Enhanced hydrocarbon recovery using microwave heating

Abstract

A downhole tool utilizing microwave energy for stimulating production of hydrocarbons from a drilled well. A microwave generator is disposed within the body of the tool and supplied with power from the surface. Microwaves generated by the tool are applied to a refractory dielectric material disposed at a lower end of the tool or to dielectric material in fluids circulated into the wellbore, or directly to the formation.

1 . A downhole tool, comprising:
 an elongated body having dimensions for fitting into a wellbore suitable for production of hydrocarbons, the enclosure having a proximal end adapted for connection to a means for lowering the enclosure into the wellbore;   a microwave generator generating electromagnetic energy at predetermined microwave wavelengths, the generator disposed within the body and operable to receive power through a cable extending through the proximal end of the enclosure;   a transmission line for transmitting the electromagnetic energy from the microwave generator to a head of an applicator located near a distal end of the body, remote from the microwave generator; and   a head attached to the body and forming a distal end of the tool.   
     
     
         2 . The downhole tool of  claim 1 , wherein at least a portion of at least one wall of the head unit being comprised of a microwave transparent, refractory material, and wherein the applicator is located at least partially within the head and radiates microwave energy through the microwave transparent refractory material. 
     
     
         3 . The downhole tool of  claim 2 , wherein the at least one exterior wall of the head is comprised of an abrasion-resistant, refractory material. 
     
     
         4 . The downhole tool of  claim 1 , further comprising at least one microwave absorbable element disposed within the head for heating the head in response to absorbing at least a portion of said microwave energy from the applicator. 
     
     
         5 . The downhole tool of  claim 3 , wherein the at least one microwave absorbing element material is comprised of one of silicon carbide, graphite, and silicon-nitride. 
     
     
         6 . The downhole tool of  claim 1 , wherein the transmission line comprises a waveguide. 
     
     
         7 . The downhole tool of  claim 1 , further comprising thermal insulation disposed within the body between the microwave generator and the head. 
     
     
         8 . The downhole tool of  claim 1 , further including means for cooling the microwave generator. 
     
     
         9 . The downhole tool of  claim 1 , wherein the microwave generator and the head are separated by a predetermined distance sufficient to substantially reduce transfer of heat from the head to the microwave generator. 
     
     
         10 . An apparatus for stimulating production in a well drilled through a hydrocarbon-bearing formation, comprising:
 a downhole tool disposed within a wellbore adjacent to a formation to be heated by the downhole tool comprising,
 an elongated body having dimensions for fitting into a wellbore suitable for production of hydrocarbons, the enclosure having a proximal end adapted for connection to a means for lowering the enclosure into the wellbore; 
 a microwave generator generating electromagnetic energy at predetermined microwave wavelengths, the generator disposed within the body and operable to receive power through a cable extending through the proximal end of the enclosure; 
 a transmission line for transmitting the electromagnetic energy from the microwave generator to a head of an applicator located near a distal end of the body, remote from the microwave generator; 
 a head attached to the body and forming a distal end of the tool; 
   means for lowering the downhole tool into the wellbore extending from the earth's surface above the wellbore, into the wellbore and connect to the downhole tool;   a power source located on the earth's surface; and   a cable for coupling the power from the power source to the microwave generator, the cable running down the wellbore.   
     
     
         11 . The apparatus of  claim 10 , wherein at least a portion of at least one wall of the head unit is comprised of a microwave transparent, refractory material. 
     
     
         12 . The apparatus of  claim 10 , wherein the at least one exterior wall of the head is comprised of an abrasion-resistant, refractory material. 
     
     
         13 . The apparatus of  claim 10 , further comprising at least one microwave absorbable element disposed within the head for heating the head in response to absorbing at least a portion of said microwave energy from the applicator. 
     
     
         14 . The apparatus of  claim 10 , wherein the at least one microwave absorbing element material is comprised of one of silicon carbide, graphite, and silicon-nitride. 
     
     
         15 . The apparatus of  claim 10 , wherein the transmission line comprises a waveguide. 
     
     
         16 . The apparatus of  claim 10 , further comprising thermal insulation disposed within the body between the microwave generator and the head. 
     
     
         17 . The apparatus of  claim 10 , further comprising fluid containing microwave absorbable material within the borehole adjacent to the head. 
     
     
         18 . A method for stimulating hydrocarbon recovery from a wellbore comprising:
 lowering a downhole tool into a wellbore adjacent to a hydrocarbon bearing formation of interest, the downhole comprising:
 an elongated body dimensioned and shaped for fitting into a wellbore drilled for production of hydrocarbons; 
 a microwave generator disposed within the body, near a proximal end of the body, for generating electromagnetic energy at predetermined microwave wavelengths, the microwave generator adapted for receiving power through a cable extending from the surface; 
 a transmission line for transmitting the electromagnetic energy from the microwave generator to an applicator located near a distal end of the body, remote from the generator; and 
 a head attached to a distal end of the body; and 
   applying power to the microwave generator with a cable extending from a power supply on the surface to the tool within the wellbore.   
     
     
         19 . The method of  claim 18 , wherein the tool is lowered on continuous tubing. 
     
     
         20 . The method of  claim 18 , further comprising circulating within the wellbore near the downhole tool a fluid containing dielectric material for heating by microwaves generated by the tool. 
     
     
         21 . The method of  claim 20 , wherein at least a portion of at least one wall of the head unit being comprised of a microwave transparent, refractory material, and wherein the applicator is located at least partially within the head and radiates microwave energy through the microwave transparent refractory material, to the microwave absorbable material. 
     
     
         22 . The method of  claim 18 , wherein the tool further comprises at least one microwave absorbable element disposed within the head for heating the head in response to absorbing at least a portion of said microwave energy from the applicator. 
     
     
         23 . The method of  claim 22 , wherein the at least one microwave absorbing element material is comprised of one of silicon carbide, graphite, and silicon-nitride.