Oil deposit extraction method of solvent assisted fireflooding gravity drainage

Abstract

The invention relates to an oil deposit extraction method of solvent assisted fireflooding gravity drainage. The method comprises a first step that the extraction area of the oil deposit is provided with a horizontal producing well and an injection-production pattern of a vertical injecting well, the horizontal producing well and the vertical injecting well are arranged on the same vertical section of the same oil layer and form an injection-production well group, and a second step that a cosolvent horizontal well is arranged between the adjacent injection-production well group of the oil layer in the first step. The cosolvent has the function of dissolving and viscosity reduction of the crude oil, the viscosity of the oil layer on the flank of the horizontal producing well of the injection-production well group is reduced substantially, and the effective production time is long and the recovery efficiency is high. Moreover, due to the horizontal tractive effort of a cosolvent cavity of the horizontal flank, a large amount of air expands toward the flank following the combustion zone, and therefore the safety risk that the air penetrates into the production well bottom directly is lowered.

Description

technical field [0001] The invention relates to a method for recovering an oil reservoir by solvent-assisted fire flooding and gravity drainage. Background technique [0002] The Toe-to Heel Air Injection (THAI) technology is a patented technology of Petrobank, Canada. Its technical principle is to deploy a horizontal production well and a vertical injection well in the same vertical section of the same oil layer. The horizontal section of the production well is located at the bottom of the oil layer, 1 to 2 meters away from the bottom of the oil layer. The vertical injection well is located vertically above the toe of the horizontal section of the horizontal production well, and the bottom of the vertical injection well is 5 to 7 meters away from the toe of the horizontal section of the horizontal production well. rice. During the production process of fire flooding, the vertical injection well and the horizontal production well first adopt steam stimulation or downhole el...

AI Technical Summary

Problems solved by technology

Laboratory experiments show that the fire flooding gravity drainage technology has the advantages of simple well pattern, fast production rate, and high recovery rate. However, Petrobank's THAI pilot test in the Whitesands project area shows that the fundamental limitations of THAI technology include the following three points The first is that when the coking zone in the burning process of the oil layer is relatively thin, and the sealing performance of the horizontal combustion section of the horizontal production well is poor, the air injected by the vertical injection well will easily enter the horizontal section of the horizontal production well, causing fire to escape, thereby burning If the screen in the horizontal section is damaged, there will be serious safety hazards; second, for ultra-heavy oil reservoirs with too high viscosity (underground viscosity > 1 million centipoise), due to the large resistance of the fire line to the lateral flank of the horizontal section, the pre-combustion The edge continues to advance along the horizontal section, while the combustion range of the flank is only 5-10 meters, which cannot effectively exploit the oil reservoir reserves between adjacent well groups; During the oil production process, the movable oil zone formed is relatively narrow, and a large amount of crude oil is burned by the injected air. According to incomplete estimates, during the pilot test of THAI in the Whitesands project area, the average air-swept area of ​​each well group, About 30% of the crude oil is burned, so the recovery rate and production efficiency are greatly reduced

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