Method for treating hydraulically-fractured wells in shales

Abstract

The present invention is directed to an improved method for the production of hydrocarbons from shales. A mixture of heated water vapor and 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.

I claim: 
     
         1 . A method of increasing hydrocarbon production from a well bore formed in subterranean rock formations, the method comprising the steps of:
 generating steam and injecting said steam into the well bore;   sealing said well to trap said steam, and maintaining the seal for a predetermined amount of time to affect conductive heating of said rock formations; and   releasing said seal to allow the flow of hydrocarbons.   
     
     
         2 . The method of  claim 1  wherein heat loss from injecting said steam to well bore is minimized by lining said well with thermal insulation. 
     
     
         3 . The method of  claim 1  wherein heat loss from steam to well bore is minimized by injecting said steam at maximum flow rates. 
     
     
         4 . The method of  claim 1  wherein said steam is injected via one or more conduits, each of said conduits having an inner and outer annulus, said outer annulus containing a low pressure gas for insulation. 
     
     
         5 . The method of  claim 4  wherein said inner annulus is formed from a slotted tube. 
     
     
         6 . The method of  claim 4  wherein a thermal packer is positioned within the conduits to reduce steam loss. 
     
     
         7 . The method of  claim 1  wherein said steam is injected at low pressures. 
     
     
         8 . The method of  claim 1  wherein N2 foam is used before said steam injection to increase said hydrocarbon production. 
     
     
         9 . The method of  claim 1  wherein swabbing is used before said steam injection to increase said hydrocarbon production. 
     
     
         10 . The method of  claim 1  wherein other gases are injected along with said steam. 
     
     
         11 . The method of  claim 1  wherein an aerial cooler is positioned near the wellhead to prepare hot produced fluids for existing surface production equipment. 
     
     
         12 . The method of  claim 1  wherein said method is employed in a shale in an oil window. 
     
     
         13 . The method of  claim 1  wherein said method is employed in a shale in a gas window. 
     
     
         14 . The method of  claim 1  wherein said method is employed in oil wells, gas wells, or gas condensate wells. 
     
     
         15 . 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. 
     
     
         16 . 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. 
     
     
         17 . 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. 
     
     
         18 . The method of  claim 1  wherein steam is cyclically injected in two or more neighboring wells having connected fracture networks.