Abstarct: کلمات کلیدی: In this thesis, a new method is presented for detecting the extent and location of pig blockage within fluid transmission pipelines using transmission pipeline modeling. The modeling of the transmission line is baxsed on the governing dynamic equations of the system, which includes continuity and momentum equations written as partial differential equations. To solve these equations, the method of characteristics is initially implemented for discretization. Using the discretized system model and the state-space representation, hypothetical blockages are added to the system states at two assumed blockage points in specific locations along the transmission line. By identifying the effects of these hypothetical blockages, the occurrence of actual blockages is detected. In the second step, using nonlinear observers such as the extended Kalman filter and adaptive extended Kalman filter the state variables of the system, including the location and magnitude of the pressure drop, are estimated with suitable precision in the presence of environmental noise. This approach is validated using the OLGA pipeline simulation software, and the error rate is compared with the output.