Dynamic Risk Analysis Of Well Kick During Offshore Drilling Phase

Faced with the narrow pressure of formation,difficult in detection of earlier kick and shallow geological configuration,deepwater drilling is riskier in a certain degree than onshore drilling with well kick.Well kick measurement is the safety barrier system to prevent well blowout and plays the decisive role in the success of drilling.Risk analysis of well control process which is after well kick could be a strong theory guidance to well control operation.Risk identification is carried out by deduction and safety barrier system theory.Based on process of deepwater drilling,evolution of invaded oil and gas,and well control safety barriers,analyzing the dynamic failure distribution of safety barriers and build a Cause-Consequence diagram for quantitative risk analysis.Build a dynamic risk quantitative analysis model based on Cause-Consequence Analysis(CCA)modified dynamic Bayesian network.Taking uncertainty in to consideration,get the failure probability change curve of safety barriers and occurrence probability of well control consequences.Compared with the calculation by non-CCA method,it is verified to be more practical.Propose a real-time risk quantitative analysis model based on deterministic and stochastic Petri net(DSPN)and get the Petri net updated.Based on the real-time data,updated DSPN is analyzed and real-time risk of this time well control operation is constructed.