Hydraulically unitary well system and recovery process (huwsrp)

Abstract

The present disclosure describes a method of recovering viscous hydrocarbons from a subterranean formation using a gravity dominated recovery process with a group of wells, the recovery process incorporating an interwell recovery phase. The group of wells is initially operated independently to establish hydraulic communication between two or more wells in the group. Once hydraulic communication is established, injection of mobilizing fluid and production of hydrocarbons continues in at least one well within the group with an excess amount of mobilizing fluid being injected into the well. At the same time, production only continues in at least one well within the group, without any injection of mobilizing fluid. The wells in the group are spaced closer together than in conventional recovery processes. The recovery process may be SAGD.

1 . A method of producing viscous hydrocarbons from a subterranean formation using a group of wells, comprising the steps of:
 i. providing two or more wells within a formation, each well having an injection means and a production means;   ii. independently operating a predominantly gravity-dominated recovery process at each of the two or more wells, the recovery process comprising injecting a first amount of a mobilizing fluid through the injection means into the formation, to mobilize the viscous hydrocarbons in the formation, and substantially concurrently producing the mobilized hydrocarbons through the production means;   iii. forming fluid chambers adjacent each of the two or more wells in the reservoir as the mobilized hydrocarbons are produced;   iv. establishing hydraulic communication between the fluid chambers for at least two of the two or more wells to form a cluster of wells;   v. continuing injection and production from at least one of the two or more wells in the cluster and ceasing injection and continuing production from at least one of the two or more wells in the cluster, wherein the injection of mobilizing fluid in the at least one well in the cluster is a second amount of mobilizing fluid, greater than the first amount of mobilizing fluid; and
 wherein the two or more wells are spaced sufficiently close to establish fluid communication between the two or more wells. 
   
     
     
         2 . The method of  claim 1  further comprising ceasing injection and continuing production at the at least one well within the cluster in step (v) that continued both injection and production, and reinitiating injection of the mobilizing fluid and continuing production at the at least one well within the cluster in step (v) that ceased injection of the mobilizing fluid. 
     
     
         3 . The method of  claim 1  further comprising the step of ceasing injection of a mobilizing fluid into the at least one well in the cluster, and injecting a non-condensable gas through the at least one well in the cluster while continuing production at the at least one other well in the cluster. 
     
     
         4 . The method of  claim 1  wherein the cluster of wells is operated as a hydraulic unit. 
     
     
         5 . The method of  claim 1  wherein the wells in the cluster are spaced so that infill wells are not required. 
     
     
         6 . The method of  claim 1  wherein the recovery process is steam assisted gravity drainage (SAGD) and the two or more wells within the formation are selected from the group consisting of SAGD well pairs or single vertical, inclined, or horizontal SAGD wells. 
     
     
         7 . The method of  claim 1 , wherein the mobilizing fluid is steam, hot water, light hydrocarbon, solvent, surfactant, non-condensing gas, or mixtures thereof. 
     
     
         8 . The method of  claim 7  wherein the solvent is one or more of a C3 to C10 solvent or hexane, or wherein the non-condensing gas is a light hydrocarbon or an oxygen containing gas. 
     
     
         9 . The method of  claim 1  wherein the injecting and/or producing is done on a continuous or interrupted basis. 
     
     
         10 . The method of  claim 1  wherein the viscous hydrocarbons are selected from the group consisting of bitumen, heavy oil, and unmobilized hydrocarbons. 
     
     
         11 . A method of producing viscous hydrocarbons from a subterranean formation using a group of wells, comprising the steps of:
 i. providing two or more wells within a formation, each well having an injection means and a production means, the injection means being positioned in the well closer to the surface than the production means;   ii. independently operating a predominantly gravity-dominated recovery method in the two or more wells comprising the steps of injecting a first amount of a mobilizing fluid through the injection means into the formation, to mobilize the viscous hydrocarbons; and substantially concurrently producing the mobilized hydrocarbons through the production means, wherein producing the mobilized hydrocarbons forms fluid chambers in the formation adjacent each of the two or or more wells;   iii. establishing hydraulic communication between the fluid chambers formed adjacent at least two of the two or more wells to form a cluster of wells; and   iv. continuing injection and production from at least one of the two or more wells in the cluster and ceasing injection and continuing production from at least one of the two or more wells in the cluster, wherein the injection of mobilizing fluid in the at least one of the two or more wells in the cluster is a second amount of mobilizing fluid greater than the first amount of mobilizing fluid;
 wherein the two or more wells are spaced sufficiently close to establish fluid communication between the two or more wells. 
   
     
     
         12 . The method of  claim 11  further comprising ceasing injection and continuing production at the at least one well within the cluster in step (v) that continued both injection and production, and reinitiating injection of the mobilizing fluid and continuing production at the at least one well within the cluster in step (v) that ceased injection of the mobilizing fluid. 
     
     
         13 . The method of  claim 11  further comprising the step of ceasing injection of a mobilizing fluid, and injecting a non-condensable gas through the at least one well in the cluster while continuing production at the at least one other well in the cluster. 
     
     
         14 . The method of  claim 11  wherein the cluster of wells is operated as a hydraulic unit. 
     
     
         15 . The method of  claim 11  wherein the wells in the cluster are spaced so that infill wells are not required. 
     
     
         16 . The method of  claim 11  wherein the recovery process is steam assisted gravity drainage (SAGD) and the two or more wells within the formation are selected from the group consisting or SAGD well pairs or single vertical, inclined, or horizontal SAGD wells. 
     
     
         17 . The method of  claim 11  wherein the mobilizing fluid is steam, hot water, light hydrocarbon, solvent, surfactant, non-condensing gas, or mixtures thereof. 
     
     
         18 . The method of  claim 17  wherein the solvent is one or more of a C3 to C10 solvent or hexane, or the non-condensing gas is a light hydrocarbon or an oxygen containing gas. 
     
     
         19 . The method of  claim 11  wherein the injecting and/or producing is done on a continuous or interrupted basis. 
     
     
         20 . The method of  claim 11  wherein the viscous hydrocarbons are selected from the group consisting of bitumen, heavy oil, and unmobilized hydrocarbons.