Device and process for stimulation and cleaning of a liquid-filled well

Abstract

The invention relates to a device for cleaning a liquid-filled well ( 10 ) comprising a tubular vessel ( 21 ), the interior of which contains at least one combustion chamber ( 30 ) and at least one hollow chamber ( 25 ) arranged in longitudinal succession, the combustion chamber ( 30 ) being at least partly filled with a fuel ( 31 ) and having an igniter ( 32 ), and the vessel ( 21 ) having at least one inflow orifice through which well fluid can flow from the outside into the vessel ( 21 ), wherein the at least one inflow orifice is provided with a closure device ( 42 ) comprising at least one closure element which loses its integrity on exceedance of a given temperature, such that the closure device ( 42 ) opens. The invention further relates to a process for stimulating and cleaning a liquid-filled well using an inventive device.

1 . A device for cleaning a liquid-filled well, comprising a tubular vessel, the interior of which comprises at least one combustion chamber and at least one hollow chamber arranged in longitudinal succession, the combustion chamber being at least partly filled with a fuel and having an igniter, and the tubular vessel having at least one inflow orifice through which well fluid can flow from the outside into the tubular vessel, wherein the at least one inflow orifice is provided with a closure device comprising at least one closure element which loses its integrity on exceedance of a given temperature, such that the closure device opens. 
     
     
         2 . The device according to  claim 1 , wherein the combustion chamber is at a lower end of the tubular vessel, and the at least one inflow orifice with its closure device is arranged at the lower end of the tubular vessel. 
     
     
         3 . The device according to  claim 2 , wherein:
 the inflow orifice is configured so as to narrow from the inside outward;   the closure device comprises a plug whose shape has been matched to the inflow orifice;   the plug is provided with a securing device which restricts the axial movement thereof away from the inflow orifice; and   the plug is connected in a thermally releasable manner to the inside of the end by virtue of the closure element.   
     
     
         4 . The device according to  claim 3 , wherein:
 the securing device comprises a connecting element and a weight element which is outside the vessel;   the connecting element is connected to the weight element and the plug; and   a radial extent of the weight element at least in one spatial direction is greater than the diameter of the inflow orifice on the outside of the lower end of the tubular vessel.   
     
     
         5 . The device according to  claim 1 , wherein:
 the combustion chamber is at the lower end of the tubular vessel;   the hollow chamber is arranged above the combustion chamber;   above the hollow chamber in turn is arranged an orifice chamber which is separated therefrom by a separating element and in the wall of which there is at least one inflow orifice with its closure device; and   a further igniter and further fuel are present in the orifice chamber, said further fuel, when it burns off, generating a temperature at which both the at least one closure element and the separating element from the hollow chamber lose their integrity.   
     
     
         6 . The device according to  claim 1 , wherein:
 the at least one inflow orifice with its closure element is within a middle region of the vessel;   a stop element is arranged below the at least one inflow orifice on the outside of the vessel;   a shell tube which is arranged around the vessel at the upper end of the vessel is secured by a thermally releasable securing element on the outer wall of the vessel; and   an upper combustion chamber present at the level of the securing element in the vessel comprises a further igniter and further fuel which, when it burns off, generates a temperature at which the securing element loses its integrity.   
     
     
         7 . The device according to  claim 6 , wherein the combustion chamber and the hollow chamber are arranged from the bottom upward between the lower end of the vessel and the upper combustion chamber, the combustion chamber being separated from the hollow chamber by a separating element, and the at least one inflow orifice being arranged at the upper end of the combustion chamber and the igniter at the lower end of the combustion chamber, and the fuel being selected such that, after ignition, it burns off from the bottom upward and the burnoff of the fuel at the upper end of the combustion chamber generates a temperature at which both the at least one closure element and the separating element from the hollow chamber lose their integrity. 
     
     
         8 . The device according to  claim 6 , wherein:
 a separation chamber, an orifice chamber and the combustion chamber are arranged from the bottom upward between the lower end of the vessel and the upper combustion chamber;   the hollow chamber is bounded at the top and bottom by separating elements; and   the orifice chamber is arranged at the level of the at least one inflow orifice and has a further igniter and further fuel which, when it burns off, generates a temperature at which both the at least one closure element and the separating element from the hollow chamber lose their integrity.   
     
     
         9 . The device according to  claim 6 , wherein:
 the hollow chamber, the combustion chamber and a separation chamber are arranged from the bottom upward between the lower end of the vessel and the upper combustion chamber;   the hollow chamber is separated from the combustion chamber by a separating element;   the at least one inflow orifice is arranged at the lower end of the combustion chamber; and   the fuel in the combustion chamber is selected such that, when it burns off in the lower end of the combustion chamber, it generates a temperature at which both the at least one closure element and the separating element from the hollow chamber lose their integrity.   
     
     
         10 . The device according to  claim 1 , wherein the fuel in the combustion chamber is a metallothermic mixture. 
     
     
         11 . A process for stimulating and cleaning a liquid-filled well, the process comprising:
 (a) introducing a device according to  claim 1  into a liquid-filled well;   (b) igniting the fuel in the at least one combustion chamber;   (c) thermally opening the closure element of the at least one inflow orifice, such that well fluid can flow into the at least one hollow chamber;   (d) optionally closing the at least one inflow orifice; and   (e) withdrawing the device from the well.   
     
     
         12 . The process according to  claim 11 , wherein, in step (a), the device is positioned in the well such that the combustion chamber is at the level of a perforation region of the production zone. 
     
     
         13 . The process according to  claim 11 , wherein step (c) is preceded by positioning of the device in the well such that the at least one inflow orifice is at the level of a perforation region of the production zone. 
     
     
         14 . The process according to  claim 11 , wherein step (c) is not initiated until a temperature of the outer wall of the device in the region of the at least one combustion chamber has cooled to a boiling temperature of the well fluid in this region.