Nam Con Son Basin Analysis: The Old and New

Abstract

Abstract Recent drilling results and activity has created a renewed interest in the Nam Con Son basin in Southern offshore Vietnam. This renewed interest follows several phases of exploration in the Nam Con Son Basin in which initial drilling and data collection allowed for the definition of a tectonic and stratigraphic definition of the Nam Con Son Basin. Incorporating the existing tectonostratigraphic interpretation with data acquired since the initial drilling campaign in the Nam Con Son Basin, Talisman Vietnam has successfully entered into the Nam Con Son Basin (NCSB). Successful integration of existing literature, tectonic models, detailed mapping, stratigraphic analysis, paleogeography and basin modeling have been used to develop an updated view of the petroleum system in the NCSB. This examination of the NCSB petroleum system presents a more complete history of the basin and therefore, a better understanding of the evolution and subsequent hydrocarbon potential. Previous workers like Matthews (1997), Hutcheson (1989), and several other authors have been instrumental in outlining the basin history and tectonic development of the NCSB. For the purposes of this paper we will use the same naming conventions developed by Matthews (1997) in order to create some continuity between previous authors and any new interpretations. By using seismic data and a range of geologic information, key basin elements have been updated and in some cases, models challenging previously accepted ideas will be proposed for the NCSB. Regional seismic mapping and a clear understanding of the relationship between tectonics, accommodation space and sedimentation rates on a regional scale have changed our view of paleogeography and added details to the regional source and reservoir distribution models. These workflows and new ideas have allowed for the identification of areas of interest in the deepwater that will be drilled in the near future to test both old and new ideas in the NCSB. Basin Fill Definition The NCSB can be subdivided into four major tectono-stratigraphic units or megasequences; although other authors have further subdivided the stratigraphy, for the purposes of this paper, we discuss only these four major units. These megasequences have been subdivided primarily through an understanding of the effects of tectonics and relative sea-level on sedimentation patterns over time. The dominant mechanism, whether tectonics or sea-level, controlling basin fill over time remains unchanged within individual megasequences. This definition and subdivision plays a crucial role in understanding the various components of the basin and aids in developing predictive models for basin analysis in areas that lack significant data. The overall balance between tectonics and relative sea-level combined with other concepts like sedimentation rates, accommodation space and differential compaction are the basis for the introduction of additional granularity within the NCSB.