In order to improve the accuracy of the acid fracturing by the multistage alternative injection in Longwangmiao Formation of Moxi-Longnvsi area

we studied the conservation rate of the conductivity of the acid corrosion fractures and the fracture surface morphology influence of different injection rounds

fluid groups and injection rate by the experiment and the numerical scanning. The results showed that the 3rd injection round obtained higher conservation rate of the conductivity of the acid etched fractures

and formed the acid corrosion groove through rock plate. With the increasing of the injection round

the increment of the conservation rate of the conductivity decreased gradually. With the same closing pressure and main acid

little different existed in the 3rd injection round when it took the gel and the authigenic acid as the preflush. With the increasing of the injection rate

the conservation rate of the conductivity of the acid etched fracture was more ideal. The optimized technology has been used in Longwangmiao Formation of Moxi-Longnvsi area. The acid-fracturing curves and fitting data indicate that the technology can realize the engineering purpose. It also provides an effective technical mean for the transformation of the low permeability reservoir.