Multipurposing of multilateral infill wells for bypass hydrocarbon recovery

Abstract

In selected aspects, the present invention provides methods and systems for recovering hydrocarbons from a reservoir involving gravity-dominated recovery processes, such as steam assisted gravity drainage (SAGD). Aspects of the invention involve the use of multilateral wells in staged production processes, so that alternative segments of wells may be used in alternative ways during a recovery process, for example repurposing sections of an injection well as a production well at a stage in a recovery process when there is surplus injection well infrastructure in place.

1 . A method of producing hydrocarbons from a subterranean reservoir, comprising:
 operating a first injector-producer well pair under a substantially gravity-dominated recovery process, the first injector-producer well pair forming a first mobilized fluid zone in the subterranean reservoir;   operating a second injector-producer well pair under a substantially gravity-dominated recovery process, the second injector-producer well pair forming a second mobilized fluid zone in the subterranean reservoir, the first injector-producer well pair and the second injector-producer well pair together being adjacent well pairs;   operating the adjacent well pairs to form a bypassed hydrocarbon region between the adjacent well pairs, the bypassed hydrocarbon region being defined by a common mobilized fluid zone formed when the first mobilized fluid zone and the second mobilized fluid zone merge;   providing a multilateral infill well, or plurality of infill wells, in the bypassed hydrocarbon region, prior to, during or after any of the foregoing operating steps, each multilateral infill well being an arm or branch of a multilateral injector well of the first or second injector-producer well pair;   operating the multilateral infill well and the adjacent well pairs to increase the mobility of hydrocarbons in the bypassed hydrocarbon region; and   operating the multilateral infill well and the adjacent well pairs under a substantially gravity-dominated recovery process to enlarge the common mobilized fluid zone, and to produce mobilized hydrocarbons from the bypassed hydrocarbon region through the multilateral infill well.   
     
     
         2 . The method of  claim 1 , wherein the common mobilized fluid zone is enlarged by injecting a mobilizing fluid through at least one active injection well of the first or second injector-producer well pair. 
     
     
         3 . The method of  claim 2 , wherein the multilateral injector well is an active injection well. 
     
     
         4 . The method of  claim 2 , wherein the multilateral injector well is not an active injection well. 
     
     
         5 . The method of  claim 3 , wherein mobilizing fluid injected through the multilateral injector well is:
 circulated through the multilateral infill well arm of the multilateral injector well;   diverted at a multilateral injector well junction to an injection arm of the multilateral injector well; and, injected into the common mobilized fluid zone through the injection arm of the multilateral injector well.   
     
     
         6 . The method of  claim 2 , wherein the mobilizing fluid comprises steam or hot water, or both. 
     
     
         7 . The method of  claim 2 , wherein the mobilizing fluid comprises a light hydrocarbon. 
     
     
         8 . The method of  claim 7 , wherein the light hydrocarbon is a C3 to C10 alkane. 
     
     
         9 . The method of  claim 1 , wherein mobilized hydrocarbons are produced from the multilateral infill well to establish fluid communication between the multilateral infill well and the common mobilized fluid zone. 
     
     
         10 . The method of  claim 1 , wherein a bypass mobilizing fluid is injected into the multilateral infill well to mobilize hydrocarbons in the bypassed hydrocarbon region. 
     
     
         11 . The method of  claim 10 , wherein the bypass mobilizing fluid comprises steam. 
     
     
         12 . The method of  claim 10 , wherein the bypass mobilizing fluid comprises a light hydrocarbon. 
     
     
         13 . The method of  claim 12 , wherein the light hydrocarbon is a C3 to C10 alkane. 
     
     
         14 . The method of  claim 1 , wherein the gravity-dominated recovery process comprises Steam-assisted Gravity Drainage (SAGD). 
     
     
         15 . The method of  claim 1 , wherein the multilateral infill well and the adjacent well pairs comprise substantially horizontal and approximately parallel segments. 
     
     
         16 . The method of  claim 1 , wherein the multilateral infill well and the adjacent well pairs, constituting a well group, are provided in a field pattern repeated longitudinally or laterally or both, to form a multiple of well groups in the field pattern. 
     
     
         17 . A system for producing hydrocarbons from a subterranean reservoir, comprising:
 a first injector-producer well pair operated under a substantially gravity-dominated recovery process, the first injector-producer well pair forming a first mobilized fluid zone in the subterranean reservoir;   a second injector-producer well pair operated under a substantially gravity-dominated recovery process, the second injector-producer well pair forming a second mobilized fluid zone in the subterranean reservoir, the first injector-producer well pair and the second injector-producer well pair together being adjacent well pairs;
 wherein operation of the adjacent well pairs forms a bypassed hydrocarbon region between the adjacent well pairs, the bypassed hydrocarbon region being defined by a common mobilized fluid zone formed when the first mobilized fluid zone and the second mobilized fluid zone merge; 
   a multilateral infill well provided in the bypassed hydrocarbon region, the multilateral infill well being an arm of a multilateral injector well of the first or second injector-producer well pair;
 wherein operation of the multilateral infill well and the adjacent well pairs increases the mobility of hydrocarbons in the bypassed hydrocarbon region; 
 and wherein the multilateral infill well and the adjacent well pairs are operated under a substantially gravity-dominated recovery process to enlarge the common mobilized fluid zone, and to produce mobilized hydrocarbons from the bypassed hydrocarbon region through the multilateral infill well. 
   
     
     
         18 . The system of  claim 17 , wherein the common mobilized fluid zone is enlarged by injecting a mobilizing fluid through at least one active injection well of the first or second injector-producer well pair. 
     
     
         19 . The system of  claim 18 , wherein the multilateral injector well is an active injection well. 
     
     
         20 . The system of  claim 18 , wherein the multilateral injector well is not an active injection well. 
     
     
         21 . The system of  claim 19 , wherein mobilizing fluid injected through the multilateral injector well is:
 circulated through the multilateral infill well arm of the multilateral injector well;   diverted at a multilateral injector well junction to an injection arm of the multilateral injector well; and,   injected into the common mobilized fluid zone through the injection arm of the multilateral injector well.   
     
     
         22 . The system of  claim 18 , wherein the mobilizing fluid comprises steam. 
     
     
         23 . The system of  claim 18 , wherein the mobilizing fluid comprises a light hydrocarbon. 
     
     
         24 . The system of  claim 23 , wherein the light hydrocarbon is a C3 to C10 alkane. 
     
     
         25 . The system of  claim 17 , wherein mobilized hydrocarbons are produced from the multilateral infill well to establish fluid communication between the multilateral infill well and the common mobilized fluid zone. 
     
     
         26 . The system of  claim 17 , wherein a bypass mobilizing fluid is injected into the multilateral infill well to mobilize hydrocarbons in the bypassed hydrocarbon region. 
     
     
         27 . The system of  claim 26 , wherein the bypass mobilizing fluid comprises steam. 
     
     
         28 . The system of  claim 26 , wherein the bypass mobilizing fluid comprises a light hydrocarbon. 
     
     
         29 . The system of  claim 28 , wherein the light hydrocarbon is a C3 to C10 alkane. 
     
     
         30 . The system of  claim 17 , wherein the gravity-dominated recovery process comprises Steam-assisted Gravity Drainage (SAGD). 
     
     
         31 . The system of  claim 17 , wherein the multilateral infill well and the adjacent well pairs comprise substantially horizontal and approximately parallel segments. 
     
     
         32 . The system of  claim 17 , wherein the multilateral infill well and the adjacent well pairs, constituting a well group, are provided in a field pattern repeated longitudinally or laterally or both, to form a multiple of well groups in the field pattern.