Practical Reservoir Monitoring Using Distributed Acoustic Sensor with Engineered Fiber

Summary Distributed Acoustic Sensing (DAS) technology enables advanced geophysical measurement methods, where the fibre optic cable is deployed as a dense, wide-aperture phase-array sensor in novel configurations. A sensing system has recently been developed that combines an engineered fiber, incorporating bright scatter centers, with a low-noise, wide dynamic-range optoelectronics DAS interrogator. This new DAS sensing system with engineered fiber offers a 20dB (100x) improvement in sensitivity and a wider dynamic range compared to that achieved with standard fiber. The step-change in the performance seeks to disrupt conventional geophysical surveying methods by combing seismic, microseismic and low frequency strain measurements, and so enabling a practical method for reservoir monitoring. In offshore applications, the permanent installation of the fiber optic along production and injection wells is enabling more frequent and cost-effective seismic data to be acquired. The next challenge is stepping out to subsea wells. We present some initial lab results demonstrating the benefits of the engineered fiber for advanced seismic acquisition in long-tie back subsea wells using only surface optoelectronics.