Digital Rendering of Sedimentary-Relief Peels: Implications for Clastic Facies Characterization and Fluid Flow

Trevisan

Krishnamurthy

2017

Sci Rep

Self Cite

Small-scale (mm to m) sedimentary structures (e.g. ripple lamination, cross-bedding) have received a great deal of attention in sedimentary geology. The influence of depositional heterogeneity on subsurface fluid flow is now widely recognized, but incorporating these features in physically-rational bedform models at various scales remains problematic. The current investigation expands the capability of an existing set of open-source codes, allowing generation of high-resolution 3D bedform architecture models. The implemented modifications enable the generation of 3D digital models consisting of laminae and matrix (binary field) with characteristic depositional architecture. The binary model is then populated with petrophysical properties using a textural approach for additional analysis such as statistical characterization, property upscaling, and single and multiphase fluid flow simulation. One example binary model with corresponding threshold capillary pressure field and the scripts used to generate them are provided, but the approach can be used to generate dozens of previously documented common facies models and a variety of property assignments. An application using the example model is presented simulating buoyant fluid (CO2) migration and resulting saturation distribution.

Section: Resultsmentioning

confidence: 99%

A method to generate small-scale, high-resolution sedimentary bedform architecture models representing realistic geologic facies

Trevisan

Krishnamurthy

2017

Sci Rep

Self Cite

“…These sediments are known to be deposited during slack flood events that are oversupplied with fine sediment fractions (Bernard and Major, 1963). The peels have specific correlation length and grain size distribution confirmed by prior analysis (Meckel, 2013). The distribution of applicable threshold pressures for these models determined from the prior grain size analyses is seen in the histograms of Fig.…”

Section: Ip Simulations Of Natural Geologic Domainssupporting

confidence: 52%

“…These models are derived from sedimentary-relief peels (Bouma, 1969) taken from modern fluvial deposits considered to be analogs for some deep geologic storage formations. The methods for model generation and subsequent IP simulation are described in Meckel (2013). Essentially the method uses the relief generated by lacquer invasion of vertically exposed unconsolidated deposits (Bouma, 1969) as a proxy for deep reservoir properties such as porosity, permeability and threshold pressure.…”

Section: Ip Simulations Of Natural Geologic Domainsmentioning

confidence: 99%

Characterization and prediction of CO2 saturation resulting from modeling buoyant fluid migration in 2D heterogeneous geologic fabrics

International Journal of Greenhouse Gas Control

Bryant

Ganesh

2015

a b s t r a c tUnderstanding the pore saturation of CO 2 injected into heterogeneous rocks for permanent storage is a key challenge for constraining storage efficiency (capacity), plume migration extent, and seismic imaging. Much work on fluid flow and saturation has focused on traditional pressure-gradient driven flow represented by viscous multi-phase Darcy flow. Here we investigate CO 2 saturations resulting from buoyancy-driven capillary flow, where buoyancy forces dominate viscous forces. These low capillary number flow regimes (Ca < 10 −4 ) exist some distance from injection wells, potentially representing the majority of the storage domain during and after injection. We simulate CO 2 -brine buoyant displacement patterns using invasion percolation (IP) methods in various decimeter-scale, highly resolved heterogeneous 2D models. Different sedimentologic fabrics result in dramatic variability of total CO 2 saturation. We seek a generalized predictive model that allows CO 2 saturation resulting from capillary flow to be estimated reasonably for 2D domains from fundamental geologic and fluid properties. We focus on three metrics of pore threshold pressure in clastic porous materials: the central value (median; mean), the range (standard deviation), and the ratio of the horizontal to vertical correlation length. These are formalized in the description of 54 clastic facies and three fabrics. An 'IP Saturation Predictor' model is derived by linear interpolation of simulation results from synthetic stochastic models representing a wide range of facies and fabrics. To validate model results, we compare the predictive model with flow simulations in model domains extracted from highly resolved natural geologic sedimentary samples at similar resolution.

“…Inaccurately representing geological heterogeneity at large scales can result in overestimation of the migration speed [Li and Benson, 2015], mismatch of breakthrough times [Green and Ennis-King, 2010;2013], and underestimation of final trapped saturation [Saadatpoor et al, 2010] and lateral extent of CO 2 [Hesse and Woods, 2010].…”

Section: Introductionmentioning

confidence: 99%

“…In the present study, we expand on the methods above and build upon previous work by Meckel [2013] and Meckel et al [2015] to address the influence of stratigraphic heterogeneity at the sub-meter scale on the containment of CO 2 for different types of sedimentary architectures.…”

Section: Introductionmentioning

confidence: 99%

Impact of 3D capillary heterogeneity and bedform architecture at the sub-meter scale on CO2 saturation for buoyant flow in clastic aquifers

Trevisan

Krishnamurthy

International Journal of Greenhouse Gas Control

2017

During the post-injection and stabilization period of geological carbon sequestration, the primary forces governing CO 2 migration and entrapment are capillarity and buoyancy, delineating a specific field of application for numerical flow models. In contrast with conventional modeling approaches that assume laminar viscous flow regime, a modified invasion percolation simulator is used to mimic the physics of fluid flow for vanishing pressure gradients.The current investigation extends a previous study simulating 2D CO 2 invasion through stochastic and natural geologic models. Research presented here expands methods for addressing role of heterogeneity on fluid migration by quantifying the influence of 3D variability in threshold capillary pressure and bedform architecture on CO 2 saturation. The goal is to develop a predictive method for volumetric storage capacity for buoyant flow conditions. Realistic sedimentary models are generated for eight common clastic facies with accurately represented bedform morphology. Resulting 3D models consist of matrix and lamina cells that are populated independently with probability density functions representative of sandstone lithologies with different grain sizes and sorting. Results from thousands of MIP simulations reveal saturation in the eight models to be a non-linear function that is primarily influenced by the contrast in threshold capillary pressures between matrix and lamina (observable lithologic heterogeneity), suggesting some predictive ability is achievable from common sedimentologic descriptors, although quantifying the independent effect of depositional architecture remains more difficult.