Proactive well diagnostic surveillance helps with safe delivery of production by effective well management and risk mitigation. The objective of the paper is to demonstrate the data analytics approach utilizing passive acoustic technology in combination with conventional methods of detecting low magnitude dynamic events behind single or multiple casing strings. The results of integrated interpretation of passive acoustic wireline technology with the data from different sources helped to make optimal decision.
Traditional well integrity diagnostic includes temperature and passive acoustic data analysis that are associated with high uncertainty. A newer generation of array passive acoustic technology with enhanced sensitivity capabilities was deployed offshore Azerbaijan. A combination of array passive acoustics data, single point temperature and distributed fiber optic data have been acquired during a multi-well campaign. Extensive review of well integrity history, downhole and surface gauge data incorporated with passive acoustic data from arrays of spectral sensors in time and depth domain helped to refine the process and evolve into a unique interpretation methodology.
The comprehensive interpretation accounted for integration of all available static and dynamic data such as: fluids and formation pressure distribution along the borehole, cement bond logs evaluation, annuli pressure and temperature, production and downhole gauge measurements, fibre optic data, temperature and passive acoustic logs. This helped to understand the low scale dynamic events behind the casing and make an informed decision on safe and reliable well operations. The sensitivity of array passive acoustic technology proved successful in detecting subtle acoustic events where conventional methods failed or had limited success. Successful results have been achieved by customizing the logging program using a multiple well evolutionary approach that improved data quality and saved rig time. Interpretation and decisions derived from each well involved multi-disciplinary well review panel sessions with specialists from subsurface & geohazards, drilling & completions, production & operations departments.
Case studies presented in this paper describe the interpretation approach of highly sensitive array passive acoustic sensors in combination with available static and dynamic point and distributed data. The logging program and interpretation approach used in this article could be considered as a basis for future applications in wells with similar design.