Abstract
Hundreds of blowouts have been reported during the history of the oil and gas drilling activities. These undesired accidents are at the cost of the life of people, in addition to the loss of the equipment and resources; thus, it is important to investigate the root causes of the blowouts in order to prevent them to occur in the future. In 2017, a blowout occurred in a development drilling well in the Middle East. It resulted in several consequences including fatalities, environmental related damages and a subsequent well capping. The incident happened mainly due to insufficient hydrostatic pressure during the tripping operation at the depth of 1132 m. The tripping was decided in order to change the bit when drilling horizontally at the depth of 2610 m. Some details regarding this blowout event will be presented in this paper and the engineering or operational activities and causal factors which led to the incident will be discussed, with the purpose of avoiding similar accidents in the future. Despite analysis of the past kick and blowout data for the whole field, the analysis of the kick volume data of the blowout well indicates that in the period of 2.66 h, the kick converted to the blowout, while in the last 7 min the kick volume reached from 172 to 341.5 bbl which was due to the sudden huge gas expansion. Such an analysis of the root cause factors was rarely made and presented in the region, as was done in this work.
•The causal factors which led to a recent blowout in a development oilwell in the Middle East were discussed, with the purpose of avoiding similar accidents in the future.•The causal factors originated from absence of critical review of the drilling program, lack of effective organizational measures over operational practices, improper management of changes, using OBM for drilling gas cap, continuation of operations with defective safety-critical equipment, and lack of proper monitoring of the mud transfers during tripping.•Lack of adherence to basic well control practices was revealed as the main root cause of the incident.•Avoiding similar blowouts is just possible by improving the learning curves from past kicks and blowouts.