A fracture study by using bipole–bipole cross-well logging

Abstract

Electrical Resistivity Tomography (ERT) can provide images of subsurface electrical structure between two boreholes. Data quality control is a key issue before ERT inversion. However, there is no effective data quality control method on an ERT survey. In this paper, a method called common current gather for a bipole–bipole array (CCGbb) was proposed to check ERT data quality in a rapid way. Synthetic models were conducted to compare the response difference between pole–pole array and bipole–bipole array. A field work at granite area was tested to verify the applicability of the proposed CCGbb method. From the results of this study, we suggested that conducting CCGbb before ERT inversion and a cross-borehole tracer test for both field data quality control and possible water conducting fractures (WCFs) delineation. ► We begin with three synthetic models to compare the resistance-depth trace difference between pole–pole array and bipole–bipole array. ► A field work demonstrated that CCG is capable of identifying noisy data from normal. Also, the lowest resistance area will located at water saturating fractures. 2D ERT inversion, tracer test were conducted to verify the result from CCG method. ► We conclude that conduct CCG first for check data quality before 2D ERT inversion. A priori fracture information will obtain from CCG to shorten tracer test time.