Downhole pulsing shock-reach extender system

Abstract

A downhole pulsing-shock reach extender apparatus for overcoming static friction resistance in coiled-tubing drilling-fluid-pressure driven downhole operations, generating pulsed hydraulic shocks at the workstring by creating a fluid-hammer condition by repeated sudden opening and closing of a set-pressure snap-acting valve, using an essentially constant or slowly changing normal drilling-fluid pressure that will not damage other components of the workstring, thereby extending the depth limit of downhole operations. A poppet and calibrated spring act as a set-pressure snap-acting valve, and a tapering constriction and constricted throat in the main flow of drilling fluid or mud builds up higher pressure to open the valve, while bypass portways allow for limited flow and equilibration around the valve. The rapid equilibration of pressure upon the opening of the valve, combined with the force of the calibrated spring, allows a rapid closing of the valve, which sets up a fluid-hammer hydraulic shock, in a repeating cycle.

I claim: 
     
         1 . A downhole pulsing-shock reach extender apparatus for overcoming static friction resistance in coiled-tubing drilling-fluid-pressure driven downhole operations, the downhole pulsing-shock reach extender comprising:
 (i) a tube body adapted to being mounted in a coiled-tubing work string, having, in use, a wellhead end and a well-bottom end;   (ii) an inflow chamber at the wellhead end of said tube body, having a diameter essentially matching the inner diameter of the coiled tubing;   (iii) a tapering constriction at the well-bottom end of said inflow chamber;   (iv) a constricted throat at the well-bottom end of said tapering constriction;   (v) a poppet chamber at the well-bottom end of said constricted throat;   (vi) a poppet movably mounted inside said poppet chamber, adapted to prevent flow from said constricted throat in a closed position and to allow flow in an open position;   (viii) a calibrated spring mounted inside said poppet chamber, adapted to exert a closing force against said poppet sufficient to prevent opening when pressure difference between said constricted throat and said poppet chamber is small, and to allow opening when pressure difference is large;   (ix) at least one bypass portway adapted to allow constant but constricted flow and pressure equilibration between said inflow chamber and said poppet chamber; and   (x) an outflow chamber at the well-bottom end of said poppet chamber, adapted to convey pressurized drilling fluid to the other components of the workstring;   where said poppet and said calibrated spring function as a set-pressure snap-acting valve;   where, in use, higher fluid pressure in said tapering constriction and constricted throat act upon said poppet until sufficient pressure to overcome said calibrated spring is reached, opening and allowing fluid to flow from said constricted throat, which, in turn, allows an increase of flow and pressure into said poppet chamber, equilibrating the pressure difference between said inflow chamber and poppet chamber, which, in turn, allows said calibrated spring to move said poppet back into position sealing said constricted throat, in a continuing cycle; and   where, in use, the continuing cycle of opening and closing the set-pressure snap-acting valve formed by said poppet and said calibrated spring sets up a fluid-hammer series of pulsing shocks which assist in overcoming the static friction forces acting to resist further entry of the drill string into the hole.   
     
     
         2 . The downhole pulsing-shock reach extender of  claim 1 , where said tube body is made of steel. 
     
     
         3 . The downhole pulsing-shock reach extender of  claim 1 , where said tube body has an outer diameter of 2.875 inches. 
     
     
         4 . The downhole pulsing-shock reach extender of  claim 1 , where said tapering constriction has a taper of from 10 to 15 degrees, inclusive. 
     
     
         5 . The downhole pulsing-shock reach extender of  claim 1 , where said constricted throat has a diameter not greater than half the diameter of said inflow chamber. 
     
     
         6 . The downhole pulsing-shock reach extender of  claim 1 , where said constricted throat has a length greater than its diameter. 
     
     
         7 . The downhole pulsing-shock reach extender of  claim 1 , where said poppet has a diameter double the diameter of said constricted throat. 
     
     
         8 . The downhole pulsing-shock reach extender of  claim 1 , where said poppet and said calibrated spring are made of brass. 
     
     
         9 . The downhole pulsing-shock reach extender of  claim 1 , where said bypass portways are arranged as openings around the diameter of said inflow chamber at the start of said tapering constriction. 
     
     
         10 . The downhole pulsing-shock reach extender of  claim 1 , where said outflow chamber has a diameter smaller than the diameter of said inflow chamber. 
     
     
         11 . The downhole pulsing-shock reach extender of  claim 1 , where said outflow chamber has a diameter not greater than 75% of the diameter of said inflow chamber. 
     
     
         12 . The downhole pulsing-shock reach extender of  claim 1 , where said outflow chamber has a diameter substantially equal to the diameter of said inflow chamber. 
     
     
         13 . The downhole pulsing-shock reach extender of  claim 1 , where said bypass portways accommodate from 10% to 33%, inclusive, of the flow in said inflow chamber. 
     
     
         14 . The downhole pulsing-shock reach extender of  claim 1 , where said bypass portways accommodate not greater than half of the flow in said inflow chamber. 
     
     
         15 . The downhole pulsing-shock reach extender of  claim 1 , where said tapering constriction has a length substantially twice the diameter of said inflow chamber.