A carbon dioxide immiscible flooding inhibition and plugging system and plugging method for low-permeability reservoirs

Abstract

The invention discloses a blocking system and a blocking method for channeling inhibition in carbon dioxide non-miscible flooding of a low permeability reservoir. The system is mainly prepared from the following raw materials in percentage by weight: 1%-2% of fine mineral particles, 0.2%-0.3% of polymer, 0.01%-0.02% of compound crosslinking agent, 0.04%-0.1% of retarder, 0.01% of deoxidant, 0.1%-0.5% of surfactant and the balance of water. By virtue of monitoring the steam injection pressure of a wellhead in real time and adjusting the system, graded control of high-pressure steam injection, 'gas channeling' and 'escape channeling' processes in the carbon dioxide non-miscible flooding is realized and the development effect of the carbon dioxide non-miscible flooding of the low permeability reservoir is improved.

Description

technical field [0001] The invention specifically relates to a carbon dioxide immiscible flooding suppression and plugging system and a plugging method for low-permeability oil reservoirs. Background technique [0002] With the continuous development of conventional oil and gas resources, the replacement of complex oil and gas resources is an important supplement to the world's oil and gas resources, and the development of low permeability reservoirs in the development of complex oil and gas resources is an important part of it. Carbon dioxide immiscible gas flooding is an effective and widely used development technology for enhancing oil recovery in low permeability oilfields. However, due to the large differences in the pore-throat structure characteristics of low-permeability reservoirs, mainly fine pores and thin throats, and large specific surface area, the surface action, microcapillary action, and electrochemical action on the solid-liquid interface are enhanced, show...

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Problems solved by technology

However, due to the large differences in the pore-throat structure characteristics of low-permeability reservoirs, mainly fine pores and thin throats, and large specific surface area, the surface action, microcapillary action, and electrochemical action on the solid-liquid interface are enhanced, showing non-Darcy Due to the characteristics of percolation, there is a pressure difference at start-up production, which leads to the phenomenon of "high injection pressure and no injection" in the early stage of carbon dioxide immiscible gas flooding development. Heterogeneity and existing micro-cracks can easily lead to "gas channeling" during carbon dioxide immiscible gas flooding

[0003] However, immiscible gas flooding with carbon dioxide in low-permeability reservoirs will also face the following problems: on the one hand, low-permeability reservoirs have high gas injection pressure at the initial stage of production, and with the increase of steam injection pressure, local high pressure is likely to form, resulting in immiscible Carbon dioxide forms a channeling channel prematurely in the upper part of the formation; on the other hand, a small amount of carbon dioxide "running away" or even "gas channeling" may occur during the normal immiscible carbon dioxide development process. These problems make the carbon dioxide immiscible gas flooding development It is difficult to achieve the ideal development effect

However, the above three technologies have strong limitations for the problem of carbon dioxide immiscible "gas channeling". Among them, the gas-water cross-injection process has a certain inhibitory effect on the carbon dioxide immiscible gas flooding process that does not form a "gas channeling" channel. However, for some low-permeability reservoirs where "gas channeling" channels have been formed, the steam injection pressure is close to 0, and the gas-water cross-injection operation has been unable to inhibit channeling; for gel and foam plugging, the gel has serious For low-permeability reservoirs that have formed gas channels, the plugging range is limited. Although foam plugging can seal along the gas channels, its strength is low.

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