High-temperature and High-Salt resisting gel water packing-off method

Abstract

The present invention relates to a high-temperature-resistant and high-salt-resistant gel water-plugging method for raising petroleum recovery efficiency. Said invention adopts three-slug injection water-plugging method, and provides the concrete steps of said three-slug injection water-plugging method. These steps are as follows: first slug, adding temporary blocking agent, its added quantity is 10-20% of total injection amount, after the temporary blocking agent is injection for 0.5-1.5 hr, closing well, the temporary blocking agent can be formed into gel, can be used for temporarily blocking the oil layer; then making second slug, injecting low-viscosity gel which is easily injected and can be formed into gel with high viscoelasticity under the condition of stratigraphic temperature, its injected quantity is 70-80% of total injection amount; and third slug, injecting cement as sealing agent, its injected quantity is 10-20% of total injection amount.

Description

technical field [0001] The invention belongs to the technique of enhancing oil recovery rate developed in oil fields, and specifically relates to a high-temperature and high-salt gel water plugging method. Background technique [0002] Indoor research work on high temperature plugging agents has been reported [1~3] , Navratil et al. from Canada mixed black wattle extract and sulfonated extract with formaldehyde and phenol to prepare a gel that can be used in high-temperature formation plugging [1，2] . Liu Chengjie and others made a blocking agent that can be used at high temperature by using rubber extract [3] . However, no successful field test of water plugging and profile control has been reported. When the existing chemical water plugging technology is used in the reservoir of >90℃, the thermal stability of the chemical agent will appear, and it will not have the selective plugging ability and the gel strength cannot reach the strength required for long-term high-...

AI Technical Summary

Problems solved by technology

When the existing chemical water plugging technology is used in the reservoir of >90℃, the thermal stability of the chemical agent will appear, and it will not have the selective plugging ability and the gel strength cannot reach the strength required for long-term high-pressure flushing when it is generally injected. There are problems such as blocking

The reasons may be: the pressure of the water layer of the oil well is higher than the pressure of the oil layer, and the plugging agent is easy to enter the oil layer when it is directly injected, resulting in oil plugging but not water blocking; the polymer plugging agent cannot form a stable gel when the temperature is higher than 120 °C; The plugging agent is easy to reverse; the cement plugging agent is difficult to inject in large doses. After solidification in the oil sand, there are still gaps between the cement and the oil sand due to the existence of the oil film on the surface of the oil sand, which cannot form a stable plug.

[0003] The water plugging of oil wells in high-temperature and high-salt reservoirs will encounter the following problems: ①The plugging agent must be stable for a long time in a high-temperature and high-salt environment; ②When the oil well is plugged in, the pressure of the water outlet layer is greater than the pressure of the oil production layer, causing most of the injected plugging agent to enter the oil layer , causing oil plugging but not water plugging or plugging ineffective; ③ Even if plugging is formed in the water layer of the oil well, the plugging layer is generally made of low-strength materials, which cannot resist the long-term erosion of high-pressure formation water, causing the plugging material to be destroyed. and spit it out

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