Artificial foam oil accelerator and flooding method for heavy oil reservoir after steam flooding

Abstract

The invention provides a displacement exploitation method for heavy oil reservoir after artificial foam primer and steam flooding. The method comprises: selecting a target oil reservoir and a target well group; stopping a well group steam injection and oil exploitation process, and injecting an artificial foam oil primer slug and a gas slug into injection wells; opening wells to exploit oil when formation pressure rises so that bottom-hole static pressure of a production well reaches a set value; after injecting the gas slug, continuing the inject steam to the injection wells, judging whether injection transfer conditions and lower economic limit are satisfied or not, and determining whether to continue oil exploitation or stop oil exploitation. By using an artificial foam oil primer in the method, it is possible to reduce crude oil viscosity and surface tension for a near-wellbore formation, gas is dispersed in micro bubble form in oil-in-water emulsion, rheological properties of crude oil are improved, oil-gas-water to-be-mixed phase fluid is formed, elasticity energy is supplemented to the formation, overall mobility of fluid in the oil reservoir is improved, mobility of crude oil is improved, and single-well productivity and final recovery are increased.

Description

technical field [0001] The invention belongs to the technical field of oil reservoir exploitation, and relates to an artificial foam oil accelerator and a displacement exploitation method of a heavy oil reservoir after steam flooding. Background technique [0002] The domestic proven heavy oil reserves amount to 1.3 billion tons, accounting for about 25%-30% of the total domestic oil reserves. Due to the high density, high viscosity and poor fluidity of heavy oil, the development effect of conventional water flooding recovery method is poor. The key to heavy oil production is to reduce viscosity and improve rheology. At present, the commonly used methods for viscosity reduction of heavy oil are: heating for viscosity reduction, emulsification for viscosity reduction, modification for viscosity reduction, and mixing with thinner for viscosity reduction; The fluid injected during the replacement process tends to creep in along fractures or high-permeability strips, resulting...

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Problems solved by technology

[0009] In the prior art, a foaming agent is added to the wellbore of a heavy oil production well to form foamed oil and change the original viscosity and rheological properties. However, this technology is suitable for the wellbore. For the formation, the temperature resistance effect of the foaming agent is poor. And the half-life period of the foaming agent at high temperature, the types of heat-resistant and salt-resistant foaming agents are limited, and the bubble performance and half-life of the foaming agent are seriously affected in the presence of crude oil

[0010] In the prior art, heavy oil depletion cold recovery technology is adopted. This technology utilizes the elastic expansion of dissolved gas and formation elastic energy as the power to drive oil to develop heavy oil reservoirs. It uses the foam oil formed under natural conditions to make the formation crude oil in foam oil. However, the reservoirs and fluid conditions that can naturally form foamy oil are very special, and most of the heavy oil reservoirs in my country do not have the conditions to form natural foamy oil flow; for water flooding Due to the high water saturation of the late heavy oil reservoir, it is difficult to form foamy oil after direct depletion and cold recovery

[0011] Therefore, there is no effective technology to form artificial foam oil to develop crude oil in reservoirs after steam flooding.

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