Petrophysical and Geomechanical Modelling for Mud-Weight Window Prediction: A 1D-MEM Analysis of Well A in South Sumatra Field, Indonesia

The optimization of drilling operations in increasingly complex geological environments, including conventional and unconventional oil and gas resources, demands geomechanical evaluations to mitigate costly non-productive time. Wellbore instability, primarily driven by inadequate mud weight design, remains a persistent operational challenge that can lead to catastrophic failures such as well collapse, tight hole conditions, and stuck pipe incidents. To address these mechanical risks, a 1-Dimensional Mechanical Earth Model (1D-MEM) provides a comprehensive analytical framework by synthesizing petrophysical measurements with localized stress profiles to determine the mechanical limits of the formation. Utilizing depth records and a suite of acoustic, density, and caliper well logs, this study constructs an integrated 1D-MEM for Well A. The analytical procedure quantifies dynamic elastic moduli and estimates rock strength parameters, specifically the uniaxial compressive strength and internal friction angle, along the wellbore trajectory. By superimposing the predicted in-situ principal stresses with the appropriate rock failure criterias, the study analytically determines the shear and tensile failure gradient. The central finding of this modelling effort establishes the precise mud weight window required to counterbalance the effective principal stresses and prevent wellbore breakouts. Establishing this optimized geomechanical parameter not only ensures operational safety and structural integrity for Well A but also yields a predictive analytical methodology that can be extrapolated to future drilling and well intervention programs within similar lithological settings.