Impact excavation system and method with suspension flow control

Abstract

A system and method for excavating a subterranean formation, according to which a suspension of liquid and a plurality of impactors are passed between a drill string to a body member for discharge from the body member to remove at least a portion of the formation. The flow of the suspension between the drill string and the body member is controlled in order to present the impactors from settling near the bottom of the formation.

1 . A system for excavating a subterranean formation within a wellbore that traverses the subterranean formation, the system comprising: a drill string for receiving a suspension of impactors and fluid; a body member for discharging the suspension in the formation to remove a portion of the formation; and one or more filters in the drill string for controlling the flow of the suspension between the drill string and the body member. 
     
     
         2 . The system of  claim 1 , wherein the impactors normally flow from a bore formed in the drill string to a bore formed in the body member; and wherein the filters prevent the flow of the impactors from the drill string to the bore in the body member. 
     
     
         3 . The system of  claim 1 , wherein the filters comprise a valve assembly that moves between an open position in which it permits the flow of the impactors from the drill string to the body member and a closed position in which the filters prevents the flow. 
     
     
         4 . The system of  claim 3 , wherein the valve assembly comprises two tubular members adapted for relative movement with respect to each other, and at least one valve member for moving between the open and closed positions in response to the relative movement. 
     
     
         5 . The system of  claim 3 , wherein the valve assembly comprises a plurality of flexible filtering elements that are parallel to one another in the open position. 
     
     
         6 . The system of  claim 3 , wherein the valve assembly comprises a plurality of flexible filtering elements that are twisted about one another in the closed position. 
     
     
         7 . The system of  claim 1 , further comprising one or more filters positioned outside of the drill string for controlling the flow of the suspension through an annulus defined between the drill string and the wellbore. 
     
     
         8 . The system of  claim 7 , wherein the impactors normally flow through the annulus between the drill string and the well bore; and wherein the filters prevent the flow of the impactors through the annulus. 
     
     
         9 . The system of  claim 1 , wherein at least one of the filters comprise a resilient whisker extending from an interior surface of the drill string. 
     
     
         10 . The system of  claim 1 , wherein at least some of the filters comprise a resilient disc extending from an interior surface of the drill string. 
     
     
         11 . The system of  claim 7 , wherein at least one of the filters comprise a resilient whisker extending from an exterior surface of the drill string. 
     
     
         12 . The system of  claim 7 , wherein at least some of the filters comprise a resilient disc extending from an exterior surface of the drill string. 
     
     
         13 . A method for excavating a subterranean formation within a wellbore that traverses the subterranean formation, the method comprising: introducing a suspension of impactors and fluid into a drill string; discharging the suspension from a body member into the formation to remove a portion of the formation; and filtering the flow of suspension between the drill string and the body member. 
     
     
         14 . The method of  claim 13 , wherein filtering comprises moving at least one valve between an open position in which it permits the flow of the impactors from the drill string to the body member, and a closed position in which it prevents the flow. 
     
     
         15 . The method of  claim 14 , wherein filtering further comprises moving two tubular members relative to each other, the valve moving between the open and closed positions in response to the relative movement. 
     
     
         16 . The method of  claim 15 , wherein moving the tubular members comprises displacing the drill string. 
     
     
         17 . The method of  claim 16 , wherein displacing the drill string comprises displacing the drill string in a longitudinal direction. 
     
     
         18 . The method of  claim 17 , wherein displacing the drill string comprises raising the drill string. 
     
     
         19 . The method of  claim 17 , wherein displacing the drill string comprises lowering the drill string. 
     
     
         20 . The method of  claim 14 , wherein filtering comprises placing valve elements parallel to one another in the open position. 
     
     
         21 . The method of  claim 14 , wherein filtering comprises twisting valve elements with respect to one another in the closed position. 
     
     
         22 . The method of  claim 14 , wherein at least one of the valves comprises a resilient whisker extending from an interior surface of the drill string. 
     
     
         23 . The method of  claim 14 , wherein at least one of the valves comprises a resilient disc extending from an interior surface of the drill string. 
     
     
         24 . The method of  claim 13 , further comprising filtering the flow of the suspension within an annulus defined between the drill string and the wellbore. 
     
     
         25 . The method of  claim 24 , wherein at least one of the valves comprises a resilient whisker extending from an exterior surface of the drill string. 
     
     
         26 . The method of  claim 24 , wherein at least one of the valves comprises a resilient disc extending from an exterior surface of the drill string.