Intelligent Distributed Acoustic Sensing for In-well Monitoring

Abstract

Abstract Interval Control Valves ICVs and Inflow Control Devices ICDs can enable optimization of the production and injection profile along the wellbore. The ICV devices are operated to increase the hydrocarbon recovery and prevent unwanted fluid production. The ICDs are selected and positioned to optimize the water flood profile. Although the operations of devices are well understood, the optimization of these devices in-situ is complex. The real-time monitoring of fluid flow along the wellbore can provide valuable information to set the position of the inflow devices and optimize the fluid flow in multilateral zones. The intelligent Distributed Acoustic Sensor (iDAS) uniquely allows the simultaneous recording of acoustic energy along many kilometers of optical fiber deployed along the wellbore. The system uses a novel digital optoelectronics detection technique that captures the amplitude and phase of the acoustic waves generated and propagated along the wellbore over a wide frequency (1mHz – 100kHz) range with a high dynamic range (>120dB). A number of signal processing techniques have been developed for processing a large array of acoustic data that can be recorded along the wellbore for monitoring the inflow at different zones. The iDAS system can be used with single-mode as well as multimode optical fibers. The iDAS system was retrofitted to existing optical fibers that were already installed along several wells in Saudi Arabia. The acoustic noise energy generated across the inflow devices and propagating along the wellbore tubing was recorded. The acoustic noise spectrum can be used to monitor the fluid flow through the inflow devices. Using array processing, the speed of sound can be determined over several sections of the tubing to identify the fluid composition. This paper reports on the results of the field trial carried in 2012 in several wells equipped with inflow devices.