Simulation of seismic events induced by CO2 injection at In Salah, Algeria

Date of Acceptance: 18/06/2015 Acknowledgments The authors would like to thank the operators of the In Salah JV and JIP, BP, Statoil and Sonatrach, for providing the data shown in this paper, and for giving permission to publish. Midland Valley Exploration are thanked for the use of their Move software for geomechanical restoration. JPV is a Natural Environment Research Council (NERC) Early Career Research Fellow (Grant NE/I021497/1) and ALS is funded by a NERC Partnership Research Grant (Grant NE/I010904).Peer reviewedPublisher PD

The microseismic response at the In Salah Carbon Capture and Storage (CCS) site

AbstractIn 2004, injection of carbon dioxide (CO2) to be stored at depth began at the In Salah Carbon Capture and Storage (CCS) site and a pilot microseismic monitoring array was installed in 2009. The In Salah project presents an unusual dataset since it is the first major non-Enhanced Oil Recovery (EOR) CCS project to be monitored for microseismicity. This paper outlines an extensive seismological study using a range of techniques, relying mainly on data from a single three-component geophone. Important information is derived from the data, such as event locations, event magnitudes and fracture characteristics, that could be used in real-time to regulate the geomechanical response of a site to CO2 injection. The event rate closely follows the CO2 injection rate, with a total of 9506 seismic events detected. The locations for a carefully selected subset of events are estimated to occur at or below the injection interval, thereby ruling out fault or fracture activation caused by CO2 migration at shallow depths. A very small number of events (11) with less well-constrained locations may have occurred above the injection interval. However, there is no microseismic evidence that these events are correlated with CO2 injection and we suggest they are caused by stress transfer rather than CO2 migration into the caprock. The observed maximum moment magnitude, Mw=1.7, is consistent with estimated fracture dimensions at the injection depth. Fracture orientation estimated using shear-wave splitting analysis is approximately NW-SE, in agreement with fracture orientations inferred from logging data. During periods of high injection rates the degree of anisotropy increases slightly and then falls back to original values when injection rates fall. This implies the CO2 is opening pre-existing fractures which then close as pressure decreases.This an important proof-of-concept study that proves the value of microseismic monitoring of CCS projects, even with a limited array. We thus recommend that microseismic monitoring arrays are installed prior to CO2 injection at future CCS sites to enhance our understanding by making baseline and comparative studies possible. This would also provide real-time monitoring of the geomechanical response to injection, allowing operators to modify injection parameters and to help ensure the safe operation of a project

DAS dataset suitable for microseismic and ANI analysis

Deliverable 1.2 concerns a DAS dataset suitable for microseismic and ambient noise interferometry (ANI). For this deliverable the DAS field dataset of FORGE is recommended. FORGE is the Frontier Organization For Research in Geothermal Energy, and is a field laboratory for developing an enhanced geothermal system in hot crystalline rock situated near the town of Milford in Utah, USA (https://utahforge.com/). The FORGE team is led by Joe Moore of Utah (and funded by the US Department of Energy) and is credited for this dataset. The dataset is completely open access, but obviously attribution would be appreciated in any publications. The FORGE dataset applies for deliverable 1.2, because it provides downhole DAS and geophone recordings of microseismic events, and covers approximately two weeks of continuous DAS recordings that can be used to test the potential of DAS for the ANI method. In addition to the FORGE dataset, various other DAS datasets have recently become publicly available that are recommended to consider as well for further work in task 1.3 and associated tasks, since they can be valuable in addressing different research aspects of the application of DAS. Table 1.1 gives a summary of the different open access datasets considered for this deliverable. This table also shows whether the datasets are suitable to be used for microseismic and ANI analysis. With this application in mind for deliverable 1.2, and when compared against alternative datasets (see Table 1.1), the FORGE dataset is considered to be especially relevant for this deliverable, since it provides both microseismic event data and continuous DAS recordings from a borehole configuration spanning a relatively long duration (17 days). The borehole configuration is preferable for the purpose of detecting micro-seismicity since it allows measurements close to the reservoir and therefore able to detect weaker events compared to a trenched deployment at the surface. FORGE concerns an enhanced geothermal system and in this setting the mechanism driving seismicity is different compared to the case of CO2 injection and storage (DIGIMON). However, the performance of the DAS cable with respect to detected seismicity is expected to be similar for the case of monitoring CO2 injection and storage as in a geothermal setting and therefore the FORGE dataset is expected to be suited for this purpose

DigiMon Final Report

"DigiMon Final Report” summarizes the ACT DigiMon project. The overall objective of the DigiMon project was 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, receiving CO2 from fossil fuel power plants, oil refineries, process plants and other industries.DigiMon Final ReportpublishedVersio

DAS field dataset to compare technologies and deployment scenarios

This report describes a Distributed Acoustic Sensor (DAS) dataset acquired by DigiMon partners at the Containment and Monitoring Institute’s (CaMI) Field Research Station (FRS), Canada, between 6th to 10th September 2021. The field dataset contributes to the Deliverable D1.1 of the DigiMon project (DAS field dataset to compare technologies and deployment scenarios), which supports tasks 1.2 and 1.3 of the 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 DAS. While the system is primarily focused on CCS projects located in 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 both active and passive seismic methods will be deployed to track the movement of CO2, for example seismic reflection to image seismic velocity changes and microseismics to capture fault activation. Acquiring seismic surveys using DAS is highly novel and offers cost-effective approach which can significantly increase the spatial resolution of the survey data; however, it has had limited use in the operational environment with several technical challenges still needing to be resolved, such as the transfer function of DAS. CaMi FRS was selected as a field test location as the site has been specifically established to advance the development of monitoring technologies and protocols for CCS operations. At CaMi FRS, several different monitoring arrays have been installed which are directly applicable to DigiMon. This includes a 5km loop of DAS optical fibre, located with a 1.1 km surface trench and two observation wells, an array of surface and borehole geophone nodes, and 6 broadband seismometers operating by the University of Bristol. This monitoring infrastructure has been primarily installed to monitor CO2 injections into the Basal Belly River sandstone formation at approximately 300m below ground level. Injection of CO2 began at FRS in 2019 and during this time microseismic events have been recorded, albeit at shallower levels than the injection point. The site therefore provides a potential DAS dataset which contains both active and passive measurements for the DigiMon project. The abundance of instrumentation including DAS, geophones, and broadband seismometers provides a unique chance to test the capacity of these instruments for C02 storage monitoring

Cross hole seismic experiment with DAS/DTS data. Svelvik CO2 field lab

Primary purposes of the fieldwork at Svelvik include the provision of datasets which supports task 1.2 ‘determining the DAS transfer function’ and task 1.3 ‘develop DAS data processing techniques and workflow’. The fieldwork also serves as a test of the novel SV wave seismic source developed as part of Task 1.4. ‘Active source technology development and optimising monitoring design.Cross hole seismic experiment with DAS/DTS data. Svelvik CO2 field labpublishedVersio