Quantitative Evaluation of Short String Gas Injection Profile Using Distributed Acoustic Sensing and Temperature Modelling Through the Long String in a Dual Completion Offshore Well, a Case Study

Abstract Objectives, Scope Managing production from multiple reservoirs is challenging, particularly in dual-string wells where conventional PLT techniques struggle to evaluate short string profiles. This paper explores the application of distributed acoustic sensing coupled with temperature modelling for short string injection profiling in dual string gas injectors, alongside a comparison between conventional PLT and modelling results for the long string. Methods, And Process The survey encompassed two runs through the long string. In the first run, temperature and acoustic data were recorded under shut-in and short string injection conditions. The second run recorded temperature, acoustic, and spinners data under shut-in and long string injection conditions. A distributed spectral acoustic tool with eight nano-synchronized sensors provided precise vertical resolution (3 ft) and distinguished flow inside the wellbore and formation. The short string's injection distribution profile was determined using an industry-proven temperature modelling technique. Results, observations, and conclusions The short string comprises hydrodynamically independent sublayers (10-30 ft thick). Distributed acoustic sensing identified active reservoir intervals for both the long and short strings, confirming reservoir flow. Typical acoustic signals and temperature anomalies for active crossflow between perforated intervals in the short string were recorded, revealing sublayer pressure differences. Non-uniform injection profiles were observed in both short and long strings, with no unwanted injection behind the casing or communication between strings. Initiative ad added information This paper elucidates how distributed acoustic sensing, paired with temperature modelling, facilitates accurate short string performance assessment, offering critical insights for reservoir management and enhancing operational efficiency in dual-string gas injector operations.