Method and apparatus for centralized thermal recovery based on an oil reservoir by electric heating edge and bottom water layers with horizontal wells

Abstract

A method for centralized thermal recovery, comprising: first, providing a horizontal well in the upper part of the water layer in which a heating system is configured; then centralized preheating the oil reservoir via electrically heating the water layer, then starting centralized producing the oil after the top of the oil layer reaches an expected temperature. An electric heating system for horizontal well to heat the water, comprising, an inner liner with the upper half slotted, a heat insulation board, a sealing board, a vacuum chamber, an electric heater, a ferrite permanent magnet rod.

1 . A method for centralized thermal recovering oil, for an oil reservoir with a water layer and an oil layer, comprising:
 providing a horizontal well in the upper part of the water layer,   centralized preheating the oil reservoir via centralized heating the water layer, and   starting centralized producing the oil after the top of the oil layer reaches an expected temperature.   
     
     
         2 . the method according to  claim 1 , wherein, comprising
 side-drilling the horizontal well from an old well extending into the top water layer, or   drilling the horizontal well that meets the water layer directly.   
     
     
         3 . the method according to  claim 2 , wherein, comprising
 drilling multi-branch horizontal wells in the top water layer.   
     
     
         4 . the method according to  claim 1 , wherein, comprising
 arranging the horizontal wells in a plane in the water layer, and   determining the depth position of the horizontal section of the horizontal well based on the oil reservoir volume, and   completing the horizontal well with gravel open-hole.   
     
     
         5 . the method according to  claim 1 , wherein, comprising
 providing a heating system inside the horizontal well.   
     
     
         6 . the method according to  claim 5 , wherein, comprising
 providing an electric-heating system inside the horizontal well.   
     
     
         7 . the method according to  claim 1 , wherein, comprising
 centralized heating the overall oil reservoir in each individual trap when electrically heating the water layer.   
     
     
         8 . the method according to  claim 1 , wherein, comprising
 keeping the pressure of the oil reservoir lower than the fracture pressure of the reservoir when electrically heating the water layer.   
     
     
         9 . the method according to  claim 1 , wherein, comprising
 starting to electrically heat formation water at high-power, and then reducing power to heat water, comprising   keeping the temperature of the horizontal well lower than Curie temperature.   
     
     
         10 . the method according to  claim 8 ,  9 , wherein, comprising
 decreasing the pressure or temperature of the oil reservoir to keep the pressure of the oil reservoir lower than the fracture pressure and the temperature lower than Curie temperature.   
     
     
         11 . the method according to  claim 1 , wherein, comprising
 stopping electrically heating after the centralized oil producing.   
     
     
         12 . the method according to  claim 1 , wherein, comprising:
 preheating the oil reservoir until the top oil becomes movable and recoverable.   
     
     
         13 . the method according to  claim 1 , wherein, comprising:
 after centralized producing the oil, separating the residual oil and the water by gravity differentiation, and   reheating the water for secondary oil recovery.   
     
     
         14 . An electric-heating system for horizontal well, comprising,
 an inner liner having a cavity;   a heat insulation board inserting into the cavity along the diameter of the inner liner;   two sealing boards provided on each side of the lower liner;   an electric heater provided on the heat insulation board in the middle of the upper cavity; and   a ferrite permanent magnet rod fixed on the inner of the upper inner liner; wherein   the lower half of the inner liner, the heat insulation board, and the sealing board form a vacuum chamber.   
     
     
         15 . the electric-heating system according to  claim 13 , wherein,
 the insulation board and the vacuum-enclosed chamber is configured to reduce downward transmission of thermal energy.   
     
     
         16 . the electric-heating system according to  claim 13 , wherein,
 the sealing board is configured to be made of a high density insulation plate.   
     
     
         17 . the electric-heating system according to  claim 13 ,  15 , comprising,
 the sealing boards provided on each side of the lower liner keep the inner liner stable; and   the insulation board is configured to be level and the slotted upper inner liner is configured to be on the top.   
     
     
         18 . the electric-heating system according to  claim 13 , wherein,
 the slotted upper half of the inner liner is configured to allow water and heat to flow.   
     
     
         19 . the electric-heating system according to  claim 13 , comprising,
 the electric heater is configured to be waterproof, spiral, and in series connection, and to   reduce the scale formation.   
     
     
         20 . the electric-heating system according to  claim 13 , wherein,
 the ferrite permanent magnet rod is configured to remove the scale.   
     
     
         21 . the electric-heating system according to  claim 13 , wherein,
 the insulation board and the vacuum chamber are configured to keep from the downward heat loss.