub-as~embly ~9a are mounted in the lower tube 3 and the tube 38 is then connected to the injec~ion ~ub-assem~ly 20.
Before the in~trument 1 can be used wi~h standard wireline drilling equipment, non magnei:ic drill rod~ ~hould be insert.ed behind ~he core barrel to isola~e the rnagne~ic compas6 ~all 33 from the inf luence of the s~eel core barre:l and drill rod~. A non magnetio drill rod section of approxima~ely 6 metres leny~h is normally adequate and the length of the tube 38 is arranged so th~at the compass ball 33 i~ po6ition~d in the approxima~:e centre of ~he ~on magnetic drill rod section. F~rther reguirements are:
(a) the ~pearhead on the core barrel ~hould ~e replaced by the toothed ~pearhead 42 which prevents rotation of the core bar~el relative to the i~strument 1 when the said core barrel and instrument are in engagement.
(b~ the swivel bearings in ~he core barrel, which allow the ccre tube to remain relatively stationary when the core barrel rot~tes during drilliny, ~hould be loc~ed by insertion of a grub sc.rew or similar device through the bearing housing of the core barrel to prevent relative movement bstween the core barrel and ~he core tube.
OPL~A.I-f~5~Ur~ INSTRU~ENT.
When an orientation of a core sample is .requirea, approximately 15cm of core are drilled, the instrument 1 is then fed into the hollow sec~ion of ~he drill string, which include~ a non-magnetic ~ection immediately above ~he core barrel. By means of ~he circulating luid being pumped through ~he drill ~ring ~he ins~rument is forced down until it locks on the core barrel, which con~ains the core sample, by means of spearhead 42 and jaw~ 40. Circulating fluid whicb may be water. water with additives. or air, i~ used in drilling to cool the drill bit and remove cu~ings which could jam the drilling equipment i~ ~he hole.
When the instrument 1 reaches the core barrel the lower tube 3 becomes stationary and the drilling fluid under the high pres~ure produced by it~ pump will. force the upper tubc 2 to move through the tube 3 as it overcomes the oppoing force due tv ~he spring 4. The ~ube 2 moves relative to ~he tube 3, and as the injector ~ub-a~embly 20 is fixed relative to ~he tube 3, the ~pigo~ 10 ~ends ~o moYe the sliding valve member 11 along the valve guide rod 15 again~t the 6pri~g 13. The action uncovers the por~ 12. A8 the drilling fluid under pressure i~ acting upon ~he ex~ernal componen~s of the in~rument~ the ~xpo~ition of ~he port 12 allows fluid under pressure ~o enter the inn~r chamber 19.
Conseguently~ a pres~ure i5 applied to ~he surface o ~he injector pin 21~ thus sealably ~liding ~he pin ~1 through ~he gland nu~ 23 and seal ~. Thl~ cre~es a .- .

pressure on the fluid 25 in t~e injection chamber 2g, which is sufficien~ to overcome ~he spring 28 and open ~he non--re~urn ball Yalve 26D The catalyst 25 thus enters the gel tube 29 and begin$ ~he gelling of the gellable fluid 32. In this way the compass ball 33 is ~e~ in t~e position it has freely assumed relative to the earth's magnetic field p~ior to gela~ion.
After allowance of the few minutes of ~ime reguired for the settin~ of the gel, the instrument 1 and the core barrel coupled in tandem are withdrawn from ~he drill s~ring by means of a grappling device on a wire line which en~ages with the spear head 5. When the in6trument coupled to the core barrel is brought to the surface, ~he da~um line (not illustrated) on the injector sub-assembly 20 projected to the bottom of the drill barrel i~ marked on the piece of core held by the core lifter. This mark is now in alignment with the datum line ~cribed on the gel tube 29 and core orientativn is established by reference to ~he compass ball 33 when the gel tube 29 i~ removed rom the instrumen~ 1.
In circumstance~ where orientation of a continuous run of bore core is required scribing diamonds or knives are fieted to the core barrel to mark all incoming core.
Individual pieces of core can ~hen be rela~ed to ~he las~
piece drilled for which orientation is determined.
As illustrat~d in ~ig. 2, the gel tube 29 is shown as being only about three-quarters full with yellable fluid 32. Thi~ i5 enough ~o submerge the compa~s 33 in a vertical or near vertical position. However if drilling o~her ~han near the vertical is reguired, ~he ~ube 29 will have ~o be filled completely, for if the compass ball 33 were to break ~he surface of the fluid, the surface tension ~ould prevent free rotation of the compass. Injection of ~he catalyst from the injection ch~mber into a compls~ely filled gel ~ube neces~ita~e~ ~he employment of a means of di~placing gellable fluid from the gel tube to accommodate the incoming cataly~t or altsrna~ively a means of increasing the volume of the gel ~ube as the catalyst i~ injected. Displacemen~
of gellable fluid from the gel tubs to accornmodate incoming ca~alys~ fluid can be accomplished by fi~ing a ~mall non-re~urn valve to ~he bot~om of ~he gel ~ube. Pre~ure applied 9~o the catalyst fluid during in3ect:ïQrl and transmi~ted ~hrollgh the gellable fluid in the s~el tube wou~ d cause ~e non return ~alve ~o open and gellabl~ fluid to be~
released in~co the ~el tube s~over cap Alternatively the gel tube can be biased by a ~;pring in ~he cover cap ayainst ~ seal at the ba~e of the spigo~ ~n the injector sub-assembl~ Pressure applied t:o the catalyst fluia and ~n~imitted to the gellable fluid in lthe gel tube would cause the gel tube to lift off it~; sealed ~eat thereby aisplacin~ ~ellable fluid ~rom the gel tube~ A short ext~nsion tube fit:ted to the no:n-return valsre in the i~iection c~amber wollld ensure that the eat~lys~: was înjec~ed at sufficieIIt depth in ~he gel tube ~o aYoid being displaced with the gellabl e fluid The tec~lniqlle used to activate the instr~ment whe~L it is ~ein~ use~ only for ~orehole ~;urvey i~ simi lar ~Lo ~:hat d~scribed îor co.re orienta~ 33 e~cept in ~wo reE;p~cts ~irstl~f the instrume}~t is purnped dow~ ~he drill ~cring witholl~ a g~ppllng device to engage with the ~;pearheed on the ~ore ~arrel. Secondl~ no attentlon need be paid to datum lines. The inclina~io~ and asimuth of ~he ho.le are deri~rea ~irectly from the compass ~all The :oregolng describ~s only some ernbodiments o~ the present invention and modîfica~:ions, obvious ~o ~hose slcilled in t~e art, can be made there~o wi~hou~ depar~ir f rom îhe scope of t~e present inverltion as def ined i n the followin~ cl~ims.

~) s~

SUPPLEMENTARY DISCL.OSURE

Figure 3 is a sec-tiona] view of -the gel tube for use with another embodiment of the presen-t invention.
Increasin~ the volume of the ~el tube as -the catalyst is injec-ted is the preferred me-thod to be usecl with a completely full ~el -tube. As shown in Fi~. 3, this involves replacing the ~el tube 29 wi-th a gel -tube 45 open a-t both ends and fitted wit~ a pis-ton 46 which under light pressure can sealably slide within -the -tube.
lYhen pressure is applied -to -the injector pin 21 and transmitted through the catalys-t fluid 25 to the gellable fluid 32 in -the gel tube 45 and -thence to -the piston, the pis-ton 46 moves increasing the volume of the gel tube 45 and permitting the injection of the catalyst fluid 25 into the gel -tube.

Claims (10)

1. A borehole survey/core orientation instrument for use with wireline drilling equipment comprising a composite cylinder having a first member telescopically linked to a second members said first member being biased away from said second member, said second member including a transparent vessel containing a plumbed magnetic compass ball submerged in a gellable first liquid, a reservoir containing a catalyst for gelling said first liquid and an injection mechanism for injecting said catalyst into said vessel via a normally closed communication means between said reservoir and said vessel, said communication means being such that compressive movement of said first member relative to said second member allows said injection mechanism to be activated causing said communication means to open and said catalyst to enter said vessel.

2. An instrument as defined in claim 1 wherein said first and second members are co-axial and partially overlapping in a telescopic manner.

3. An instrument as defined in claim 1 wherein said normally closed communication means comprises a ball resiliently biased towards a seat and co-operative therewith to form a one way valve.

4. An instrument as defined in claim 1 wherein a movement of said first member toward said second member opens a port allowing pressurized fluid to activate said injection mechanism, whereby said injection mechanism pressurizes said catalyst causing it to open and flow through said normally closed communication means into said vessel.

5. An instrument as defined in claim 4 including connecting means adapted to attach and rigidly hold said instrument to a core sampling device.

6. An instrument as defined in claim 1 wherein said vessel comprises a transparent bulk having a first datum line for alignment with a second datum line on said second member.

7. An instrument as defined in claim 6 wherein said compass ball is marked to identify its magnetic north and horizontal compass axes.

8. An instrument as claimed in claim 1 wherein said vessel comprises a non-return valve openable under a predetermined pressure to allow egress of said gellable fluid when injection of said catalyst into said vessel causes the pressure in said vessel to exceed said predetermined pressure.

9. A borehole survey/core orientation instrument for use with wireline drilling equipment comprising: a composite cylinder having first and second generally cylindrical members being co-axial, partially co-extensive, fitted for limited relative telescopic movement and including resilient bias means urging said two members apart; a plumbed magne-tic compass ball submerged in a gellable liquid within a transparent vessel attached to said second member, said vessel including a datum line for alignment with a corresponding mark on said second member and said compass ball having marks to identify the magnetic north direction and the horizontal axis of the compass;
a normally closed port openable upon telescopic move-ment of at least a minimum distance of said first member relative to said second member to allow pressu-rized fluid to enter a normally closed separate chamber within said second member; and a reservoir within a piston/cylinder arrangement containing a catalyst for gelling said gellable liquid, said piston being actu-able by fluid pressure in said separate chamber to in-ject said catalyst through a normally closed one way valve into said vessel causing said gellable liquid to gel.

CLAIMS SUPPORT BY SUPPLEMENTARY DISCLOSURE

10. An instrument as claimed in claim 1 wherein said vessel comprises a displaceable piston member for accommodating injection of said catalyst in said vessel when substantially filled with said gellable liquid.