Systems and methods for enhancing steam distribution and production in sagd operations

Abstract

A system for recovering hydrocarbons from a subterranean formation with steam-assisted gravity drainage (SAGD) includes a steam injection well. The steam injection well includes a first portion extending from the surface through an unconsolidated layer of the formation to a consolidated layer of the formation, a second portion extending horizontally through the consolidated layer, and a plurality of third portions extending from the second portion. Each third portion extends upward from the second portion into the unconsolidated layer of the formation and a hydrocarbon reservoir in the unconsolidated layer of the formation. In addition, the system includes a production well. The production well includes a first portion extending from the surface through the unconsolidated and a second portion extending horizontally through the unconsolidated layer. The second portion of the production well is vertically positioned above the second portion of the steam injection well.

What is claimed is: 
     
         1 . A system for recovering hydrocarbons from a subterranean formation with steam-assisted gravity drainage (SAGD), the formation including an unconsolidated layer containing a hydrocarbon reservoir and a consolidated layer disposed below the unconsolidated layer, the system comprising:
 a steam injection well including a first portion extending from the surface through the unconsolidated layer to the consolidated layer, a second portion extending horizontally through the consolidated layer, and at least one third portion extending from the second portion, wherein each third portion extends upward from the second portion into the unconsolidated layer of the formation and the hydrocarbon reservoir;   a production well including a first portion extending from the surface through the unconsolidated layer and a second portion extending horizontally through the unconsolidated layer, wherein the second portion of the production well is vertically positioned above the second portion of the steam injection well.   
     
     
         2 . The system of  claim 1 , wherein the second portion of the production well is disposed in the unconsolidated layer proximal the consolidated layer. 
     
     
         3 . The system of  claim 2 , wherein the second portion of the production well is disposed at a minimum height H measured vertically from an interface between the consolidated layer and the unconsolidated layer, wherein the minimum height H is less than 5.0 meters. 
     
     
         4 . The system of  claim 3 , wherein the minimum height H is about 1.0 meter. 
     
     
         5 . The system of  claim 1 , wherein the steam injection well includes a fourth portion extending horizontally through the unconsolidated layer, wherein the fourth portion of the steam injection well is vertically positioned above the second portion of the production well. 
     
     
         6 . The system of  claim 1 , wherein the formation includes a fluid impermeable barrier disposed within the unconsolidated layer;
 wherein an upper portion of the hydrocarbon reservoir is disposed above the fluid impermeable barrier and a lower portion of the hydrocarbon reservoir is disposed below the fluid impermeable barrier;   wherein the second portion of the injection well and the second portion of the production well are positioned below the fluid impermeable barrier;   wherein at least one of the third portions of the steam injection well extends upward through the fluid impermeable barrier and is configured to transport steam from the second portion of the steam injection well to the upper portion of the hydrocarbon reservoir.   
     
     
         7 . The system of  claim 6 , further comprising a passage extending through the fluid impermeable barrier, wherein the passage has an upper end disposed in the unconsolidated layer above the fluid impermeable barrier and a lower end disposed in the unconsolidated layer below the fluid impermeable barrier. 
     
     
         8 . The system of  claim 7 , wherein a slotted liner is disposed in the passage and a slotted liner is disposed in each of the third portions of the steam injection well that extend upward through the fluid impermeable barrier. 
     
     
         9 . The system of  claim 8 , wherein each slotted liner comprises:
 a first plurality of slots positioned above the fluid impermeable barrier; and   a second plurality of slots positioned below the fluid impermeable barrier.   
     
     
         10 . The system of  claim 7 , wherein the passage is configured to transport hydrocarbons from the unconsolidated layer above the fluid impermeable barrier to the unconsolidated layer below the fluid impermeable barrier. 
     
     
         11 . The system of  claim 10 , wherein the passage is configured to transport steam from the unconsolidated layer below the fluid impermeable barrier to the unconsolidated layer above the fluid impermeable barrier. 
     
     
         12 . The system of  claim 1 , further comprising a valve disposed along each third portion of the steam injection well proximal the second portion of the steam injection well;
 wherein each valve has an open position allowing fluid communication between the second portion of the steam injection well and the corresponding third portion of the steam injection well, and a closed position preventing fluid communication between the second portion of the steam injection well and the corresponding third portion of the steam injection well.   
     
     
         13 . A method for producing hydrocarbons from a subterranean formation with steam-assisted gravity drainage (SAGD), the formation including an unconsolidated layer containing a hydrocarbon reservoir and a consolidated layer disposed below the unconsolidated layer, the method comprising:
 (a) drilling a first portion of a steam injection well through the consolidated layer of the formation;   (b) drilling a plurality of second portions of a steam injection well upward from the first portion of the steam injection well into the unconsolidated layer;   (c) drilling a first portion of a production well through the unconsolidated layer of the formation.   
     
     
         14 . The method of  claim 13 , further comprising:
 (d) flowing steam through the first portion of the steam injection well to the second portions of the steam injection well;   (e) flowing steam from the first portion of the steam injection well into at least one of the second portions of the steam injection well during (d); and   (f) injecting steam from the at least one of the second portions of the steam injection well into the unconsolidated layer of the formation during (e).   
     
     
         15 . The method of  claim 14 , further comprising:
 (g) reducing the viscosity of the hydrocarbons and flowing the hydrocarbons through the unconsolidated layer into the first portion of the production well; and   (h) producing the hydrocarbons in the first portion of the production well to the surface.   
     
     
         16 . The method of  claim 14 , further comprising:
 selectively preventing the flow of steam from the first portion of the steam injection well into one or more of the second portions of the steam injection well.   
     
     
         17 . The method of  claim 13 , wherein (b) comprises:
 drilling at least one of the second portions of the steam injection well upward through a fluid impermeable barrier extending through the unconsolidated layer of the formation;   wherein an upper portion of the unconsolidated layer is disposed above the fluid impermeable barrier and a lower portion of the unconsolidated layer is disposed below the fluid impermeable barrier;   wherein an upper portion of the hydrocarbon reservoir is disposed above the fluid impermeable barrier and a lower portion of the hydrocarbon reservoir is disposed below the fluid impermeable barrier.   
     
     
         18 . The method of  claim 17 , further comprising:
 drilling a passage through the fluid impermeable barrier.   
     
     
         19 . The method of  claim 17 , further comprising:
 (d) flowing steam through the first portion of the steam injection well to the second portions of the steam injection well;   (e) flowing steam from the first portion of the steam injection well into at least one of the second portions of the steam injection well during (d); and   (f) flowing steam upward in the at least one of the second portions of the steam injection well through the fluid impermeable barrier during (e); and   (g) injecting steam from the at least one of the second portions of the steam injection well into the upper portion of the hydrocarbon reservoir.   
     
     
         20 . The method of  claim 18 , further comprising:
 (d) flowing steam through the first portion of the steam injection well to the second portions of the steam injection well;   (e) flowing steam from the first portion of the steam injection well into at least one of the second portions of the steam injection well during (d); and   (f) flowing steam upward in the at least one of the second portions of the steam injection well through the fluid impermeable barrier during (e);   (g) injecting steam from the at least one of the second portions of the steam injection well into the upper portion of the hydrocarbon reservoir;   (h) flowing hydrocarbons from the upper portion of the hydrocarbon reservoir through the passage into the lower portion of the unconsolidated layer.   
     
     
         21 . The method of  claim 20 , further comprising:
 flowing hydrocarbons from the passage through the lower portion of the unconsolidated layer into the first portion of the production well; and   flowing hydrocarbons through the first portion of the production well to the surface.   
     
     
         22 . The method of  claim 13 , further comprising:
 drilling each second portion of the steam injection well upward across an interface between the consolidated layer and the unconsolidated layer;   identifying a location where each second portion crosses the interface while drilling each second portion;   utilizing the locations where the second portions cross the interface to determine the location of the first portion of the production well within the unconsolidated layer.   
     
     
         23 . A method for producing hydrocarbons from a subterranean formation with steam-assisted gravity drainage (SAGD), the formation including an unconsolidated layer containing a hydrocarbon reservoir and a consolidated layer disposed below the unconsolidated layer, the method comprising:
 (a) flowing steam from the surface through a subterranean steam injection well extending through the unconsolidated layer of the formation and into the consolidated layer of the formation;   (b) flowing steam through the steam injection well from the consolidated layer of the formation into the unconsolidated layer of the formation; and   (c) injecting steam from the injection well into the unconsolidated layer of the formation.   
     
     
         24 . The method of  claim 23 , further comprising:
 (d) flowing hydrocarbons from the hydrocarbon reservoir into a portion of a production well extending through the unconsolidated layer of the formation; and   (e) producing hydrocarbons in the production well to the surface.   
     
     
         25 . The method of  claim 24 , wherein a fluid impermeable barrier extends through the unconsolidated layer of the formation and divides the hydrocarbon reservoir into a lower portion disposed below the fluid impermeable barrier and an upper portion disposed above the fluid impermeable barrier;
 wherein (b) further comprises flowing steam through the injection well and the fluid impermeable barrier;   wherein (c) further comprises injecting steam from the injection well into the upper portion of the hydrocarbon reservoir.   
     
     
         26 . The method of  claim 25 , further comprising:
 (f) flowing hydrocarbons downward through a passage in the fluid impermeable barrier.   
     
     
         27 . The method of  claim 23 , wherein the injection well includes a first portion extending horizontally through the consolidated layer of the formation and a plurality of second portions extending from the first portion into the unconsolidated layer of the formation. 
     
     
         28 . The method of  claim 27 , wherein at least one of the second portions extends through a fluid impermeable barrier in the unconsolidated layer of the formation, wherein the fluid impermeable barrier divides the hydrocarbon reservoir into a lower portion disposed below the fluid impermeable barrier and an upper portion disposed above the fluid impermeable barrier. 
     
     
         29 . The method of  claim 27 , further comprising:
 drilling each second portion from the first portion across an interface between the consolidated layer and the unconsolidated layer;   identifying a location where each second portion crosses the interface while drilling each second portion;   utilizing the locations where each second portion crosses the interface to position a horizontal portion of a production well extending from the surface through the unconsolidated layer of the formation.