US 3680645 A
A method and apparatus for drilling holes in ice by melting the ice at the bottom of a drill hole to form a water reservoir and cooling the wall to re-freeze the upper portion of the water reservoir so that a continuous ice shell is maintained around the drill hole.
Description (OCR text may contain errors)
United States Patent Horbach, deceased et al. 51 Aug. 1, 1972  METHOD AND DEVICE FOR DRILLING 2,193,219 3/ 1940 Bowie et al. 175/1 7 HOLES IN ICE 2,684,669 7/1954 Ostrowski ..l75/1l 2,786,652 3/1957 Wells ..l75/213 X  f i x 2,931,187 4/1960 Perkins ..17s 17 x k 3,115,194 12/1963 Adams ..17s 11 g M" 3,152,651 10/1964 Ross ..17s/11 3,390,729 7/1968 Aamot ..l75/l8 X 1 Asslgnw Rite 3,482,640 12/1969 Browning ..11s/17 x  Filed: Oct. 2, 1969 M  Appl. No.: 863,176 Primary Examiner-James A. Leppink Assistant Examiner-Richard E. F avreau 30 Foreign Application Priority um J 5 9? July 19, 1969 Germany ..P 19 36 902.9  ABSTRACT  US. Cl ..l75/16, 175/18 A method and apparatus for drilling holes in ice by  Int. Cl. F251: 5/04 melting the ice at the bottom of a drill hole to form a  Field of Search ..l75/l6, 17, ll, 18, 213 water reservoir and cooling the wall to re-freeze the upper portion of the water reservoir so that a continu-  References Cited ous ice shell is maintained around the drill hole.
AV UNITED STATES PATENTS 13 Claims, 1 Drawing Figure 945,209 l/ 1910 Avery ..l75/ l 7 METHOD AND DEVICE FOR DRHLING HOLES IN ICE The present invention relates to a method and a device for drilling holes in ice. Drilling in ice is of interest for the exploration of the Arctic and Antarctic ice caps as well as for the exploitation of oil fields underlying these ice caps. Practical experiments have shown that the drilling methods known to date do not lead to any satisfactory results. In the case of the Rotary Drilling Method, generally applied today, considerable heat is developed in the area of the drill point,
which melts the ice and leads to uncontrollable hol-- lows. The consequence of this is that the development of the hole is absolutely uncontrollable and that uncontrollable melting occurs, which continues up to the surface of the ice and even jeopardizes the stability of the drilling derrick anchored in the ice. So far no means is known by which these phenomena in Rotary Drilling could be prevented.
in addition to the Rotary Method, only the Percussion Drilling Method is known so far, in which, with the aid of a rope or a string of drill pipe, a sleeve is driven into the ice by repeated percussion. By this method only low drilling rates and comparatively shallow depths can be reached, so that this method is uneconomical and the achievable hole depths, in many cases, are insuflicient. Not lastly because of the great hardness of the ice, it appears impossible that, by this method, better results could be achieved in ice than by the Rotary Method dealt with above.
Accordingly, the basis of the invention is the task of providing an ice drilling method pemii tting the drilling of satisfactory deep holes and which in addition is economical.
According to the present invention, this task is accomplished by melting of ice at the bottom of the hole by heat supply, so that at the bottom of the hole a kind of water reservoir is formed, and by cooling the wall of the hole at a certain distance from the bottom to such a low temperature that part of the previously melted ice is frozen again to form an ice shell constituting the confines of the drill hole and the top of the water reservoir, while redundant melted ice is removed from the hole.
By cooling the wall of the hole above the water reser voir being formed, it is ensured that this water reservoir does not expand uncontrollably, but remains confined to the area surrounding the bottom of the hole, whereby a controlled sinking of the floor, and thus a controlled drilling of the hole is guaranteed. By cooling the wall of the hole and by the freezing of part of the melted ice on the wall it can also be ensured that the hole has a smooth wall and a defined inside diameter. Removal of the redundant melted ice from the hole can be effected by having it displaced by solid particles, as formed by the necessary drilling unit, or else by means of compressed air or flushing liquids.
The method which is the subject of the present invention is economical too, for there is no need for complicated rotary equipment, requiring much power, for a drill bit and the drill rods carrying the bit, nor for complicated suspension means for the rotary drill; furthermore, it is no longer necessary to replace a bit which has become blunt, as is frequently required in the case of the Rotary Method, and which always requires extraction of the whole string of drill rods from the hole. The equipment required for melting practically does not wear out and the penetration rate mainly depends only on heat supply and on the possibility of partly freezing the melted ice, so that comparatively high drilling rates can be achieved. As no strings of rotary drill rods are needed and since there are no tools, frequently to be replaced, at the end of the bottom rod, the drill rods required for the method which is the subject of the present invention may remain in place as a casing of the hole, so that no additional string of casing, narrowing the hole, need be installed either. On the contrary, a hole of any diameter can be drilled, because the rods need not accommodate any torques, which become excessively high with the Rotary Method, when the working diameter of the bit exceeds certain limits. Moreover, for a rotary drilling unit, the drill rods must have a big cross section, in order that it can accommodate such torques, and, therefore, the strings of rods become extremely heavy in the case of great depths, for which reason the hole diameters are limited, too. As no such torques are produced by the method which is the subject of the present invention, the rods may be made with thin walls, so that larger diameters are possible also from the point of view of permissible weight. Nevertheless, when applying the method which is the subject of the present invention, a mainly vertical drilling of holes is achieved, because, during the melting of the ice, there do not occur any radial forces which might deflect the rod from the vertical direction.
The method which is the subject of the present invention may also be used, when rock is included in the ice, because, on account of the melting of the ice, the rock material sinks with the floor of the hole. If required, it is possible to remove by pressure flushing the solid particles collecting in the water reservoir, such as particles from rock included in the ice.
As mentioned above, the present invention also covers a drilling unit for using the method which is the subject of the present invention. This drilling unit, justlike known drilling units, has a hollow drill rod, but an annular melting head which can be heated is mounted at the bottom end of the drill rod. Above this melting head, the drill rod is provided with a cooling device keeping its outside face at a temperature of less than 0 centigrade, and with a heat-insulating material on its inside.
The heated annular melting head mounted to the bottom end of the drill rod of this drilling unit melts the ice at the bottom of the drill rod, so that the water reservoir mentioned above is developed in the area surrounding the melting head. While the drill rod sinks farther down, the melted ice displaced by the drill rod rises within the drill rod and is removed continuously from the top end of the drill rod. The cooling device causes ice to form on the circumference of the drill rod at the upper edge of the water reservoir, thus closing and sinking the top of the water reservoir at a speed corresponding to the sinking of the reservoirs floor due to the melting of the ice. Thus, a hole develops which closely encompasses the drill rod and presents a continuous smooth surface. The weight of the drill rod ensures that the drill rod does not bind in the ice hole, and it would also be possible, if required, to provide the outside of the drill rod with a suitable sliding face, for instance with a coat of polytetrafluor ethylene.
- 3 In a further embodiment of thepresent invention, the
elolss'esitsintherneltinghead.'Iheelectriclinesleading tothese heating elements maybe min a simple mannerthroughcavitiesofthedrill-rod,which,asthe case'ma'y be, may be double-walled. Simple cooling results from arrangement ofcoolingjackets or coiled at the end ofthe drill rod which arefed with a coolant'through linesrun through cavirod, which,asthecasemaybe, maybe I double-walled; I
- lt isconceivable, for' example, to use means operatingon'thebssisofthePeltierefiectandthecoolingelementsofwhicharearrangedinthedrillrodsareatobe cooled, while the elements giving up heat are located in the area'of the melting head. Since,'due to removal of melted ice by pumping, more ice is melted than melted mustbe frozenagain by the cooling means, it is 'necessaryflnspite ofthe coolingofthewall ofthe hole,
- g to supply excess-heat, for which the Joule heat may be used which is produced in the case of a Peltier arrangement, In' any cue, for the control of melting and freezing, feelers may be arranged at the bottom end of the drill rod,.especially for temperature measuring and for measuring the expansion of the water reservoir.
In the case of a highly preferred embodimentof the invention, the heat-insulating material fills the drill rod 3 completely, and two pipes preferably arranged concentrically' onefin the other pass through the insulating material, one'ot' the pipes being used for the introduc- 4 albeingarranged head.Abovethisheat-insulaungring8,inspaee9 betweenthewallsofdrillrodLther'eisacoolingjscket lowhichpreferablyisofannularformationandwhich isdirectlyincontactwiththeinaideofouterwallllof drillrodL'Ihiscoolingjacketisdividedbyapartition l2intotwocompartments l3andl4arrangedconcentrically'oneinthe otherandcomrmmicating otherattheir bottoms. ThecoolingjacketsUO) com-u partment l3borderingontheouterwall 11 ofdrillrod 1 ist'edthroughaline l5 with'a-coolant, whichatter pssing through outer compartment l3 runs through innercompartment 14, which itleavesthroughlinelo. Lines Hand 16, too, areinstalledinthespacebetween thetwowallsofdrillrodlandareconnectedtoarefrigeratingmachine,'notshowninthedrawing,whichmaybe'arrangedonthesurfaceoratasuitablepointot'- thedrillrod.
2o The interior ofdrill rod 1 a filled with heat-insulating matefiall7,andtwopipesl8andl9placedconcentricallyonewithintheotherandextendingapproximately down into meltinghead4arearrangedconcentrically withhollowdrillrodl.
Asshowninthedrawing,theheatsupplytothemeltingheadbymeansofheatingelementficausesawater reservoirlotodevelopatthebottomendofdrillrodl, th'mreservoirsurrotuxiingmeltinghead4andthebottomendofdrillrodlinacertainareakedundant meltediceriseswithinpipes18andl9andmaybe removedfromtheupperendsofthesepipes. ltis also possible, by introducing compressed air for example into outer pipe 19, to press the water through inner I pipe 18 out of hollow drill rod l..The water 5 inreservoirlfliscommunicatingwiththewater containedindrillrodlthrouglhopeninpflprovidedfor.
this purpose in melting head Expansion water I reservoir 20 is prevented by surtion of compressed air or'of a flushing liquid and the 40 roundingdrillrod l-atthe upperedgeofr'eservoirZtlby otherfor; removalof melted ice and/or solid particles originally included in the ice.
\ "Further detailsandarrangements according present invention will be noted from the detailed and-explanations g'ivenhereinafter on the 5 basis'of; an arrangement shownias an example onthe fdrawingvlhefeaturesshownonthedrawingormentioned in may be used individually or'in any-combination with-each other for other.
menu in accordance with'the'present invention. The
drawing schematically shows a longimdinal section of bottom'end ofa drill rod ofa unit in ac- ,cordance with the present invention,the drill rod being in a hole formed in an ice layer. arrangementshown onthedrawingcomprisesa double-walled hollow drillrod 1 into hole 2 intoanicymass3. Atthebottomendofdrillrod 1 there is an annular hollow melting head 4,;the bottom ofwhich ends in a cutting edge 5 through'which it is in v contact with'the bottom of the hole 2. .Cli'is e to the cuttingedges, inside melting head 4, there is trolled refreezing of-melted ,ice and without any mechanicalforce'b'eing--exerted, a hole is which,duetotheabsenceoflateralmechanicalforces, canbedrilledinaverystraightline,andthuswithout 5'0 from a diameterot'whichmaybeselec'tedstwillwithinwide limits, because the factorsinvolved in other cun'ent drillingmethodsandlimitingtheholediameterareinexistentinthis'case'.Solid 'fireservoir 20 may readily beremoved from'thewater reservoirbypressureflushing,whichisusedinasimilar manneras in Rotary Furthermore, if required, drillrod 1 can be'leftas acasing'infthehole after completion of same, althoughthe annuhr ice layer rod 1 forms asmooth casing, which in many -dispensingwithacasinganyway.'lhepo mibilityof makingholesofalargediameter,on'theotherhand,is
5 important for introducing petroleum extraction lines, it
to be extracted is very warm, it may be of advantage to leave the double-walled drill rod in the holes as a casing and to provide it, all over its length, with cooling means which ensure that the wall of the hole remains frozen and thus keeps its stability, while at least one of pipes 18 and 19 embedded in insulating material within the drill rod, can be used as a petroleum extraction line.
It is understood that the present invention is not limited to the arrangement presented as an example, but that variations from same are possible without exceeding the scope of the present invention. Thus it is possible to install the electric lines and the cooling lines as well as pumping pipe 18 inside drill rod 1 and to dispense with the double-wall formation of the drill rod 1. Installation of these lines within the drill rod may possibly be of advantage for mounting couplings. Furthermore, it is possible to provide coiled cooling pipes instead of a cooling jacket, such coiled cooling pipes being attached to the inside of the drill rod or to the outside of same. Such cooling pipes may then extend all over the length of the drill rod, possibly having a pitch increasing with height. It is also conceivable to use burner units instead of electric heating elements. Moreover, there is a possibility, as shown on the right half of the drawing, to use instead of the separate heating and cooling elements or in addition to such, a Peltier arrangement 22, 23 the cooling elements 22 of which are arranged at the bottom end of drill rod 1 and the heating elements 23 of which are in the area of melting head 4. Feelers 24 serve to monitor the temperature in the area of water reservoir 20 and in the melting zone and/or to measure the expansion of the water reservoir and to control the rate of heating and cooling to be provided.
Having thus fully described my invention, what I claim as new and wish to secure by Letters Patent is:
1. Method of drilling a hole in ice comprising melting said ice at the bottom of said hole to form at said bottom of said hole a water reservoir, cooling the wall of said hole at a certain distance from said bottom to such a low temperature that part of the previously melted ice is re-frozen to form an ice shell constituting the confines of said hole and the top of said water reservoir, and removing excess melted ice from said hole.
2. Method in accordance with claim 1, characterized by pressure-flush removal, of solid particles from the water reservoir where they have accumulated.
3. Drilling unit for drilling holes in ice comprising a hollow drill rod, an annular melting head adapted to be heated and positioned at the bottom 'end of said drill rod, a cooling means positioned above said melting head for keeping the outside face of said drill rod at a temperature of less than 0 centigrade, and a heat insulating material positioned on the inside of said hollow drill rod.
4. Drilling unit in accordance with claim 3, characterized by the fact that said melting head has a cutting edge at its bottom end.
5. Drilling unit in accordance with claim 3, characterized by heat insulation being provided between said melting head and said drill rod.
6. Drilling unit in accordance with claim 3, characterized by the fact that electric heating elements are arranged in said melting head and that electric lines leading to these heating elements are run through cavities f od h' d bl o Q ab coe anz evi claim 3, characterized by the fact that, at the bottom end of said drill rod cooling means are provided which are fed with a coolant through lines, which are run through cavities of drill rod which, is doubled-walled.
8. Drilling unit in accordance with claim 3, characterized by the fact that, for heating said melting head i and for cooling drill rod, a Peltier arrangement is used.
9. Drilling unit in accordance with claim 3, characterized by the fact that, at the bottom end of the drill rod, feelers for detecting the presence of melted ice are arranged.
10. Drilling unit in accordance with claim 3, characterized by the fact that the heat-insulating material completely fills said drill rod and that two pipes run through it, one of which is used for introducing a flushing fluid and the other for removing melted ice and/or solid particles of material included in the ice.
11. Drilling unit in accordance with claim 10, characterized by said pipes being arranged concentrically one in the other.
12. A method of forming a hole in ice having a defined boundary comprising:
1. melting said ice in the region in which said hole is desired thereby forming a reservoir of water in the vicinity thereof,
2. re-freezing the upper portion of said reservoir of water to form a hole in said ice having said defined boundary, and
3. removing water from said water reservoir in excess of the amount required to form, upon re-freezing, said defined boundary.
13. An apparatus for forming a hole in ice comprismg:
l. a hollow drill tube,
2. a melting head means, annularly arranged at the lower end of said hollow drill tube, for melting said ice,
3. a cooling means, positioned above said melting head means, for cooling the exterior surface of said drill tube to re-freeze the upper portion of the melted ice so that said hollow drill tube is encased by said ice,
4. an insulating means, located between said melting head means and said cooling means, for limiting the conduction of heat therebetween, and
5. a means, operatively arranged in the lower end of said hollow drill tube, for removing melting ice in excess of the amount required to form, upon refreezing, the encasing ice.