The Prediction of Surge and Swab Pressures and Critical Pipe Running Speed While Tripping in a 12 1/4-in. Hole (Gachsaran Formation) of Maroun Field in Iran

Maroun field is a large oil field located in southern Iran. The producing formations in this field are deposited under the Gachsaran formation, which has an extremely high value of pore pressure. The mud density through the Gachsaran formation usually exceeds 20 ppg. In this situation the pipe running velocity is a critical issue and careless moving of the drill string may cause the risk of kick or formation breakdown. The purpose of this study is to develop a model for prediction of critical pipe running speed. The method of study is the basis of simple fluid flow equations and computer programming is used to simplify primary data analyzing. New correlations are developed using multiple regression method and SPSS software for predicting critical pipe running speed using only simple input data such as well geometry and drilling fluid properties, which can be measured using American Petroleum Institute testing methods.