Text

theses

This report is a contribution to the Mid-Atlantic Offshore Carbon Storage Resource Assessment Program (MAOCSRAP), a Department of Energy funded multi-institutional effort to evaluate several rift basins located offshore of the East Coast of North America for carbon capture and storage (CCS) potential. Previous studies have noted the presence of Cretaceous sands in the Eastern half of the Georges Bank Basin (GBB) have reservoirs that have a high potential for storage of supercritical CO2, but most of the research in this basin was conducted between 1976 - 1982 and focused on potential petroleum. No additional research or data have been acquired since a drilling embargo was placed on the surrounding area in 1988 by both the Canadian and US governments. My task has been to compile and analyze the data available from exploratory surveys and drilling of 10 wells over 30 years ago through the use of a modern analysis software platform, and reevaluate it using modern tools and modern sequence stratigraphic methods to construct a better understanding of the development of the GBB through time and its potential as a CCS target.
There are six different 2D seismic surveys covering different areas of the GBB. These surveys were conducted at different times, by different exploratory companies, with different targets and goals. I have combined these six different data sets into one data set and added available well log data from the ten exploratory wells drilled in the basin in order to correlate two Cretaceous sand units from the Baltimore Canyon Trough to the GBB.
I identified the Logan Canyon Formation and the Missisauga Formation by their Gamma Ray (GR) character in several well logs, and constructed a preliminary well cross section of the basin. I then projected the GR logs onto the nearest 2D seismic profile, used my formation tops from the GR cross section to identify their correlating seismic reflectors, and traced those reflectors around the GBBB using a majority of the available seismic data. Some surveys did not have sufficient resolution at my target depths to provide useful results. The results of integrating these two different data types helped refine my interpretation. I then further refined my correlation of the two target formations by examining the stacking patterns of the parasequences visible on the GR logs. This allowed me to identify and correlate three sequences within the Logan Canyon Formation, and three sequences within the Missisauga Formations.
I determined that the Logan Canyon Formation is too shallow for CCS in the GBB, because the formation top lies above the minimum safe depth required to maintain supercritical pressure in liquid CO2 pumped into the seabed. The MAOCSRAP project stipulated 1000 meters below sea level (mbsl) for this cutoff depth, and over half of the Logan Canyon top lies above this depth. The Logan Canyon Formation also lacks a sufficient seal to prevent any injected material from migrating upward past the formation top where the top is deeper than 1000 mbsl.
The Missisauga Formation has excellent potential for CCS in the GBB. It lies deep enough to maintain necessary storage pressure, and it is overlain by the Naskapi Formation, a basin-wide shale unit that acts as a confining bed for any injected materials. However, the heterolithic sands deposited in likely fluvial environments present a less desirable reservoir than the deltaic sands of the Logan Canyon Formation. I conclude that the GBB is a possible target for carbon storage, though less so than the Baltimore Canyon Trough.
 

ETD_9372

M.S.

Includes bibliographical references

by Stephen Graham

doi:10.7282/t3-g4sf-c024

ETD graduate

The author owns the copyright to this work.