Fault-related fracture modeling in the complex tectonic environment of the Malay Basin, offshore Malaysia: An integrated 4D geomechanical approach

Abstract

In the South-East prong of Eurasia prevails a positive tectonic inversion, where the Malay Basin and its complex oil and gas reservoirs were formed. Therefore, the characterization of the natural fracture network originated from the complex multi-tectonic events of this area remains challenging. This contribution presents a 4D innovative approach for improving the geomechanics-based assessment of fault-related fractures in such exigent environment. The workflow consists of several steps to reduce uncertainties in the fractured reservoir modeling, both in estimating (i) the paleo-geometry of the main structures using 3D reconstruction techniques and (ii), the paleo-tectonic stresses using fracture-based stress inversion technology, both steps being essential to comprehensive geomechanical simulations through geological time. This acute fractured reservoir characterization workflow was therefore applied in a field development plan in the Malay Basin, offshore Malaysia. Well data analysis, refined seismic interpretations, 2D/3D structural restorations and paleo-stress inversions were integrated to manage uncertainties in the discrete fracture simulation. The model reveals evidences of two successive tectonic events: a Paleogene extension with a normal-slip fault regime (σH => N66°) and a Neogene contraction with a strike-slip fault regime (σH => N174°). This tectonic inversion is associated with a redirection of the far field stress, as well asthe location and orientation of the natural fracture network during its growth. The proposed workflow improves the understanding of the fractured reservoir characterization greatly and is of help to appraise future development plans better.