Bottom-up solvent-aided process and system for hydrocarbon recovery

Abstract

Solvent may be injected into a hydrocarbon reservoir at an increasingly elevated vertical level to allow vapor of the solvent to contact and mobilize viscous hydrocarbons in the reservoir, for producing mobilized hydrocarbons. Solvent may be injected into a mobile zone below a viscous hydrocarbon zone, to allow solvent vapor to ascend to mobilize viscous hydrocarbons in the viscous hydrocarbon zone. A vertical or slanted injection well may be used to inject the solvent into the reservoir, and a production well spaced horizontally apart from the injection well may be used to produce fluids from the reservoir. A bottom-up solvent-aided process may comprise injecting water and liquid solvent into the mobile zone, and then injecting heated water and solvent into the mobile zone.

What is claimed is: 
     
         1 . A method comprising:
 injecting a solvent into a hydrocarbon reservoir at an increasingly elevated vertical level to allow vapor of the solvent to contact and mobilize viscous hydrocarbons in the reservoir; and   producing mobilized hydrocarbons from the reservoir.   
     
     
         2 . The method of  claim 1 , comprising vaporizing the solvent to allow vapor of the solvent to ascend in the reservoir, wherein the vertical level at which the solvent enters the reservoir is increasingly elevated as viscous hydrocarbons are mobilized by the solvent and are displaced from their original location. 
     
     
         3 . The method of  claim 1 , wherein the injecting comprises injecting the solvent into a mobile zone below a viscous hydrocarbon zone in the reservoir, and increasingly elevating the vertical level of solvent injection as the mobile zone expands upward due to mobilization of viscous hydrocarbons in the hydrocarbon zone, gravity drainage of mobilized viscous hydrocarbons, and lateral displacement of mobilized viscous hydrocarbons. 
     
     
         4 . The method of  claim 1 , wherein the solvent is injected through an injection well having a plurality of injection openings distributed at different vertical levels. 
     
     
         5 . The method of  claim 4 , wherein the injection openings are distributed between a top level and a bottom level of the hydrocarbon reservoir. 
     
     
         6 . The method of  claim 4 , comprising feeding the solvent and a heated aqueous fluid to the injection well for injection into the reservoir through the injection openings. 
     
     
         7 . The method of  claim 6 , wherein the heated aqueous fluid comprises heated water. 
     
     
         8 . The method of  claim 6 , wherein the heated aqueous fluid comprises steam. 
     
     
         9 . The method of  claim 6 , wherein the feeding comprises feeding a mixture of the solvent and the heated aqueous fluid to the injection well. 
     
     
         10 . The method of  claim 6 , wherein the feeding comprises feeding the solvent and the heated aqueous fluid separately to the injection well. 
     
     
         11 . The method of  claim 6 , wherein the feeding comprises alternately feeding the solvent and the heated aqueous fluid to the injection well. 
     
     
         12 . The method of  claim 4 , wherein the solvent is at least partly vaporized in the injection well. 
     
     
         13 . The method of  claim 1 , wherein the solvent is at least partly vaporized in the reservoir. 
     
     
         14 . The method of  claim 4 , wherein the heated aqueous fluid is conditioned to facilitate vaporization of the solvent before the solvent contacts viscous hydrocarbons in the reservoir and subsequent condensation of the solvent when the solvent comes into contact with viscous hydrocarbons. 
     
     
         15 . The method of  claim 1 , wherein the solvent comprises an alkane or alkene having 2 to 9 carbon atoms. 
     
     
         16 . The method of  claim 3 , wherein the mobile zone is a pre-existing water zone at a base portion of the reservoir. 
     
     
         17 . The method of  claim 3 , comprising creating the mobile zone at a base portion of the reservoir prior to injecting the solvent. 
     
     
         18 . The method of  claim 3 , comprising injecting a non-condensing gas into the mobile zone. 
     
     
         19 . The method of  claim 4 , wherein the mobilized hydrocarbons are produced from a vertical or slanted production well. 
     
     
         20 . The method of  claim 3 , comprising providing a plurality of wells extending into the mobile zone through the hydrocarbon zone, the plurality of wells comprising a production well for producing fluids from the mobile zone, and an injection well for injecting the solvent into the reservoir at different vertical levels. 
     
     
         21 . The method of  claim 20 , wherein the plurality of wells comprises spaced apart first and second wells each configured for use alternately as the injection well or the production well, and wherein the solvent is alternately injected through one of the first or second wells, and the mobilized hydrocarbons are alternately produced through the other of the first and second wells. 
     
     
         22 . The method of  claim 1 , comprising injecting the solvent with a heated aqueous fluid and producing mobilized hydrocarbons at different horizontal locations within the mobile zone, thus facilitating horizontal fluid flow within the mobile zone. 
     
     
         23 . The method of  claim 22 , comprising concurrently injecting the solvent and heated aqueous fluid and producing mobilized hydrocarbons. 
     
     
         24 . The method of  claim 22 , comprising alternately injecting the solvent and heated aqueous fluid and producing mobilized hydrocarbons. 
     
     
         25 . A system for recovering hydrocarbons from a subterraneous reservoir comprising an overlying viscous hydrocarbon zone and an underlying mobile zone, the system comprising:
 an injection well extending into the mobile zone through the hydrocarbon zone, the injection well having injection openings distributed at different vertical levels in both the hydrocarbon zone and the mobile zone; and   a production well spaced horizontally apart from the injection well and extending into the mobile zone for producing mobilized hydrocarbons from the mobile zone;   wherein the injection well is configured to inject a solvent and a heated aqueous liquid into the mobile zone through injection openings adjacent to the mobile zone to mobilize hydrocarbons in the hydrocarbon zone, such that the solvent can be injected into the reservoir at increasingly elevated vertical levels when mobilized hydrocarbons in the hydrocarbon zone drain downward due to gravity.   
     
     
         26 . The system of  claim 25  wherein the injection well is configured to inject a non-condensing gas into the reservoir. 
     
     
         27 . The system of  claim 25 , wherein the injection well and the production well are vertical or slanted wells. 
     
     
         28 . The system of  claim 25 , comprising an array of injection and production wells spaced horizontally apart from one another. 
     
     
         29 . The system of  claim 25 , wherein each one of the injection well and the production well is configured for use alternately as an injection well or a production well. 
     
     
         30 . A method comprising:
 injecting a solvent into a hydrocarbon reservoir through a mobile zone below a viscous hydrocarbon zone in the hydrocarbon reservoir, to allow vapor of the solvent to ascend in the reservoir to mobilize viscous hydrocarbons in the viscous hydrocarbon zone, wherein the solvent is injected through an injection well completed to provide a plurality of injection openings distributed over a vertical extent that initially extends into both the mobile zone and the viscous hydrocarbon zone; and   producing mobilized hydrocarbons from the reservoir through the mobile zone with a production well, wherein the production well is horizontally spaced from the injection well to provide a horizontal pressure gradient in the mobile zone for inducing horizontal movement of fluids within the mobile zone.   
     
     
         31 . The method of  claim 30 , comprising vaporizing the solvent to allow vapor of the solvent to ascend in the reservoir. 
     
     
         32 . The method of  claim 30 , comprising increasingly elevating the vertical level of solvent injection as the mobile zone expands upward due to mobilization of viscous hydrocarbons in the hydrocarbon zone, gravity drainage of mobilized viscous hydrocarbons, and lateral displacement of mobilized viscous hydrocarbons. 
     
     
         33 . The method of  claim 30 , wherein the injection openings are distributed between a top level and a bottom level of the hydrocarbon reservoir. 
     
     
         34 . The method of  claim 30 , comprising feeding the solvent and a heated aqueous fluid to the injection well for injection into the reservoir through the injection openings. 
     
     
         35 . The method of  claim 34 , wherein the heated aqueous fluid comprises heated water. 
     
     
         36 . The method of  claim 34 , wherein the feeding comprises feeding a mixture of the solvent and the heated aqueous fluid to the injection well. 
     
     
         37 . The method of  claim 30 , wherein the solvent is at least partly vaporized in the injection well. 
     
     
         38 . The method of  claim 30 , wherein the solvent is at least partly vaporized in the reservoir. 
     
     
         39 . The method of  claim 30 , wherein the solvent comprises an alkane or alkene having 2 to 9 carbon atoms. 
     
     
         40 . The method of  claim 30 , wherein the mobile zone is a pre-existing water zone at a base portion of the reservoir. 
     
     
         41 . The method of  claim 30 , comprising creating the mobile zone at a base portion of the reservoir prior to injecting the solvent. 
     
     
         42 . The method of  claim 30 , comprising injecting a non-condensing gas into the mobile zone. 
     
     
         43 . A method for recovery of hydrocarbons in a bottom-up solvent-aided process from a hydrocarbon reservoir comprising an overlying viscous hydrocarbon zone and an underlying mobile zone, the method comprising:
 injecting water and liquid solvent into the mobile zone, to improve and maintain fluid communication within the mobile zone;   injecting heated water and solvent into the mobile zone to allow vapor of the solvent to ascend in the hydrocarbon reservoir to mobilize viscous hydrocarbons in the viscous hydrocarbon zone, wherein the heated water and solvent are injected through an injection well completed to provide a plurality of injection openings distributed over a vertical extent in at least the mobile zone; and   producing mobilized hydrocarbons from the reservoir through the mobile zone with a production well, wherein the production well is horizontally spaced from the injection well to provide a horizontal pressure gradient in the mobile zone for inducing horizontal movement of fluids within the mobile zone.   
     
     
         44 . The method of  claim 43 , wherein a mixture of the heated water and solvent is fed into the injection well. 
     
     
         45 . The method of  claim 43 , wherein the heated water is heated to a temperature sufficient to vaporize at least a substantial portion of the solvent in the injection well. 
     
     
         46 . The method of  claim 43 , wherein the heated water is heated to a temperature sufficient to vaporize at least a substantial portion of the solvent when the solvent is injected into in the mobile zone. 
     
     
         47 . The method of  claim 43 , wherein the water is conditioned to facilitate vaporization of the solvent before the solvent contacts viscous hydrocarbons in the reservoir and subsequent condensation of the solvent when the solvent comes into contact with viscous hydrocarbons. 
     
     
         48 . The method of  claim 43 , wherein the solvent comprises an alkane or alkene having 2 to 9 carbon atoms. 
     
     
         49 . The method of  claim 43 , wherein the injection well and production well are vertical or slanted wells. 
     
     
         50 . The method of  claim 43 , comprising concurrently producing mobilized hydrocarbons and injecting the heated water and solvent. 
     
     
         51 . The method of  claim 43 , comprising alternately injecting the heated water and solvent and producing mobilized hydrocarbons.