Multiwell DAS Microseismic and Strain Measurements Diagnostics

Abstract

Increasingly fiber optic networks are being used to monitor various processes in the subsurface. Amongst these are aspects of induced seismicity or fracture network generation tied to injection processes for storage purposes or more often, for unconventional reservoir development. Here we present how Distributed Acoustic Measurements (DAS) can be processed for joint microseismic (MS) and low frequency strain (LF-DAS). Using a three-dimensional network of fibers during an unconventional reservoir development we analyze the dual measurements taken from various vintage points.The material presented here validates the premise that fiber optic microseismic is tool that provides a measurement of stage activity during unconventional programs. By presenting multiwell DAS microseismic data, it is shown how some location biases that can occur with conventional geophone arrays can be overcome. We show how the availability of two or three fibers can provide the necessary ray distribution to do accurate 3D mapping of events. The significance of this work is that broad band DAS measurements that include MS and LF strain are an effective tool to illuminate the mechanisms for fracture generation. 3D distributions of DAS MS and LF strain events provide the framework for a more accurate description of the injection processes and its reservoir response during stimulation. By combining the two measurements in a multiwell setting we reveal how this two complimentary, but simultaneously run, measurements illuminate the subsurface and fracturing process.