Well control is one of the crucial tasks in drilling oil or gas reservoirs. It affects the overall cost of completing a well and in some cases leads to fatalities and numerous damages to environment.
During drilling 12 1/4″ hole size at depth of 615m, well 24 of Naft shahr located in the Western part of Iran was blown out in 2010. The entire drilling rig got fire and due to extreme temperature, substructure and wellhead were buried by mast, rig floor, top drive and drawworks. The temperature at the wellhead was estimated to be almost 950°C and pressure around 900 psi. These added to the difficulty of the kill operation. Moreover, the seepage of gas in the area around the well made the operation for the personnel very difficult.
Two parallel approaches were employed to control the well. They consisted of well capping (top kill) and relief wells (bottom kill). With a close observation of the process and a precise program, the top kill technique worked out and the well was controlled after an unbelievable time period of 38 days. One of the main issues in this operation was the removal of large debris around the wellhead.
In this paper, the details of the steps taken during the 38 days including the engineering design of the both approaches, the preparation of the area, removal of the debris, employing stinger and smoke stack, and the utilization of relief well as a development well are presented.