Method for treating shale formations using cyclic steam injection

Abstract

A mixture of heated water vapor, hot water, and optional solvent gases are injected into the formation through the wellhead, and the well and fracture network are filled with steam. The injection is ceased and the heated water vapor and solvent gases are allowed to soak, allowing the rock to take in the heat of the steam in the fractures via thermal conduction. The well is then opened allowing the well to produce hydrocarbons, and pressure of fluid in the fractures to drop. Oil and gas from the reservoir will then flow into the well and to the surface.

1 . A method of increasing production of hydrocarbons from a wellbore formed in subterranean rock formations, the method comprising:
 generating steam and injecting said steam into the wellbore;   sealing said wellbore to trap said steam, and maintaining a seal for a period of time to affect conductive heating of said rock formations;   releasing said seal to allow a flow of hydrocarbons; and   repeating the method until a desired amount of hydrocarbons is extracted.   
     
     
         2 . The method of  claim 1  wherein heat loss from injecting said steam to wellbore is reduced by installing a thermal insulation along a length of a vertical section of the wellbore. 
     
     
         3 . The method of  claim 1  wherein steam is injected into the wellbore at a flow rate to reduce heat loss. 
     
     
         4 . The method of  claim 1  wherein said steam is injected via one or more conduits, wherein multiple such conduits form an inner and outer annulus, said outer annulus containing a gas for insulation. 
     
     
         5 . The method of  claim 4  wherein a thermal packer is positioned to reduce steam loss. 
     
     
         6 . The method of  claim 1  wherein N 2  foam is injected before said steam injection to increase said hydrocarbon production. 
     
     
         7 . The method of  claim 1  wherein the well is swabbed before said steam injection to increase said hydrocarbon production. 
     
     
         8 . The method of  claim 1  wherein other gases are injected along with said steam. 
     
     
         9 . The method of  claim 1  wherein an aerial cooler is positioned to prepare hot produced fluids for existing surface production equipment. 
     
     
         10 . The method of  claim 1  wherein said method is employed in a shale in an oil window. 
     
     
         11 . The method of  claim 1  wherein said method is employed in a shale in a gas window. 
     
     
         12 . The method of  claim 1  wherein said method is employed in oil wells, gas wells, or gas condensate wells. 
     
     
         13 . The method of  claim 1  wherein additives are injected along with the steam, said additives comprising at least one of salts, surfactants, chemically reactive agents, pH-altering agents, nanoparticles, gases, and solvents. 
     
     
         14 . The method of  claim 1  wherein agents are injected intermittently with steam injection, said agents comprising at least one of surfactants, chemically reactive agents, pH-altering agents, nanoparticles, gases, and solvents. 
     
     
         15 . The method of  claim 1  wherein steam is generated downhole in said wellbore, where said steam may be generated by either downhole steam generators, electromagnetic heating, downhole electrical heater cables, or exothermically reactive injectants. 
     
     
         16 . The method of  claim 1  wherein steam is cyclically injected in two or more neighboring wells having connected fracture networks. 
     
     
         17 . The method of  claim 1  wherein steam is injected in one well while steam and hydrocarbons are being produced in a neighboring well having a connected fracture network, followed by a period of switching which well is being injected with steam and which well is producing steam and hydrocarbons.