Multisensory 3D saliency for artficial attention systems

In this paper we present proof-of-concept for a novel solution consisting of a short-term 3D memory for artificial attention systems, loosely inspired in perceptual processes believed to be implemented in the human brain. Our solution supports the implementation of multisensory perception and stimulus-driven processes of attention. For this purpose, it provides (1) knowledge persistence with temporal coherence tackling potential salient regions outside the field of view, via a panoramic, log-spherical inference grid; (2) prediction, by using estimates of local 3D velocity to anticipate the effect of scene dynamics; (3) spatial correspondence between volumetric cells potentially occupied by proto-objects and their corresponding multisensory saliency scores. Visual and auditory signals are processed to extract features that are then filtered by a proto-object segmentation module that employs colour and depth as discriminatory traits. We consider as features, apart from the commonly used colour and intensity contrast, colour bias, the presence of faces, scene dynamics and also loud auditory sources. Combining conspicuity maps derived from these features we obtain a 2D saliency map, which is then processed using the probability of occupancy in the scene to construct the final 3D saliency map as an additional layer of the Bayesian Volumetric Map (BVM) inference grid

Naturally propped fractures caused by quartz cementation preserve oil reservoirs in basement rocks

MB is in receipt of a postgraduate studentship from PTDF (Nigeria). Skilled technical support was provided by M. Baron and J. Still. Two reviewers made valuable criticisms that improved the paper.Peer reviewedPostprin

Rethinking soil water repellency and its management

Soil water repellency (SWR) is a widespread challenge to plant establishment and growth. Despite considerable research, it remains a recalcitrant problem for which few alleviation technologies or solutions have been developed. Previous research has focused on SWR as a problem to be overcome, however, it is an inherent feature of many native ecosystems where it contributes to ecosystem functions. Therefore, we propose a shift in the way SWR is perceived in agriculture and in ecological restoration, from a problem to be solved, to an opportunity to be harnessed. A new focus on potential ecological benefits of SWR is particularly timely given increasing incidence, frequency and severity of hotter droughts in many regions of the world. Our new way of conceptualising SWR seeks to understand how SWR can be temporarily alleviated at a micro-scale to successfully establish plants, and then harnessed in the longer term and at larger spatial scales to enhance soil water storage to act as a “drought-proofing” tool for plant survival in water-limited soils. For this to occur, we suggest research focusing on the alignment of physico-chemical and microbial properties and dynamics of SWR and, based on this mechanistic understanding, create products and interventions to improve success of plant establishment in agriculture, restoration and conservation contexts. In this paper, we outline the rationale for a new way of conceptualising SWR, and the research priorities needed to fill critical knowledge gaps in order to harness the ecological benefits from managing SWR

Burial-related fracturing in sub-horizontal and folded reservoirs: Geometry, geomechanics and impact on permeability

Applied Geolog

Modelling 3D Discrete Fracture Networks using 2D outcrop data

The main challenge of naturally fractured reservoirs (NFRs) is understanding how fractures behave in the subsurface outside the radius of influence of wells. Fractured outcrop analogues provide geological concepts that can be used to extrapolate fracture data outside the well control. Numerous methods for studying fractured outcrops are available but they all have different disadvantages. We propose a new methodology using Digifract 1.0 software that allows for quick digitization of fractures resulting in a statistically significant quantitative dataset. This approach is used in a carbonate quarry in France to digitize height, dip and azimuth of nearly 1800 non-stratabound fractures on vertical outcrop walls, taking into account assumptions and pitfalls that are often overlooked. The 2D height and spatial distributions of two non-stratabound fracture sets identified in the quarry follow power-law distributions. Applying the 2D distributions in FracMan stochastic fracture simulation software results in 3D DFNs that honour the properties of the 2D distributions. The 3D DFNs form percolating clusters of fractures but for the assumed subsurface conditions the fracture networks would not percolate. The maximum fracture size and the dispersion in the orientation distribution have the largest effect on the percolation threshold. Fracture spacing in 3D is very similar to fracture spacing in 2D. There is a significant sampling error in fracture spacing measurements along scanlines that are not perpendicular to the average fracture dip. The most commonly used correction, Terzaghi, corrects for this as long as the angle between the fracture dip and the scanline is larger than 30 degrees. For smaller angles no uniform correction method has been found.Applied GeologyGeotechnologyCivil Engineering and Geoscience

Calibrating discrete fracture-network models with a carbonate three-dimensional outcrop fracture network: Implications for naturally fractured reservoir modeling

Modeling naturally fractured reservoirs requires a detailed understanding of the three-dimensional (3D) fracture-network characteristics, whereas generally only one-dimensional (ID) data, often suffering from sampling artifacts, are available as inputs for modeling. Additional fracture properties can be derived from outcrop analogs with the scanline method, but it does not capture their full two-dimensional (2D) characteristics. We propose an improved workflow based on a 2D field-digitizing tool for mapping and analyzing fracture parameters as well as relations to bedding. From fracture data collected along 11 vertical surface outcrops in a quarry in southeast France, we quantify uncertainties in modeling fracture networks. The fracture-frequency distribution fits a Gaussian distribution that we use to evaluate the intrinsic fracture density variability within the quarry at different observation scales along well-analog scanlines. Excluding well length as a parameter, we find that 30 wells should be needed to fully (i.e., steady variance) capture the natural variability in fracture spacing. This illustrates the challenge in trying to predict fracture spacing in the subsurface from limited well data. Furthermore, for models with varying scanline orientations we find that Terzaghi-based spacing corrections fail when the required correction angle is more than 60°. We apply the ID well analog data to calculate 3D fracture frequency using stereological relations and find that these relations only work for cases in which the orientation distribution is accurately described, as results greatly vary with small changes in the orientation distribution. Copyright ©2014. The American Association of Petroleum Geologists. All rights reserved

Predicting multi-scale deformation and fluid flow patterns in folds using 3D outcrop models and mechanical modelling

Natural fracture patterns in folded carbonates are highly heterogeneous. The present-day fractures are often the result of pre-folding, syn-folding and post-folding related fractures. Furthermore, syn-folding fractures may differ in different domains of the fold. Although there are studies that characterize fracture patterns in outcropping folds, there is still a poor understanding of the relation between large-scale deformation (i.e. folding), and small-scale deformation (i.e. fractures), especially in terms of stresses and process-based predictions of fractures. Our overarching goal is to assess the sensitivity of reservoir-scale flow to different fracture patterns and different fracture properties. Therefore we build multi-scale models of 3D fracture networks in outcropping folds in the foothills of the Tunisian Atlas (central Tunisia). The fracture data is collected from outcrops using efficient methods that collect both fractures and the 3D geometry of the outcrops. We interpret small-scale deformation in terms of stresses and combine this with fold-scale mechanical models to predict the fracture patterns in 3D throughout the fold. The 3D model is used to model fracture fluid flow. This work presents a new approach to outcrop studies, that distinguishes different stages of fracturing and uses stresses to make predictions about fracture patterns in similar structures.Geoscience & EngineeringCivil Engineering and Geoscience

Modeling 3D Fracture Network in Carbonate NFR: Contribution from an Analogue Dataset, the Cante Perdrix Quarry, Calvisson, SE France

The full 3D characterization of fracture networks is a key issue in naturally fractured reservoir modeling. Fracture geometry (e.g., orientation, size, spacing), fracture scale (e.g., bed-confined fractures, fracture corridors), lateral and vertical variations, need to be defined from limited, generally 1D, data. In order to populate a 3D reservoir model, one needs to define, at the field scale, how the fracture network is distributed in between wells and, at the reservoir cell scale, how the fracture properties can be summarized to fully represent the matrix-fracture flow exchange. With well data only, the problem is clearly undersized and we need to define other sources of information, such as relationships between fracturing at well and large-scale drivers, for example, or derive the missing gap from outcrop data, which provide qualitative concepts or quantitative relationships between fracture parameters. The study presented in this article aims at modeling, at the reservoir cell scale, 3D fracture networks from quarry outcrops. An innovative data collection method is used; this allows a full characterization of the fracture network in 2D, which provides the basic inputs required for the construction of DFN models. In turn, the reality of the fracture network can be compared to the simplification that we make while drilling through these networks and ultimately summarizing them as a double porosity reservoir cell, and some basic lessons can be learned.Geoscience & EngineeringCivil Engineering and Geoscience