TY - JOUR
T1 - Mechanical properties of Mesozoic rift basin formations
AU - Zakharova, Natalia V.
AU - Goldberg, David S.
N1 - Funding Information:
Multiple research projects carried over the years in the Newark basin have accumulated extensive core and borehole data, allowing for evaluation of the physical and mechanical properties of these sediments. In the early 1990’s, the Newark basin Coring Project (NBCP) collected over 6,700 m of core spanning a nearly complete stratigraphic section in the central part of the basin from the lower Stockton to upper Feltville formations (Olsen et al. ; see Figs. and ). This continuous coring record was acquired by offset drilling: a transect of 7 boreholes drilled across the basin that each penetrated a marker horizon allowing correlation to an adjoining hole. A dataset of basic geophysical logging measurements was also acquired in all the holes, allowing for hole-to-hole and petrophysical correlations (Goldberg et al. ). More recently, these data were complemented by two shallower boreholes drilled and logged in the northern part of the Newark basin, on the campus of Lamont-Doherty Earth Observatory (Goldberg and Burgdorff ; Zakharova et al. ). Finally, as a part of comprehensive screening of sedimentary basins for geologic CO storage by the U.S. Department of Energy (DOE) (e.g., Goodman et al. ), the TriCarb consortium conducted a stratigraphic testing program in the northeastern Newark basin. For this poroject, TriCarb drilled a deep borehole, NYSTA TandemLot-1 (Fig. ), with limited coring but extensive geophysical survey and logging, and a new basement-penetrating hole, Lamont Test Well-4, with nearly continuous coring and a full suite of geophysical logs (Zakharova et al. ; Collins et al. , ). The geomechanical analysis described in this paper draws on the extensive core collection from the NBCP and TriCarb boreholes and was funded by the DOE. 2
Funding Information:
The data presented in this paper were acquired under DOE award DE-FE0023334. We thank TerraTek Schlumberger for help with desining custom protocols for mechanical rock testing and Dan Collins from Geostock Sandia, LLC for project management.
Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
PY - 2021/8
Y1 - 2021/8
N2 - Abstract: The Newark basin is one of the largest Mesozoic rift basins in Eastern North America, which preserves tectonic and climatic archives and has been considered for geologic CO2 storage. This paper describes geomechanical properties of the Newark basin formation, focusing primarily on mudstone intervals. Compressive strength, elastic moduli and acoustic velocities were evaluated with a series of triaxial tests at confining pressures ranging from 0 to 41 MPa. The predominantly lacustrine mudstones are characterized by XRD clay content from 30 to 70%, and a large range of compressive strength, from 50 to 300 MPa, in excess of most published values for clay-rich rocks. The strength does not exhibit a strong relationship to clay content and can vary significantly for similar lithotypes. Important factors affecting rock strength in these rift basin formations are: (a) albitization by sodium metasomatism, which increases strength; and, (b) thin bedding, which introduces significant strength anisotropy, most pronounced in the Lockatong mudstones. Unlike rock composition, the elastic moduli correlate well with compressive strength. Overall, our results indicate high spatial heterogeneity of mechanical properties in these rift basin formations and a lack of characteristic strength ranges for common lithotypes in the Newark Supergroup and/or specific formations in the Newark basin. However, a strong correlation of acoustic velocity and elastic moduli with compressive strength would allow using those parameters to estimate strength when direct measurements are not available. Article highlights: Compressive strength of the Newark basin mudstones exhibits poor correlation to clay contentThe mudstone strength is greater than most published values for similar lithologiesThe mudstone strength is affected by albitization due to sodium metasomatism.
AB - Abstract: The Newark basin is one of the largest Mesozoic rift basins in Eastern North America, which preserves tectonic and climatic archives and has been considered for geologic CO2 storage. This paper describes geomechanical properties of the Newark basin formation, focusing primarily on mudstone intervals. Compressive strength, elastic moduli and acoustic velocities were evaluated with a series of triaxial tests at confining pressures ranging from 0 to 41 MPa. The predominantly lacustrine mudstones are characterized by XRD clay content from 30 to 70%, and a large range of compressive strength, from 50 to 300 MPa, in excess of most published values for clay-rich rocks. The strength does not exhibit a strong relationship to clay content and can vary significantly for similar lithotypes. Important factors affecting rock strength in these rift basin formations are: (a) albitization by sodium metasomatism, which increases strength; and, (b) thin bedding, which introduces significant strength anisotropy, most pronounced in the Lockatong mudstones. Unlike rock composition, the elastic moduli correlate well with compressive strength. Overall, our results indicate high spatial heterogeneity of mechanical properties in these rift basin formations and a lack of characteristic strength ranges for common lithotypes in the Newark Supergroup and/or specific formations in the Newark basin. However, a strong correlation of acoustic velocity and elastic moduli with compressive strength would allow using those parameters to estimate strength when direct measurements are not available. Article highlights: Compressive strength of the Newark basin mudstones exhibits poor correlation to clay contentThe mudstone strength is greater than most published values for similar lithologiesThe mudstone strength is affected by albitization due to sodium metasomatism.
KW - Compressive strength
KW - Elastic moduli
KW - Mesozoic rift basins
KW - Mudstones
KW - Newark basin
KW - Strength anisotropy
UR - http://www.scopus.com/inward/record.url?scp=85108091402&partnerID=8YFLogxK
U2 - 10.1007/s40948-021-00263-4
DO - 10.1007/s40948-021-00263-4
M3 - Article
AN - SCOPUS:85108091402
VL - 7
JO - Geomechanics and Geophysics for Geo-Energy and Geo-Resources
JF - Geomechanics and Geophysics for Geo-Energy and Geo-Resources
SN - 2363-8419
IS - 3
M1 - 70
ER -