Current paper represents dynamic multiphase flow simulation applied to realistic transient scenario of pigging one of the two parallel 24-inch trunkline that transfer oil and gas production to Tengiz Second Generation Plant. Despite pigging is inevitable and required activity, it creates a big challenge for receiving facility causing inlet separators level fluctuations and as worst case Plant Emergency shutdown. OLGA dynamic simulation tool is able to predict multiphase flow behavior over required time and changed conditions (or inputs). This work was done to compare software predicted liquid slugs as pigging result versus real historical data. The consistency in results was reached by using accurate input data such as rigorous geometry, tuned fluid file for Tengiz oil, and accurate assessment of the real slugs. For instance, Plant separator level accumulation factor made both realistic and OLGA predicted trends really close to each other. Reached consistency gives a credit to use software for slugs prediction and creating according operational procedures to eliminate their impact to the Plant.