Mud and sand blockage prevention and control technology suitable for water injection of loose sandstone reservoir

Abstract

The invention relates to a mud and sand blockage prevention and control technology suitable for water injection of a loose sandstone reservoir. According to the technical scheme, before water is injected into a stratum through an injection well, a salt water slug is injected into the stratum firstly, then a wetting reversal agent solution slug is injected, then a clay stabilizer solution slug is injected, and finally water injection is started. Salt comprises inorganic salt and organic salt. A wetting reversal agent is mainly a nonionic organic amine surfactant, a cationic surfactant and the like. A clay stabilizer is a clay particle migration prevention agent and is mainly an organic nonionic polymer, an organic cationic polymer and the like. The mud and sand blockage prevention and control technology has the beneficial effects that the technological operation is simple, hydration expansion and hydration dispersion of clay in the loose sandstone stratum can be effectively inhibited in the water injection process, mud and sand particle migration can be prevented from blocking a fluid seepage channel, and the permeability of the water injection stratum is not reduced; and meanwhile, the water injection sweep efficiency and the oil washing efficiency can be improved, secondary oil recovery and tertiary oil recovery are combined, and therefore the water injection recovery rate is increased.

Description

technical field [0001] The invention relates to a process technology for water injection and oil recovery in an oil field, in particular to a mud-sand clogging prevention and control technology suitable for water injection in unconsolidated sandstone reservoirs. Background technique [0002] Oilfield water injection is an important oil recovery technical measure after primary oil recovery, also known as secondary oil recovery. The main principle of water injection oil recovery is to inject water into the reservoir through the injection well to supplement the formation energy, and use the injected water to drive the crude oil in the reservoir into the production well, and then extract it through artificial lift. [0003] Unconsolidated sandstone reservoirs have low rock cementation strength and high clay mineral content. During water injection, hydration swelling, hydration dispersion, and particle migration of clay are prone to occur, and particle migration and blockage will...

AI Technical Summary

Problems solved by technology

[0003] Unconsolidated sandstone reservoirs have low rock cementation strength and high content of clay minerals, and clay hydration expansion, hydration dispersion, and particle migration are prone to occur during water injection. Particle migration blockage occurs at the pore throat of the seepage channel, resulting in a decrease in the permeability of the water injection formation, reducing the water injection efficiency and the recovery factor of the production well

In order to overcome the above shortcomings, various chemical agents, such as polymers, alkalis and surfactants, are usually added to the injection water, which not only increases the cost of water injection oil recovery, but also prematurely transfers to the stage of chemical flooding (that is, tertiary oil recovery) , so that the water injection production cycle is significantly shortened

In addition, it has not fundamentally solved the problem of mud and sand plugging caused by clay hydration and particle migration that plague the water injection process of unconsolidated sandstone reservoirs.

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