The Loss of Primary barrier: An Integrated Approach of Downhole Leak Location and Quantification. Case Study

Abstract

Failure of the primary barrier in most cases results in observable sustained annulus pressure. For other such cases, sustained annulus pressure may not result, and leak associated fluid movement remains confined to deeper intervals, for example as cross flows. This manuscript introduces a comprehensive approach to assess the current status of primary and secondary barriers and, for this case of integrity loss, to quantify the downhole leaks rates. The assessment includes: Determining individual pipe wall thickness of first two concentric metal barriers using electromagnetic pulse logging techniqueSpectral Noise Logging to locate the active leaks and to verify the sealing integrity of cement barriersHigh Precision Temperature logging for downhole leak rate quantification utilizing temperature modeling The paper contains the physics of measurement, lab and field tests of the barrier assessment technologies, followed with a case study: A single string gas producer, with sustained A-annulus pressure. Additional survey findings allowed the identification and quantification of a crossflow resulting from leaks.