A METHOD FOR REMOVAL OF WATER FROM DRILL HOLES DURING DEEP DRILLING AND A DEVICE FOR PERFORMING THE METHOD

Abstract: A method for removal of water from drill holes during deep drilling, with use of drilling air conveyed via the tubular drill stem, whereby the drill stem (3) is provided with a number of mutually spaced apart blowing valves (5), which are arranged automatically to open and close said valves in relation to the ratio between the pressure of the drilling air in the drill stem (3) and external forces acting upon a valve body (13) forming part of said blowing valve, whereby said valves (5) are arranged directly in the material of the drill stem (3) or in the material of a separate tube section (6) concentric with the drill stem and having the same outer diameter as the drill stem resp., and which valves are arranged successively in a direction from above and downwards at their positions in the drill stem to emit jets of said drilling air to the space between the drill stem (3) and the wall of the hole for causing the water to be blown up layer by layer from the top and downwards. The valve incorporates a valve body (13), which is axially movable in a through bore (8) in the material (6) of the drill stem between an outer and an inner valve seat (11 and 12 resp.), each such valve being adapted during influence of the drilling air pressure at one hand and the water pressure outside the drill stem on the other hand, to be moved axially in a guide (16) in order automatically to be moved between a position closing the valve against the inner seat (12), an intermediary position opening the valve and a position closing the valve against the outer seat (11) due to the pressure difference between air pressure and liquid pressure.

Description: A METHOD FOR REMOVAL OF WATER FROM DRILL HOLES DURING DEEP DRILLING AND A DEVICE FOR PERFORMING THE METHOD Background of the invention The invention refers to a method and a device for removal of water from drill holes during deep drilling, with use of drilling air conveyed via the tubular drill stem, whereby the drill stem is provided with a plurality of mutually spaced apart blowing valves, which are arranged automatically to open and close in relation to the ratio between the pressure of the drilling air in the drill stem and external forces acting upon a valve body forming part of said blowing valve. During drilling through water-bearing formations it is probable that water will penetrate into the drill hole, especially at drilling of deep bui'ά'ϊ. During the very drilling operation the drilling air is sufficient to cause the penetrating water to be blown up from the drill hole. At interruptions in the drilling it may however occur that the drill hole is completely filled with water. In order to recommence the drilling it is t h en necessary to remove the water from the hole. For being a b le to use the drilling air con entionally as a lifting me d ium it is necessary to have a drilling air pressure with the capacity of lifting the entire water column in the drill hole, an d this is possible with use of ordinary compressor equipment an d t h e like for drill depths of about 200 meters only. The air pressure that can be obtained with stan d ard compressors is insufficient for lifting the water column at bigger hole depths. The practical solution which has earlier been used in t h is case is that the down-the-hole drill is hoisted to a level at which the weight of the water column thereabove is so low t h at the drilling air can lift it. The down-the-hole d rill is thereupon again lowered to another appropriate level until the OMPI ~ entire water column in the drill hole has been blown up. This is an operable method, but it is of course very timewasting and it requires much work. In order to provide a more simple solution of this problem it has earlier been suggested to use drill tubes equipped with two supply conduits for drilling air, one of said conduits thereby continuously being connected to the pressure air source. Each conduit is provided with its own outlet nozzle, one of which is arranged at the lower end of the drill stem and the other being arranged at a distance above said lower end. When the drill reaches such a depth that the drilling air has no capacity of lifting the liquid the drilling air connection is manually switched over from the nozzle at the bottom end to that located at a higher level. The drilling air hereb -will have a smaller column of water to act upon and is therefore able to lift it . The lower nozzle can thereupon again correspondingly be switched to the drilling air. In this manner it is possible to increase the possible work depth, but only to a limited extent, and the method is at the same time prolix and complicated. From DE-AS 1190415 it is further known to arrange an external drilling air conduit in a drill stem having a length of not more than 200 meters, whereby the conduit is equipped with a number of spaced apart blowing nozzles opening into the interior of the drill stem and each one incorporating a housing with a differential plunger and a second plunger movable therein and by means of which the drilling air conduit via a complex system of channels can be connected to anyone of said blowing nozzles in relation to the ratio between the drilling air pressure and the pressure exerted by the column of water. Due to the complicated design of the blowing nozzles, this device will become rather expensive and there is furthermore big risks that the nozzles can be struck by malfunction. This equipment is furthermore not useful for bigger depths than about 200 meters when using drilling air of normal air pressure. _ Purpose and most essential features of the invention The purpose of the invention is to provide a method and a device for removal of water from a drill hole during deep drilling with use of the drilling air in the drill stem and which method provides an efficient and yet simple solution of the problem, whereby it is possible without extra work directly to lift up the water which has gathered in the drill hole during intervals in the drilling work and without the necessity of lifting the down-the-hole drill and without need of using unnormally heavy compressor equipment and the method for achieving this is characterized by the features defined in the annexed claim 1. The device for performing the method is characterized by the features defined in the annexed claim 2. Description of the drawing The invention will hereinafter be further described with reference to an embodiment shown in the accompanying drawing. Figure 1 shows scematically drilling with a device according to the invention , Figure 2 is a detail view of a portion of the drill stem shown in Figure 1 , as seen in section, and Figure 3 shows a valve forming part of the device according to the invention . Description of the embodiment In figure 1 is schematically shown a drilling rig 1 having a derrick 2 and a drill stem 3 carried thereby, and which latter is feed with drilling air from a compressor 4 located on the ground and being of conventional type and normal performance. The drill stem extends to a very big depth and the depth of the hole can be 2000 meters or more. This has been illustrated in the figure by the drill stem being shown broken— The long drill stem is provided with a plurality of blowing " va preferably spaced apart at equal distances, which valves can be arranged e.g. at each fiftieth meter along the drill stem. In figure 2 is shown in cross section a portion of the drill stem in the region of a valve 5, and from this view it can be seen that the valve consists of an intermediary tube section S in the drill stem, having an internally thicker central wall portion 7 formed as a restriction, in which is made a drilled through hole 8 with a seat 9 for a valve body shown in figure 3. The hole 8 is preferably drilled under an angle to the longitudinal direction of the drill stem, on one hand for making better use of the wall thickness of the tube section and on the other hand as it is appropriate that the orifice of the blowing nozzle is directed obliquely upwards, i.e. mainly in the direction it is desired to lift a water column present outside the drill stem. Figure 3 shows in a cross-section and in bigger scale a portion of the valve 5 adjacent the through hole 8. From the figure it can be seen how the outer part of the through hole is threaded and that a seat body 10 is screwed into the hole, which seat body is provided with a bevelled seat edge 11 , which is concentric with and facing a correspondingly bevelled seat edge 12 on the seat surface 9 in the wall portion 7 of the drill stem. These two bevelled seat edges 11 ,12 are spaced apart and in the space between them there is disposed a valve body 13 having bevelled surfaces 14,15 corresponding to the seat edges 11 , 12. The valve body has a smaller axial length than the distance between the seat edges 11 , 12 and it is movable in axial direction in this space, whereby it can reach closing engagement either with the seat edge 11 or 12. The valve body 13 is by aid of a spring 1S biased against a position where the surface 15 is in contact with the seat edge 12, and this spring, which rests with its end turned away from the valve body against a shoulder on the seat body 10, will at the same time act as a guide for the valve body. The function of the device according to the invention is the following. - _ At interruption of the supply of drilling air during drilling to big depths, the drill hole will soon be filled with water, if the drilling is made in water-bearing formations. The pressure of the water column upon the bottom of the hole will amount to the depth of the hole/10 and it is termed in kg/m . At a hole depth of 2000 meters the theoretical water column 2 pressure would then be 200 kg/m , which is about 10 times the pressure delivered by a standard compressor, and it would hereby not be possible to empty the hole by blowing without using the slow method described in the introduction. By the fact that the drill stem 3 is provided with a number of simple but automatically operating blowing valves 5 located at rather short distances from each other, it is possible to achieve that the water column is lifted in steps beginning at the upper part thereof, with use of the device according to the invention. By arranging such valves 5 with interspaces of e.g. 50 meters it is theoretically possible to use a pressure of 5 kg/m only, which is well inside the normal capacity of ordinary compressors. When the drill stem 3 after interruption of the drilling (or of the drilling air supply only) is again subjected to the air pressure, and the drill hole is full of water, the upper valve 5 e.g. at a depth of 50 meters w ll open and a water column of 50 meters will be blown up. When the water has been blown .up the u.pper valve is closed and the second valve at a depth of 100 meters is opened, whereby another 50 meters of water column is blown up. In this manner all valves 5 are in turn activated to blow up 50 meters of water column until the entire hole is emptied. The following requirements regarding the valves must be f.. I filled if the device shall operate in the intended manner: When the drill stem is under no pressure, during inter;.)'.. in the drilling, the valves must all be closed to ascertain that water can not enter into the drill stem from the outside. BU REA OMPI ,> W1PO - The valve must open when the air pressure in the drill stem increases above the external water pressure. The valve must again close when the water column located above the valve, has been blown up. These requirements are fulfilled thereby that the valve body 13, partly due to the spring 16 and partly due to the external water pressure, is urged in such a direction that the valve 0 surface 15 seals off against the seat edge 12 when the air pressure in the drill stem is lower than the sum of spring pressure and water pressure; the valve operates as a non-return val e. When the air pressure increases in the drill stem and becomes equal to or exceeds water pressure + spring pressure the valve body T3 , against the action of spring pressure and water pressure, will be moved axially from its position described above, whereby the spring 16 will guide the valve body and 0: balance it in an intermediate position, whereby drilling air will flow out through the valve and cause the water column laying thereabove between the drill stem and the drill hole wall to be blown up. 5 When the water column thus has been blown up, the resistance to the air flow will be markedly reduced and the velocity of air through the valve will increase heavily. The valve hereby acts as a so called tube rupture valve, whereby the valve body 13 by means of the increased air flow is urged in axial U direction and will come to sealingly contact between the valve surface 14 and the seat edge 11. When this state has been reached for one valve the valve situated immediately therebelow will operate in the same 5 manner until all valves have performed there opening and closing functions and the drill hole is completely emptied of water. Ouring drilling with continuous supply of drilling air the drilling air will thereupon, via the opening situated at the drill bit, bring about a continuous lifting movement of penetrating water. The invention is not limited to the embodiment of the invention shown in the drawing and described in connection thereto but modifications are possible within the scope of the following claims. OMP

Claims: C L A I M S 1. A method for removal of water rom drill holes during deep drilling, with use of drilling air conveyed via the tubular drill stem, whereby the drill stem (3) is provided with a plurality of mutually spaced apart blowing valves (5) , which are arranged automatically to open and close said valves in relation to the ratio between the pressure of the drilling air in the drill stem (3) and external forces acting upon a valve body (13) forming part of said blowing valve, c h a r a c t e r i z e d t h e r e y, that said valves (5) are arranged directly in the material of the drill stem (3) or in the material of a separate tube section (6) concentric with the drill stem and having the same outer diameter as the drill stem resp. , and which valves are arrange'd successively in a direction from above and downwards at their positions in the drill stem to emit jets of said drilling air to the space between the drill stem (3) and the wall of the hole for causing the water to be blown up layer by layer from the top and downwards. 2. A device for removal of water from drill holes during deep drilling, with use of drilling air conveyed via the tubular drill stem, whereby the drill stem (3) has a number of mutually spaced apart blowing valves (5) arranged along it and intended for performing the method according to claim 1 , c h a r a c t e r i z e d t h e r e b y, that each one of said valves incorporates a valve body (13) , which is axially movable in a through bore (8) in the material ( 6) of the drill stem between an outer and an inner valve seat ( 11 and 12 resp.) , each such valve being adapted during influence o the drilling air pressure at one hand and the water pressure outside the drill stem on the other hand, to be moved axially in a guide (16) in order automatically to be moved between a position closing the valve against the inner seat (12) , an intermediary position opening the valve and a position closing the valve against the outer seat (11 ) due to the pressure difference between air pressure and liquid pressure. ■3. A device according to claim 2, c h a r a c t e r i z e d t h e r e b y, that the guide for the valve body (13) is formed by a spring (16) adapted simultaneously to bias the the valve body (13) against a position in which it engages one of the seats (12) . 4. A device according to claim 2 or 3 , c h a r a c t e r i z e d t h e r e b y, that each valve (5) is arranged in a internally thickend portion (7) of the material (6) of the drill stem formed as a restriction . 5. A device according to anyone of claims 2 - 4, c h a r a c t e r i z e d t h e r e b y, that the through bore (8) of the valve is arranged under an angle to the longitudinal direction of the drill stem (3).

Inventors: STRINDBERG CONNY, STRINDBERG, CONNY
Applicants: TUNG GEOTEKNISK BORRNING, TUNG GEOTEKNISK BORRNING C. STRINDBERG
Application year: 1984
Main classification: E21B21
IPC codes: E21B21, E21B43