Fluid loss control flapper valve

Abstract

A system for completing a well bore, comprises, a string having a housing having an inner diameter, the housing defining an inner channel, a valve seat having an inner diameter coupled to the housing, a flapper pivotally coupled to the valve seat, the flapper configured to move from a first open position to a second closed position; and a sleeve positioned in the inner channel of the valve seat and configured to retain the flapper in the first open position. The flapper has an arcuate orientation that is generally concentric with the housing when the flapper is in the first open position, the flapper isolates a region of the inner channel of the housing below the flapper from a region of the inner channel of the housing above the flapper when the flapper is in a closed position, and the flapper may move to the second closed position when the sleeve is withdrawn from the inner channel of the valve seat.

1 . A system for completing a well bore, comprising:
 a string having a housing having an inner diameter, the housing defining an inner channel;   a valve seat having an inner channel, the valve seat being coupled to the housing;   a flapper pivotally coupled to the valve seat, the flapper configured to move from a first open position to a second closed position; and   a sleeve positioned in the inner channel of the valve seat and configured to retain the flapper in the first open position;   wherein the flapper has an arcuate orientation that is generally concentric with the housing when the flapper is in the first open position, the flapper isolates a region of the inner channel of the housing below the flapper from a region of the inner channel of the housing above the flapper when the flapper is in a closed position, and the flapper may move to the second closed position when the sleeve is withdrawn from the inner channel of the valve seat.   
   
   
       2 . The system of  claim 1 , wherein the string is a production string. 
   
   
       3 . The system of  claim 1 , wherein the string is a completion string. 
   
   
       4 . The system of  claim 1 , wherein the flapper is configured to be opened by breaking the flapper into a plurality of fragments. 
   
   
       5 . The system of  claim 4 , wherein the flapper comprises a series of profiles in a surface of the flapper, and the flapper is configured to break into the plurality of pieces generally defined by the profiles. 
   
   
       6 . The system of  claim 4 , wherein the flapper comprises a first material and a second material, and the second material is more susceptible to the effects of corrosive agents, heat, solvents, and/or pressure. 
   
   
       7 . The system of  claim 4 , wherein the sleeve is configured to apply a force sufficient to break the flapper, on the flapper after the flapper has moved to the second closed position. 
   
   
       8 . The system of  claim 1 , wherein the housing comprises a thinned portion for receiving the valve seat and the flapper. 
   
   
       9 . The system of  claim 8 , wherein the valve seat is coupled to a collar that is received within the thinned portion of the housing. 
   
   
       10 . The system of  claim 1 , wherein the inner channel of the valve seat is substantially unobstructed by the flapper when the flapper is in the open position. 
   
   
       11 . A system for completing a well bore, comprising:
 a string having a housing having an inner diameter, the housing defining an inner channel;   a valve seat having an inner channel, the valve scat being coupled to the housing;   a flapper pivotally coupled to the valve seat, the flapper configured to move from a first open position to a second closed position, and the flapper being configured to be reopened by breaking the flapper into a plurality of fragments, and the inner channel of the valve seat being substantially unobstructed by the flapper when the flapper is in the open position; and   a sleeve positioned in the inner channel of the valve scat and configured to retain the flapper in the first open position;   wherein the flapper has an arcuate orientation that is generally concentric with the housing when the flapper is in the first open position, the flapper isolates a region of the inner channel of the housing below the flapper from a region of the inner channel of the housing above the flapper when the flapper is in a closed position, and the flapper may move to the second closed position when the sleeve is withdrawn from the inner channel of the valve seat.   
   
   
       12 . The system of  claim 11 , wherein a diameter of the inner channel of the valve seat is substantially the same as the inner diameter of the housing at a position immediately downhole of the valve seat. 
   
   
       13 . The system of  claim 11 , wherein the sleeve is configured to apply a force sufficient to break the flapper, on the flapper after the flapper has moved to the second closed position. 
   
   
       14 . The system of  claim 11 , wherein the flapper comprises a first material and a second material, and the second material is more susceptible to the effects of corrosive agents, heat, solvents, and/or pressure. 
   
   
       15 . The system of  claim 11 , wherein the housing includes a valve region having a second inner diameter larger than an inner diameter of a region adjacent to the valve region, and the valve seat is disposed within the valve region. 
   
   
       16 . A method of completing a well comprising:
 drilling a subterranean well bore through a first production zone and a second production zone;   running a completion string in the well bore;   completing a region of the well bore adjacent to the first production zone, wherein completing includes delivering a completion fluid through a sleeve;   at least partially isolating the region of the well bore adjacent to the first production zone by closing a flapper valve having a curved flapper, wherein closing includes partially withdrawing the sleeve from the first production zone;   completing a region of the well bore adjacent to the second production zone; and   opening the flapper valve.   
   
   
       17 . The method of  claim 16 , wherein the well is an oil or natural gas well. 
   
   
       18 . The method of  claim 17 , wherein the flapper is pivotally coupled to a valve seat having an inner channel, the flapper being configured to move from a first open position to a second closed position, and the inner channel of the valve seat being substantially unobstructed by the flapper when the flapper is in the open position. 
   
   
       19 . The method of  claim 17 , wherein the step of opening the flapper valve includes breaking the flapper into a plurality of fragments by applying pressure, corrosive agents, solvents, and/or heat to the flapper. 
   
   
       20 . The method of  claim 17 , wherein the flapper valve is coupled to the completion string.