Outcrop-scale fracture analysis and seismic modelling of a basin-bounding normal fault in platform carbonates, central Italy

Volatili, Tiziano; Agosta, Fabrizio; Cardozo, Néstor; Zambrano, Miller; Lecomte, Isabelle; Tondi, Emanuele

doi:10.1016/j.jsg.2022.104515

Cited by 17 publications

(9 citation statements)

References 85 publications

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“…Consequently, many scholars have conducted research on shale natural fractures [21,[33][34][35][36] and the multi-scale dimensional evaluation of natural fractures in shale has been a hot topic [22,37,38]. Information about natural fractures, such as fracture density, filler, orientation, width, and length, can be obtained from shale outcrops [39] and the natural fracture orientation can serve as a vital indicator of the present-day stress field [40]. Additionally, full-diameter shale drill cores can be used to study natural fractures, and macroscopic fractures can be described by observing fresh, unweathered shale cores [22].…”

Section: Introductionmentioning

confidence: 99%

Microscopic Analysis of Natural Fracture Properties in Organic-Rich Continental Shale Oil Reservoirs: A Case Study from the Lower Jurassic in the Sichuan Basin, China

Bai

Huang

Wang

et al. 2023

JMSE

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Natural fractures are of paramount importance in storing carbon in shale oil reservoirs, where ultra-low porosity and permeability necessitate their essentiality for enhanced oil recovery. Therefore, comprehensively clarifying the characteristics of natural fractures in shale oil reservoirs is imperative. This paper focuses on investigating the microscopic features of natural fractures in organic-rich continental shale oil reservoirs that are commonly found in the Lower Jurassic strata of the Sichuan Basin, employing them as a representative example. Multiple methods were utilized, including mechanical testing, Kaiser testing, multi-scale CT scanning (at 2 mm, 25 mm, and 100 mm scales), and a numerical simulation of fluid seepage in fracture models. The results revealed that the in situ stress of the target seam displays the characteristic of σH > σv > σh, with σv and σh being particularly similar. The relatively high lateral stress coefficient (ranging from 1.020 to 1.037) indicates that the horizontal stresses are higher than the average level. Although the 2 mm CT scan provides a more detailed view of fractures and connected pores, it primarily exhibited more pore information due to the high resolution, which may not fully unveil additional information about the fractures. Thus, the 25 mm shale core is a better option for studying natural fractures. The tortuosity of the different fractures indicated that the morphology of larger fractures is more likely to remain stable, while small-scale fractures tend to exhibit diverse shapes. The simulations demonstrated that the stress sensitivity of fracture permeability is approximately comparable across different fracture scales. Therefore, our research can enhance the understanding of the properties of natural fractures, facilitate predicting favorable areas for shale oil exploration, and aid in evaluating the carbon storage potential of shale oil reservoirs.

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Section: Introductionmentioning

confidence: 99%

Microscopic Analysis of Natural Fracture Properties in Organic-Rich Continental Shale Oil Reservoirs: A Case Study from the Lower Jurassic in the Sichuan Basin, China

Bai

Huang

Wang

et al. 2023

JMSE

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“…Conventional geological data obtained by the scanline method on the outcrops are frequently used for the acquisition of fracture orientation, spacing, aperture, trace length, roughness, etc. [15][16][17][18]. The determination of internal rock mass fracturing can be undertaken through the study of borehole cores, geophysics, or statistical methods based on a surface fracture analysis.…”

Section: Introductionmentioning

confidence: 99%

3D Discrete Fracture Network Modelling from UAV Imagery Coupled with Tracer Tests to Assess Fracture Conductivity in an Unstable Rock Slope: Implications for Rockfall Phenomena

et al. 2023

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The stability of a rock slope is strongly influenced by the pattern of groundwater flow through the fracture system, which may lead to an increase in the water pressure in partly open joints and the consequent decrease in the rock wall strength. The comprehension of the fracture pattern is a challenging but vital aspect in engineering geology since the fractures’ spatial distribution, connectivity, and aperture guide both the water movement and flow quantity within the rock volume. In the literature, the most accepted methods to hydraulically characterise fractured rocks in situ are the single borehole packer test, the high-resolution flow meters for fractures, and the artificial tracer tests performed in boreholes. However, due to the high cost a borehole requires and the general absence of wells along coastal cliffs, these methods may not be appropriate in rockfall-prone areas. In this study, an unsaturated rocky cliff, strongly affected by rockfalls, was investigated by combining kinematic analysis, Discrete Fracture Network (DFN) modelling, and artificial tracer tests. The DFN model and potential rock block failure mechanisms were derived from high-resolution 3D virtual outcrop models via the Structure from Motion (SfM) photogrammetry technique. An artificial tracer was injected using a double ring infiltrometer atop the recharge zone of the slope to determine the infiltration rate and validate the DFN results. The DFN and tracer test methods are frequently used at different spatial scales and for different disciplines. However, the integration of digital photogrammetry, DFN, and tracer tests may represent a new step in rockfall and landslide studies. This approach made possible the identification of groundwater flow patterns within the fracture system and revealed about a 10-day tracer transit time from the injection area and the monitored slope, with similar conductivity values gathered from both the DFN and tracer test. Planar and wedge failures with volumes ranging from 0.1 and 1 m3 are the most probable failure mechanisms in the areas. The results were consistent with the delay between the intense rainfall and the slope failures previously documented in the study area and with their mechanisms.

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“…Other issues include the magnitude and resolution of the fractures applied in the modelling. Due to the limited dataset, only specific sizes or scales of fractures could be modelled, which is common, especially in the sub-seismic fracture networks [13][14][15][16]. Ideally, to properly depict the fracture network within a carbonate platform reservoir, a comprehensive dataset with a resolution ranging from micro-scale to macro-scale is required; however, capturing all the data at once is ambitious and challenging.…”

Section: Introductionmentioning

confidence: 99%

“…However, analysing the analogue may lead to a better understanding of the subsurface condition and reduce ambiguity at the fracture scale. Analogue studies allow for a detailed structural characterisation of fracture networks at several scales, spanning from millimetres to metres and providing a better solution for upscaling in modelling the fracture network and reducing fracture underestimation [13,15,22,23]. Furthermore, a better prediction of the subsurface can be formed by considering the impact and origin of secondary porosity and permeability.…”

Section: Introductionmentioning

confidence: 99%

Fracture Network Analysis of Karstified Subis Limestone Build-Up in Niah, Sarawak

Ong,

Jamaludin

2023

Applied Sciences

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Understanding complex carbonate fracture networks and karstification at various geological scales is challenging, especially with limited multi-scale datasets. This paper aims to reduce uncertainty in the fracture architecture of Central Luconia karstified reservoirs by narrowing observational gaps between seismic and well data by using the discrete fracture models of exposed limestone outcrops as analogues for the subsurface carbonate reservoir. An outcrop-based fracture network characterisation of a near-surface paleo-karst at Subis Limestone combined with lineament analysis was conducted to extract fracture parameters. The karst structure was first delineated using a digital elevation map and outcrop examination. Then, topology analysis was performed, following the creation of two-dimensional discrete fracture models. Two main fracture sets oriented northeast–southwest and northwest–southeast and 79 potential dolines were identified. Fracture intersections, northeast–southwest major orientations, and drainage systems highly influenced the karst features. The Subis Limestone fracture model revealed that the highest number of fractures and total length of fractures were concentrated in the northern part of the Subis Limestone build-up (X: 250–350, Y: 150–250) and became denser towards the northwest direction of the outcrop (X: 600–800). The fractures in the Subis paleo-karsts appear isolated, with I-nodes ranging from 0.74 to 0.94. Hence, it is crucial to incorporate matrix porosity into multiple scales of fracture network modelling to improve upscaling and the modelling of fracture–vug networks, as well as to minimise the underestimation of discrete fracture networks in fractured and karstified limestone.

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Outcrop-scale fracture analysis and seismic modelling of a basin-bounding normal fault in platform carbonates, central Italy

Cited by 17 publications

References 85 publications

Microscopic Analysis of Natural Fracture Properties in Organic-Rich Continental Shale Oil Reservoirs: A Case Study from the Lower Jurassic in the Sichuan Basin, China

Microscopic Analysis of Natural Fracture Properties in Organic-Rich Continental Shale Oil Reservoirs: A Case Study from the Lower Jurassic in the Sichuan Basin, China

3D Discrete Fracture Network Modelling from UAV Imagery Coupled with Tracer Tests to Assess Fracture Conductivity in an Unstable Rock Slope: Implications for Rockfall Phenomena

Fracture Network Analysis of Karstified Subis Limestone Build-Up in Niah, Sarawak

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