Fracture Corridors in Fold and Thrust Zone, Devonian Sandstones Icla Syncline (Bolivia)

Fracture corridors are zones of high density of persistent fractures within a rock bearing scarcer diffuse fractures. They occur at all scales from cm to km. The underground hydraulic properties of fracture corridors are well characterized but their structural architecture is poorly constrained because of their sub-seismic resolution. Particularly, their distribution laws and geomechanic conditions of growth remain poorly known. The aim of this study is to decipher the tectonic condition and the geometry for fracture corridors affecting the Devonian sandstones of Huamapampa formation (Icla syncline, Bolivia). This formation is the stratigraphic and structural analogue for many gas field located in the area of the Icla Syncline. We proceeded a structural analysis in the field at metric scale, an analysis of Digital Outcrop Models from photogrammetry at pluri-metric scale, and 3D structural models with Gocad at the Syncline scale. We show that fracture corridors of the Icla Syncline are early and transverse, and they formed at the early onset of the folding. They formed as anastomosing sets as a function of the stratigraphic distribution of the layered sandstones. Fracture corridors are observed at all scales with a vertical persistence depending on the mechanical stratigraphy.