Publications

Wellbore stability issues in Offshore North West Java (ONWJ) field cause high friction coefficient during tripping, longer tripping time due to pack off and even stuck pipe during drilling operation. Borehole breakout is one of the major of wellbore stability issues leading to those problems, and being more risky when drilling Extended Reach Drilling (ERD) wells. Borehole breakout is very extensive for ERD wells as the wellbore stress difference reaches at maximum with increment of inclination in normal stress regime Sv>SH>sh (M.S.Asadi and Khaksar, A., 2015). Furthermore, borehole breakout in ERD wells are more challenging while drilling interbedded shale and depleted sandstone formation. For the past years, low mud weight which slightly above the pore pressure was used to prevent excessive fluid penetration to the depleted formation regardless adequate mud weight to balance the shale's shear stress. Even though inhibitive water based mud has already been applied to minimize the reactivity of shale, borehole breakout are still observed. New approach preventing borehole breakout by applying adequate mud weight to overbalance the shale’s shear stress based on shear failure gradient analysis and using optimal bridging agent to minimize loss circulation in sand formation looks effective. An attempt has been made to perform the shear failure gradient analysis for the ERD wells in BM field to get the shear failure characteristic of BM field for the future development. In our workflow, the logging data and offset well information have been incorporated to generate predictive pore, fracture and shear failure gradient. These approaches have been applied to BM-6 which already proven to minimize borehole breakout that happened in BM-7. As the outcome, the new approach in preventing borehole breakout has been made to determine the optimum well design for not only for the future wells in BM filed but also in whole ONWJ area regards to trajectory, safe mud weight window, and casing setting depth. Keywords: wellbore stability, borehole breakout, shear failure gradient, Extended Reach Drilling