Abstract:The attribute of faults is the basis on fault automatic tracking. However, the attributes include some false information from stratification and noises, which make the position and intersection relationship of fault system not clear, and it is difficult to identify and take up the fault. Furthermore,the fault extension has a certain direction, which is different from noise. Based on this characteristics, the gradient direction of the block is calculated to constrain the ant tracking range, and the consistency of direction is calculated to differentiate between the fault and the noise. Finally, faults will be tracked automatically in the coherence data volume or other fault enhanced data volume by ant colony algorithm. In addition, automatic tracking faults are refined by Zhang-Suen algorithm to obtain the fault line that can be applied to seismic interpretation. The results of numerical model show that this method is feasible and available in the automatic tracking fault and suppression of noise. Field data processing results also show that algorithm based on constraints of the gradient direction is an effective method to trace the fault, and has certain advantages in improving calculation efficiency, decreasing calculation amount and reducing noise.