Side and bottom water layer thermal recovery method allowing electrically heating oil deposit in horizontal well

Abstract

Thermal recovery method via electrically heating edge- and bottom-water layer by horizontal wells is presented. Edge- and bottom-water layer is electrically heated by using a plurality of horizontal wells that are located at the upper part of edge- and bottom-water layer, so that the temperature of the whole oil deposit is increased to a state in which in-place oil can flow, by using the theory of centralized heat supply to improve the thermal recovery efficiency. Also disclosed is an electric heating structure for a horizontal well. The electric heating structure is provided with a sieve pipe. A plurality of ferromagnetic permanent magnets is deployed at the upper part of the inner side of the sieve pipe. Spring-shaped electric heating rods serially connected together are disposed in the middle. A heat separation board is disposed in the position of a horizontal diameter. A half lower sieve pipe is sealed and is hollow and jointly separate heat in combination with the heat separation board, and the down transfer of heat energy is reduced.

1 . One thermal recovery method via electrically heating edge- and bottom-water layers, and the electrical heaters are settled in the horizontal wells so that the water layers could be electrically evenly heated until the temperature of the whole reservoir rises up to what needed for in-place oil to flow, the in-place oil could be thermally recovered; which is different from the method of partially heating oil layer at present. 
     
     
         2 . The structure design characteristic of electrical heater of the horizontal well is that several ferrite permanent magnet bars are fixed at the top of the inner liner and the spring electrical heating bars with series connection are set in the middle part; heat insulation board is set at the horizontal diameter of the liner; the lower liner, in cooperation with heat insulation board to insulate heat, is sealed in vacuum to reduce the downward transmission of thermal energy. 
     
     
         3 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal wells, which is stated in  claim 1 , its characteristic is that the Principle Foundation  1  belongs to the central heating and the temperature of the whole reservoir could be risen by heating the edge- and bottom-water layers, which is different from the conventional thermal recovery method by partially heating the oil layer within single well. 
     
     
         4 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal wells, which is stated in  claim 1 , its characteristic is that the Principle Foundation  2  points out that the oil, gas and water layers can be regarded as a sealed temperature and pressure system, like the pressure cooker; the temperature and pressure of inner reservoir can be improved quickly to the flow state of the in-place oil by electrically heating the edge- and bottom-water layers of the oil reservoirs. 
     
     
         5 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal wells, which is stated in  claim 1 , its characteristic is that the Principle Foundation  3  is the “immersion heater” electric kettle heating method; heating the edge- and bottom-water layer of oil reservoirs through water-proof electrical heater so that the whole oil reservoir can be heated with saving time, saving electricity, saving of fort, cheap, convenience, safety, environmental protection and high efficiency. 
     
     
         6 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal wells, which is stated in  claim 1 , its characteristic is that the Principle Foundation  4  is “steaming buns with steamer”; controlling the lifting range of reservoir temperature and pressure by confining the electrical heating time, temperature and recovery methods and save energy by controlling the position of horizontal well in the water layer. 
     
     
         7 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal wells, which is stated in  claim 1 , its characteristic is that the Principle Foundation  5  is gravity differentiation phenomenon of cold and hot water; heat loss of electrically heating edge- and bottom-water layers only behaves as the heat conduction between upper hot water and lower cold water; most of the thermal energy moves upward; keeping eletrically heating the edge- and bottom-water layers can improve the temperature of the whole reservoir effectively. 
     
     
         8 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal wells, which is stated in  claim 1 , its characteristic is that the Principle Foundation  6  points out that most oft he oil and gas reservoirs develope edge- and bottom-water layers and contain sufficient formation water resources, which can provide enough material guarantee for electrically heating edge- and bottom-water layers by horizontal wells, and at the sametime, provide good refrigerant for electrical heater. 
     
     
         9 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal wells, which is stated in  claim 1 , its characteristic is that the Principle Foundation  7  is the representation of geothermal gradient; the deeper the formation water layer buries, the higher the geothermal temperature is and the less electrical energy is needed and the more energy-saving the thermal recovery method via electrically heating edge- and bottom-water layers is. 
     
     
         10 . According to the thermal recovery method via electrically heating edge-and bottom-water layers by horizontal well s, which is stated in  claim 1 , its characteristic is that the Principle Foundation  8  points out that according to the relationship between formation water temperature and pressure, the formation pressure is 3˜20 MPa and the water boiling point is 132.9˜211.4° C. The higher the pressure is, the higher the boiling point is; when the temperature is below the boiling point, the reservoir can be heated to reach the oil movable state (condition for in-place oil to flow 80˜150° C.). 
     
     
         11 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal well s, which is stated in  claim 1 , its characteristic is that the Principle Foundation  9  points out that at present the long distance transportation material is relatively mature and the technic of electrically heating magnet descaling can settle the scaling problem during electrically heating process effectively and keep the heating effect of electrical heater in good state, which can satisfy the requirements of electrically heating edge- and bottom-water layers by horizontal wells in deep and super-deep layers. 
     
     
         12 . According to the thermal recovery method via electrically heating edge- and bottom-water layers by horizontal well s, which is stated in  claim 1 , its characteristic is that the Principle Foundation  10  uses the viscosity-reduction effect/wax-precipitation effect of in-place oil, the expansion pressure of formation, gas driving effect by overflow of the dissolved gas from water to recover oil.