Interpretative approach of electrical resistivity data for efficiency implantation of drilling on basement zone : Case of Guibéroua (Côte d’Ivoire)

Résumé

As part of the drilling of holes at Guibéroua, geophysical prospecting campaigns are being carried out. Sites (F1 and F2) are generally identified in order of priority at the level of each locality. However, this order is not often the good one because of the failures obtained during the drilling. This raises problem of identifying objective geophysical criteria in order to increase the chances of success at the first attempt at drilling. This work proposes an interpretation approach to electrical resistivity data for a judicious choice of drilling sites. From these data, electrical profiles were represented. On these, various forms of anomalies were identified at which fracturing index (IF) were calculated. The results show that the most common forms of anomaly in the study area are «U», «V», «W»; those of form «M» are rare. The Highest average fracturing index (IFm) is observed at the level of «V»-shaped anomalies. This indicates that the latter correspond to the most fractured zones of the study area. They are therefore most likely to be aquifers. Also, drillings that have been implanted there have provided good flow for the village hydraulics. «U» shape anomalies have a low IFm. They are among the least fractured sites in the study area. This is confirmed by the very low flow rates of the boreholes that were implanted. As for «W» shape anomalies, although the IFm is weak, they are ideal for boreholes implantation with regard to the high flows obtained. This study shows that, in addition to the form of the anomaly, the fracturing index is an important parameter to take into account in the choice of drilling sites. The use of these two parameters can guarantee a high success rate of drillings.