This blog focuses upon stylolites which are structures that either form during burial or by later tectonic movements and have a serrated appearance on rock surfaces.
Deformation bands (permeability reducing) and open fractures (enhancing) can co-exist in a sandstone reservoir but owing to timing (the d-bands form early during burial), the open fractures can still assist or provide essential reservoir permeability.
Induced fractures are not always easy to distinguish from open fractures. It is important though as induced fractures should not be included in the reservoir model.
Pink (Devonian age) mudstones on the bank of the River Tay (Perthshire, UK) are intensively fractured - including joints and larger through going fractures Here we look at some of their characteristics including some splaying geometries.
Natural fractures can improve the permeability of tight rock and are therefore often targeted by oil wells. But where do they occur in the reservoir and how do we find them ?