Sagd control in leaky reservoirs

Abstract

The use of a water recycle ratio for controlling at least one Steam Assisted Gravity Drainage (SAGD) parameter in a leaky bitumen reservoir. Further, a process to control a steam injection rate for an individual SAGD well pair, in a leaky bitumen reservoir wherein the process replaces a pressure control for an SAGD steam injection rate with a volume control determined by a Water Recycle Ratio (WRR).

1 . The use of water recycle ratio for controlling at least one SAGD parameter in a leaky bitumen reservoir. 
     
     
         2 . A process to control a steam injection rate for an individual Steam Assisted Gravity Drainage (SAGD) well pair, in a leaky bitumen reservoir, wherein said process comprises replacing a pressure control for an SAGD steam injection rate with a volume control determined by a Water Recycle Ratio (WRR). 
     
     
         3 . The use of  claim 1  wherein said at least one parameter is selected from volume rate, pressure, temperature, and combinations. 
     
     
         4 . The process of  claim 2 , where the leaky bitumen reservoir is determined to be leaky by at least one of geological knowledge of an interspersed Water Lean Zone (WLZ), top water or bottom water. 
     
     
         5 . The process of  claim 2 , where the leaky bitumen reservoir is determined leaky by a cold water injection test prior to SAGD initiation. 
     
     
         6 . The process of  claim 2 , where the leaky bitumen reservoir is deemed leaky when after 200 days or more of SAGD operation using pressure control for steam injection, the SAGD has a WRR that varies from 1.0 by more than 10 percent. 
     
     
         7 . The process of  claim 2 , where a sub-cool control is maintained for liquids production. 
     
     
         8 . The process of  claim 2 , where volume rate control is instituted by injecting a pre-set target volume rate of steam into the SAGD injector well. 
     
     
         9 . A process for controlling a steam injection volume rate in a Steam Assisted Gravity Drainage (SAGD) process in an impaired reservoir, wherein the steam injection volume rate is controlled by
 i. Continually measuring a Water Recycle Ratio (WRR) for an SAGD well pair;   ii. Establishing a target for WRR; and   iii. If the actual WRR is less than the target WRR, reducing the steam injection rate until the target is achieved;   iv. If the actual WRR is greater than the target WRR, increasing the steam injection rate until the target is achieved.   
     
     
         10 . The process of  claim 9  where the target WRR is between 0.9 and 1.0. 
     
     
         11 . The process of  claim 9 , where the target WRR is between 1.0 and 1.5. 
     
     
         12 . The process of  claim 2 , wherein the leaky bitumen reservoir is leaky due to an interspersed water lean zone (WLZ) within a net pay zone in said reservoir. 
     
     
         13 . The process of  claim 2 , where the leaky bitumen reservoir is leaky due to a top water zone. 
     
     
         14 . The process of  claim 2 , where the leaky bitumen reservoir is leaky due to a bottom water zone 
     
     
         15 . The process of  claim 2 , wherein the leaky bitumen reservoir is leaky due to multiple factors comprising WLZ, top water and bottom water. 
     
     
         16 . The process of  claim 2 , wherein the bitumen is a hydrocarbon with <10 API density and >100,000 cp viscosity, at native reservoir conditions. 
     
     
         17 . The process of  claim 8 , wherein the measured SAGD pressure in the reservoir does not exceed:
 i) the reservoir parting pressure, for unconsolidated reservoirs;   ii) the reservoir fracturing pressure, for consolidated reservoirs.   
     
     
         18 . The process of  claim 17 , where the measured SAGD pressure does not exceed about 80 percent of the parting pressure or the fracturing pressure. 
     
     
         19 . The process of  claim 16 , where the bitumen reservoir is located in the Athabasca region of Alberta, Canada. 
     
     
         20 . The process of  claim 2 , where the minimum operating pressure is equal to the native reservoir pressure.