Geophysical Investigation of Loss of Circulation in Borehole Drilling: A Case Study of Auchi Polytechnic, Auchi, Edo State, Nigeria

Geophysical investigation of loss of circulation in Borehole drilling at the Auchi Polytechnic Auchi, Etsako West L.G.A, Edo State, Nigeria was carried out. Electrical resistivity sounding techniques with Schlumberger array for Vertical Electrical Sounding (VES 1) was used while modified Schlumberger array was used for Vertical Electrical Sounding (VES 2) with Australia Energy Market Commission (AEMC) Soil Resistivity meter. The Digital Ground Resistance and Soil Resistivity Tester model 6470-B was used. The Tester was produced by Australia Energy Market Commission. Geographical coordinate were obtained from a Global Positioning System (GPS) device. The quantitative interpretation of the resistivity sounding curves was done to obtain the layer thicknesses and resistivities with the computer assisted iteration techniques. Five and four geoelectric layers were resolved for Vertical Electrical Sounding (VES 1) and Vertical Electrical Sounding (VES 2) respectively. The loss of circulation within this borehole occurs around the depth of 36m. The loss zones are permeable and aerated with very high resistivity values. The void spaces within the soil layer in the horizon are not conducive. Pre-drilling geophysical investigation should not be optional but a necessity for every borehole drilling project in order to know the subsurface geology.