Scope of Application

This technology is applicable to pressure drop and augmented injection of injection well of medium to low permeability sandstone reservoir. 

Principles 

With features of gradual ionizing of medium to strong inorganic acids and organic acid, the active H+ and some F- in acid liquid can be slowly released. Acid liquid can maintain low pH value for a lone time to perform deep penetration and plug releasing.

Technical Indicators

1.Corrosion inhibition rate: ≤6.0g/m2.h (90°C)； 

2.anti-swelling rate: ≥75％ (90°C);

3.Concentration of stable Fe3: ≥70mg/mL; 

4.Surface tension: ≤30mN/m;

5.Interfacial tension: ≤30mN/m;

6.Good compatibleness with formation fluid

Performance Features 

1. Acid liquid is featured with low reaction speed and high active penetrability, capable of removing deep damage such as stratum scale and water sensitivity caused by water injection; 

2.The reaction speed of acid liquid with quartz and feldspar is faster than clay mineral; it can greatly improve the original permeability of stratum; 

3.Acid liquid system is well compatible with stratum and no secondary precipitation will occur; 

4.It can effectively remove the polluted organic sediment and resist the acid sludge and emulsification;

5.It is featured with low corrosion rate and good anti-swelling capacity and will not change the original water-wet feature of stratum.

Field Applications

Since 2004, this technology has been applied to 155 wells/times at many major oil fields nationwide with process success ratio of 100%, efficiency of 87.2%, obtaining obvious effects of pressure drop and augmented injection.