DAS Processing Workflow

This report addresses deliverable D1.6 of the DigiMon project, which covers the processing workflow for datasets acquired by Distributed Acoustic Systems (DAS), and follows on from the DAS Preprocessing workflow report (DigiMon Deliverable 1.4), which captured the key stages required to prepare the raw seismic data for the main processing stages. The workflows are specifically for microseismic and ambient noise interferometry methods, which are both passive seismic methods that seek to image CO2 movement within a storage reservoir and potential breaches of the reservoir

Project report on WP1 outcomes relevant to other WPs

This report summaries some of the key technologies that have been studied and developed through WP1 with the purpose of transferring these finding to other WPs in the DigiMon project. The objective of the DigiMon project is to develop an early-warning system for Carbon Capture and Storage (CCS) which utilises a broad range of sensor technologies including Distributed Acoustic Sensing (DAS). While the system is primarily focused on the CCS projects located in the shallow offshore environment of the North Sea, it is also intended to be adaptable to onshore settings. Some of the key areas that the systems will monitor include the movement of the plume within the reservoir, well integrity and CO2 leakage into the overburden. A combination of different methods will be adopted to monitor these key areas, which include active and passive seismics, gravimetry, temperature and chemical sensing. This report focuses on technology and methods which have been developed by the DigiMon project and is not intended as a technology review, which is instead the focus of the DigiMon deliverable 2.3 Technology Readiness Assessment

Critical technology elements (WP1)

The overall objective of the DigiMon project is to “accelerate the implementation of CCS by developing and demonstrating an affordable, flexible, societally embedded and smart Digital Monitoring early warning system”, for monitoring any CO2 storage reservoir and subsurface barrier system. Within the project the objective of WP1 was to develop individual technologies, data acquisition, analysis techniques and workflows in preparation for inclusion in the DigiMon system. The technologies and data processing techniques developed as part of WP1 include distributed fibre-optic sensing (DFOS) for seismic surveys and chemical sensing, 4D gravity and seafloor deformation measurements, a new seismic source and seismic monitoring survey design. For these technologies the key targets for WP1 were • Develop individual components of the system to raise individual technology readiness levels (TRLs), • Validate and optimise processing software for individual system components, • Develop an effective Distributed Acoustic Sensing (DAS) data interpretation workflow. This work was performed with the expected outcomes of • Raising the DAS TRL for passive seismic monitoring, • An assessment the feasibility of using Distributed Chemical Sensing (DCS) for CO2 detection, • Reducing the cost of 4D gravity and seafloor deformation measurements

Structural delineation at the Los Humeros geothermal field, Mexico, by P-wave reflection retrieval from noise

Mathematical Geodesy and Positionin

Ambient noise seismic reflection interferometry at the Los Humeros geothermal field, Mexico

Integration of results from active seismic, passive seismic and well data reduces the uncertainties of several subsurface parameters that are of interest for cost-effective geothermal production operations in Los Humeros. In this study, we present results from the application of ambient noise seismic interferometry (ANSI) to retrieve zero-offset reflected P-waves from continuous seismic data recorded at the Los Humeros geothermal field, Mexico. This study is inspired by encouraging results from the application of ANSI for body wave reflection retrieval that was reported in 2016 for a geothermal field located at Reykjanes peninsula, Iceland (Verdel et al., 2016). Continuous broadband and short-period seismic recordings provided insightful reflection information that corresponded well, in relevant depth intervals, with reflectivity retrieved from the correlation of coda waves from a distant but very strong earthquake. That work was carried out within the context of EU’s Seventh Framework research and innovation program IMAGE. Encouraged by these findings, it was decided to conduct a new study following a similar approach within the context of the GEMex project, a European-Mexican collaboration. The purpose of GEMex is to gain an improved understanding of the geological structure and geothermal reservoir behaviour for two geothermal fields: Los Humeros and Acoculco. In the following, we address data selection and processing aspects related to the retrieval of reflected P-waves from Los Humeros seismic noise recordings. The retrieved reflections are compared with modelled reflectivities at two station locations at a close distance from the location where the seismic interval velocities that are used in the modelling were available from the literature. The reflected P-wave information provides structural detail about the field at locations directly underneath the employed seismic stations.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Mathematical Geodesy and Positionin