Estimation of anisotropic properties of fractures in Presco campus of Ebonyi State University Abakaliki, Nigeria using Azimuthal resistivity survey method

Odoh I. Ben¹* and A. G Onwuemesi²

¹Department of Geology and Exploration Geophysics, Ebonyi State University,

P.M.B. 053 Abakaliki 480001, Nigeria.

²Department of Geological Sciences, Nnamdi Azikiwe University Awka, P.M.B. 5025, Awka, Anambra State, Nigeria.

*Corresponding author. E-mail: lifeaquifer2000@yahoo.co.uk

Tel: +234-8037240806.

Accepted 15 September, 2009

   Abstract

This study determined and characterized the anisotropic properties of fractures in Presco Campus of Ebonyi State University Nigeria for evaluation of groundwater development and flow within the area. The azimuthal resistivity survey results show that there is significant anisotropy between 0 – 50 m depth and that the fractures at depths of 28.3, 40 and 50 m strike NE-SW, NW-SE and N-S, respectively. Variation of apparent resistivity is strongest between 112.2⁰ and 135⁰; and between 40 and 50 m depth. Coefficient of Anisotropy, l, ranges between 1.23 and 1.44 while fracture porosity varies from 0.02 - 0.09 in the area. The coefficient of anisotropy (l) has been shown to have the same functional form as permeability anisotropy to a first order. Thus, a higher coefficient of anisotropy (l) implies higher- permeability anisotropy. The results also indicate better permeability and porosity at the depth of 40 and 50 m.

Key words: Electrical anisotropy, fractured shale, porosity, permeability, Abakaliki.