Root causes analysis of the Blow out of oil and gas wells in the drilling industry using Bow-Tie Analysis

One of the major concerns in the oil and gas drilling industry are Blowouts. Blowout could have severe consequences, such as fire and explosions, releases of toxic gases and environmental disasters. The aim of this study is to identify the root causes of kick and blowout in drilling industry. In this study, FTA investigates root causes of a kick while ETA explores the possible consequences (including blowout) arising from a kick. Bow Tie Analysis (BTA) combines FTA and ETA to explore the root causes and consequences (blowout) of a kick in onshore exploration 28 basic event (root causes) have been identified for kick. Also to mitigate kick consequences, 8 safety barriers recognized. The probability of kick and blowout was calculated as 1/23× and 2/94×,respectively. The order of importance measure of each root causes was listed. In this study, Getting into the high pressure zone and not filling well with drilling mud during the trip up, was identified as the most important root causes of kick. Furthermore, early diagnosis of kick and the proper functioning of Blow-Out Preventer (BOP) were recognized as the first safety barrier to prevent the blowout.