REMINDER: November 10th, 2022 DGS Luncheon Presentation – Suresh Dande, ESG Solutions Inc.

FusionArray^TM: Improving the value of both active and passive source data acquired by a single fiber optic array through data integration

Suresh Dande 

Abstract:

Use of fiber optics Distributed Acoustic Sensing (DAS) data in monitoring the hydraulic fracturing of unconventional reservoirs, Enhanced Geothermal Systems (EGS) and to monitor geological CO₂ sequestration is growing. The fiber optic array provides high spatial resolution and larger receiver aperture at a lower cost compared to the conventional geophone array. However, the main disadvantage of fiber is its limitation on sensitivity for waves with incidence angle 90⁰ to the fiber. In other words, fiber acts as a single component geophone with most sensitivity to waves propagating along the fiber and least sensitivity to waves propagating across the fiber. Because of this sensitivity limitation, there is a 360⁰ azimuthal uncertainty in microseismic event locations around the fiber. One of the ways to solve the azimuthal uncertainty is to use multiple fiber wells (minimum of three). However, it is very rare to have more than one well dedicated to fiber monitoring. The best way to solve the azimuthal uncertainty associated with a fiber array is to deploy a single fiber wireline with 3C geophones (FusionArray^TM) attached to the end of the wireline. The objective of this work is to show case studies with microseismic, surface VSP and cross-well seismic data acquired on a FusionArray^TM.

The first case study is from a hydraulic fracturing project with fiber and geophones in the same well. We utilize the azimuth information estimated from the geophones and co-locate microseismic events that are recorded both on fiber and geophones. We observe a significant improvement in the accuracy of the event locations after co-location due to the addition of azimuth and increased receiver aperture. The second case study is a science experiment conducted at the University of Houston shallow test wells. The goal of this experiment is to compare the data between geophones and fibers (single mode and multimode) acquired on a FusionArray^TM with different source types (borehole and surface). In both case studies fiber data is converted to a geophone equivalent particle velocity to allow comparison of the amplitudes between the two sensor types and their sensitivity to different sources.

Suresh Dande is currently working as Fiber Optics Subject-Matter Expert at ESG Solutions. He is responsible for leading and developing fiber optics data acquisition and processing technology. He previously worked as Geophysical Software Developer at ESG Solutions and as a geophysicist at Sigma Cubed Inc.  He has 10+ years of experience in monitoring and processing borehole microseismic data. From 2009-2011, Suresh worked as a CSIR Research intern in Aeromagnetics at National Geophysical Research Institute, India. Suresh Dande received an M. Sc degree in Geophysics from Andhra University (India), an M.S degree in Geology from Southern Illinois University, and a Ph.D. degree in Geophysics from the University of Houston.