System and method for producing oil

Abstract

The present invention provides a system and method for producing oil in which an ether-containing formulation is injected into a formation containing oil and an oil-immiscible formulation is injected into the formation, and oil is produced from the formation. The oil-immiscible formulation has a salt content of at most 5 wt. % and is comprised of water having a salt content of at most 5 wt. %.

What is claimed is: 
     
         1 . A system for producing oil from an underground formation comprising:
 a first well above the formation;   a mechanism to inject an ether-containing formulation comprising into the formation, where the ether-containing formulation comprises an ether containing from 2 to 6 carbon atoms;   a mechanism to inject an oil-immiscible formulation into the formation where the oil-immiscible formulation has a salt content of at most 5 wt. % and is comprised of water having at most 5 wt. % salt content; and   a mechanism to produce oil from the formation,   wherein at least one of the mechanism to inject the ether-containing formulation into the formation, the mechanism to inject an oil-immiscible formulation into the formation, or the mechanism to produce oil from the formation is located at the first well.   
     
     
         2 . The system of  claim 1  wherein the ether-containing formulation comprises from 5-100 wt. % dimethyl ether. 
     
     
         3 . The system of  claim 1  wherein the oil-immiscible formulation comprises at least 80 wt. % water having a salt content of at most 5 wt. %. 
     
     
         4 . The system of  claim 1  wherein the oil-immiscible formulation is comprised of water having a salt content of at most 3 wt. %. 
     
     
         5 . The system of  claim 1  wherein the first well comprises an array of from 5 to 500 wells. 
     
     
         6 . The system of  claim 1  further comprising a second well at a distance from the first well, wherein the mechanism to inject the ether-containing formulation into the formation is located at the first well and the mechanism to produce oil from the formation is located at the second well. 
     
     
         7 . The system of  claim 6  wherein the second well comprises an array of from 5 to 500 wells. 
     
     
         8 . The method of  claim 6  wherein the mechanism to inject the oil-immiscible formulation into the formation is located at the first well. 
     
     
         9 . The system of  claim 6 , further comprising a third well at a distance from the first well and at a distance from the second well wherein the mechanism to inject the ether-containing formulation into the formation is located at the first well and the mechanism to inject the oil-immiscible formulation into the formation is located at the third well. 
     
     
         10 . The system of  claim 9  wherein the third well comprises an array of from 5 to 500 wells. 
     
     
         11 . The system of  claim 1  wherein the mechanism for injecting the ether-containing formulation is located at the first well and further comprising a mechanism for producing the ether-containing formulation adjacent to the first well. 
     
     
         12 . The system of  claim 1  wherein the mechanism for producing oil from the formation also produces the ether and water from the formation, where the system further comprises a mechanism for separating a mixture of ether and water from the oil produced by the mechanism for producing oil from the formation. 
     
     
         13 . The system of  claim 1  wherein the mechanism for injecting the oil-immiscible formulation into the formation is configured to inject the oil-immiscible formulation into the formation after the ether-containing formulation is initially injected into the formation by the mechanism for injecting the ether-containing formulation into the formation. 
     
     
         14 . A method for producing oil, comprising:
 injecting an ether-containing formulation into a formation containing oil, where the ether-containing formulation comprises an ether containing from 2 to 6 carbons;   injecting an oil-immiscible formulation into the formation, where the oil-immiscible formulation comprises water having a salt content of less than 5 wt. %; and   producing oil from the formation.   
     
     
         15 . The method of  claim 14  further comprising the steps of:
 contacting the ether-containing formulation with oil in the formation to mobilize oil in the formation wherein mobilizing the oil leaves an oil residuum containing an ether in the formation; and 
 contacting the oil-immiscible formulation with the oil residuum and separating a portion of the ether from the oil residuum into the oil-immiscible formulation. 
 
     
     
         16 . The method of  claim 14  further comprising the steps of:
 producing the ether and water with the oil from the formation; and 
 separating the ether and water from the produced oil, ether, and water and injecting at least a portion of the separated ether and water into the formation. 
 
     
     
         17 . The method of  claim 14  wherein the ether-containing formulation comprises from 5-100 wt. % dimethyl ether. 
     
     
         18 . The method of  claim 14  wherein the oil-immiscible formulation comprises at least 80 wt. % water having a salt content of at most 5 wt. %. 
     
     
         19 . The method of  claim 14  wherein the oil-immiscible formulation is comprised of water having a salt content of at most 3 wt. %. 
     
     
         20 . The method of  claim 14  wherein the ether-containing formulation comprises one or more hydrocarbons other than the ether, carbon dioxide, carbon monoxide, nitrogen, or mixtures thereof. 
     
     
         21 . The method of  claim 14  further comprising heating the ether-containing formulation prior to injecting the ether-containing formulation into the formation or while within the formation. 
     
     
         22 . The method of  claim 14  wherein the ether-containing formulation is injected into the formation at a pressure of from 0 to 37,000 kilopascals above the formation pressure as determined immediately prior to injecting the ether-containing formulation into the formation. 
     
     
         23 . The method of  claim 14  wherein the ether-containing formulation comprises the ether and water, where the water in the ether-containing formulation has a salt content at least 1 wt. % greater than the salt content of the oil-immiscible formulation. 
     
     
         24 . The method of  claim 14  further comprising contacting a sufficient amount of the ether-containing formulation with oil in the formation to increase the swelling factor of the oil in the formation. 
     
     
         25 . The method of  claim 14  further comprising contacting a sufficient amount of the ether-containing formulation with oil in the formation to reduce the viscosity of the oil in the formation. 
     
     
         26 . The method of  claim 14  further comprising contacting a sufficient amount of the ether-containing formulation with oil in the formation to reduce the bubble point of the oil in the formation. 
     
     
         27 . The method of  claim 14  further comprising the step of converting the oil produced from the formation into a material selected from the group consisting of a transportation fuel, a heating fuel, a lubricant, a chemical, and a polymer. 
     
     
         28 . The method of  claim 14  wherein the oil-immiscible formulation is injected into the formation after initially injecting the ether-containing formulation into the formation.