Seismic stratigraphy of the Georges Bank Basin: implications for carbon sequestration

• Main Author: Adams, Alexandra Cathren
• Format: Text
• Language: unknown
• Published: No Publisher Supplied 2019
• Subjects: naskapi
• Online Access: https://dx.doi.org/10.7282/t3-arnh-jz68; https://rucore.libraries.rutgers.edu/rutgers-lib/61674/

I evaluate Cretaceous sediments in the western part of the Georges Bank Basin (WGBB), offshore Massachusetts, United States, for carbon capture and storage (CCS) potential as part of Mid-Atlantic Offshore Carbon Storage Resource Assessment Program (MAOCSRAP). Previous studies have recognized that Cretaceous sands in the GBB may be viable targets for carbon injection due to the high porosity and permeable nature of the reservoirs, as well as a suitable cap rock confinement, but questioned their suitability due to shallow burial depths. Using the modern techniques of sequence stratigraphy and a modern analysis software tool (Petrel), I evaluate WGBB CCS potential using ~13,800 km of recently released 2D multi-channel (MCS) profiles integrated with 10 previously interpreted geophysical well-logs from the Eastern GBB. By mapping significant seismic horizons, defining internal reflection terminations and seismic geometries correlated with depositional facies, I identify five Cretaceous seismic sequences within four sedimentary units. The Berriasian to Barremian fluvial-deposited sand-prone Missisauga Formation was deposited during a regressive interval with northern-sourced sediment depocenters. A transition to a relatively thin shale-rich depositional sequence, the Naskapi Shale, represents the beginning of a major marine transgression initiated during the early Aptian. As sedimentation rates increased in the Albian to early Cenomanian, and sequence depocenters subsequently shifted landward, depositional environments transitioned from primarily terrestrial to nearshore/shelf/deltaic coeval with deposition of the thick, sandy Logan Canyon Formation sequences. Slightly irregular, hummocky, low-angle Albian clinoforms occur in the southeastern region. Reflection surfaces become more parallel upsection, coinciding with deeper paleowater depths. Prograding Cenomanian shingled clinoforms associated with toplap and downlap indicate prodelta to nearshore environments. Turonian to Coniacian deposition of the shale Dawson Canyon Formation and a shift in sedimentary depocenters to outer shelf deposits suggest a marine regression following the Aptian to late Cenomanian rise in relative sea-level. The sand reservoirs are mapped below the depth of supercritical CO2 storage (~800 m) and have sufficient shale cap rock confinement, therefore supporting the Lower Cretaceous Missisauga sands and mid-Cretaceous Logan Canyon sands in the southeastern subarea as potential viable targets for effective CCS. However, to assure successful sequestration, wells must be drilled locally to provide accurate porosity and permeability values, as well as to reinforce interpretations of the depositional facies and lithostratigraphy.