Influence of fluvial crevasse-splay deposits on sandbody connectivity: Lessons from geological analogues and stochastic modelling

Colombera, Luca; Mountney, Nigel P.

doi:10.1016/j.marpetgeo.2021.105060

Cited by 16 publications

(8 citation statements)

References 162 publications

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“…channel fills, accretion packages, crevasse splays) (e.g. Colombera & Mountney, 2021; Dreyer, 1990; Dreyer et al, 1990; Willis & Tang, 2010). At the most basic level, coarse‐grained sedimentary rock such as sandstone or conglomerate is typically porous and can serve as high‐quality reservoir rock while fine‐grained sedimentary rock forms barriers to subsurface fluid flow (Beard & Weyl, 1973).…”

Section: Introductionmentioning

confidence: 99%

Reconstructing subsurface sandbody connectivity from temporal evolution of surface networks

et al. 2022

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Characterization of groundwater aquifers and hydrocarbon reservoirs requires an understanding of the distribution and connectivity of subsurface sandbodies. In deltaic environments, distributary channel networks serve as the primary conduits for water and sediment. Once these networks are buried and translated into the subsurface, the coarse-grained channel fills serve as primary conduits for subsurface fluids such as water, oil or gas. The temporal evolution of channels on the surface therefore plays a first-order role in the 3D permeability and connectivity of subsurface networks. Land surface imagery is more broadly available than topographic or subsurface data, and time-series imagery of river networks can hold useful information for constraining the shallow subsurface.However, these reconstructions require an understanding of the degree to which channel bathymetry and river kinematics affect connectivity of subsurface sandbodies. Here, we present a novel method for building synthetic cross sections using overhead images of an experimental delta. We use principal components analysis to extract river networks from surface imagery, then couple this with an inverse-CDF method to estimate channel bathymetry, to generate a time-series of synthetic delta topography. This synthetic topography is then transformed, accounting for deposition and subsidence, to produce synthetic stratigraphy that differentiates coarse-grained channel fill from overbank and offshore deposition. We find that large-scale subsurface architecture is relatively insensitive to details of channel bathymetry, but instead is primarily controlled by channel location and kinematics. We analyse the connectivity of sand bodies and the geometries of barriers to flow and find that periods of rapid sea-level rise have more variability in sand body connectivity. We also find that barrier width decreases downstream during all sea-level phases. Our method generates synthetic stratigraphy that closely resembles the large-scale architecture and 2-dimensional connectivity of the real stratigraphy built during the experiment it was based

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Section: Introductionmentioning

confidence: 99%

Reconstructing subsurface sandbody connectivity from temporal evolution of surface networks

et al. 2022

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“…It should be noted that only two sand bodies were identified in the boreholes, mainly owing to wet drilling, while detailed field studies (sections I-III) allowed recognition of as many as four sandy units (see Figs 5, 7). This discrepancy also could be due to the amalgamation of sand bodies (van Toorenenburg et al, 2016;Burns et al, 2019;Colombera and Mountney, 2021;Rahman et al, 2022a, b;and other references therein).…”

Section: Description Of the Studied Sectionsmentioning

confidence: 98%

Four in one: a new crevasse-splay complex in the middle Miocene of central Poland

Widera,

Dziamara,

Klęsk

et al. 2024

ASGP

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Crevasse splays are typical overbank (extra-channel) deposits, present in all alluvial systems, particularly common on the floodplains of meandering and anastomosing rivers (Makaske, 2001;Miall, 2006;Boggs, 2012;Zieliński, 2014). They form adjacent to the margins of river channels, when the natural levees are locally breached by floodwater. The accumulation of sediments, mainly sand, takes place during the initial stage of a flood. Coarser sediment fractions (medium and fine sands) are deposited closer to the river channel, in the proximal zone of spill-out, while finer fractions (if present) tend to be deposited farther away, in the distal zone of the floodplain (e.g.,

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“…The fluvial sedimentary processes that created the shallow subsurface should be similar to current fluvial processes if the time span between them is relatively short (Liang et al., 2016; Miall, 2014; Rongier et al., 2017). Researchers have quantitatively considered the architecture of fluvial features, such as channels, point bars, crevasse‐splays, and their migration processes in trying to understand reservoir heterogeneity and connectivity (Colombera & Mountney, 2021; Colombera et al., 2017; Donselaar & Overeem, 2008; Gouw & Hijma, 2022). Furthermore, the influence of geomorphologic processes on fluvial deposits is central to process‐based reservoir models (Grimaud et al., 2022; Liang et al., 2015), rule‐based methods (Colombera et al., 2018), and random‐walk simulations (van Dijk et al., 2016b).…”

Section: Introductionmentioning

confidence: 99%

Predicting Subsurface Architecture From Surface Channel Networks in the Bengal Delta

Khan

Ahmed

et al. 2023

JGR Earth Surface

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In the Bengal Delta, more than 150 million inhabitants rely on groundwater as their primary source of water due to its accessibility and lower risk of microbial contamination compared to surface water (Bangladesh Bureau of Statistics, 2011). However, 27.5 million people are drinking groundwater with high levels of geogenic arsenic in the shallow Abstract Groundwater is the primary source of water in the Bengal Delta but contamination threatens this vital resource. In deltaic environments, heterogeneous sedimentary architecture controls groundwater flow; therefore, characterizing subsurface structure is a critical step in predicting groundwater contamination. Here, we show that surface information can improve the characterization of the nature and geometry of subsurface features, thus improving the predictions of groundwater flow. We selected three locations in the Bengal Delta with distinct surface river network characteristics-the lower delta with straighter tidal channels, the mid-delta with meandering and braided channels, and the inactive delta with transitional sinuous channels. We used surface information, including channel widths, depths, and sinuosity, to create models of the subsurface with object-based geostatistical simulations. We collected an extensive set of lithologic data and filled in gaps with newly drilled boreholes. Our results show that densely distributed lithologic data from active lower and mid-delta are consistent with the object-based models generated from surface information. In the inactive delta, metrics from object-based models derived from surface geometries are not consistent with subsurface data. We further simulated groundwater flow and solute transport through the object-based models and compared these with simulated flow through lithologic models based only on variograms. Substantial differences in flow and transport through the different geologic models show that geometric structure derived from surface information strongly influences groundwater flow and solute transport. Land surface features in active deltas are therefore a valuable source of information for improving the evaluation of groundwater vulnerability to contamination. Plain Language SummaryThe structure of groundwater aquifers affects how groundwater and contaminants move through them. In deltas, dynamic river networks are responsible for depositing sediments that ultimately form subsurface aquifers. Therefore, the characteristics of the surface river channel network should provide information about the structure of the subsurface. We tested this idea using a large set of sedimentary data from the Bengal Basin. We created models of the subsurface based on the surface network and showed that the subsurface data reflect the model characteristics in deltas that are actively depositing sediment. Using these subsurface models as input for groundwater flow models, we showed that incorporating this surface information is important for being able to predict how contaminants move in groundwater.XU ET AL.

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Influence of fluvial crevasse-splay deposits on sandbody connectivity: Lessons from geological analogues and stochastic modelling

Cited by 16 publications

References 162 publications

Reconstructing subsurface sandbody connectivity from temporal evolution of surface networks

Reconstructing subsurface sandbody connectivity from temporal evolution of surface networks

Four in one: a new crevasse-splay complex in the middle Miocene of central Poland

Predicting Subsurface Architecture From Surface Channel Networks in the Bengal Delta

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