Wellbore Integrity Assessment with Casing-based Advanced Sensing

Abstract

Wellbore integrity is of paramount importance to subsurface resource extraction, energy storage and waste disposal. After installation, the casing and cement are subject to mechanical stress due to near-well pressure changes and fluid induced corrosion. This is exacerbated for geothermal wells where produced water is at high temperature, which can accelerate corrosion rates. The current state-of-the-art technologies for wellbore integrity assessments are mostly downhole logging tools, such as wireline based acoustic, electromagnetic and mechanical tools. While these tools can provide high-resolution assessment of borehole conditions, they are intrusive in terms of borehole occupancy and interruption to the normal operation of the wells. In addition, these measurements are performed infrequently due to high cost, and are incapable of providing frequent data to better predict borehole degradation trajectory, which can help provide early warning of potential borehole failures. We are developing a novel, non-invasive, casing based approach for wellbore integrity assessment, combining fast/low cost screening with higher-precision investigation. Our approach is based on monitoring the response of the casing when energized at the wellhead, thereby interrogating the casing without well intervention. Lab, field and numerical approaches are used in our study, and early results from numerical simulations have illustrated the sensitivity of the approach to changes of wellbore characteristics due to corrosion-induced damages. Laboratory and field experiments are underway to demonstrate technology sensitivity, optimize data acquisition and improve numerical simulations.