3D GEOMECHANICS MODEL WITH PLANE OF WEAKNESS ANALYSIS IN THE ALPHA FIELD, NORTH MADURA

• Main Author: Adhyaksa Brata, Restio
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53789
• Institution: Institut Teknologi Bandung

Alpha field located at offshore North Madura, East Java Indonesia. This area is part of the North East Java Basin at southern Sundaland and classified as back-arc basin which relatively stable and low tectonic activities. This field has economic hydrocarbon reserve, therefore the development was planned by targeting several upcoming wells. The drilling process when penetrated Kujung Formation encounter cavings and well collapse problems. The problems had caused non-productive rig-time and spent huge costs. 1D geomechanics model had been applied in each well in the previous drilling, but the main problem still occurred. The invalid geomechanics model prediction must be solved for the success of next well drilling. Depositional settings of mixed siliciclastic and carbonate lead to the variation of lightology and rock geomechanics properties over the studied field. This lateral variation caused the invalid prediction of the 1D geomechanics model in the upcoming well trajectories. The 3D geomechanics model is constructed by using 1D geomechanics model supported by seismic attributes as guidance to propagate the geomechanics properties stochastically over the field. The 3D geomechanics model is able to capture the variation of the geomechanics properties over the studied field and leads to the valid Poroelastic insitu stress calculation. The blocky-platy cavings observed in the Kujung-2 and Kujung-3 Formation caused by the failures of the bedding planes. The risk of bedding plane of weakness failure was not analysed in the previous drilling campaign. Plane of weakness in laminated shale which failed due to drilling activities can be calculated by using Kirsch and Lekhnitskii-Amadei method. This method rotates the normal and shear stress follows the lamination dip and well trajectory. 3D geomechanics model integrated with plane of weakness calculation used for the wellbore stability analysis to prevent rock and bedding failures in the next well drilling.