High Definition Acoustic and Temperature Logging for the Diagnosis of Complex Annuli Leaks and Communication

Abstract Maintaining annuli integrity is critical for safe and optimized well operations. Monitoring of tubing casing annulus (TCA) and casing-casing annulus (CCA) pressures is mandatory as it gives a direct indication of possible seal or tubular failures that may lead to a negative impact on HSE or well production. In cases where the observed annuli pressures suggest leaks and possible communication between tubing and TCA or TCA and CCA, a comprehensive plan should be put in place to detect and evaluate the possible leak sources and paths that will allow for proper remedial actions. Logging techniques using spectral noise logging (SNL), and high precision temperature Logging (HPT) are one way to diagnose the source of a leak and communication path between 2 adjacent casings (for example TCA and CCA). The operation is performed by running the HPT and SNL log under shut in conditions to establish a base line, followed by logging under dynamic conditions. Dynamic conditions can include bleeding off the TCA pressure while all other annuli and tree valves are shut-in and injecting into the tubing-casing annulus while bleeding off the CCA. The dynamic passes aim to activate the leak points. The SNL and HPT will capture the corresponding temperature and Spectral noise events revealed by the fluid flow though the leak points. These are compared to the base line shut in logs. The SNL is run in stations and can capture noise generated by fluid movement in a wide range of strength (decibels) and frequency within a wide scanning radius, while HPT can capture minor temperature changes of 0.02 Deg F. The paper will discuss an example where the HPT and SNL were run along with a set of conventional sensors such as GR, CCL, and pressure in a HPHT gas well to diagnose leak points and a possible communication path between the TCA and CCA. The Logging operation was carried out rig-less with minimum intervention using wire line under the shut in and dynamic conditions. Spectral noise logging precisely captured the leak points and drew a clear picture of the casing integrity breaches in multiple points. The results of the diagnostics and evaluation will now be used to design the appropriate remedial actions required to restore the well to the desired condition for production.