Method of solvent recovery from a solvent based heavy oil extraction process

Abstract

The present disclosure relates to production of a bitumen product from a subterranean reservoir with improved processes for solvent recovery at end of production or near end of production (i.e., “late life”) of heavy oil from a solvent-based heavy oil extraction process. The process include converting at least some of the wells in the subterranean reservoir, and injecting gas phase dilution agent into the reservoir, converting at least a portion of the liquid solvent to a gas phase, and recovering, in the vapor phase, at least a portion of the solvent remaining in the reservoir.

1 . A process for the recovery of a solvent from a subterranean reservoir containing a solvent and a heavy oil, the process comprising:
 a) recovering a heavy oil from a subterranean reservoir utilizing a solvent-assisted gravity drainage process wherein a portion of a solvent from the solvent-assisted gravity drainage process remains located in the subterranean reservoir;   b) injecting a gas phase dilution agent into the subterranean reservoir;   c) contacting at least a portion of the gas phase dilution agent with the solvent;   d) vaporizing at least a portion of the solvent that is in the liquid phase to produce a vaporized solvent; and   e) extracting at least a portion of the gas phase dilution agent and the vaporized solvent from the subterranean reservoir.   
     
     
         2 . The process of  claim 1 , wherein, prior to the injecting of the gas phase dilution agent, the solvent in the subterranean reservoir comprises both the liquid phase and a gas phase. 
     
     
         3 . The process of  claim 2 , wherein step e) includes extracting at least a portion of the liquid phase of the solvent from the subterranean reservoir. 
     
     
         4 . The process of  claim 1 , wherein the gas phase dilution agent comprises a non-condensable gas which remains in vapor phase at pressure and temperature of the subterranean reservoir. 
     
     
         5 . The process of  claim 4 , wherein the gas phase dilution agent comprises at least 50 wt % of the non-condensable gas at the operating pressure and temperature of the subterranean reservoir. 
     
     
         6 . The process of  claim 4 , wherein the non-condensable gas comprises C 1 , C 2 , C 3 , N 2 , CO 2 , natural gas, produced gas, flue gas or any combination thereof. 
     
     
         7 . The process of  claim 6 , wherein the non-condensable gas comprises CO 2 . 
     
     
         8 . The process of  claim 1 , wherein the gas phase dilution agent comprises a heating agent, wherein the heating agent is injected at a temperature greater than the operating temperature of the subterranean reservoir. 
     
     
         9 . The process of  claim 8 , wherein heating agent is comprised of the non-condensable gas, steam or a combination thereof. 
     
     
         10 . The process of  claim 9 , wherein heating agent is the non-condensable gas. 
     
     
         11 . A system for the recovery of a solvent from a subterranean reservoir containing a solvent and a heavy oil, the system comprising:
 a subterranean reservoir containing an existing solvent comprising a liquid phase and a heavy oil;   a first injector fluidly connected to the subterranean reservoir, wherein the injector is located to inject a gas phase dilution agent into the subterranean reservoir, so as to contact at least a portion of the gas phase dilution agent with the existing solvent and vaporize at least a portion of the existing solvent to produce a vaporized solvent; and   a first NCG/vaporized solvent production well located within the subterranean reservoir and fluidly connected to the first injector;   wherein the first NCG/vaporized solvent production well is configured to recover a portion of the gas phase dilution agent and a portion of the vaporized solvent.   
     
     
         12 . The system of  claim 11 , wherein
 the first injector is an NCG injection well which was previously configured as a first existing injection well to inject the existing solvent into the subterranean reservoir, and wherein the NCG injection well is configured to inject the gas phase dilution agent into the subterranean reservoir; and   the first NCG/vaporized solvent production well which was previously configured as a first existing production well to recover the existing solvent and the heavy oil in the liquid phase from the subterranean reservoir is configured to additionally recover a portion of the existing solvent in the liquid phase and a portion of the heavy oil.   
     
     
         13 . The system of  claim 11 , comprising at least two well pairs located in the subterranean reservoir, wherein
 a first well pair is comprised of the first injector which was previously configured as a first existing injection well to inject the existing solvent into the subterranean reservoir and a first existing production well; and   a second well pair is comprised of the first NCG/vaporized solvent production well, wherein the first NCG/vaporized solvent production well was previously configured as a second existing injection well to inject the existing solvent into the subterranean reservoir or was previously configured as a second existing production well to recover the existing solvent and the heavy oil in the liquid phase from the subterranean reservoir.   
     
     
         14 . The system of  claim 11 , comprising at least three well pairs located in the subterranean reservoir, wherein
 a first well pair is comprised of the first injector which was previously configured as a first existing injection well to inject the existing solvent into the subterranean reservoir, and a first existing production well;   a second well pair is comprised of a second injector which was previously configured as a second existing injection well to inject the existing solvent into the subterranean reservoir wherein the second injector is an NCG injection well, and wherein the NCG injection well has been configured to inject the gas phase dilution agent into the subterranean reservoir, and a second existing production well; and   a third well pair is comprised of the first NCG/vaporized solvent production well which was previously configured as a third existing injection well to inject the existing solvent into the subterranean reservoir or was previously configured as a third existing production well to recover the existing solvent and the heavy oil in the liquid phase from the subterranean reservoir;   wherein each of the wells run in a substantially horizontal direction within the subterranean reservoir, and the three well pairs are oriented in a substantially horizontal direction with respect to each other in the subterranean reservoir and the third well pair is between the first well pair and the second well pair in the substantially horizontal direction.   
     
     
         15 . The system of  claim 11 , comprising at least three well pairs located in the subterranean reservoir, wherein
 a first well pair is comprised of the first injector which was previously configured as a first existing injection well to inject the existing solvent into the subterranean reservoir, and a first existing production well;   a second well pair is comprised of the first NCG/vaporized solvent production well which was previously configured as a second existing injection well to inject the existing solvent into the subterranean reservoir or was previously configured as a second existing production well to recover the existing solvent and the heavy oil in the liquid phase from the subterranean reservoir; and   a third well pair is comprised of a second NCG/vaporized solvent production well which was previously configured as a third existing injection well to inject the existing solvent into the subterranean reservoir or was previously configured as a third existing production well to recover the existing solvent and the heavy oil in the liquid phase from the subterranean reservoir;   wherein each of the wells run in a substantially horizontal direction within the subterranean reservoir, and the three well pairs are oriented in a substantially horizontal direction with respect to each other in the subterranean reservoir and the first well pair is between the second well pair and the third well pair in the substantially horizontal direction.   
     
     
         16 . The system of  claim 11 , comprising at least two well pairs and an infill well located in the subterranean reservoir, wherein
 a first well pair is comprised of the first injector which was previously configured as a first existing injection well to inject the existing solvent into the subterranean reservoir, and a first existing production well;   a second well pair is comprised of a second injector which was previously configured as a second existing injection well to inject the existing solvent into the subterranean reservoir wherein the second injector is an NCG injection well, and wherein the NCG injection well is configured to inject the gas phase dilution agent into the subterranean reservoir, and a second existing production well; and   an infill well is utilized as the first NCG/vaporized solvent production well   wherein each of the wells run in a substantially horizontal direction within the subterranean reservoir, and the two well pairs are oriented in a substantially horizontal direction with respect to each other in the subterranean reservoir and the first NCG/vaporized solvent production well is located between the first well pair and the second well pair in the substantially horizontal direction and is in fluid connection with both the first injector and the second injector.   
     
     
         17 . The system of  claim 11 , comprising at least two well pairs and an infill well located in the subterranean reservoir, wherein
 a first well pair is comprised of the first NCG/vaporized solvent production well which was previously configured as a first existing injection well to inject the existing solvent into the subterranean reservoir or was previously configured as a first existing production well to recover the existing solvent and the heavy oil in the liquid phase from the subterranean reservoir; and   a second well pair is comprised of a second NCG/vaporized solvent production well which was previously configured as a second original injection well to inject the existing solvent into the subterranean reservoir or was previously configured as a second existing production well to recover the existing solvent and the heavy oil in the liquid phase from the subterranean reservoir, wherein the second NCG/vaporized solvent production well is configured to recover a portion of the gas phase dilution agent and a portion of the vaporized solvent;   wherein the first injector is an infill well which is utilized as a first NCG injection well; and   wherein each of the wells run in a substantially horizontal direction within the subterranean reservoir, and the two well pairs are oriented in a substantially horizontal direction with respect to each other in the subterranean reservoir and the first NCG injection well is located between the first well pair and the second well pair in the substantially horizontal direction and is in fluid connection with both the first NCG/vaporized solvent production well and the second NCG/vaporized solvent production well.   
     
     
         18 . The system of  claim 11 , wherein
 the first injector is fluidly connected to the top of the reservoir to provide a gas cap; and   the reservoir contains at least one well pair comprising a first existing injection well and a first existing production well;   wherein the first existing injection well or the first existing production well is converted to the first NCG/vaporized solvent production well which was previously configured as an existing injection well to inject the existing solvent into the subterranean reservoir or which was previously configured as an existing production well to inject the existing solvent into the subterranean reservoir.   
     
     
         19 . The system of  claim 18 , wherein the subterranean reservoir comprises more than one injector fluidly connected to the top of the reservoir to provide the gas cap; wherein each injector is located to inject a gas phase dilution agent into the subterranean reservoir, so as to contact at least a portion of the gas phase dilution agent with the existing solvent and vaporize at least a portion of the existing solvent to produce a vaporized solvent. 
     
     
         20 . The system of  claim 11 , further comprising a surface facility, wherein the surface facility comprises:
 a separation facility, that is fluidly connected to at least the first NCG/vaporized solvent production well, wherein at least a portion of the recovered vaporized solvent is separated from the recovered gas phase dilution agent, forming a separated vaporized solvent and a separated gas phase dilution agent;   a compression facility, that is fluidly connected to the separation facility, wherein at least a portion of the separated gas phase dilution agent is compressed to a higher pressure to form a compressed gas phase dilution agent; and   a heating facility, that is fluidly connected to the separation facility, wherein at least a portion of the compressed gas phase dilution agent is heated to a higher temperature to form a heated gas phase dilution agent;   wherein the heating facility is fluidly connected to the first fluid injector, wherein at least a portion of the heated gas phase dilution agent is injected into the subterranean reservoir.