Low pressure fluid storage technique for a high pressure application

Abstract

A technique for pre-storing an application fluid in coiled tubing for use in a downhole application. The technique includes filling the coiled tubing with the application fluid in a manner that utilizes pressures substantially below that of the pressures utilized in the downhole application itself. The coiled tubing may then be charged to near the application pressure and placed in hydraulic communication with a well for the downhole application. Thus, the coiled tubing may serve as an application fluid storage device without the requirement of coiled tubing deployment or associated equipment and related costs.

We claim: 
     
         1 . A method of delivering an application fluid to a downhole location in a well from a wellsite, the method comprising:
 filling the coiled tubing with the application fluid at a filling pressure with the coiled tubing positioned at the oilfield surface; and   transferring the application fluid from the coiled tubing to the downhole location at an application pressure that is substantially greater than the filling pressure.   
     
     
         2 . The method of  claim 1  further comprising storing the application fluid in the coiled tubing at the wellsite for an operator-determined period after the filling thereof and prior to the transferring of the application fluid to the downhole location. 
     
     
         3 . The method of  claim 1  further comprising increasing pressure in the coiled tubing from the filling pressure to a pre-application pressure that is closer to the application pressure than the filling pressure in advance of the transferring of the fluid from the coiled tubing to the downhole location. 
     
     
         4 . The method of  claim 1  wherein the transferring of the application fluid from the coiled tubing to the downhole location comprises pumping a driving fluid in communication with the coiled tubing at the application pressure to direct the application fluid from the coiled tubing to the well. 
     
     
         5 . The method of  claim 4  further comprising introducing a barrier plug to the application fluid in the coiled tubing in advance of the pumping of the driving fluid to minimize mixing of the application fluid and the driving fluid. 
     
     
         6 . The method of  claim 4  wherein the viscosity of the driving fluid is greater than the viscosity of the application fluid to minimize mixing of the application fluid and the driving fluid. 
     
     
         7 . The method of  claim 4  further comprising remotely opening a valve for a predetermined period to direct a predetermined amount of the application fluid from the coiled tubing. 
     
     
         8 . The method of  claim 1  further comprising:
 deploying the coiled tubing in an interventional downhole application; and 
 retiring the coiled tubing from further interventional downhole deployment based on an assessment of coil life therefor, the deploying of the coiled tubing and the retiring thereof taking place in advance of the filling of the coiled tubing with the application fluid. 
 
     
     
         9 . A system for positioning at an oilfield, the system comprising:
 a tubular storage device having a surface to volume ratio of at least about 1, the volume to accommodate an application fluid for use in an application at the oilfield;   a transfer pump coupled to the tubular storage device for filling the device with the application fluid at a filling pressure; and   an application pump coupled to the tubular storage device for pressurizing the filled device to a pressure substantially greater than the filling pressure.   
     
     
         10 . The system of  claim 9  wherein the application fluid includes at least one constituent having a size of greater than about 4 mm. 
     
     
         11 . The system of  claim 10  wherein the constituent is selected from a group consisting of a fiber, balls, proppant, projectiles, diverter material, a fiber pill, a viscous pill, cement particles and particles of irregular shape. 
     
     
         12 . The system of  claim 9  wherein the filling pressure is under about 500 PSI. 
     
     
         13 . The system of  claim 12  wherein the application pump is a triplex pump and the substantially greater pressure is in excess of about 15,000 PSI. 
     
     
         14 . The system of  claim 13  wherein the triplex pump accommodates a driving fluid substantially free of constituents having a size of greater than about 4 mm. 
     
     
         15 . The system of  claim 14  wherein the tubular storage device is coiled tubing. 
     
     
         16 . The system of  claim 15  wherein the system further comprises:
 a support reel to accommodate the coiled tubing in a wound manner thereabout; and 
 a port supported by the reel for controlled fluid communication with the coiled tubing to allow introduction of a plug barrier between the driving fluid and the application fluid. 
 
     
     
         17 . A fluid storage assembly for positioning at an oilfield to support a downhole application in a well, the assembly comprising:
 non-interventional coiled tubing for retaining at the oilfield to supply stored application fluid therein to the well for the application; and   a reel to support the coiled tubing wound thereabout, the reel accommodating a low pressure line coupled to the coiled tubing for filling with the application fluid at a filling pressure and accommodating a high pressure line coupled to the coiled tubing for pressurizing the application fluid in the coiled tubing to a pressure substantially greater than the filling pressure.   
     
     
         18 . The fluid storage assembly of  claim 17  wherein the non-interventional coiled tubing is of a capacity to store in excess of 30 barrels of the application fluid. 
     
     
         19 . The fluid storage assembly of  claim 17  wherein the non-interventional coiled tubing comprises coiled tubing with a predetermined interventional coil life that is retired to a non-interventional status after about 75% of the coil life. 
     
     
         20 . The fluid storage assembly of  claim 17  further comprising containment bars located about the reel to reinforce the non-interventional coiled tubing during the pressurizing of the application fluid therein.