A mechanical earth model with velocity matching algorithm for predicting shear wave velocity using offset well data from an Iranian oilfield

A Mechanical Earth Model (MEM) provides the geomechanical properties required for wellbore stability, well completion, hydraulic fracturing, and mud weight design. This study presents a one-dimensional MEM for a vertical well in a Berriasian–Santonian oilfield in southwest Iran. Shear wave velocity was not measured in the target well and was instead predicted from an adjacent offset well using a velocity matching algorithm that aligns compressional delay times. The novelty of this approach lies in systematically reconstructing missing shear data to enable MEM construction under data-limited conditions. The MEM includes pore pressure, in situ stress fields, and rock mechanical properties along the well path. Static laboratory tests were correlated with dynamic log data to generate continuous rock strength profiles. Using these inputs, a mud weight window was computed and compared with drilling operations. The predicted window showed good agreement with observed breakouts in FMI logs and daily drilling reports. Stability analysis across several intervals indicated that the most stable wellbore trajectory varies with depth due to changes in stress regime and mechanical properties. The method assumes sonic similarity between adjacent wells and is limited by the small number of core samples and incomplete log coverage. Nevertheless, the study demonstrates that velocity matching from an offset well is a practical tool for MEM development, improving wellbore stability prediction and trajectory optimization.

کلیدواژه ها:

Mechanical Earth Model ، Elastic properties ، In-situ stress ، wellbore stability ، Mud weight window