Semi Quantitative Risk Analysis of Well Blowout During Reactivation Phase Using Relief Well Technique

The oil and gas field development was carried out by PT X located in theOf shore North West Java Block, in the North Sea area of West Java. Y Well isone of the development wells drilled by PT X with the aim of producing gas toincrease the company's production. With the case study in the Y well in the Java Sea, drilling activity was completed in 2011. In 2019 the well reactivation activity wascarried out. During the reactivation activity, gas bubbles appear in the surface ofof shore platform and Rig Z. To overcome the problem of blowout relief well wasdrilled. Research methodology in this paper is carried out by identifying hazards inthe process planning and executing of Relief Well and describing them in possibilitiesand consequences also developing strategies and mitigations that can be carried outto reduce the risks that might occur at the level with a high risk assessment. Riskanalysis in this paper uses Risk Scoring Index with Crystal Ball simulation software tosimulate the risk value. In the Risk Scoring Index model, the significant probabilityrisk value consists of: subsurface risk, NPT (Non Productive Time) of drillingequipment, blowout and combined with the consequences consisting of: safety, theenvironment, financial impacts that may arise, and the company's reputation. Basedon calculation results simulation, the average risk value of 12.3 at the high level isobtained and by evaluating and mitigating preventive measures, the risk value can bereduced to average of 7.3 at the medium level. The most influential value on the levelof risk is the uncertainty factor in the subsurface condition, where the weight of theassessment for the possibility of risk factors is considered high