Fracture-cave type carbonate reservoir waterflooding oil replacement recovery method

Abstract

The invention discloses a fracture-cave type carbonate reservoir waterflooding oil replacement recovery method, comprising the steps: 1, pilot flooding; in case of inadequate fracture-cave type reservoir elastic energy, pilot flooding is implemented within a cycle prior to normal waterflooding to determine well positions suitable for waterflooding oil replacement, and then waterflooding speed is determined according to the type of a reservoir body; 2, a proper amount of high specific gravity liquid having larger specific gravity than crude oil and insoluble with the crude oil is injected into the reservoir in order to fill in formation voidages and restore formation pressure; 3, well closing, replacement of the oil and the high specific gravity liquid is implemented by means of gravitational differentiation of the oil and the high specific gravity liquid, and the high specific gravity liquid sinks to the lower part of the reservoir body to form secondary bottom water, thereby driving oil upwards and lifting oil-water interface; and 4, well is opened for oil recovery when wellhead pressure is recovered to basically stable level. According to the invention, the replacement of crude oil and oilfield sewage is implemented by injecting the high specific gravity liquid insoluble with crude oil, such as the oilfield sewage, into oil well, and the crude oil and the oilfield sewage are converged at the upper part of fracture cavity or at the bottom of higher well in order to achieve oil recovery once again.

Description

technical field [0001] The invention relates to a method for producing water in place of oil in carbonate rock fracture-cavity reservoirs. Background technique [0002] Tahe Oilfield carbonate fracture-vuggy reservoirs have the characteristics of diverse types of storage space, poor connectivity of reservoir bodies, complex fluid flow state and oil-water relationship, and have experienced multi-stage tectonic movements, multi-stage Accumulation and other processes belong to carbonate fracture-cavity reservoirs related to ancient weathering crust. Due to the low degree of understanding of the development law of fracture-cavity bodies and the characteristics of fluid flow in reservoirs, there is no corresponding development theory and development method for the development of fracture-cavity reservoirs at home and abroad, resulting in the failure of development or the development level of such reservoirs. Low, the depletion development recovery rate of this kind of oil reserv...

AI Technical Summary

Problems solved by technology

Due to the low degree of understanding of the development law of fracture-cavity bodies and the characteristics of fluid flow in reservoirs, there is no corresponding development theory and development method for the development of fracture-cavity reservoirs at home and abroad, resulting in the failure of development or the development level of such reservoirs. Low, the depletion development recovery rate of this type of reservoir is very low, the recovery rate is less than 10%

Due to the small reservoir body of this kind of single well reservoir, the formation energy is insufficient within a short time of putting into production, the production declines sharply, and it is difficult to maintain normal production. low efficiency

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