Structural interpretation in the Bolivian southern Sub-Andean: from surface to hydrocarbon prospect generation

de Mena O.; Peña D.; Bonora M.; Olaya J.; Gil W.; Limachi R.; Goitia V.H.; Carballo J.; Zapata T.; Zamora G. · Andean Structural Styles: A Seismic Atlas (2022) · DOI: 10.1016/b978-0-323-85175-6.00027-4

Resumen

High relief, mountainous jungle conditions and outcropping formations, ranging in age from Quaternary to Upper Devonian in the core of the structures, make the southern Subandean region of Bolivia one of the most challenging areas for seismic interpretation and the definition of hydrocarbon drilling prospects. In these complex geological settings, topographic and geological maps and their correlation with existing well data are the only hard data available. Therefore, it is important that this information (stratigraphic columns, thicknesses, and lithological descriptions) must be accurate as it will constitute the basic input for geological and structural models. The topography, the structural complexity, and the variability in the mechanical stratigraphy make the acquisition and processing of geophysical data (seismic, gravimetric, and magnetotelluric) challenging. Nevertheless, despite the low quality, careful geophysical observations help to constrain interpretations and capture the range of structural uncertainties. In this chapter, we present an interpretation workflow along a W-E seismic line that combines all the available data to build a comprehensive structural model for one of the south Subandean ranges of Bolivia. This workflow begins with the analysis of the surface geological information as direct constraints that must be honored and followed with observations of the subsurface data that become indirect constraints for the structural interpretation. This workflow was validated through forward modeling that honors as much as possible the time constraint to reduce the number of possible structural models and quantify uncertainties in prospects definition. This workflow used relied on continuous interactions between the various disciplines involved. This approach allowed the multidisciplinary team to define exploratory prospects and manage most of the associated uncertainties and risks.