Slow plugging agent for oil wells suitable for acid-sensitive reservoirs

Abstract

The invention discloses oil well slow blocking remover suitable for an acid-sensitive reservoir, and belongs to the technical field of oilfield exploitation. The slow blocking remover is composed of preprocessing liquid, main processing liquid and post-processing liquid, the preprocessing liquid is prepared from glacial acetic acid, ammonium chloride, citric acid, water block removal agents, inhibitors and butyl cellosolve, the main processing liquid is prepared from citric acid, fluoroboric acid, ammonium chloride, water block removal agents, inhibitors and butyl cellosolve, and the post-processing liquid is prepared from glacial acetic acid, ammonium chloride, citric acid, water block removal agents, inhibitors and butyl cellosolve. According to the blocking remover, blocking removal treatment is conducted on the reservoir by means of acetic acid and the citric acid in three phases, the purpose of increasing the blocking removal depth is achieved by delaying the acidic rock reaction speed, blocking is removed, and damage caused to hydrochloric acid and hydrofluoric acid sensitive reservoir can be avoided simultaneously, efficient blocking removal to the reservoir is achieved, and single well yield is recovered and increased.

Description

technical field [0001] The invention relates to an oil well slow plugging removal agent, in particular to an oil well slow plugging removal agent suitable for acid-sensitive reservoirs, and belongs to the technical field of oil field exploitation. Background technique [0002] During the drilling process of oilfield development, the drilling fluid will inevitably come into contact with the rocks and fluids of the reservoir, and sometimes the drilling fluid may be lost to the reservoir. Fissure fluid enters the reservoir. After the reservoir comes into contact with external fluids, it is easy to cause changes in wettability, water lock, capillary pressure, etc., resulting in a decrease in the relative permeability of the oil phase, and may also cause clay swelling, particle migration, inorganic salt precipitation, and crude oil emulsification , Precipitation of wax and asphaltene, etc., these consequences will cause different degrees of clogging in the reservoir, affecting t...

AI Technical Summary

Problems solved by technology

After the reservoir comes into contact with external fluids, it is easy to cause changes in wettability, water lock, capillary pressure, etc., resulting in a decrease in the relative permeability of the oil phase, and may also cause clay swelling, particle migration, inorganic salt precipitation, and crude oil emulsification , wax and asphaltene precipitation, etc., these consequences will cause different degrees of clogging in the reservoir, affecting the seepage of crude oil to the wellbore, resulting in a decline in oil well production

[0003] At present, plugging removers commonly used in oilfields with hydrochloric acid or hydrofluoric acid as the main component and corresponding additives can remove pollution and plugging in the near wellbore area of ​​the oil well, but this type of plugging remover is not suitable for acid-sensitive reservoirs. Plugging remover is used in acid-sensitive reservoirs, which not only cannot achieve the purpose of removing pollution and plugging, but also causes secondary pollution and plugging. secondary injury

For example, the invention patent of Publication No. CN103740353A discloses a composite plug-removing agent, which consists of a pre-treatment liquid, a main treatment liquid, an active plug-removing liquid and a post-treatment liquid, wherein both the pre-treatment liquid and the main treatment liquid contain organic acids and Inorganic acid component, the organic acid is acetic acid, and the inorganic acid is hydrochloric acid and hydrofluoric acid. The blockage remover can relieve the blockage caused by conventional colloid, asphaltene and inorganic solid phase particles. It has good retarding performance and can effectively prevent Precipitation of iron ions and formation of acid slag are suitable for plugging removal treatment of staged fracturing and production horizontal wells in ultra-low permeability reservoirs, but not for acid-sensitive reservoirs

Images