Drill rig and methods for directional drilling

Abstract

A device for measuring inclination is suspended to a cable passing through a duct formed in the rods of the drill string. A mechanism for winding and unwinding the cable allows to raise and drop the measuring device within the lowermost rod, engaging it with or disengaging from a mule shoe. This is performed without the need to unscrew the rods and open the string. A valve element may close the duct through which the cable passes. In one embodiment, directional drilling is performed supplying low pressure fluid through tubular rods having a single duct. In another embodiment, high pressure fluids are supplied through rods having two or more coaxial ducts.

What is claimed is: 
     
         1 . A drill rig for directional drilling, comprising:
 a self-propelled vehicle ( 10 );   a drilling mast ( 11 ) carried by the self-propelled vehicle;   a top-drive rotary head ( 12 ), translatable along an axis (x) parallel to the mast ( 11 ), the head having a rotatable part ( 12   c ) rotationally drivable around said axis and defining a through cavity ( 13 ), and a rotationally stationary part ( 12   a );   a string of threadedly coupled tubular rods ( 14 ) having respective axially extended communicating cavities ( 15 ) and defining altogether at least one duct adapted to convey at least one fluid to at least one bore ( 18 ) obtained in a bottom element of the string, wherein the string comprises at least one upper tubular rod ( 14   a ) lockable in the through cavity ( 13 ) of the rotatable part ( 12   c ) of the rotary head;   at least one fluid supplying device ( 23 ,  123 ,  124 ) idly mounted for rotation on a rod ( 14   b ) located below the rotary head, for supplying at least one fluid through the duct ( 15 );   a boring tool ( 16 ) mounted at the bottom of the string ( 14 ) of rods;   a device ( 40 ) for measuring inclination suspended by a cable ( 22 ) passing through the duct ( 15 ) formed by the rods;   a winding and unwinding mechanism ( 31 ) for moving the cable ( 22 );   a mule shoe assembly ( 17 ,  28 ), comprising a guiding surface ( 28 ) integral to the device ( 40 ) and a key member ( 17 ) within a bottom rod ( 14   c ) of the string, adapted to engage the guiding surface ( 28 ) and guide the device in a desired orientation with respect to the bottom rod ( 14   c );   at least one valve member ( 30 ), associated with the duct ( 15 ), and mounted on the string above said at least one fluid supplying head and above the top-drive rotary head, the valve member being capable of reaching a closure position closing the duct and an open position opening the duct.   
     
     
         2 . The drill rig of  claim 1 , wherein the valve member ( 30 ) is an annular valve idly mounted for rotation about the axis (x) above an upper end of a top rod ( 14   a ) of the string. 
     
     
         3 . The drill rig of  claim 2 , wherein the annular valve ( 30 ) is mounted on the upper end of the top rod ( 14   a ) through the interposition of a swivel connector ( 19 ), the swivel connector having
 an inner tubular element ( 19   b ) having a through axially extending cavity ( 20 ) which is communicating and aligned axially and rotationally integral with the inner cavity of the upper rod ( 14   a );   an outer tubular element ( 19   a ) which is mounted rotationally idle to the inner tubular element ( 19   b ) and is integral with the annular valve ( 30 ).   
     
     
         4 . The drill rig of  claim 3 , further comprising an anti-rotation element ( 21 ) which engages a rotationally stationary part ( 12   a ) of the rotary head ( 12 ) and the outer tubular element ( 19   b ) of the swivel connector to maintain the outer tubular element ( 19   b ) rotationally stationary. 
     
     
         5 . The drill rig of  claim 2 , wherein the annular valve ( 30 ) is a pneumatically operated pinch valve. 
     
     
         6 . The drill rig of  claim 1 , wherein the rods of the string have a single central duct ( 15 ) and wherein the apparatus comprises a single fluid supplying device ( 23 ), mounted below the rotary head, for supplying a fluid through the single duct ( 15 ). 
     
     
         7 . The drill rig of  claim 1 , wherein:
 the upper tubular rod ( 14   a ) which is lockable to the rotatable part ( 12   c ) of the rotary head has a single, axially extending through cavity;   the string comprises a plurality of tubular dual-passage rods ( 14   b ,  14   c ), wherein each dual-passage rod comprises two coaxial tubes which have   a central, axially extending cavity communicating with the through cavity of the upper tubular rod ( 14   a ) so as to define altogether a first central duct ( 15 ) capable of conveying a fluid to at least one bore ( 18 ) obtained in a bottom element of the string;   an axially extending annular cavity communicating with the annular cavities of the other dual-passage rods so as to define altogether a second peripheral duct ( 151 ) adapted to convey a fluid to at least one bore ( 18   a ) obtained in a bottom element of the string;   two fluid supplying devices idly mounted for rotation on one or two dual-passage rods mounted below the rotary head:
 a first fluid supplying device ( 123 ) for supplying a fluid through the peripheral duct ( 151 ), and 
 a second fluid supplying device ( 124 ) for supplying a fluid through the central duct ( 15 ); 
   
       and wherein the valve member ( 30   a ) is associated with the central duct ( 15 ) and is mounted above the second fluid supplying device ( 124 ). 
     
     
         8 . A method of performing directional drilling, comprising the steps of:
 performing a directional drilling in a soil by means of the drill rig of  claim 1 , supplying a drilling fluid in the duct ( 15 ) through the fluid supplying device ( 23 );   interrupting the supply of drilling fluid and stopping the motion of the rotary head and the string of rods;   bringing the at least one valve member ( 30 ,  30   a ) into open position;   without unscrewing the rods to open the string, lowering the inclination measuring device ( 40 ) into the duct ( 15 ), bringing the mule shoe assembly ( 17 ,  28 ) to an engaged condition so as to orient the inclination measuring device ( 40 ) in a desired orientation with respect to the bottom rod ( 14   c ) of the string;   measuring the inclination of the bottom rod by means of the device ( 40 );   lifting the device ( 40 ) by means of the cable ( 22 ) so as to disengage the mule shoe assembly and rotationally release the device ( 40 ) from the string;   optionally, performing maneuvers to correct the inclination of the string;   bringing the at least one valve member ( 30 ,  30   a ) into the closed position;   resuming drilling and supplying drilling fluid through the duct ( 15 ).   
     
     
         9 . The method of  claim 8 , wherein the step of bringing the valve member ( 30 ,  30   a ) into the closed position is preceded by the step of completely removing the measuring device ( 40 ) from the string of rods, pulling the device ( 40 ) upward by rewinding the cable ( 22 ), without unscrewing the rods of the string. 
     
     
         10 . The method of  claim 8 , wherein
 the step of bringing the valve member ( 30 ) into the closed position is performed by hermetically closing the valve member ( 30 ) around the cable ( 22 ), and   the subsequent step of resuming the drilling is performed keeping the measuring device ( 40 ) suspended to the cable ( 22 ) inside the duct ( 15 ), simultaneously keeping the valve member element ( 30 ) rotationally stationary.   
     
     
         11 . A method of performing directional drilling, comprising the steps of:
 performing a directional drilling in a soil by means of the drill rig according to  claim 7 , supplying a drilling fluid in the second peripheral duct ( 151 ) through the second fluid supplying device ( 124 );   interrupting the supply of drilling fluid and stopping the movements of the rotary head and the rod string;   bringing the valve member ( 30   a ) into the open position;   without unscrewing the rods to open the string, lowering the inclination measuring tool ( 40 ) into the first central duct ( 15 ), bringing the mule shoe assembly to an engaged condition so as to orient the measuring device in a desired orientation with respect to the bottom rod ( 14   c ) of the string;   measuring the inclination of the bottom rod by means of the device ( 40 );   lifting the device ( 40 ) via the cable ( 22 ) so as to disengage the mule shoe assembly and rotationally release the device from the string;   optionally, performing maneuvers to correct the inclination of the string;   resuming the drilling and the supply of drilling fluid in the second duct ( 151 ) through the second fluid supplying device ( 124 );   upon completion of the drilling, completely removing the device ( 40 ) from the rod string, pulling the device upward by rewinding the cable ( 22 ), without unscrewing the rods of the string;   bringing the valve member ( 30   a ) into the closed position so as to close the first central duct ( 15 );   lifting the string of rods while supplying a consolidating fluid in the first central duct ( 15 ) through the first fluid supplying device ( 123 ).