Grout delivery

Abstract

A grout delivery system for delivery of grout to a downhole location within a borehole. The grout comprising a settable mixture of first and second flowable components. The grout delivery system is adapted to be conveyed to the location within the borehole to which grout is to be delivered and to be subsequently retrieved. The delivery system comprises a delivery head, a first reservoir for receiving a charge of the first component, and a second reservoir for receiving a charge of the second component. The delivery system is operable to cause supplies of the first and second components to be conveyed to a mixing zone at the delivery head where they are mixed to form the grout and delivered into the borehole.

1 . A delivery system for delivery of a flowable substance as a mixture of first and second flowable components to a downhole location within a borehole, the delivery system being configured to be accommodated within a drill string located in the borehole and exposed to fluid within the drill string, the delivery system comprising a delivery head, a first reservoir for receiving a charge of the first flowable component, a second reservoir for receiving a charge of the second flowable component, and actuation means operable to cause a supplies of the first and second flowable components to be conveyed to the delivery head at which they are mixed and delivered into the borehole, the actuation means being responsive to fluid pressure arising in use from fluid delivered into the drill string in the borehole, a control valve means for controlling the supply of fluid pressure to the actuation means, the control valve means being operable to allow admission of fluid under pressure in response to a fluid pressure supply exceeding a prescribed level, and a further control valve means for preventing entry of fluid from borehole into the reservoirs through the delivery head, the further control valve means being disposed between the delivery head and the reservoirs and operable to allow fluid flow between the reservoirs and the delivery head upon the fluid pressure in the reservoirs exceeding a prescribed level. 
     
     
         2 . The delivery system according to  claim 1  wherein the first and second reservoirs are configured as chambers of variable volume, whereby volume contraction of the chambers causes the first and second components to be expelled therefrom and conveyed to the delivery head. 
     
     
         3 . The delivery system according to  claim 2  wherein each variable volume chamber is defined by a piston and cylinder arrangement, with the piston being selectively moveable within the cylinder to effect volume variation of the chamber. 
     
     
         4 . The delivery system according to  claim 3  wherein the actuation means is responsive to fluid pressure to cause volume contraction of the chambers. 
     
     
         5 . The delivery system according to  claim 4  wherein the actuation means comprises the pistons, the arrangement being that the pistons are responsive to fluid pressure exerted on the sides thereof opposed to the chambers to move within the respective cylinders and thereby cause volume contraction of the chambers. 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . The delivery system according to  claim 1  wherein the delivery head defines a mixing zone at which the first and second components are brought together for mixing to form a flowable fluid mixture. 
     
     
         11 . The delivery system according to  claim 10  wherein the mixing zone comprises a mixing chamber. 
     
     
         12 . The delivery system according to  claim 11  wherein the delivery head comprises a body and the mixing zone is defined within the confines of the body. 
     
     
         13 . (canceled) 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . A grout delivery system for delivery of grout comprising a settable mixture of first and second flowable grout components into a borehole, wherein the grout delivery system comprises a delivery system according to  claim 1 , and wherein the first and second flowable grout components comprise said first and second flowable components. 
     
     
         17 . (canceled) 
     
     
         18 . A method of delivery of a flowable substance as a flowable mixture comprising first and second flowable components, the method comprising use of a delivery system according to  claim 1 . 
     
     
         19 . A method of delivery of grout as a settable flowable mixture comprising first and second components into a borehole, wherein the method comprising use of a grout delivery system according to  claim 16 . 
     
     
         20 . A method of delivery of a flowable substance as a flowable mixture comprising first and second components, the method comprising conveying a charge of the first component and a charge of the second component separated from each other from a first location to a second location at the downhole location, mixing the first and second components at the second location to form the flowable mixture, and discharging the flowable mixture into the borehole. 
     
     
         21 . The method according to  claim 20  wherein the flowable substance comprises a settable mixture of first and second grout components and wherein the first component comprises the first grout component and the second component comprises the second grout component. 
     
     
         22 . (canceled) 
     
     
         23 . A grout delivery system for delivery of grout comprising a settable mixture of first and second flowable components to a downhole location within a borehole, the delivery system being configured to be accommodated within a drill string located in the borehole and exposed to fluid within the drill string, the delivery system comprising a delivery head, a first reservoir for receiving a charge of the first flowable component, a second reservoir for receiving a charge of the second flowable component, and actuation means operable to cause a supplies of the first and second flowable components to be conveyed to the delivery head at which they are mixed and delivered into the borehole, the actuation means being responsive to fluid pressure arising in use from fluid delivered into the drill string in the borehole, a control valve means for controlling the supply of fluid pressure to the actuation means, the control valve means being operable to allow admission of fluid under pressure in response to a fluid pressure supply exceeding a prescribed level, and a further control valve means for preventing entry of fluid from borehole into the reservoirs through the delivery head, the further control valve means being disposed between the delivery head and the reservoirs and operable to allow fluid flow between the reservoirs and the delivery head upon the fluid pressure in the reservoirs exceeding a prescribed level. 
     
     
         24 . (canceled) 
     
     
         25 . The delivery system according to  claim 5  wherein the control valve means for controlling the supply of fluid pressure to the actuation means is incorporated in a fluid flow path comprising an inlet end section configured for exposure to fluid within the drill string and an outlet section configured for communication with pistons to exert fluid pressure thereon upon opening of control valve means. 
     
     
         26 . The delivery system according to  claim 25  wherein the control valve means comprises a valve seat and a valve member movable into and out of sealing engagement with the valve seat in response to the fluid pressure supply exceeding said prescribed level.