Abstract: Acidfracturing technology with solid nitric powder is a new one for acidizing,in recent years,its basic principle is that the liquid nitric acid is transformed into acid powder first,and then the acid powder is injected into the designed fractures that are just made by the fracturing fluid by nonactive liquid.After that,the releasing fluid is injected into the formation and the acid powder will release.The released acid will react with rocks to make the fracture faces etched and realize deep reform with the realized H⁺.With the idea of hydraulic fracturing of microencapsulated gel breaker technique and phase separation method,using ethyl cellulose and paraffin as coating material for solid nitric powder,the ration is 1.5:10.0 and 1.5:6.0respectively,the microencapsulated solid nitric acid can be injected into the formation with water based liquid.Under normal pressure or high pressure,the corrosion rate of microencapsulated solid nitric acid system is lower than hydrochloric acid liquid;its dissolution rate for rocks is different from hydrochloric acid liquid,with the time increasin,dissolution rate increases,the properties is good to realize deep acid,also,it has the same dissolution capacity as hydrochloric acid liquid.By analyzing flow conductivity of fractures after acidizing,it is demonstrated that complex acidizing fluid composed of hydrochloric acid and microencapsulated solid nitric acid is of higher flow conductivity after acidizing.

Key words: microcapsule, solid nitric acid, acidizing, acid/rock reaction, acidcrossive fracture flow conductivity