Advances in an Integrated Analysis Workflow of Distributed Acoustic Sensing and Distributed Temperature Sensing for Water Injection Profiling on a Horizontal Well

Abstract

Abstract This paper describes advances in an integrated analysis workflow of Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS) for water injection profiling on a horizontal well, completed with Limited Entry Liners (LEL). The well is completed as an injector with Limited Entry Liner (LEL), MRC horizontal lateral made of 18 separated zones with packers, each with variable numbers of holes. DAS and DTS data were acquired on coiled tubing, over an acid stimulation period followed by a water injection period. Previous analysis of the dataset, SPE-203065, focused on DTS warm-back models and highlighted challenges in the process; the use of the DAS data was limited. Recent re-processing of the data using advanced acoustic signal processing techniques was performed to extract several flow characteristics. Both transient and steady state injection conditions were analyzed: High-definition low frequency slow strain DAS was extracted over the shut-in to injection transient to compute an initial injection velocity profile as well as a stage level injection distribution across the liners. During steady state flow, acoustic denoising algorithms were applied to the DAS data in order to generate a spectral noise log of high signal to noise ratio (SNR) for the detection of all major injection points. Video animations were generated of spectral noise logs over time, to evaluate the dynamic behavior of the injection profile from start to end. The warm-back DTS data was analyzed for a qualitative assessment of the injection Finally, a quantitative injection profile was computed, and the results were compared against a separate PLT log at both stage and nozzle levels. The results of the transient and steady state flow analysis converged and showed the highest water intake to occur over the heel-ward stages. The depths of highest rate of change in injection velocity, aligned with the strongest acoustic signals from the enhanced noise log. Inversely, the weaker acoustic outflow activities over the middle and toe sections aligned with the smaller velocity changes. The video animations showed a stable injection profile over time. The qualitative DTS analysis confirmed the overall DAS-based injection profile. The comparison with the PLT injection allocation highlighted clear differences in the profiles. These are being discussed, as well as the possible causes for the discrepancies. This analysis demonstrates the strength of an integrated DAS and DTS analysis workflow using both transient and steady state conditions. DAS array processing techniques enabled the extraction of high-definition transient thermal plumes, allowing for an early injection profile, which was further strengthened by high SNR spectral noise logging.