Geomechanical study with outcrop samples to improve drilling performance for an exploration well in Northwest Africa

A geomechanical survey of selected rock samples from outcrops and shallow stratigraphic wells taken from the vicinity of the prospect area has been conducted in order to obtain data and parameters useful for the selection of optimum drill bits prior to the drilling of a wildcat well in a frontier basin located in NW Africa. The available geological and drilling information suggests that the basin rocks are hard to very hard and abrasive, what will significantly increase the costs of the planned wildcat. Thus, this work is aimed at reducing drilling costs and to improve ROPs at the time of drilling by assessing realistic working properties from the drill bit selection point of view. The geomechanical survey included UCS, CCS, Schmidt hammer rebound and point load indexes, V-P & V-S wave propagation data (including high pressure hydrostatic determinations) and slake durability tests. A summary of the main results is presented here.