Publications

Drilling activity in deep-water exploration areas is challenging due to limited geological information, little or no calibration data and narrow drilling mud window. In such area, a robust well planning with integrated geomechanical input is critical for successful drilling with minimum non-productive time. This paper presents a case study of an integrated geomechanical modelling consisting of pre-drill pore pressure and geomechanical modelling for an exploration well X-1 located in the Andaman Sea, Offshore Indonesia, followed by post-drill analysis.

The offset wells drilled in the area of interest varied in water depth between ~800m to 1200m. Drilling experiences from daily drilling reports were utilized to evaluate and summarize the most relevant geomechanical events. All the geomechanical parameters were calculated and calibrated with available actual data. Overall, the geomechanical model in this part of the Andaman Sea from the five offset wells available showed consistency and can be grouped by water depths.

The calibrated geomechanical model from the two most relevant offset wells were used as reference to carry out wellbore stability assessment for the planned exploration well together with a fault stability assessment as the well was planned to intersect five faults. The output of the study provided the mud weight recommendation based on the wellbore stability and fault stability assessment that governed the mud window.

The planned exploration well was then drilled following the mud weight recommendations from the mid case; the well was drilled safely until the planned well total depth by meeting all exploration objectives. Zero non-productive time due to wellbore stability was recorded. The post-drill analysis was then carried out by incorporating all the actual data available. In overall, it was found that post-drill model to be similar to the regional geomechanical model. These integrated efforts by muti-disciplinary team during preplanning till execution made this exploration campaign a successful one.