ABSTRACT This chapter will address the innovative and bold exploration approach that has led the French company Total and its Argentinean partner Tecpetrol to achieve what is one of the largest gas discoveries of the south Bolivian sub-Andean basin of the 2000–2010 decade. This discovery, named Incahuasi, is the result of multidisciplinary teamwork covering a period of 4 years from the initial geological concept definition to the drilling and testing of the discovery well Incahuasi-X1. The overall approach can be summarized as a combination of controlled risk decision making based on a regional geological knowledge and the development of new techniques such as the definition of dedicated biostratigraphy charts. This approach enabled the multidisciplinary team to manage most of the uncertainties attached to this specific foothills context and define a workflow that led to success. The successful testing of the Incahuasi-X1 exploration well in 2004 led to a multi-tcf discovery currently under development. Located more than 120 km (75 mi) north of the existing Devonian gas fields, it opened a new exploration domain. It also highlights the benefit of a multidisciplinary and innovative approach in challenging areas such as the fold belts from prospect generation to discovery in a time constraint domain.

Abstract Improvements of geophysical acquisition and processing techniques and coring data give a new insight into the architecture of large subaquatic dunes. A field of dunes, with amplitudes ranging from 0.7 to 9.4 m. has been studied in the Bay of Bourgneuf. near the Loire inlet, France. Results show that the bedforms have steep lee sides and distinct asymmetry, and that the internal structure consists of steeply-dipping cross-strata truncated by several orders of bounding surfaces. The true dip angle of the laminae, measured on a core collected from a 3.6-m-high dune, suggests the existence of sandflow or sandfall processes, similar to those previously described in eolian dunes or small intertidal bedforms. The combined effect of waves and tidal currents is proposed to explain the strong asymmetry of the structures and the origin of bounding surfaces. Even if these dunes can be considered as tidal bedforms, seismic and core data suggest that the internal structure is probably the result of episodic, rather than cyclic, processes. If compared to the sand waves described by Visser from sheltered environments, this type of sandbody should be difficult to interpret in the stratigraphic record, because it does not display any "tidal criteria" (tidal bundles, mud couplets).