Mineral Fracture Research Articles

Radioimaging Evaluation of Primary Bone Tumors and Tumor like Lesions

Background: Bone tumour is relatively rarely encountered by radiologist, so sometimes it creates diagnostic difficulty. Aim over study was to determine the X-ray CT and MRI characteristics of different primary bone tumours and tumour like lesion and correlation of radiologic diagnosis with histopathologic diagnosis whenever possible. To understand the advantages and limitations of different radio-imaging techniques. Subjects and Methods: We have studied total 45 cases of primary bone tumour and tumour like lesions during study of 15 months duration in department of Radiodiagnosis, Baroda Medical College, Vadodara, Gujarat, India. First radiological diagnosis and differential diagnosis was given than histopathologic examination was done in all malignant and indeterminate lesions for final diagnosis. Results: Out of 45 patients 21 (46.6%) were female and 24 (53.3%) were male. Benign and malignant lesions were 69% and 31% respectively. Multiple lesions were common with osteochondroma, hemangioma and multiple myeloma. Most common malignant tumour was osteosarcoma and benign tumour was osteochondroma. Pathologic fracture was seen in 6 patients but out of them 2 fractures were missed on radiograph. Skip lesions were seen in two malignant lesions which was missed on radiograph and CT but it was easily detected on MRI. Conclusion: Radiography is baseline investigation for evaluation of bone tumor and tumour like lesions. Pathological fracture and matrix mineralization can be better seen on CT. MR is superior in detection skip lesion, soft tissue and marrow extension.

Semi-analytical models of mineral dissolution in rough fractures with permeable walls

Mineral dissolution in fractures is largely affected by the flow field within the fracture opening. The flow field maintains transport of the dissolved solutes and influences the concentration gradient and thermodynamic driving force for the mineral dissolution. In this study, we focus on investigating two factors that influence mineral dissolution in fractures: fracture wall roughness and interporosity fluid exchange or the flux through the fracture walls. The classical cubic law for the flow in parallel-plate channels cannot describe the flow in a fracture with rough permeable walls. The wavy, irregular shape of the rough boundaries can result in local flow features and might cause a shift of the overall flow and dissolution regime. At low Reynolds numbers, roughness simply increases the surface area available for mineral dissolution. Moreover, at higher Reynolds numbers, the inertial effects become important and the non-linear flow, flow instabilities, and reverse flow will form. With the creation of eddies and vorticities in the area adjacent to the walls, a flow dead zone forms that reduces the reactive surface area. In the presence of interporosity fluid exchange between the fracture and its surrounding rock, the non-zero fluid velocity on the fracture walls influences the local concentration gradient. In addition, the newly introduced fluid may facilitate or suppress the fracture wall mineral dissolution depending on its composition. This work highlights the compound effect of roughness and fluid flux through the walls on fracture mineral dissolution. For this purpose, the asymptotic solutions of the steady-state Navier–Stokes equations with non-zero velocity on the borders are used to determine the velocity field within the fracture opening. The quadratic and cubic corrections to Darcy’s law are expected as a result of the wall roughness and the flow through the walls. The flow field is coupled with a transport module and a geochemical model (PHREEQC). As a test case, we investigate calcite dissolution in a single fracture at a different influx rate. For each flow rate, a flat fracture and two sets of rough profiles with and without the permeable walls were compared. The simulation results showed that compared to impermeable walls, the pervious walls result in a non-uniform non-periodic mineral dissolution along the fracture, which is more focused at the inlet. At low Reynolds numbers, the hotspots of dissolution are slightly shifted from the smaller cross sectional area to the larger cross sectional area. The effective reaction rate for mineral dissolution of fracture walls increases with an increase in fracture surface roughness. It is shown that at low Reynolds numbers, the permeable fracture walls can improve the effective reaction rate significantly. At relatively larger Reynolds numbers, the impact of flux through the walls on the effective reaction rate is less important, but for some roughness profiles, still not negligible.

МТ/МВ ДОСЛІДЖЕННЯ В ЗОНІ ЕНДОКОНТАКТУ КОРНИНСЬКОГО ГРАНІТНОГО МАСИВУ

In 2018-2019, work was carried out to study the deep geoelectric structure of a complex system of intersection of the sub-latitudinal zone between the Andrushevsky and Masherinsky faults and the sub-meridional between Brusilovsky and Olshansky. Plane synchronous observations of the lowfrequency natural electromagnetic field of the Earth of ionospheric-magnetospheric origin in a wide range of periods are made. The transmission operators of MT/MV fields were evaluated using the PRC-MTMV software package. The obtained tipper estimates for periods of geomagnetic variations from 50 to 3100 s, curves of apparent resistance and impedance phases from 20 to 10000 s. According to the interpretation of the results of magnetotelluric studies, the Brusilovsky deep fault in the form of a subvertical surface lowresistance anomaly was clearly recorded. Analyzing these and previous works, it can be stated that within the Volyn megablock Ukrainian shield, the Brusilovsky deep fault is manifested by an anomalous highly conductive structure from the surface. Within the framework of the Rosinsky megablock, the Brusilov fault zone is not completely anomalous, and only its individual components (Velikoerchik fault) are anomalous, its conductivity decreases almost four times. The western border of the Korninsky massif is less clearly distinguished, as the relatively electrically conductive from the surface, which is most likely associated with the surface conductivity of minor sedimentary deposits or fracturing of rocks in the crystalline basement. It should also be emphasized that on pseudo-sections of magnetotelluric parameters, the SUS point (picket 14 km) did not appear to be anomalous, but the behavior of the curves for different polarizations, and especially low magnetovariational characteristics, may indicate that the deep structure of the region must be classified as heterogeneous. Moreover, this point is located near the zone of metasomatically altered rocks and multidirectional faults of low rank. One explanation of this may be that the processes of secondary changes in granitoids do not lead to an increase in porosity, the solutions which are filtered are immediately saturated with calcium and alkalis, filling the fluid flow paths.

Homocystinuria a rare cause of low BMD in young patients: A case report with literature review

Background: Homocystinuira is a rare autosomal recessive disorder in the metabolism of sulfur-containing amino acid caused by mutations in the cystathionine beta-synthase gene which encodes the pyridoxine (Vitamin B6) dependent enzyme cystathionine beta-synthase. It is characterized by significant elevations in plasma and urine homocysteine concentrations, which could be associated with increased risk of fracture. Methods: We describe a case of Homocystinuria who suffered from a low impact patellar fracture with a literature review to highlight the critical relationship between homocysteine level and bone health. Results: We reported a 36-year-old female with a diagnosis of Homocystinuria due to pyridoxine (B6) unresponsive severe Cystathionine Beta-Synthase deficiency. After a minor knee injury she developed a right patellar fracture and her X-ray revealed osteopenia. On examination, she has severe scoliosis in the spine with bilateral aphakia (absence of the lens of the eye). Her labs showed, persistent high Homocysteine above 100 umol/L, Methionine: 383 umol/L (10-42), Vitamin D 12 ng/ml. Her spine X-ray revealed very severe scoliosis with osteopenia but no vertebra fracture. Her DXA scan showed her Z-Score was within the expected range for her age in hip, spine and 1/3 radius areas, however her ultra-distal radius Z-Score was -4.0. Her Homocystine level was mostly higher than 100 due to non-compliance with dietary advice and treatment. High homocysteine levels in Homocystinuric patients impair the function of bone cells that regulate bone remodeling as well as bone material properties such as collagen cross-linking. This imbalance between bone formation and resorption may lead to a low BMD and fracture in patients with homocystinuria. Interestingly, even in general population hyperhomocystinemia with a plasma level of more than > 13 nmol/ml has been found to be associated with low BMD and an increased risk of fractures that is independent of BMD. Deficiencies in vitamin B6, B12, or folate can lead to increased serum levels of Homocysteine as these vitamins act as co-factors for various enzymes involved in homocysteine metabolism. This can be easily rectified with dietary intervention. Conclusion: In young patients with a fracture or low bone mineral density, hyperhomocystinemia could play an important role in the pathogenesis. This should be included in the work up for secondary causes for osteoporosis for this age-group. Simple dietary measures and vitamin B6, folate and B12 supplement should be considered as adjuvant therapeutic option for any patient with osteoporosis and fractures, if deficient. Possibly the BMD of the ultra-distal radius is the most sensitive to detect bone changes in these patients.

Fracture-mediated deep seawater flow and mantle hydration on oceanic transform faults

Fluid-rock interaction on oceanic transform faults (OTFs) is important for both the deformation behavior of the lithosphere and volatile cycling in the Earth. Rocks deformed and exhumed at OTFs preserve information about the depth extent of fluid percolation and the nature of fluid-rock interactions within these fault zones. In this study, we focus on five dredges from the Shaka and Prince Edward OTFs on the ultraslow spreading Southwest Indian Ridge that recovered significant volumes of deformed mantle rocks. Samples are predominantly mylonites that have been deformed to high strains in the fault zone, but also contain several generations of fractures. Based on the mineral assemblages in fractures and shear bands combined with thermobarometry analysis, we identified three distinct temperature ranges of fluid-mantle interactions associated with deformation. At low temperature (LT), this leads to crystallization of serpentine (± talc ± amphibole ± chlorite) at <500–550°C. At medium temperature (MT), chlorite and amphibole crystallized at ∼500–750°C. At high temperature (HT), amphibole (± second generation peridotitic minerals) crystallized. The composition of minerals in HT fractures and shear bands indicates that fracturing and fluid flow occur up to temperatures of at least 850–875°C. Combining these results with modeled geotherms for both faults suggests that seawater percolation extended to depths of 20–25 km and that serpentinization extended to ∼11–13 km. The evolution of fault zone structure induced by deep fluid-rock interaction and progressive formation of LT, MT and HT mylonites on OTFs results in weakening and strain localization within the oceanic lithosphere, and suggests that the global transform system may represent a large reservoir of volatiles in the Earth's lithosphere.

Crustal Structure of the Eastern Arunta Region, Central Australia, From Magnetotelluric, Seismic, and Magnetic Data

AbstractWe present a 3‐D inversion of magnetotelluric data acquired along a 340‐km transect in Central Australia. The results are interpreted with a coincident deep crustal seismic reflection survey and magnetic inversion. The profile crosses three Paleoproterozoic to Mesoproterozoic basement provinces, the Davenport, Aileron, and Warumpi Provinces, which are overlain by remnants of the Neoproterozoic to Cambrian Centralian Surperbasin, the Georgina and Amadeus Basins, and the Irindina Province. The inversion shows conductors near the base of the Irindina Province that connect to moderately conductive pathways from 50‐km depth and to off‐profile conductors at shallower depths. The shallow conductors may reflect anisotropic resistivity and are interpreted as sulfide minerals in fractures and faults near the base of the Irindina Province. Beneath the Amadeus Basin, and in the Aileron Province, there are two conductors associated strong magnetic susceptibilities from inversions, suggesting they are caused by magnetic, conductive minerals such as magnetite or pyrrhotite. Beneath the Davenport Province, the inversion images a conductive layer from ∼15‐ to 40‐km depth that is associated with elevated magnetic susceptibility and high seismic reflectivity. The margins between the different basement provinces from previous seismic interpretations are evident in the resistivity model. The positioning and geometry of the southern margin of the crustal conductor beneath the Davenport Province supports the positioning of the south dipping Atuckera Fault as interpreted on the seismic data. Likewise, the interpreted north dipping margin between the Warumpi and Aileron Province is imaged as a transition from resistive to conductive crust, with a steeply north dipping geometry.

Fluid compartmentalization of Devonian and Mississippian dolostones, Western Canada Sedimentary Basin: petrologic and geochemical evidence from fracture mineralization

Integrated petrographic, geochemical, and fluid inclusion study of fracture mineralization and associated host rock in selected Mississippian and Devonian carbonates extending from southeastern Alberta to northwestern British Columbia, Canada, aims to quantify the type and nature of fluid precipitated saddle dolomite and late calcite cement and their origin. Petrographic and isotopic evidence from both the Devonian and Mississippian fracture-filling carbonates indicate the presence of a hydrothermal fluid source. The δ18O isotopic values for the Devonian saddle dolomite (−14.62‰ to −3.75‰ VPDB, average −11.12‰) combined with enriched 87Sr/86Sr isotopic ratios (0.70827–0.71599, average 0.71006) and higher homogenization temperatures (Th = 74–194.6 °C, average 126.8 °C) and salinity values (7.7–26.6 wt.% NaCl, average 16.2 wt.% NaCl) show significant differences from the Mississippian saddle dolomite, which is characterized by less negative δ18O isotopic values (−12.53‰ to −7.82‰ VPDB, average −9.14‰), less radiogenic 87Sr/86Sr isotopic ratios (0.70859–0.70943, average 0.70887), and lower homogenization temperatures (Th) and salinity values of fluid inclusions (87.6–214.2 °C, average 136.3 °C; 2.0–13.2 wt.% NaCl, average 9.6 wt.% NaCl). Later fracture- and vug-rimming blocky calcite cement records comparable or slightly lower values of δ18O (−16.31‰ to −4.08‰ VPDB, average −9.76‰) and 87Sr/86Sr (0.70784–0.709743, average 0.70868) and much lower salinity values (0–22.5 wt.% NaCl, average 2.86 wt.% NaCl) for samples mostly from the Mississippian age group. These results possibly suggest two different hydrothermal episodes related to early (Antler) and late (Laramide) tectonic events that affected the Western Canada Sedimentary Basin with possible compartmentalization of hydrothermal systems and their associated brines in the basin.

The formation of irregular polygonal ridge networks, Nili Fossae, Mars: Implications for extensive subsurface channelized fluid flow in the Noachian

Roughly 16,000, ∼20–50 m wide, morphologically diverse, erosionally resistant ridges have been exhumed and mapped in Noachian-aged terrain across a large region in Nili Fossae and the Nilosyrtis Highlands. However, the formation of these landforms has been widely debated. Their morphology and geologic context suggest surface processes such as aeolian, fluvial, and glacial sedimentary deposition are unlikely candidates for their formation. Possible subsurface ridge formation mechanisms include: 1) volcanic dike intrusions along pre-existing fractures, 2) breccia dikes from impact cratering, 3) clastic dikes or deformation bands, and 4) chemical alteration or precipitation of minerals in or along pre-existing fractures or faults. The ridges are being exhumed from a phyllosilicate-bearing host rock, but whether the ridges themselves have an aqueous origin remains unknown. Although, previous studies used comparative morphology to assess their formation, each hypothesized formation mechanism implies different mineralogical suites possibly detectable in remotely sensed spectral data.Here we combine spectral and morphological analyses to assess the origin of a subset of ridges (n = 797) that have irregular polygonal ridge network morphology. We use observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and High Resolution Imaging Science Experiment (HiRISE), supplemented with Context Camera (CTX) imagery, to analyze the spectral signatures and geometry in order to 1) measure ridge morphology (orientation and intersection angles) and 2) isolate the spectral signatures of the ridges from their host unit to evaluate hypothesized ridge formation mechanisms. The irregular polygonal nature, near-orthogonal intersections, and lack of dominant orientation are characteristics consistent with fracture propagation under horizontal near-isotropic extensional stress in a physically heterogeneous host rock (inconsistent with impact- or volcanic-related features). Alternatively, very shallow clastic intrusion could produce similar ridge geometry.Our key findings are: 1) ridge orientation-frequency and distribution suggest mineralization or cementation of subsurface fractures or shallow clastic intrusions as favored formation mechanisms and 2) ridges share all the diagnostic spectral features of Mg-smectite (saponite) and/or mixed-layered talc-saponite clays of the host materials; however, ridges express weaker absorptions. If the CRISM spatial and/or spectral resolution has not limited our ability to detect a spectrally unique cementing agent, then both grain size or texture and visible to near-infrared inactive mineralogy could be responsible for the ridge's weaker spectral absorptions (such as quartz and silica, some oxide group minerals, and amorphous materials). Our results imply that shallow subsurface groundwater and hydrothermal activity was likely extensive prior to and during the opening of the Nili Fossae and played an integral role in the formation of the ridges observed throughout the region.

Integrated Study Aids Characterization and Modeling of Natural-Fracture Networks

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 186043, “An Integrated Study To Characterize and Model Natural-Fracture Networks of Gas-Condensate Carbonate Reservoirs, Onshore Abu Dhabi,” by Budour Ateeq, Mohamed El Gohary, Khalid Al Ammari, and Rashad Masoud, ADCO; Abdelwahab Noufal, ADNOC; Ghislain de Joussineau and Martin Weber, Beicip Franlab; and Dinesh Agrawal, IFP Middle East Consulting, prepared for the 2017 SPE Reservoir Characterization and Simulation Conference and Exhibition, Abu Dhabi, 8–10 May. The paper has not been peer reviewed. Natural fractures can have a significant effect on fluid flow by creating permeability anisotropy in hydrocarbon reservoirs. They can also play an undesirable role in reservoir subsidence and compaction during depletion, with important consequences for production strategy. The investigation of these effects motivated a comprehensive integrated fracture study of three reservoirs from a giant gas-condensate field in Abu Dhabi. The main objective was to build 3D fracture models and compute fracture properties of each reservoir, to be used in dynamic simulations. Introduction The studied reservoirs are gas-condensate-bearing in a carbonate field onshore Abu Dhabi. The field has an anticlinal structure and consists of a series of stacked reservoirs, among which three (Reservoirs A, B, and C) were part of this study. For each reservoir, the production comes mainly from the large gas-bearing area above the gas/oil contact, which is surrounded by a thin peripheric oil rim. The studied field has a long production history; Reservoir A has produced oil and gas for 30 years. Minor fracturing was observed during routine core analyses in the past, but a comprehensive fracture characterization at field scale was never conducted. Because fractures may have a major bearing on production and could play a significant role in rock compaction and collapse during reservoir depletion, an important objective was to ascertain the risk related to the geomechanical stability of these reservoirs because of the presence of natural-fracture networks. Work Flow An integrated work flow was applied in order to characterize fracture distribution and flow effect in the reservoirs properly. The work flow consisted of the following key steps: Fracture characterization from 3D seismic data and subsequent detection of fracture corridors Fracture characterization from core data Fracture characterization from borehole image data Fracture characterization from well dynamic data Conceptual fracture model Building of a 3D fracture model Dynamic calibration of the 3D model using flowmeter and well-test data Upscaling and computation of equivalent fracture properties for the simulation grid using the calibrated model Static Fracture Characterization Fracture characterization using the seismic data initiated the work flow and was followed by the interpretation of fractures from borehole images and core data. Fracture Characterization From 3D Seismic Data. This task was performed to detect the seismic and the subseismic faults and fracture corridors within the three reservoirs. Seismic fracture-facies maps and fracture-index maps were created on the basis of post-stack discontinuity attributes (e.g., curvature, polar dip, and similarity) computed from the inverted seismic cube.

Diagenesis in Mesozoic carbonate rocks in the North Pyrénées (France) from mineralogy and fluid inclusion analysis: Example of Rousse reservoir and caprock

Fluid-rock interaction is of key interest for deciphering the geodynamic history of complex geological environments. In this paper, we describe the mineralogy and petrography of the Rousse reservoir (the Upper Jurassic “Dolomie de Mano” formation) as well as the reconstruction of its thermal and pressure history. We also investigate the base of the reservoir caprock (the Campanian breccia). A satellite of the giant gas field of Lacq in the south-west of France, Rousse was a gas producer until it moves to a CO2 storage site in 2010. Rousse is located within a deep, isolated, faulted, carbonate Jurassic horst overlain by a 4500 m thick overburden that is composed of a series of turbiditic flysch deposits of Upper Cretaceous (Cenomanian) to Tertiary (Eocene) age. Cores were sampled from two wells, Rousse 1 and 2, and were analyzed by ICP-MS, XRD, SEM, EPMA, TEM, cathodoluminescence and fluid inclusion techniques. Pressure-Temperature (P-T) conditions were derived by modeling data from fluid inclusions trapped in the fracture minerals of the “Dolomie de Mano” formation and the Campanian breccia. In the “Dolomie de Mano”, diagenesis was dominated by three dolomite episodes followed by a calcite stage in fractures. The second and third dolomitizations were associated with fracturing episodes. These dolomites precipitated from low-saline (<1 mol·kg−1 eq. NaCl) hydrothermal fluids at temperatures around 150 °C. These two characteristics exclude dolomitization during a synsedimentary slope brecciation event and also the role of hypothetical secondary brines. In the Campanian breccia, dolomitization is marginal and the main precipitation is calcite. In association, two types of fluid inclusion (liquid water-vapor and vapor) can be distinguished in the two formations and are marked by predominant CH4 and variable CO2 contents. The presence of gas inclusions in the reservoir as in the caprock is indicative of several gas invasions. A P-T modeling of the geologic evolution of the area reveals two periods of fluid circulation: a first stage (150–170 °C, 20 MPa) during the Late Jurassic to Early Cretaceous for the reservoir rock, corresponding to the rifting period of the North-Pyrénées western zone; and a second stage (170 °C, 41 MPa) during the late Eocene period in breccias, corresponding to the Pyrenean compression period. The petrophysical properties of the reservoir, marked by an intense fracture network, were acquired early during an extensional period, whereas the impact of fluids associated with a period of compression appears to have been limited in space to drainage of tectonic origin. Finally, we note significant similarities between the petrographic and fluid signatures of the Chaînons béarnais, in the folded orogenic wedge located south of the North Pyrenean Frontal Thrust, and Rousse, located in the foreland basin to the North. Nevertheless, the temperature recorded in the Chaînons béarnais reached 300–350 °C, much higher than in Rousse due to its position in the vicinity of an over-thinned palaeomargin during the early Cretaceous.

Mineralogical Controls on Frictional Strength, Stability, and Shear Permeability Evolution of Fractures

AbstractMassive fluid injection into the subsurface can induce microearthquakes by reactivating preexisting faults or fractures as seismic or aseismic slip. Such seismic or aseismic shear deformations may result in different modes of permeability evolution. Previous experimental studies have explored frictional stability‐permeability relationships of carbonate‐rich and phyllosilicate‐rich samples under shear, suggesting that friction‐permeability relationship may be primarily controlled by fracture minerals. We examine this relationship and identify the role of mineralogy (i.e., tectosilicate, carbonate, and phyllosilicate content) using direct‐shear experiments on smooth saw‐cut fractures of natural rocks and sintered fractures with distinct mineralogical compositions. These results indicate that the friction‐permeability relationship is controlled by mineralogy. Frictional strength and permeability change upon reactivation decrease with phyllosilicate content but increase with tectosilicate content. In contrast, the reverse trend is observed for frictional stability (a‐b). However, the permeability change decreases with carbonate content while both frictional strength and stability increase. The permeability change always decreases with an increase in frictional stability. This relationship implies a new mechanical‐hydro‐chemical coupling loop via a linkage of frictional properties, mineralogy, and permeability.

CO2 charged brines changed rock strength and stiffness at Crystal Geyser, Utah: Implications for leaking subsurface CO2 storage reservoirs

CO2 geological storage in saline aquifers results in acidification of resident brine. Chemical reactions between acidified brine and rock minerals lead to dissolution and precipitation of minerals at various time scales. Mineral dissolution and precipitation are often neglected in assessing the mechanical integrity of target storage formations, yet, changes in rock strength and deformational behavior can impact trapping mechanisms. This study shows the impact of exposure to CO2-charged brine on shear strength and stiffness of various outcrop rocks evaluated through triaxial testing. The tested rocks were exposed to CO2-charged brine over geological time at a naturally occurring near-surface seepage along the Little Grand Wash Fault and Salt Wash Grabens, which include the Crystal Geyser site near the town of Green River, Utah. Prior work suggests that this site provides a near-surface structural analog for possible fault-controlled CO2 leakage over time scales that exceed expected injection time scales (10–100 years). Results show mechanical alteration in various aspects: (1) CO2-charged brine alteration at near-surface conditions results in mineral dissolution/precipitation and reduction of shear strength and brittleness of Entrada sandstone and Summerville siltstone samples, and (2) carbonate precipitation in fractured Mancos shale leads to matrix stiffening and fracture mineralization resulting in overall stiffer and likely tighter shale. Additional discrete element simulations coupled with a bonded-particle-model confirm the role of cement bond size alteration as one of the main controls for rock chemo-mechanical alteration in sandstones. The chemo-mechanical alteration path that mimics cement dissolution (under stressed subsurface conditions) results in vertical compaction and lateral stress relaxation. Overall, results show that rock exposure to CO2-charged brine can impart distinct petrophysical and geomechanical changes according to rock lithology and location with respect to major CO2 conduits. While mineral dissolution in the storage rock may result in undesired reservoir strains and changes of stresses, mineral precipitation downstream from a leakage path can help seal potentially induced fractures.

FRACTURE (VEIN) MINERALS IN AMPHIBOLITE ROCKS ON THE SOUTHERN EDGE OF THE KRIVAJA–KONJUH MASSIF (BOSNIA AND HERZEGOVINA)

Herzegovina is part of the Dinarides Central Ophiolite Zone, known in literature as the Bosnian Ophiolite Zone. Within the ophiolite zone, there are 6 ophiolite complexes in Bosnia among which the Krivaja-Konjuh Ophiolite Complex stands out with its size.The paper presents the results on research to date of fracture (vein) minerals in the Bosnian Ophiolite Zone, with accent put on research of vein (fracture) minerals on the southern edge of the Krivaja–Konjuh Ophiolite Complex. The following were conducted in the research on fracture (vein) minerals: an optical examinations by polarization microscope, x-ray examinations and chemical analysis by an electronic microprobe. The following were determined as fracture (vein) minerals in amphibolite rocks: prehnite, zeolite minerals (laumontite, thomsonite, mesolite and analcime), epidote-clinozoisite, chlorite, calcite, then plagioclases, quartz, garnet minerals and corundum. In contact zone between these rocks and metadiabases, the followings were determined: prehnite, epidote and subordinate clinozoisite and quartz.

2017 WSGC Elijah High-Altitude Balloon Payload

The 2017 WSGC Elijah High-Altitude Balloon Payload Fellowship focused on three different topics for high altitude research: Modular Payload Design, Balloon Dynamics, and Energy Harvesting. A modular payload system was created using advanced manufacturing methods, which improved assembly and field operation. Minor structural fracturing was observed upon recovery. All instrumentation recovered were functioning. Vertical flight dynamics of a high-altitude balloon were studied to create a model that was compared against experimental data. Predictions did not accurately replicate GPS altitude data, possibly due to incorrect internal-balloon pressure readings and underlying assumptions. Habitability of high-altitude environments were explored by monitoring insect analog in pressurized environment. A slow pressure leak induced insects into a comatose state. Radiation was detected visually with camera.Investigated energy generation from balloon kinematics. Flight data not obtained but flight simulation data produced average voltage = 0.0039 V and total energy = 245.13 J.

Pressure-Transient Characteristics of Fractured Horizontal Wells in Unconventional Shale Reservoirs With Construction of Data-Constrained Discrete-Fracture Network

Summary Unconventional shale reservoirs require massive and multistage hydraulically fractured horizontal wells to produce economically. Induced hydraulic fractures interacting with in-situ natural fractures result in complex or discrete fracture networks (DFNs). Even though well-testing characteristics in fractured reservoirs with vertical wells have been investigated extensively, there is a lack of good understanding of well-testing response for hydraulically fractured horizontal wells in complex fracture networks. First, three practical approaches are presented regarding how to generate complex fracture networks in the context of developing unconventional shale reservoirs with hydraulically fractured horizontal wells. Complex fracture networks can be generated (1) from stochastic algorithms that enter fracture density, length, and strike distributions, or (2) from the flowing-producing DFN (FP-DFN) area that is constrained by microseismic information, or (3) from digitization of realistic outcrop maps. Then, new unstructured fracture gridding and discretization techniques specially tailored for complex fracture networks are developed to handle nonuniform fracture aperture, extensive fracture clustering, and nonorthogonal fracture intersections. Finally, the numerical simulation of pressure buildup is performed in complex fracture networks that are generated from three proposed approaches with both synthetic and field examples. Flow regimes are identified and are discussed on the basis of pressure-derivative plots. Complex fracture networks show that the most representative characteristics are formation/fracture bilinear flow and formation linear-flow regimes. The appearance of the bilinear-flow regime during early period might not be clear because of the impact of the wellbore-storage effect as both the wellbore volume and the volume of the larger natural fractures in communication with the wellbore. In addition, the microseismic-based approach reduces the uncertainties of fracture characterization with percentiles of FP-DFN areas. The pressure-buildup response observed clearly indicates that the higher the percentiles of FP-DFN areas (or intense naturally fractured portion of the completion), the lower the pressure difference and derivative curves. Fracture mineralization affects pressure-buildup responses significantly. The decrease in nonuniform fracture apertures causes pressure-diagnostic plots to shift upward. The effect of boundary in the outcrop-based complex fracture network shows an early deviation from the formation linear-flow regime. No classic dual-porosity behavior is observed in all cases to quantify related parameters. Three practical techniques are proposed to generate complex fracture networks. Pressure-transient characteristics are identified and summarized. Further research areas are discussed and highlighted. The combination of techniques such as microseismic, horizontal core, production logging or some method to characterize the fracture network can be used to close the loop between the inferred network and the response that it should exhibit during pressure-transient analysis.

Bone mineralization and densitometric evaluation of vertebral fractures in women 6-21 years after the onset of anorexia nervosa symptoms.

We attempted to assess bone mineralization and the frequency of fractures occurrence in women with a history of treatment of anorexia nervosa (AN) in adolescence. 47 women (age 20-36.8 years) were re-examined 6.33-21,2 years after the onset of AN symptoms. Bone mineral density (BMD) of total body, lumbar spine, femoral neck, total hip (DXA) and densitometric Vertebral Fracture Assessment (VFA) were performed on 46 of women and BAP, P1NP, CTX, estradiol, testosterone, cortisol, IGF-1, leptin, DHEA-S on 45 of women entered for the current study. Current BMD results were compared with available baseline results from the time of hospitalization. Currently BMD Z-score <-1 examined at any location occurred in 28 from 46 women (including Z-score <-2 in 5 women). In 11 from 12 women with reduced BMD at the time of hospitalization current total body BMD was within the normal range. Lumbar spine BMD was normalized or improved respectively in 5 and 6 from 15 women. Currently increased levels/activity of bone formation markers: P1NP in 27 (60%) and BAP in 28 women (62.2%) were observed. In 7 women (15.6%) increased values of bone formation markers with increased marker of bone resorption (CTX) occurred. Osteoporotic fractures and fractures in the spine in VFA were not observed during the observation period. Despite early treatment of adolescent-onset AN and good outcomes of the treatment, decreased BMD was currently present in 60.9% of women. During follow-up normalization or significant improvement in BMD results (total body, lumbar spine) were observed in majority of cases.

Subarctic physicochemical weathering of serpentinized peridotite

Frost weathering is effective in arctic and subarctic climate zones where chemical reactions are limited by the reduced availability of liquid water and the prevailing low temperature. However, small scale mineral dissolution reactions are nevertheless important for the generation of porosity by allowing infiltration of surface water with subsequent fracturing due to growth of ice and carbonate minerals. Here we combine textural and mineralogical observations in natural samples of partly serpentinized ultramafic rocks with a discrete element model describing the fracture mechanics of a solid when subject to pressure from the growth of ice and carbonate minerals in surface-near fractures. The mechanical model is coupled with a reaction–diffusion model that describes an initial stage of brucite dissolution as observed during weathering of serpentinized harzburgites and dunites from the Feragen Ultramafic Body (FUB), SE-Norway. Olivine and serpentine are effectively inert at relevant conditions and time scales, whereas brucite dissolution produces well-defined cm to dm thick weathering rinds with elevated porosity that allows influx of water. Brucite dissolution also increases the water saturation state with respect to hydrous Mg carbonate minerals, which are commonly found as infill in fractures in the fresh rock. This suggests that fracture propagation is at least partly driven by carbonate precipitation. Dissolution of secondary carbonate minerals during favorable climatic conditions provides open space available for ice crystallization that drives fracturing during winter. Our model reproduces the observed cm-scale meandering fractures that propagate into the fresh part of the rock, as well as dm-scale fractures that initiate the breakup of larger domains. Rock disintegration increases the reactive surface area and hence the rate of chemical weathering, enhances transport of dissolved and particulate matter in the weathering fluid, and facilitates CO2 uptake by carbonate precipitation. Our observations have implications for element cycling and CO2 sequestration in natural gravel and mine tailings.

A Geochemical and Isotopic Study of Crystalline Rock at Chalk River, Ontario, Canada

Crystalline rock is one of several proposed long term storage sites for accumulated nuclear waste. The primary concern during long residence times (>100 Ka) is the transportation of hazardous materials by groundwater migration. The main pathways for fluid flow and material transport in crystalline rock tend to be porosity due to fractures caused by the tectonic stresses after initial deposition. Investigation and understanding of existing fractures and the precipitated minerals within them offer powerful tools to understand and predict the future stability of a site. Several methods were utilized to assist in investigating the hydrogeological history of the crystalline bedrock below the Chalk River site. These were chiefly focused on the fracture mineral, chemistry, and isotopes and their relationship to associated groundwaters. Multiple generations were identified within the fracture filling minerals themselves consisting primarily of calcite precipitated from several fluids under variable hydraulic conditions. The overall objective of this investigation was to identify if evidence exists for recent low temperature mineral formation, none of which were found despite a varied depositional history.

Experimental insights into geochemical changes in hydraulically fractured Marcellus Shale

Hydraulic fracturing applied to organic-rich shales has significantly increased the recoverable volume of methane available for U.S. energy consumption. Fluid-shale reactions in the reservoir may affect long-term reservoir productivity and waste management needs through changes to fracture mineral composition and produced fluid chemical composition. We performed laboratory experiments with Marcellus Shale and lab-generated hydraulic fracturing fluid at elevated pressures and temperatures to evaluate mineral reactions and the release of trace elements into solution. Results from the experiment containing fracturing chemicals show evidence for clay and carbonate dissolution, secondary clay and anhydrite precipitation, and early-stage (24–48 h) fluid enrichment of certain elements followed by depletion in later stages (i.e. Al, Cd, Co, Cr, Cu, Ni, Sc, Zn). Other elements such as As, Fe, Mn, Sr, and Y increased in concentration and remained elevated throughout the duration of the experiment with fracturing fluid. Geochemical modeling of experimental fluid data indicates primary clay dissolution, and secondary formation of smectites and barite, after reaction with fracturing fluid. Changes in aqueous organic composition were observed, indicating organic additives may be chemically transformed or sequestered by the formation after hydraulic fracturing. The NaCl concentrations in our fluids are similar to measured concentrations in Marcellus Shale produced waters, showing that these experiments are representative of reservoir fluid chemistries and can provide insight on geochemical reactions that occur in the field. These results can be applied towards evaluating the evolution of hydraulically-fractured reservoirs, and towards understanding geochemical processes that control the composition of produced water from unconventional shales.

Hydrochemical impact of construction of the western section of the Hallands\xe5s rail tunnel in Sweden

This paper presents a study of the hydrochemical changes that took place during construction of a section of the Hallandsås rail tunnel in southwest Sweden based on monitoring from spring 2011 to summer 2012. Leakage into the tunnel during construction caused lowering of the groundwater levels, which in turn resulted in a decrease in or absence of base flow in the streams. The water in the streams became dominated by meteoric water during the drawdown periods. Meanwhile, wetlands were aerated, and oxygen could penetrate to oxidise reduced S, releasing acids and SO4. The results for the groundwater in the bedrock differed spatially depending on local geological conditions. In each of the three monitored boreholes, higher redox potentials, higher concentrations of organic matter and lower concentrations of dissolved Mn and Fe were observed. In two of the boreholes, oxidation of pyrite, FeS2, present as a fracture mineral, caused the formation of SO4 and acids with subsequent falls in pH and alkalinity. Leakage into underground constructions generally shortens the residence time of the groundwater significantly. Silicate weathering would thus become less important for the hydrochemistry compared to processes that occur during shorter time frames. As regards the durability of the tunnel, the hydrochemical changes observed in two of the three boreholes indicate a more aggressive environment for several parameters known to increase corrosivity of steel. The recovery of the groundwater levels occurred rapidly following completion of the waterproofing systems in the Tunnel. However, hydrochemical recovery with regard to major ions and pH occurred gradually and with an expected duration of several years.