Geomechanical and Fracture Network Interpretation of a Devonian Outcrop

2021 ◽  
pp. 1-16
Author(s):  
Scott McKean ◽  
Simon Poirier ◽  
Henry Galvis-Portilla ◽  
Marco Venieri ◽  
Jeffrey A. Priest ◽  
...  
Keyword(s):  
Large Scale ◽  
Multiple Scales ◽  
Fracture Network ◽  
Natural Fracture ◽  
Small Scale ◽  
Nugget Effect ◽  
Schmidt Hammer ◽  
Unconventional Reservoir ◽  
Fracture Anisotropy ◽  
Fracture Intensity

Summary The Duvernay Formation is an unconventional reservoir characterized by induced seismicity and fluid migration, with natural fractures likely contributing to both cases. An alpine outcrop of the Perdrix and Flume formations, correlative with the subsurface Duvernay and Waterways formations, was investigated to characterize natural fracture networks. A semiautomated image-segmentation and fracture analysis was applied to orthomosaics generated from a photogrammetric survey to assess small- and large-scale fracture intensity and rock mass heterogeneity. The study also included manual scanlines, fracture windows, and Schmidt hammer measurements. The Perdrix section transitions from brittle fractures to en echelon fractures and shear-damage zones. Multiple scales of fractures were observed, including unconfined, bedbound fractures, and fold-relatedbed-parallel partings (BPPs). Variograms indicate a significant nugget effect along with fracture anisotropy. Schmidt hammer results lack correlation with fracture intensity. The Flume pavements exhibit a regionally extensive perpendicular joint set, tectonically driven fracturing, and multiple fault-damage zones with subvertical fractures dominating. Similar to the Perdrix, variograms show a significant nugget effect, highlighting fracture anisotropy. The results from this study suggest that small-scale fractures are inherently stochastic and that fractures observed at core scale should not be extrapolated to represent large-scale fracture systems; instead, the effects of small-scale fractures are best represented using an effective continuum approach. In contrast, large-scale fractures are more predictable according to structural setting and should be characterized robustly using geological principles. This study is especially applicable for operators and regulators in the Duvernay and similar formations where unconventional reservoir units abut carbonate formations.

Fracture Characterization in Deep Gas Reservoirs to Identify Fracture Enhanced Flow Units, Offshore Abu Dhabi

2021 ◽  
Author(s):  
Jialiang Hu ◽  
Pradeep Menon ◽  
Amna Al Yaqoubi ◽  
Mohamed Al Shehhi ◽  
Mahmoud Basioni ◽  
...  
Keyword(s):  
Large Scale ◽  
Poisson Ratio ◽  
Fracture Network ◽  
Open Fractures ◽  
Natural Fracture ◽  
Abu Dhabi ◽  
Small Scale ◽  
Upward Movement ◽  
Flow Units ◽  
Fracture Intensity

Abstract High gas flow rates in deep-buried dolomitized reservoir from an offshore field Abu Dhabi cannot be explained by the low matrix permeability. Previous permeability multiplier based on distance to major faults is not a solid geological solution due to over-simplifying reservoir geomechanics, overlooking folding-related fractures, and lack of detailed fault interpretation from poor seismic. Alternatively, to characterize the heterogeneous flow related with natural fractures in this undeveloped reservoir, fracture network is modelled based on core, bore hole imager (BHI), conventional logs, seismic data and test information. Limited by investigation scale, vertical wells record apparent BHI, and raw fracture interpretation cannot represent true 3D percolation reflected on PLT. To overcome this shortfall, correction based on geomechanics and mechanical layer (ML) analysis is performed. Young's modulus (E), Poisson ratio (ν), and brittleness index are calculated from logs, describing reservoir tendency of fracturing. Other than defining MLs, bedding plane intensity from BHI is also used as an indicator of fracture occurrence, since stress tends to release at strata discontinuity and forms bed-bounded fractures observed from cores. Subsequently, a new fracture intensity is generated from combined geomechanics properties and statistics average of BHI-derived fracture occurrence within the ML frame, which improves match with PLT and distinguishes fracture enhance flow intervals consistently in all wells. Seismic discontinuity attributes are used as static fracture footprints to distribute fractures from wells to 3D. The final hybrid DFN comprises large-scale deterministic zone-crossing fractures and small-scale stochastic bed-bounded fractures. Sub-vertical open fractures are dominated by NE-SW wrenching fractures related with Zagros compression and reactive salt upward movement. There is no angle rotation of fractures in different fault blocks. Open fractures in other strikes are supported by partial cements and mismatching fracture walls on computerized tomography (CT) images. ML correlation shows vertical consistence across stratigraphic framework and its intensity indicates fracture potential of vertical zones reflected by tests. Fracture-enhanced flow units are further constrained by a threshold in both combined geomechanics properties and statistics average of raw BHI fracture intensity in ML frame. As a result, final fracture network maps reservoir brittleness and flow potential both vertically and laterally, identifying fracture regions along folding axis not just major faults, evidenced by wells and seismic. According to the upscaling results, the case study reveals a type-III fractured reservoir, where fractures contribute to flow not to volume. Fracture network enhances bed-wise horizontal communication but also opens vertical feeding channels. Fracture permeability is mainly influenced by aperture and intensity, while aspect ratio, fracture length, and proportion of strikes and dips mainly influence permeability distribution rather than absolute values. This study provides a production-oriented characterization workflow of natural fracture heterogeneity based on correction of raw BHI in undeveloped fields.

The Stratigraphy of Pre-Tertiary Economic Basement in South Jambi B Block, South Sumatra Basin

2021 ◽  
Keyword(s):  
Significant Contribution ◽  
Fracture Network ◽  
Natural Fracture ◽  
Fracture Density ◽  
The South ◽  
The North ◽  
Fracture Intensity ◽  
Parent Rocks ◽  
Major Fault ◽  
Essential Function

As one of the most promising plays, the Pre-Tertiary basement play holds a significant contribution to the latest success of exploration efforts in the South Sumatra Basin, which then includes the South Jambi B Block. Yet, the natures of the Pre-Tertiary unit in this block remains unsolved. Lithology variability, spatial irregularity, genetic ambiguity, and different reservoir characteristic are indeterminate subjects in the block are the main focus here. The ultimate goals of this study are to better characterize the unit and gain more understanding in calibrating the remaining potential. Based on this study, The Pre-Tertiary units are mainly originated from layered marine-deltaic sedimentary parent rocks with carbonate, intruded by spotty granite where the concentration of each parent rocks varies at the north, the middle, and southern part. Secondly, both lithology heterogeneity and natural fracture density create distinctive reservoir deliverability at each structure. The storage concept is an essential function of natural fracture intensity and diversity, supported by matrix porosity that varies across a different succession of lithology. Lastly, this study observes that major fault orientation is essential in constructing the fracture network. Evidence from several image logs across the study area concludes that most of the interpreted fractures are oriented subparallel to the major faults. The northern belt area is relatively affected by NW-SE Neogene structure, where the southern area is recognized to be affected by both Neogene compression and pre-existing Paleogene structure.

scholarly journals WS-AM: Weakly Supervised Attention Map for Scene Recognition

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1072 ◽  
Author(s):  
Shifeng Xia ◽  
Jiexian Zeng ◽  
Lu Leng ◽  
Xiang Fu
Keyword(s):  
Large Scale ◽  
Multiple Scales ◽  
Scene Recognition ◽  
Small Scale ◽  
Great Success ◽  
Global Feature ◽  
Benchmark Datasets ◽  
Local Mean ◽  
Weakly Supervised ◽  
Fully Connected

Recently, convolutional neural networks (CNNs) have achieved great success in scene recognition. Compared with traditional hand-crafted features, CNN can be used to extract more robust and generalized features for scene recognition. However, the existing scene recognition methods based on CNN do not sufficiently take into account the relationship between image regions and categories when choosing local regions, which results in many redundant local regions and degrades recognition accuracy. In this paper, we propose an effective method for exploring discriminative regions of the scene image. Our method utilizes the gradient-weighted class activation mapping (Grad-CAM) technique and weakly supervised information to generate the attention map (AM) of scene images, dubbed WS-AM—weakly supervised attention map. The regions, where the local mean and the local center value are both large in the AM, correspond to the discriminative regions helpful for scene recognition. We sampled discriminative regions on multiple scales and extracted the features of large-scale and small-scale regions with two different pre-trained CNNs, respectively. The features from two different scales were aggregated by the improved vector of locally aggregated descriptor (VLAD) coding and max pooling, respectively. Finally, the pre-trained CNN was used to extract the global feature of the image in the fully- connected (fc) layer, and the local features were combined with the global feature to obtain the image representation. We validated the effectiveness of our method on three benchmark datasets: MIT Indoor 67, Scene 15, and UIUC Sports, and obtained 85.67%, 94.80%, and 95.12% accuracy, respectively. Compared with some state-of-the-art methods, the WS-AM method requires fewer local regions, so it has a better real-time performance.

Modelling large-scale fractured reservoirs efficiently for geothermal energy and groundwater flow

2020 ◽  
Author(s):  
Simon Oldfield ◽  
Mikael Lüthje ◽  
Michael Welch ◽  
Florian Smit
Keyword(s):  
Fluid Flow ◽  
Geothermal Energy ◽  
Large Scale ◽  
Fractured Reservoirs ◽  
Fracture Network ◽  
Natural Fracture ◽  
Fracture Networks ◽  
Persistent Problem ◽  
Fracture Evolution ◽  
Rapid Generation

<p>Large scale modelling of fractured reservoirs is a persistent problem in representing fluid flow in the subsurface. Considering a geothermal energy prospect beneath the Drenthe Aa area, we demonstrate application of a recently developed approach to efficiently predict fracture network geometry across an area of several square kilometres.</p><p>Using a strain based method to mechanically model fracture nucleation and propagation, we generate a discretely modelled fracture network consisting of individual failure planes, opening parallel and perpendicular to the orientation of maximum and minimum strain. Fracture orientation, length and interactions vary following expected trends, forming a connected fracture network featuring population statistics and size distributions comparable to outcrop examples.</p><p>Modelled fracture networks appear visually similar to natural fracture networks with spatial variation in fracture clustering and the dominance of major and minor fracture trends.</p><p>Using a network topology approach, we demonstrate that the predicted fracture network shares greater geometric similarity with natural networks. Considering fluid flow through the model, we demonstrate that hydraulic conductivity and flow anisotropy are strongly dependent on the geometric connection of fracture sets.</p><p>Modelling fracture evolution mechanically allows improved representation of geometric aspects of fracture networks to which fluid flow is particularly sensitive. This method enables rapid generation of discretely modelled fractures over large areas and extraction of suitable summary statistics for reservoir simulation. Visual similarity of the output models improves our ability to compare between our model and natural analogues to consider model validation.</p>

scholarly journals Assemblages and Scale in Archaeology

2017 ◽  
Vol 27 (1) ◽  
pp. 127-139 ◽  
Author(s):  
Oliver J.T. Harris
Keyword(s):  
Large Scale ◽  
Multiple Scales ◽  
Daily Life ◽  
Critical Issue ◽  
Small Scale ◽  
Processes Of Change ◽  
Origins Of Agriculture ◽  
The Real ◽  
Historical Processes

The growing interest in assemblages has already opened up a number of important lines of enquiry in archaeology, from the morphogenetic capacities of matter through to a rethinking of the concept of community. In this paper I want to explore how assemblages allow us to reconceptualize the critical issue of scale. Archaeologists have vacillated between expending energy on the ‘great processes’ of change like the evolution of humanity, the colonization of the globe or the origins of agriculture, and focusing on the momentary, fleeting nature of a small-scale ethnographic present. Where archaeologists have attempted to integrate different scales the result has usually been to turn to Annales-influenced or time perspectivism-driven approaches and their fixed, linear and ontologically incompatible layers of history. In contrast, I will use assemblages to examine how we can rethink both the emergence of multiple scales and their role in history, without reducing the differences of the small-scale to an epiphenomenal outcome of larger events, or treating large-scale historical processes as mere reifications of the ‘real’ on-the-ground stuff of daily life. As we will see, this approach also has consequences for the particular kind of reality we accord to large-scale archaeological categories.

scholarly journals Field experimental design for pesticide leaching – a modified large-scale lysimeter

2005 ◽  
Vol 7 ◽  
pp. 41-44
Author(s):  
Bertel Nilsson ◽  
Jens Aamand ◽  
Ole Stig Jacobsen ◽  
René K. Juhler
Keyword(s):  
Large Scale ◽  
Preferential Flow ◽  
Fracture Network ◽  
Transport Processes ◽  
Natural Fracture ◽  
Field Scale ◽  
Flow Paths ◽  
Undisturbed Soil ◽  
Flow And Transport ◽  
Preferential Flow Paths

Recent research on Danish groundwater has focused on clarifying the fate and transport of pesticides that leach through clayey till aquitards with low matrix permeability. Previously, these aquitards were considered as protective layers against contamination of underlying groundwater aquifers due to their low permeability characteristics. However, geological heterogeneities such as fractures and macropores have been recognised as preferential flow paths within low permeable clayey till (e.g. Beven & Germann 1982). The flow velocities within these preferential flow paths can be orders of magnitude higher than in the surrounding clay matrix and pose a major risk of transport of contaminants to the underlying aquifers (e.g. Nilsson et al. 2001). Previous studies of transport in fractured clayey till have focused on fully saturated conditions (e.g. Sidle et al. 1998; McKay et al. 1999). However, seasonal fluctuations of the groundwater table typically result in unsaturated conditions in the upper few metres of the clay deposits, resulting in different flow and transport conditions. Only a few experiments have examined the influence of unsaturated conditions on flow and solute (the dissolved inorganic and organic constituents) transport in fractured clayey till. These include smallscale laboratory column experiments on undisturbed soil monoliths (e.g. Jacobsen et al. 1997; Jørgensen et al. 1998), intermediate scale lysimeters (e.g. Fomsgaard et al. 2003) and field-scale tile drain experiments (e.g. Kjær et al. 2005). The different approaches each have limitations in terms of characterising flow and transport in fractured media. Laboratory studies of solute transport in soils (intact soil columns) are not exactly representative of field conditions due to variations in spatial variability and soil structure. In contrast, field studies hardly allow quantification of fluxes and mechanisms of transport. Column and lysimeter experiments are often limited in size, and tile-drain experiments on field scale do not provide spatial resolution and often have large uncertainties in mass balance calculations. Thus, in order to represent the overall natural fracture network systems on a field scale with respect to acquiring insights into flow and transport processes, the lysimeter needs to be larger than normal lysimeter size (< 1 m3). A modified large-scale lysimeter was therefore constructed by the Geological Survey of Denmark and Greenland (GEUS) at the Avedøre experimental field site 15 km south of Copenhagen (Fig. 1). This lysimeter consisted of an isolated block (3.5 ×3.5 ×3.3 m) of unsaturated fractured clayey till with a volume sufficient to represent the overall preferential flow paths (natural fracture network) within lowpermeable clayey till at a field scale.

scholarly journals The Aesthetics of Making

2021 ◽  
Author(s):  
◽  
Matt Buttimore
Keyword(s):  
Architectural Design ◽  
Large Scale ◽  
Multiple Scales ◽  
Small Scale ◽  
Urban Context ◽  
Production Scale ◽  
Community Culture ◽  
Detail Design ◽  
The People ◽  
Cultural Implications

<p><b>As the architectural design process evolves and embraces new techniques and technologies and mass production is more readily available, the relationship between designer and craftsman has become more distant. As we look to produce more and more architecture every year on a larger production scale, the craft and detail of the architecture begin to fall at the wayside. As we lose this relationship, the culture and identity of a place are also lost as these technologies are not responding to specific site and cultural implications.</b></p> <p>One such site where this is applicable is the small coastal town of Onemana in the Coromandel, a town of slightly more than 300 homes constructed as a single development in the 1980s. The rush to produce more homes and on a larger scale has meant the town’s architecture does not reflect the community culture or coastal identity of the place or the people who live there. </p> <p>This thesis argues that there is an existing relationship between craftsperson and designer and explores how this relationship and detail design can generate and inform architectural design. Understanding this relationship will generate detail design that has a more powerful outcome on the spatial qualities of the architecture and generates my own detail design language. It also argues that there exists a relationship between detail design and the urban environment, which is not fully utilised in the industry.</p> <p>The thesis proposes that this can be achieved by testing and evaluating this hypothesis across three scales and three types of urban context. The three test sites identified are a small scale private dwelling, a mid-scale cultural installation and a large scale town centre. Using the process of beginning with detail design, architectural installations will be implemented and evaluated before moving to the following location. As result the method will be proven to work across multiple scales and reflect a variety of cultural inputs.</p>

scholarly journals Large-scale natural fracture network patterns: Insights from automated mapping in the Lilstock (Bristol Channel) limestone outcrops)

2021 ◽  
Author(s):  
Rahul Prabhakaran ◽  
Janos Urai ◽  
Giovanni Bertotti ◽  
Christopher Weismüller ◽  
David Smeulders
Keyword(s):  
Large Scale ◽  
Fracture Network ◽  
Natural Fracture ◽  
Automated Mapping ◽  
Network Patterns

Some comparisons between heterogeneous and homogeneous layers for nonlinear SH waves in terms of heterogeneous and nonlinear effects

2020 ◽  
pp. 108128652094635 ◽  
Author(s):  
Dilek Demirkuş
Keyword(s):  
Solitary Wave ◽  
Large Scale ◽  
Multiple Scales ◽  
Nonlinear Effects ◽  
Small Scale ◽  
Solitary Wave Solutions ◽  
Nls Equation ◽  
Sh Waves ◽  
Wave Solutions ◽  
The One

This paper aims to make some comparative studies between heterogeneous and homogeneous layers for nonlinear shear horizontal (SH) waves in terms of the heterogeneous and nonlinear effects. Therefore, with this aim, two layers are defined as follows: on the one hand, one layer consists of hyperelastic, isotropic, heterogeneous, and generalized neo-Hookean materials; on the other hand, another layer is made up of hyperelastic, isotropic, homogeneous, and generalized neo-Hookean materials. Moreover, it is assumed that upper boundaries are stress-free and lower boundaries are rigidly fixed. The method of multiple scales is used in both analyses, in addition to using the known solutions of the nonlinear Schrödinger (NLS) equation, called bright and dark solitary wave solutions; these comparisons are made, numerically, and then all results are given for the lowest branch of both dispersion relations, graphically. Moreover, these comparisons are observed both on a large scale and on a small scale, not only in terms of the bright and dark solitary wave solutions but also in terms of the heterogeneous and nonlinear effects.

Use of High-Resolution DIDSON Sonar to Quantify Attributes of Predation at Ecologically Relevant Space and Time Scales

2013 ◽  
Vol 47 (1) ◽  
pp. 33-46 ◽  
Author(s):  
Victoria E. Price ◽  
Peter J. Auster ◽  
Laura Kracker
Keyword(s):  
High Resolution ◽  
Time Scales ◽  
Large Scale ◽  
Multiple Scales ◽  
Predation Rate ◽  
Visual Observation ◽  
Small Scale ◽  
Dual Frequency ◽  
Predator Prey ◽  
Space And Time

AbstractPredator-prey interactions of large vagile fishes are difficult to study in the ocean due to limitations in the space and time requirements for observations. Small-scale direct underwater observations by divers (ca. <10 m radius) and large-scale hydroacoustic surveys (10 s m2 to 100 s km2) are traditional approaches for surveying fish. However, large piscivorous predators identify and attack prey at the scale of meters to tens of meters. Dual-Frequency Identification Sonar (or DIDSON) is a high-resolution acoustic camera operating in the MHz range that provides detailed continuous video-like imaging of objects up to a range of 30 m. This technology can be used to observe predator-prey interactions at ecologically relevant space and time scales often missed by traditional methods. Here we establish an approach for quantifying predation-related behaviors from DIDSON records. Metrics related to predator and prey group size, prey responses to predation, predation rate, predator strategies, and the nonrandom use of landscape features by both predator and prey are described. In addition, relationships between patterns in these attributes are tested and issues regarding sampling strategies for future studies are discussed. We suggest that approaches combining direct visual observation and acoustic sampling at multiple scales are required to quantify variation in these relationships across underwater landscapes.

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