It is the largest hydropower project in Equatorial Guinea. In view of the fact that most of the reservoir area is covered with primitive tropical forests, which cannot be effectively investigated by manual operation, thus 3S technology is applied. Considering the large width of the fault zone almost along the river and the influenced zone as well as the broken rock mass, the electrical prospecting and integrated logging method are used to investigate the geological conditions and to identify the concealed structures such as fracture zones and weathering cystids.