3D Structural restoration and Geomechanical Forward Modeling in a visco- plastic medium to natural fracture prediction in a Malay producing field, offshore Malaysia

摘要

In order to ensure a successful drilling campaign,it was required to obtain knowledge of the possible location of natural fractures generated by different tectonic events affecting the Malay Basin through geological time to a high level of certainty. The acquired information would assist in the optimization of well trajectories to avoid these naturally fractured regions which would likely result in severe wellbore instability problems. The Malay Basin underwent an extensional phase during the Oligocene period with deposition of lacustrine source rocks.The Miocene was a time of fluvio-deltaic source and reservoir deposition and a compressional phase starting Early Miocene resulted in a positive structural inversion with a strong lateral component.A major unconformity underlined the peak of the tectonic inversion.The objective of the study was to model the heterogeneous paleo-stress and paleo-strain states by the construction of a geomechanical forward model in a visco-plastic medium using 3D restored model and then to relate the predicted strain and stresses in the fracture characterization process. The technique used to perform the restoration was based on the Finite Element Method,particularly suited for modeling complex geological structures.The paleo-stress was recovered from geomechanical forward modeling of restored structures at each geological time-step in order to calculate the internal stress condition and plastic strain distribution accumulated through geological time.