Challenge

Tallgrass MLP Operations, LLC (Tallgrass) required support in permitting and setting up baseline monitoring activities at the Eastern Wyoming Sequestration (EWS) Hub for CO₂ sequestration.

Solutions

Tallgrass contracted with GLA in 2023 to serve as the lead technical consultant supporting Class VI and California Air Resources Board (CARB) permitting and baseline monitoring activities for the Eastern Wyoming Sequestration (EWS) Hub. Our team provided end-to-end project support from field data acquisition to permit applications. We first provided geochemical modeling using PHREEQC in which our team conducted multiphase equilibrium modeling to assess chemical interactions among CO₂ injectate, formation fluids, reservoir mineralogy, cementitious materials, and casing steel. We then used these results to complete permit applications, including EPA Class VI application to inject, Subpart RR, and the CARB sequestration site application and revised application components to address CARB high-level screening comments and changes to the project in the intervening time period. All geologic, petrophysical, seismic, and well construction reports for the applications to inject were reviewed and certified by Wyoming-licensed professionals on our team.

GLA also prepared Monitoring, Reporting, and Verification (MRV) plans for covering all EWS Hub projects based on our geochemical modeling and coordinated geologic and petrophysical interpretations. These plans addressed delineation of the monitoring area, baseline characterization, CO₂ mass balance methodology, QA/QC procedures, and site-specific monitoring strategies (e.g., atmospheric, groundwater, soil gas, and seismic). GLA also designed and implemented a baseline program that included quarterly groundwater sampling, atmospheric monitoring, and vegetation NDVI analysis. Our team continues to implement the monitoring program, which includes sampling and laboratory coordination through Eurofins. In particular, out team managed fluid sampling from Halliburton Reservoir Description Tools (RDT) during well drilling and supported alternative laboratory identification for high-pressure CO₂-rich fluid analysis.

Results

GLA has delivered over a dozen separate technical reports for the project, all integrated across regulatory frameworks. Our work has ensured the successful creation and implementation of a CO₂ Sequestration project for all EWS hub projects.