Study On The Formation Damage From The Inflow Fluids And Acid Treatment In The Honghe Oilfield

Honghe oilfield is a tight sandstone reservoir with the characteristic of low permeability,low porosity,small pore throat radius and high capillary pressure.The formation will be seriously damaged by the drilling fluid and the fracturing fluid.The production of the Honghe oilfield was very low due to the lack of theoretical basis of damage mechanism.There existed a short valid period problem during the acidizing plugging removal stimulation which leaded to the high percent of the low production wells.So,studying on the formation damage and acid treatment is very necessary for the Honghe oilfield.The 12,36 and 37 well areas of Honghe oilfield was taken as a research subject.The kinds and contents of clay mineral were studied through the XRD and SEM technique.According to the experiment of the sensitivity of the Honghe reservoir,12 and 37 well areas were strongly sensitive to the water and 37 well area were strongly sensitive to the hydrochloric acid.Through the core analysis,the damage ratio of the drilling was 41.1 percent and the fracturing fluid was 25.7 percent.The most serious damage to the Honghe oilfield was the water blocking damage.The formation was also damaged by the invasion of the solid particles,inorganic scale,wetting reverse damage,emulsification blocking,water and hydrochloric acid sensitivity damage.According to the damage mechanism of the Honghe oilfield,the acid plug remover was studied.The acid treatment system formulation was studied through the corrosion ratio and the acidizing additive.Eventually,the acidizing treatment system was developed.Fluo boric acid and acetic acid were used to the 12 well area.Fluo boric acid and citric acid were used to the 36 well area.fluosilicic acid and acetic acid were used to the 37 well area.The three acidizing systems can slow down the velocity of the acid and sandstone which can enter into the deep area of the Honghe oilfield reservoir.Then the systems can be effective for a long time.The additive can remove the water blocking damage,prevent the hydroxide deposition,and remove the wetting reverse damage and the emulsification blocking damage.The acidizing systems can improve the matrix permeability by 92.5 percent.The quantity of the acids which can be used to guide field construction was calculated by the establishing coordinate.