Use of Underground Access to Improve Steam Distribution in SAGD Operations

Abstract

A system for recovering hydrocarbons from a subterranean formation with steam-assisted gravity drainage comprises a subterranean access tunnel extending through the formation. In addition, the system comprises a steam injection well extending through the formation above a portion of the tunnel. Further, the system comprises a production well extending through the formation above the portion of the tunnel. Still further, the system comprises a plurality of horizontally spaced bores extending upward from the access tunnel through the formation.

What is claimed is: 
     
         1 . A system for recovering hydrocarbons from a subterranean formation with steam-assisted gravity drainage (SAGD), the formation including a fluid impermeable barrier and a hydrocarbon reservoir having at least a portion positioned above the barrier, the system comprising:
 a subterranean access tunnel extending through the formation;   a steam injection well extending through the formation above a portion of the tunnel;   a production well extending through the formation above the portion of the tunnel; and   a plurality of horizontally spaced bores extending upward from the access tunnel through the formation.   
     
     
         2 . The system of  claim 1 , wherein the portion of the access tunnel, the steam injection well, and the production well are each positioned below the fluid impermeable barrier; and
 wherein the bores extend through the fluid impermeable barrier.   
     
     
         3 . The system of  claim 2 , wherein the steam injection well and the production well extend from the access tunnel. 
     
     
         4 . The system of  claim 3 , wherein the steam injection well includes a portion extending horizontally through the formation; and
 wherein the production well includes a portion extending horizontally through the formation.   
     
     
         5 . The system of  claim 3 , wherein the steam injection well is vertically spaced above the production well. 
     
     
         6 . The system of  claim 5 , wherein the portion of the access tunnel extends horizontally through the formation. 
     
     
         7 . The system of  claim 6 , wherein the bores are configured to transport steam from the steam injection well to the portion of the hydrocarbon reservoir above the barrier. 
     
     
         8 . The system of  claim 7 , wherein the bores are configured to transport hydrocarbons from the portion of the hydrocarbon reservoir above the barrier to the production well. 
     
     
         9 . The system of  claim 2 , wherein the bores are laterally spaced from the steam injection well and the production well. 
     
     
         10 . The system of  claim 2 , wherein a slotted liner is disposed in each bore. 
     
     
         11 . The system of  claim 10 , wherein each slotted liner comprises:
 a first plurality of slots positioned adjacent the production well;   a second plurality of slots positioned adjacent the injection well; and   a third plurality of slots positioned above the fluid impermeable barrier.   
     
     
         12 . The system of  claim 10 , wherein each slotted liner includes a plug or a valve configured to prevent fluids in the liners from flowing directly into the access tunnel. 
     
     
         13 . A method for producing hydrocarbons from a reservoir in a subterranean formation, the reservoir having at least a portion disposed above a fluid impermeable barrier in the formation, the method comprising:
 (a) constructing an access tunnel that extends through a subterranean formation below the fluid impermeable barrier;   (b) drilling a steam injection well from the access tunnel into the formation below the fluid impermeable barrier;   (c) drilling a production well from the access tunnel into the formation below the fluid impermeable barrier; and   (d) drilling at least one bore upward from the access tunnel into the formation and through the fluid impermeable barrier.   
     
     
         14 . The method of  claim 13 , further comprising:
 (e) flowing steam upward in the at least one bore through the fluid impermeable barrier; and   (f) injecting the steam from the at least one bore into the formation above the fluid impermeable barrier after (e).   
     
     
         15 . The method of  claim 14 , further comprising:
 (g) flowing hydrocarbons from the portion of the reservoir above the barrier downward in the at least one bore through the fluid impermeable barrier after (f).   
     
     
         16 . The method of  claim 15 , wherein (e) further comprises:
 flowing steam through the injection well; and   flowing steam from the injection well into the at least one bore.   
     
     
         17 . The method of  claim 15 , wherein (g) further comprises:
 flowing hydrocarbons from the at least one bore into the production well; and   flowing hydrocarbons through the production well.   
     
     
         18 . The method of  claim 13 , further comprising:
 running a slotted liner through the production well;   running a slotted liner through the injection well; and   running a slotted liner through the at least one bore.   
     
     
         19 . A method for producing hydrocarbons from a reservoir in a subterranean formation, the reservoir having at least a portion disposed above a fluid impermeable barrier in the formation, the method comprising:
 (a) flowing steam from a subterranean injection well below the fluid impermeable barrier into a bore extending upward through the fluid impermeable barrier; and   (b) flowing steam upward in the bore through the fluid impermeable barrier.   
     
     
         20 . The method of  claim 19 , further comprising:
 (c) flowing hydrocarbons from the reservoir into the bore after (b);   (d) flowing hydrocarbons downward in the bore through the fluid impermeable barrier; and   (e) flowing hydrocarbons from the bore into a subterranean production well below the fluid impermeable barrier.   
     
     
         21 . The method of  claim 19 , wherein (a) comprises:
 (a1) flowing steam from an injection liner disposed in the injection well through a slot in the injection liner into the formation;   (a2) flowing steam in the formation into the bore through a slot of a liner disposed in the bore.   
     
     
         22 . The method of  claim 20 , wherein (e) comprises:
 (e1) flowing hydrocarbons from a liner disposed in the bore through a slot in the liner into the formation; and   (e2) flowing hydrocarbons in the formation into a production liner disposed in the production well through a slot in the production liner.