Fracture Spacing Variability and the Distribution of Fracture Patterns in Granitic Geothermal Reservoir: A Case Study in the Noble Hills Range (Death Valley, CA, USA)

Scanlines constitute a robust method to better understand in 3D the fracture network variability in naturally fractured geothermal reservoirs. This study aims to characterize the spacing variability and the distribution of fracture patterns in a fracture granitic reservoir, and the impact of the major faults on fracture distribution and fluid circulation. The analogue target named the Noble Hills (NH) range is located in Death Valley (DV, USA). It is considered as an analogue of the geothermal reservoir presently exploited in the Upper Rhine Graben (Soultz-sous-Forêts, eastern of France). The methodology undertaken is based on the analyze of 10 scanlines located in the central part of the NH from fieldwork and virtual (photogrammetric models) data. Our main results reveal: (1) NE/SW, E/W, and NW/SE fracture sets are the most recorded orientations along the virtual scanlines; (2) spacing distribution within NH shows that the clustering depends on fracture orientation; and (3) a strong clustering of the fracture system was highlighted in the highly deformed zones and close to the Southern Death Valley fault zone (SDVFZ) and thrust faults. Furthermore, the fracture patterns were controlled by the structural heritage. Two major components should be considered in reservoir modeling: the deformation gradient and the proximity to the regional major faults.

Classification and Management of Failed Fixation of the Volar Marginal Fragment in Distal Radius Fractures

Greater understanding of specific fracture patterns following distal radius fractures has arisen with the advent of volar plating. The volar marginal fragment (VMF) is a small peripheral piece of bone which is critical to carpal stability. Failure to achieve good fixation of the VMF can result in volar subluxation of the carpus and distal radioulnar joint instability. Due to its small, distal nature, this fragment can be easily missed and difficult to fix. Loss of reduction of the VMF following operative fixation presents specific challenges and surgical considerations dictated by patient characteristics and timing. Our goal of this review is to present a classification system for these failed VMFs which can help guide surgical treatment as well as expected outcomes.

Ogden Type I to III tibial tubercle fractures in skeletally immature patients: is routine anterior compartment fasciotomy of the leg indicated?

Purpose Determine the frequency of compartment syndrome of the leg after displaced, operatively treated modified Ogden I to III tibial tubercle fractures (TTFxs), evaluate the preoperative assessment and use of advanced imaging, and need for prophylactic fasciotomies. Methods Retrospective analysis of operatively treated, displaced modified Ogden I to III TTFxs, at our level 1 paediatric trauma centre between 2007 and 2019. Modified Ogden Type IV and V fracture patterns were excluded. Fracture patterns were determined by plain radiographs. Results There were 49 modified Ogden I to III TTFxs in 48 patients. None had signs nor symptoms of vascular compromise, compartment syndromes or impending compartment syndromes preoperatively. In all, 13 of the 49 fractures underwent anterior compartment fasciotomy at surgery; eight of the 13 had traumatic fascial disruptions, which were extended surgically. All incisions were primarily closed. There were no instances of postoperative compartment syndromes, growth arrest, leg-length discrepancy or recurvatum deformity postoperatively. All patients achieved radiographic union and achieved full range of movement. Conclusion The potentially devastating complications of compartment syndrome or vascular compromise following TTFx did not occur in this consecutive series of patients over 12 years. The presence of an intact posterior proximal tibial physis and posterior metaphyseal cortex (Modified Ogden TTFx Type I to III) may mitigate the occurrence of vascular injury and compartment syndrome. Plain radiographs appear appropriate as the primary method of imaging TTFxs, with use of advanced imaging as the clinical scenario dictates. Routine, prophylactic fasciotomies do not appear necessary in Ogden I to III TTFxs, but should be performed for signs and symptoms of compartment syndrome. Level of evidence Level IV

Terrestrial photogrammetry: a method to gather data on fractures for DFN modelling from exposed rock surfaces

The stochastic generation of discrete fracture networks (DFN) is a method for modelling fracture patterns used to assess the in situ fragmentation in a volume of rock. The DFN modelling approach is based on the assumption that the natural fragmentation of rocks is a function of the length and connectivity of the fractures within the considered volume of rock. Thus, in order to generate a site-specific DFN, the primary geometric properties of the fracture surfaces within the rock volume (especially orientation, size and fracture intensity as well as the local spatial variability) must be defined as distribution functions (Elmo et al., 2014). The required base statistics are usually obtained from fracture analysis on boreholes, exposed rock surfaces or (to a limited extent) 3D seismics (e.g. Bisdom et al., 2014; Bemis et al., 2014). We adopted a terrestrial close-range photogrammetry approach to capture several outcrops and analyse fracture traces on the exposed rock surfaces, the chosen workflow is based around the use of free and open-source software. Images were acquired from several quarries in the Weschnitzpluton, a granodioritic to quartz monzodioritic pluton in the Bergstrasse Odenwald (e.g. Altherr et al., 1999) using a consumer-grade Nikon D5300 DSLR with fixed focal length instead of a drone or Lidar-system for legal reasons, partially tree-lined outcrops and cost efficiency. Since point clouds obtained from photogrammetry are inherently dimensionless, we used a spherical target with compass and bubble level for scale and proper spatial orientation (Froideval et al., 2019). The exact geolocation is not particularly important for the task, so the use of GPS, total station or georeferenced ground control points is not necessary. Dense point clouds were computed using the open source SfM photogrammetry suite Meshroom (AliceVision, 2021), which can be used for manual or semi-automatic detection of fracture surfaces and their orientation (Schnabel et al., 2007) and to generate orthorectified images of the rock surface to trace fracture lengths and nodes in a GIS (Nyberg et al., 2018). Our investigations proved terrestrial photogrammetry to be a valuable and easily accessible tool in the documentation of natural fracture patterns and a robust base for the generation of DFN networks.

Fold-Related Fracture Distribution in Neogene, Triassic, and Jurassic Sandstone Outcrops, Northern Margin of the Tarim Basin, China: Guides to Deformation in Ultradeep Tight Sandstone Reservoirs

Ultradeep (6-8 km depth) low-porosity sandstone oil and gas reservoirs, in the Kuqa thrust belt of Tarim Basin, are an important natural gas supply source of China. Both opening and shear-mode fractures are extremely necessary reservoir elements for gas production in these rocks but are challenging to characterize with sparse core and well log observations. Here, we use outcrops of some of the same units from four exposed folds to describe fracture types and patterns. These four folds have a range of shapes that are representative of folds at depth. At the Dongq, Kuqa, Misib, and Tuger anticlines, we analyzed fracture type, cross-cutting and abutting relations, density, spatial arrangement, kinematic aperture, orientation, and mineral fill. One-dimensional inventories, field sketches, photographs, and LiDAR imagery documented fracture patterns. Most dips of all fractures shown everywhere on the fold are greater than 60 degrees (over 50%). Fracture kinematic apertures are 3 mm to ~6 mm, and fracture density is 0.5 traces/m to ~1.5 traces/m. All fractures are divided into shear mode (or small faults) and opening mode. Shear-mode fractures, with high dips that strike N-S, mutually crosswise arranged with intersection angles of 30-60 degrees, are found extensively on the flanks of these folds. In contrast, most opening-mode fractures strike E-W, are arranged parallel to each other, and are localized in fold hinges. Besides, exposed folds (reservoir analogues, figure 1) in a proximal (hinterland, Tuger and Misib) position have fracture abundance distributions and aperture size patterns compatible with fold-related fracture development whereas distal (basinward, Kuqa and Dongq) folds lack this correlation, but patterns in distal folds might be explained by overprinted effects of lithological heterogeneity on fracture abundance or the effects of nearby faults. The positive correlation between fold-related strain and fracture spatial distribution in the northern (proximal) folds permitted inference of fracture patterns in deep wells.

Virtual fracture clinic reduces patient X-ray volume for common wrist and ankle fractures

Background Virtual fracture clinics (VFC) have been widely adopted worldwide as part of the changes in healthcare delivery during the COVID-19 pandemic. They have been shown to be a safe and effective method of delivering trauma care for injuries which do not require immediate intervention or specialist management, whilst maintaining high levels of patient satisfaction. Aims Our aim was to evaluate whether VFCs reduce the volume of X-rays performed for common fractures of the wrist and ankle. Methods A retrospective cohort review was performed. The pre-VFC group consisted of 168 wrist and 108 ankle referrals from March to September 2019. The VFC group included 75 wrist and 68 ankle referrals, during the period March to September 2020. The total number of X-ray images, carried out within a 3-month period for each fracture was summated, with statistical analysis performed following fracture pattern classification. Findings A statistically significant decrease in mean X-rays was observed for isolated stable fracture patterns, such as non-displaced distal radius, − 0.976 (p = 0.00025), and Weber A ankle fractures, − 0.907 (p = 0.000013). A reduction was also observed for more complex fracture patterns such as dorsally displaced distal radius, − 0.701 (p = 0.129) and Weber B ankle fractures, − 0.786 (p = 0.235), though not achieving statistical significance. Conclusions Virtual fracture clinics can reduce X-ray frequency for common stable wrist and ankle fractures, with resultant benefits for both patients and healthcare systems. These benefits may be sustained in patient care beyond the current COVID-19 pandemic.

3D Mapping of Intra-articular Calcaneal Fractures

Background: The management of intra-articular calcaneal fractures (ICFs) still faces a challenge. Available research about the anatomic patterns of ICFs is lacking. We aimed to define the pattern of ICFs by a three-dimensional (3D) mapping and determine whether there are consistent fracture patterns and comminution zones. Methods: 67 patients of ICFs with available computed tomographic (CT) scans were identified. The calcaneal fractures fragments on CT were multiplanar reconstructed and virtually reduced. 3D heat mapping was subsequently created by graphically superimposing all fracture lines onto a standard calcaneal template. Mapping of fracture lines and comminution zones in both the axial and sagittal planes were performed. Results: The cohort included 26 (38.8%) left calcaneal fractures, 27 (40.30%) right calcaneal fractures, and 14 (20.9%) cases with bilateral fractures. Comminuted fractures accounted for 92.5% of all fractures. Sagittal 3D mapping demonstrated that fracture lines were concentrated in the critical angle of Gissane and extended posteriorly to the rear of the tuberosity of the lateral wall and the anterior of the medial process of the calcaneus tuberosity but with more significant variation in the medial wall. The mean angle of fracture lines concerning the long axis of the calcaneal (LAC) was 29.1°and 19.2° in the lateral wall and medial wall, respectively. Axial 3D mapping demonstrated that fracture lines were primarily concentrated in the area anterior to the posterior joint facet and extended along the posterior joint facet and calcaneus sulcus to the posteriorly of the tuberosity. The mean angle of fracture lines concerning the LAC was 11° in the axial wall. 3D mapping demonstrated that the comminution zones are closely related to the internal structure and fracture mechanism. Conclusion: The data presented have elucidated there are consistent characteristic fracture patterns and comminution zones for ICFs. This study provides visual guidelines to understand fracture morphology, which may assist with fracture classification, preoperative planning, fixation concepts development, and internal structure analysis.