The horizontal well has the charecteristics of large span and strong heterogeneity

the damage caused by drilling

completion and exploitation is characterized by strong heterogeneity

and the efficiency of the general acidizing is low. Considering the existing technical bottleneck

we proposed a design of the efficient acidizing in heterogeneous carbonate reservoirs based on the description of damage characteristics

the optimization of acidizing modes

and the injection parameters

meanwhile

built a set of 3D fine mathematical models for the simulation of the damage of the h

orizontal wells

the optimization of acidizing modes and parameters

and the evaluation after acidizing. Based on the method above and the mathematical models

we carried out the systemic simulation of a horizontal well. The results show that the damage degree of the horizontal well is extremely uneven in the 3D space. In accordance with the general acidification

multistage acidification and partial acidification respectively

then we carried out the simulation analysis by using the diverting acid system with the strength of 0.5 m

3

/m. The partial acidification was better than the other two modes and its comprehensive skin coefficient decreased from 4.717 to -0.083. The optimum design of the process parameters was also carried out in the fourth part of the partial acidification. The optimal acid injection rate was 2 m

3

/min and the optimal acid volume was 66 m

3

. The results can solve the problem of the unsatisfactory matrix acidizing effect of the long section of the horizontal wells in carbonate reservoirs

and optimize the controllable parameters（such as treatment parameters） and uncontrollable parameters（such as formation parameters）

in order to achieve the reasonable and high efficiency acidification.