Seismic imaging of complex geometry : Forward modeling of sandstone intrusions

We acknowledge the support of sponsoring companies of Phase 3 of the Sand Injection Research Group (SIRG). The Norwegian Petroleum Directorate (NPD) are thanked for providing seismic data from Volund oil field. Also, we wish to acknowledge NORSAR Innovation AS for providing the academic licence for the SeisRoX software and the California Bureau of Land Management for facilitating access to the outcrop area.Peer reviewedPostprin

Introduction : Subsurface sand remobilization and injection

Acknowledgement Thanks are due for informal information provided on the Nanaimo, Tierra del Fuego and Neoquen basins (David Hodgson), the East Carpathian Fold Belt (Alexandra Tamas) and the Paraná Basin (Gus- tavo Zvirtes). Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.Peer reviewedPublisher PD

Prolonged post-rift magmatism on highly extended crust of divergent continental margins (Baiyun Sag, South China Sea)

Three-dimensional (3D) seismic, borehole and geochemical data reveal a prolonged phase of post-rift magmatism on highly extended crust of the Baiyun Sag, South China Sea. Two volcanic complexes are identified and described in the context of continental rifting and diachronous continental breakup of the South China Sea. Biostratigraphic data from exploration wells BY7-1 and BY2, complemented by K–Ar datings from core samples, confirm that magmatic activity in the Baiyun Sag occurred in two main stages: (1) a first episode at the base of the Miocene (23.8 Ma); and (2) a second episode occurring at the end of the Early Miocene (17.6 Ma). The relative location of volcanic complexes in the Baiyun Sag, and their stratigraphic position, reveals prolonged magmatism inboard of the ocean–continent transition zone during continental breakup. We suggest that magmatism in the Baiyun Sag reflects progressive continental breakup in the South China Sea, with the last volcanic episode marking the end of a breakup sequence representing the early post-rift tectonic events associated with the continental breakup process. Seismic and borehole data from this breakup sequence records diachronous magma emplacement and complex changes in depositional environments during continental breakup

An Introduction to Glaciated Margins::The Sedimentary and Geophysical Archive

A glaciated margin is a continental margin that has been occupied by a large ice mass, such that glacial processes and slope processes conspire to produce a thick sedimentary record. Ice masses take an active role in sculpting, redistributing and reorganizing the sediment that they erode on the continental shelf, and act as a supply route to large fan systems (e.g. trough mouth fans, submarine fans) on the continental slope and continental rise. To many researchers, the term ‘glaciated margin’ is synonymous with modern day areas fringing Antarctica and the Arctic shelf systems, yet the geological record contains ancient examples ranging in age from Precambrian to Cenozoic. In the pre-Pleistocene record, there is a tendency for the configuration of the tectonic plates to become increasingly obscure with age. For instance, in the Neoproterozoic record, not everyone agrees on the location of rift margins and some fundamental continental boundaries remain unclear. Given these issues, this introductory paper has two simple aims: (1) to provide a brief commentary of relevant Geological Society publications on glaciated margins, with the landmark papers highlighted and (2) to explain the contents of this volume

The early Quaternary North Sea Basin

The onset of the Quaternary (2.58 Ma) corresponds to significant paleo-environmental events, such as the intensification and southward extension of Northern Hemisphere glaciation. In the North Sea Basin a significant late Cenozoic succession has been identified as a high-resolution archive of paleo-environmental changes during the Pliocene and Pleistocene. However, the identification of the base of the Quaternary has been a long-standing issue owing to lack of stratigraphic calibration. This study incorporates continuous, regional 3D seismic data with high-quality chronostratigraphic markers to map the base-Quaternary surface at high resolution across the entire North Sea. Depth conversion, backstripping, seismic geomorphology and sedimentation rate calculations are integrated to analyse the paleogeographical evolution of the North Sea Basin and its infill of c. 83 × 103 km3 of northward prograding marine to deltaic sediments. The basin is 600 km long from SSE to NNW and largely localized above residual topography of the Mesozoic graben system. During the earliest Quaternary (2.58 – 2.35 Ma) paleo-water depths were c. 300 ± 50 m and solid sedimentation rates (calculated from 0% porosity) c. 32 km3 ka−1. The base-Quaternary provides an important marker for further studies of the changing environment of the Quaternary of NW Europe as well as resource and shallow geohazard analysis. Supplementary material: A base Quaternary two-way travel time structure map is available at https://doi.org/10.6084/m9.figshare.c.390034

Seismic volcanostratigraphy of the western Indian rifted margin: The pre-Deccan igneous province

The Indian Plate has been the focus of intensive research concerning the flood basalts of the Deccan Traps. Here we document a volcanostratigraphic analysis of the offshore segment of the western Indian volcanic large igneous province, between the shoreline and the first magnetic anomaly (An 28 ∼63 Ma). We have mapped the different crustal domains of the NW Indian Ocean from stretched continental crust through to oceanic crust, using seismic reflection and potential field data. Two volcanic structures, the Somnath Ridge and the Saurashtra High, are identified, extending ∼305 km NE-SW in length and 155 km NW-SE in width. These show the internal structures of buried shield volcanoes and hyaloclastic mounds, surrounded by mass-wasting deposits and volcanic sediments. The structures observed resemble seismic images from the North Atlantic and northwest Australia, as well as volcanic geometries described for Runion and Hawaii. The geometry and internal seismic facies within the volcanic basement suggest a tholeiitic composition and subaerial to shallow marine emplacement. At the scale of the western Indian Plate, the emplacement of this volcanic platform is constrained by structural lineations associated with rifting. By reviewing the volcanism in the Indian Ocean and plate reconstruction of the area, the timing of the volcanism can be associated with eruption of a pre-Deccan continental flood basalt (∼75-65.5 Ma). The volcanic platform in this study represents an addition of 19-26.5% to the known volume of the West Indian Volcanic Province. Copyright 2011 by the American Geophysical Union

A regional CO 2 containment assessment of the northern Utsira Formation seal and overburden, northern North Sea

From Wiley via Jisc Publications RouterHistory: received 2020-12-31, accepted 2021-01-05, pub-electronic 2021-03-08, pub-print 2021-06Article version: VoRPublication status: PublishedFunder: Natural Environment Research Council; Id: http://dx.doi.org/10.13039/501100000270Abstract: Upscaling Carbon Capture and Storage requires identification of suitable storage sites, with robust reservoir seals. The Utsira Formation in the northern North Sea has been flagged as a target for further storage. However, there are no regional studies of seal variability addressing heterogeneities that could facilitate seal bypass. This study aims to: (a) identify, assess and map the elements that promote or restrict fluid migration, (b) develop a matrix to regionally map containment confidence (CC) and (c) rank the different areas for CO2 containment across the Utsira Formation. The seal and overburden were mapped using a high‐resolution, pre‐stack depth‐migrated 3D broadband seismic reflection dataset and 141 exploration wells. Seal geometry, sandstone presence and sandstone connectivity in the seal and overburden were assigned relative CC scores, which were summed to map overall CC of the Utsira Fm. Indicators for shallow gas and migration were mapped and correlated with the other elements. Areas with the lowest CC are in the west of the Utsira Fm. Here, sandstones within the Seal Interval are connected through the overburden via sandy submarine fans. In the southeast, dipping stratigraphy downlaps onto the Utsira Fm., increasing the potential for connection with glacially‐derived channel‐lobe systems in the overburden. The areas with the highest CC are the central and northeast parts of the Utsira Fm., where the Seal Interval is mudstone‐dominated and parallel to the reservoir, and channel‐lobe systems identified in the Overburden Interval are disconnected from the reservoir. This area coincides with a thick depocentre of the northern Utsira Fm. These results can be used to inform CO2 storage site selection and constrain future CO2 plume simulation analyses for the Utsira Fm. The CC matrix outlined here can also be adapted and applied to regionally assess the containment of other potential CO2 storage reservoirs in any setting