Feasibility of a Surface-Based Controlled Source Electromagnetic Method for Detection of Buried Pipelines and Corrosion Effects

Abstract

The controlled source electromagnetic (CSEM) geophysical method is used for a number of purposes, including exploration and characterization of oil and geothermal deposits. Here, based on idealized modeling scenarios, we explore an adaptation of the method to remotely inspect shallow buried pipelines and determine its suitability for monitoring corrosion because of the sensitivity of CSEM responses to electrical conductivity contrasts within the subsurface. We show that the electric field response from an in-line transmitter-receiver configuration provides more diagnostic information than the broadside configuration while both are likely to detect the pipeline response in the presence of ambient noise. The presence of a conductive pipeline is considerably easier to detect in sandy soils than in clays and there is a reduction in amplitude and response shape when the pipeline is resistive. In-line responses can diagnose the level of corrosion, although it is difficult to distinguish between a highly corroded pipeline and one with a break. In cases where a pipeline break is present, some data processing may be required to precisely locate the break.