1D Geomechanical Modelling for Wellbore Stability Analysis in West Java Basin: Fjord Field

Abstract

This research is about a 1D geomechanics that is used to analyze wellbore stability in Fjord field. The problem in Fjord field is when the exploration drilling activities are carried out on C-1 and R-1 wells, caving occurs a lot due to the used of mud weight that is less optimal. That is what causes the wellbore instability which is marked by the number of the caving when viewed with the caliper log. So, it is necessary to do the research to determine the in-situ stress, the geomechanical parameters, and the optimum equivalent mud weight. This research was conducted by determining the geomechanical parameters with the preceding methods to generate the wellbore stability model that can be used to analyze the wellbore stability in the Fjord field in C-1 and R-1 wells. The result from determining the geomechanical parameters on this field is the type of the in-situ stress in both C-1 and R-1 wells in all of the formations is normal stress state regimes. Because, the value of vertical stress is bigger than the horizontal stress in all of the formations. And in the 1D geomechanics analysis, mechanical properties were obtained in each formation in both of the wells. The results from analyzing the wellbore stability are the failure types that happened when carried out the exploration drilling are breakout and shallow knockout, and from the safe mud window that was obtained, recommendations of the optimum mudweight was given to carried out the next drilling activity.