Shallow overland flows in steady state can become unstable and break up into destructive surges. The following data documents maximum growth rates for disturbances to uniform steady flows on a fixed slope in a one-dimensional shallow-layer model that incorporates the mechanics of erosion and deposition of monodisperse sediment, documented in sections 2 and 4 of the following freely available preprint: https://arxiv.org/abs/2007.15989. The data comprises the following 4 columns, separated by spaces: grain diameter, Froude number, solid fraction and maximum growth rate. Grain diameter refers to the characteristic diameter of erodible particles, non-dimensionalised by the steady flow depth h0. Froude number, Fr, is a dimensionless constant defined as Fr = u0 / sqrt(h0 * g'), where u0 is the velocity of the steady flow and g' is gravitational acceleration resolved perpendicular to the slope. Solid fraction is a number between 0 and 1 that describes the proportion of solid particles in the flowing mixture. A solid fraction of 0 denotes a purely fluid flow and a solid fraction of 1 denotes a saturated mixture containing a maximum packing of solid particles. Maximum growth rate refers to the largest linear growth rate for perturbations to a uniform flowing layer with the corresponding properties given in the prior 3 columns. The model formulation describes the dynamics of 4 unknown observables: flow height, flow velocity, solids concentration and bed height. By taking the 'maximum' in this case, we mean the maximum over these 4 flow fields that may be perturbed by an environmental disturbance and also the maximum over all possible wavelengths of disturbance. We note that in this dataset, flows with a maximum growth rate equal to zero or small positive values (e.g. up to machine precision) are stable; flows with strictly positive growth rate are unstable. Zero growth rate indicates that the maximum growth rate is given by a neutrally stable perturbation and such perturbations always exist for reasons of symmetry in the model. For each grain diameter and Froude number in the dataset, there exist two steady uniform states with different solid fractions. Therefore two files are supplied - one containing data for the more dilute states and the other containing data for the more concentrated states. These various technical details, as well as full documentation of the model and the parameters used are explained more fully in the aforementioned paper.

Predicting oil production from chalk reservoirs relies on quantifying contributions from fracture and matrix porosity, which change during compaction. Cl isotopes in water characterise fluid transport processes. Chalk matrix microporosity and fractures will give different values. We will combine two novel methods, trace water extraction from dry oil and Cl isotopes to characterise porosity from produced fluid. High pressure lab. experiments carrying fracture/matrix porosity in cores will give characteristic brine geochemistry related to poroperm to calibrate field values. We will compare fluid derived porosity regime with values measures on field core. Porosity changes from geochemistry will be compared with compaction in the field.

These datasets are for samples collected from Volcan de Colima (Mexico) which is at coordinates: 19°30’46" N 103°37’02" W / 19.512727°N 103.617241°W. This volcano erupts magmas that are crystal-bearing, making those cooled volcanic rocks ideal for experimentation. And so samples were cored from blocks from that volcano and those cores were then returned to high temperatures (up to 1000 C) and then deformed under controlled stresses. These data form the central part of this publication: https://doi.org/10.1016/j.jvolgeores.2024.108198. The deformation experiments were performed at LMU (Munich, Germany). The volcano coordinates from which the samples were collected are given above. The samples were deformed in a high temperature hydraulic press equipped with acoustic emission sensors. This is the ideal device for determining the behaviour of the magmas from Volcan de Colima under the same stresses and temperatures at which they were erupted. The data give key clues as to the modes of flow behaviour of the magma in volcanoes. This work provides generalised insights into magma flow behaviour.

Stability of a reactive front in a heterogeneous porous medium characterised by a statistical description of a permeability and/or reactivity will be studied. Stochastic partial differential equations will be formulated. The feasibility of solving these stochastic differential equations will be evaluated in this proof of concept proposal, and the expected values and variances for the growth rate and wavelength of the disturbances determined as a function of input parameters. The results will have significant impact on areas such as reactive diagenesis in oil reservoirs and acid treatments of well bores. The investigators will interact with Mobil Tec Co., who are partially matching the proof of concept grant.

The project will develop and explore the application of scaling methods to strongly heterogeneous flow fields; investigate the loss and retention of information by scaling over large space and long time scale ranges; and, define the dependence between large space/long time scale migration behaviour and the underlying geological model. High resolution, highly accurate flow and transport simulation data sets for a large number of realisations possessing the high variance and strong textures observed in actual geological systems using alternative geological simulators will be used to test upscaling approaches reported in the physical sciences literature and to identify improving upscaling laws where the existing laws are inadequate.

This proposal is to test the hypothesis that secondary (crack) porosity can be treated as a scaling problem in both fracture and fluid percolation theory. This will be achieved by measurements of elastic, transport and mechanical properties on rock samples with known and controlled crack densities (crack porosities) that span the percolation threshold under a wide range of stress conditions. The measured data will be used to calibrate and validate generic models for fluid and fracture percolation that can then be upscaled to predict permeability at the reservoir scale from wireline logs.

Coupled (mechanical-hydraulic) numerical models based on the distinct element method will be used to investigate the behaviour of fluid flow in fractured rock-masses under stress. Flow localization is predicted at some critical stress; parameters affecting this localization will be investigated. Flow in the vicinity of boreholes and by grain infiltration will be simulated. The models will be tested against field observations and hydraulic tests in boreholes.

Reservoir quality in hydrocarbon reservoir sandstones can be greatly influenced by mineral cementation or dissolution. This can change porosity by 50% and permeability by 105. Such processes were partly controlled by palaeo-hydrogeology. The micro-isotopic and micro-geochemical composition within cements holds a detailed zonation record of palaeo-hydrogeology, which can now be investigated by new micro-scale analytical technology. We will combine conservative tracers and palaeopressures from fluid inclusions with natural isotopic tracers measured by ion and laser microbeam instruments. Statistically based sampling will enable reliable up-scaling to calibrate blocks in basin-scale computer models. This will integrate microanalysis with basin architecture. Study sites are selected to resolve conflicting interpretations of characteristics cementation processes.

This project will use the techniques of stereolithography and PIV directly to measure the fluid velocity field in complex, 2D, geologically realistic media with multi-scaled heterogeneities. The resulting velocity fields will be published widely and will provide an invaluable resource for the validation of models of fluid flow in complex geometries for which validation ID presently impossible. Three specific studies will also be undertaken; a) a detailed investigation of the non-linear interaction between matrix and fracture flow, b) a study of the scaling laws in the region of the percolation threshold in the presence of fractal fracture populations and significant matrix permeability and c) an examination of the scaling of the velocity flow field and how this reflects material scaling with a view to identifying potential rules for upscaling of fluid simulations.

The aim of the proposed project is to study evolution in the spatial characteristic of coupled flow and porosity development in heterogeneous porous media. We will develop a modelling engine and methodologies to generate porosity templates for use in flow and transport models of fractured aquifers. Although the primary motivation for this study is to enhance our ability to predict flow and contaminant transport in vulnerable fractured aquifers, such as the chalk, the approach is generic and we foresee a wide range of scenarios where the model may be applied. The work has three specific objectives: 1) to produce a generic model of porosity development, 2) to investigate percolation, scaling and self-organisation phenomena in porosity development due to flow, and 3) to model pore structure and flow histories for a range of natural and anthropogenic problems.