Complex plug removal water injection agent used for water injection well of sandstone reservoir and preparation method thereof

Abstract

The invention provides a complex plug removal water injection agent used for a water injection well of a sandstone reservoir and a preparation method thereof, and discloses a self-synthesized organic cation low molecular weight polymer with well prevention of clay swelling and transport of clay particle, and excellent anti-erosion property. According to the invention, selected and used hydrofluoric acid, formic acid and acetic acid have well dissolution and corrosion properties for sandstone and retarding property, so that the action between the acid and the sandstone is slowed down, the depth of the entering of the acid is increased to be able to acidize deeply so as to effectively relieve the plug of rock particles and scales; a self-synthesized phosphinic acid group polyacrylic acid biopolymer anticrustator has well anti-calcium scale ability to retard the plug of scales, the added dyhydroxylpolyoxy propylene polyoxyethylene ether has excellent anti-emulsification and demulsification abilities for the emulsification caused by water injection and acidification of an oil field, and the using of the complex plug removal water injection agent makes innovative demonstration effect for improving the oil productivity.

Description

technical field [0001] The invention relates to the preparation of a composite plug-removing and injection-increasing agent, which is especially suitable for water injection wells in sandstone reservoirs. The plug-removing and injection-increasing agent obtained by the formula and method has excellent use effect. Background technique [0002] Oilfield water injection development is the main method of oilfield secondary recovery. The main water source for oilfield water injection is oilfield sewage. With the exploitation of oilfields, the water content in crude oil continues to increase. At the same time, with the progress of water injection, the water injection pressure gradually increases due to formation pollution and other reasons. During the water injection production process, due to storage damage, It is easy to cause formation blockage, which greatly reduces the production during water injection production, makes water injection pressure rise rapidly, and makes water i...

AI Technical Summary

Problems solved by technology

[0003] Therefore, for low-permeability or ultra-low-permeability reservoirs, the protection of oil layers is more important. For these low-permeability reservoirs, the pressure rise caused by water injection is particularly prominent, and there are basically problems of under-injection, which require plugging removal and injection enhancement technology. After the water injection well is transformed, after the water phase of the water injection invades the pores of the reservoir, it will form a water phase blockage in the pores around the well wall, and there is a capillary pressure on the water-gas or water-oil curved interface. The wellbore must overcome this additional capillary pressure. If the reservoir energy is not enough to overcome this pressure, the water blockage cannot be eliminated, which will eventually affect the recovery rate of the reservoir and cause water lock damage. To reduce this damage, it is required to reduce the capillary pressure, and the injected water phase is in contact with the formation water in the reservoir. Due to the incompatibility of the water, calcium scale precipitation may be formed and precipitated under the high temperature environment of the formation, resulting in blockage damage