Integration between magnetic and gravity data at the Zelten platform, the southeast part of Sirt Basin Libya. Zelten Platform is first discovered oil field in Libya. It shows numerous geological structures of different tectonic events. The methods adopted can assist in locating the hidden subsurface structures. The platform is characterized by the NW-SE trending rift that belongs to the Early Cretaceous age (during the collapse of Sirt Arch). The study aimed to define the structural geology that assisted in the development of future exploration in this area. The analyses utilized several filtering and transformation algorithms to help in structural modeling. For instance, the total horizontal gradient and tilt angle derivative were applied for the edge detection of the tectonic boundaries. The results show NW-SE and NNW-SSE patterns that represents faults that controlled the positions of the troughs and platforms at the Sirt basin. On the other hand, Euler deconvolution and 2D forward modeling were utilized to determine the depth of the basement. The Integrated models deduced revealed that the main faults trends are NW-SE which refer to the rift phases and crustal extension period that occurred during the Mesozoic time (early cretaceous). Also, the basement depth ranges from 6.5 km to 8 km according to the structures that affected the study area., Abdelhakim Eshanibli, Amin Khalil, Abdellatif Younis and Hussin Ghanoush., and Obsahuje bibliografii
This paper presents the subject related to the technology of creating fractures into a rock, as well as the subject related to the effect of the proppant embedment phenomenon on the effective packed fracture in a reservoir rock. This phenomenon occurs after the performed hydraulic fracturing treatment of hydrocarbon reservoirs, during closing of the rock mass. A key part of this experiment was to investigate the depth of proppant grains penetration into the fracture wall (shale rock) and size of damage to the fracture wall surface. The embedment phenomena effects on decrease in the width fracture packed with proppant. The tests were performed for shale rock initially soaked with fracturing fluid, lightweight ceramic proppant grains with a grain size of 0.600÷0.300 mm (medium diameter of proppant grains of 0.450 mm), low surface concentration of proppant of 2.44 kg/m2. Time of exposure of proppant grains to compressive stress of a value 48.3 MPa for 6 hours at 70 oC. Test results indicate that the developed testing methodology may be used for corrected evaluation of the fracturing fluid as well as proppant in hydraulic fracturing treatment of unconventional reservoirs, especially shale rocks. and Maslowski Mateusz, Kasza Piotr, Wilk Klaudia.
Using the FLAC3D numerical simulation method, the characteristics of mining stress evolution, fault activation patterns, and fault energy evolution characteristics are simulated and analyzed in the process of the footwall and hanging wall working face heading to a normal fault. The study shows that the fault cut off the mining stress propagation of overlying strata, and the stress blocking effect due to the fault is evident. When working faces head towards a fault, the abutment pressure and the vertical stress of the surrounding rock increase first and subsequently decrease. The abutment pressure of the coal wall and fault is highest when the distances to the fault are 40 m and 30 m for the footwall and hanging wall working faces, respectively. Moreover, the hanging wall mining stress is higher than the footwall mining stress. Fault activation in high-located strata precedes that in low-located strata when working faces head towards the normal fault. Energy is gradually accumulated before unstable fault events take place because of mining, and fault instability quickly releases a lot of energy. The mining stress concentration and fault activation due to faults easily result in rock bursts and mine seismicity, Wu Quan-sen, Jiang Li-shuai and Wu Quan-lin., and Obsahuje bibliografické odkazy
Permeability plays an important role in the field of geotechnical engineering. Under high temperature and high pressure condition, the physical-chemical and structure properties (such as decomposition, oxidation, dehydration, evaporation, phase transition etc.) of rock have obviously changing, which are significant affected the rock permeability. In order to analyze the influence of temperature and confining pressure on the permeability of rock (sandstones, siltstones and conglomerates) data for permeability was obtained from the literature. The results indicate that temperature and confining pressure have great influence on the permeability of rock, especially for sandstone. There is a threshold temperature and when the heating temperature is lower than the threshold temperature, the permeability of sandstone gradually increases with an increase in temperature. When the heating temperature is higher than 300 ºC (especially 400 ºC), the permeability rapidly increases. The permeability of sandstone decreases gradually with the confining pressure increases. This study of the relationship between rock permeability and temperature and confining pressure lays a foundation for investigations of multi-disciplinary issues regarding high temperatures and high pressures and it can be used for the study of petroleum storage and safe nuclear waste disposal., Zhenlong Ge, Qiang Sun and Wenping Li., and Obsahuje bibliografii
The case study of a ground steps creation due to underground mining in Upper Silesia Basin, where for many years was conducted intensive hard coal extraction has been presented in this paper. This type of linear discontinuous deformations is considered as an important threat to the surface building constructions and elements of underground technical infrastructure. This threat is even more important, that presently still we do not have methods for predictions of such phenomena, and protection of building constructions against such damages is difficult, if not impossible. On the basis of the analyzes results shown in the paper, the following factors were pointed, that favor the formation of mining-induced ground steps: the presence of fault outcrops in the vicinity of extraction fields, multiple extraction in several coal seams led to the same border and large values of tensile horizontal strain., Piotr Strzałkowski and Roman Ścigała., and Obsahuje bibliografické odkazy
When using the PPP method, it is recommended to take into account the tropospheric influences for obtaining reliable estimates. Global Navigation Satellite System (GNSS) observations taken at low elevation suffer more strongly from atmospheric, antenna phase center variation and multipath effects, hence the observations are noisier than those at higher elevation angle, but they are essential to decorrelate the estimated station height and tropospheric zenith delay (ZTD). To relate the ZTD in the direction of an observation, the so-called mapping function (MF) are used. In this article the influence of different mapping function was studieds such as: Niell mapping function (NMF), Global Mapping Function (GMF) in conjunction with the Global Pressure and Temperature 2-GPT2, Vienna Mapping Function 1 and no mapping function. The MF were used at different elevation cutoff angles - 50 , 70, 100 and 150. The impact was analyzed: a) on the postfit residuals of the ionospheric free combination for phase (LC) and for pseudorange (PC), b) daily variability for North, East and Up component; c) evaluation of coordinates repeatability and how they are affected by the changes of the cutoff elevation angle and mapping function. The analyzed data was taken from 4 EUREF stations for a period of one month - October 2015. By using the VMF1 mapping function, the lowest value was obtained for the postfit residuals of the LC combination for all the stations. The difference in daily variation between each individual solution for the horizontal component is at the level of ~0.3 ÷ 0.5 mm, with smaller effect on the East component compared to North, whereas the Up component is at the level of ~1.0 ÷ 1.5 mm. The standard deviation (SD) is used as a measure of station position repeatability and the results suggested that for high precision determination a cutoff elevation angle of 100 should be used., Sorin Nistor, Norbert-Szabolcs Suba and Aurelian-Stelian Buda., and Obsahuje bibliografii
a1_The Miocene Ishim Formation is characterized by a considerable distribution area within the southwestern Siberia. These deposits are highly dispersed and are composed mainly of angular quartz grains of aleuritic and pelitic fractions. The study of the Ishim Formation is of interest both for investigating the origin of the sediments, and for justifying these rocks as a new type of mineral raw material for the local construction materials industry. This paper presents the results of first complex studies of the Ishim Formation deposits from two outcrops Masali and Bigila. The studies included determination of the particle size distribution on the laser particle analyzer, semiquantitative determination of the mineral composition (X-ray diffraction analysis), as well as, determination of contents of sesquioxides (X-ray fluorescence analysis), rare and trace elements (Inductively Coupled Plasma Mass Spectrometry) and measurement of specific surface area. The most representative samples were chosen for petrographic studies. In certain extent these deposits are characterized by quite high degree of homogeneity of the mineral, chemical, and granulometric compositions. The main component is SiO2 (about 70 %); other most important components are Al2O3 (about 14 %) and Fe2O3 (2-5 %). At the same time, deposits of the upper part of the Ishim Formation are depleted in CaO, MnO, MgO, TiO2, and P2O5. This is probably due to the fact that the proportion of clayey minerals in the upper part of the formation is lower than that in the lower one. The contents of trace elements in the Ishim Formation are lower or close to their clarke values in the Earth's crust. This is with the exception of such elements as Eu, Tb, Cr, and Sb, which form a strong anomaly and, to a lesser extent, a number of other elements that is probably related to the tectonic setting during the period of sedimentation., a2_The CIA values vary from 68-70 in the lower unit of the Ishim Formation at the transition to the sandy facies to 75-80 in the upper one, which indicates a moderate weathering of rocks. The results obtained testify to the fact that these deposits were formed under the conditions of degrading shallow water bodies. A distinct geomorphological confinement to boundaries of the Neogene river paleovalleys, continuity, high dispersion and, predominantly, quartz composition allow us to consider these deposits as a promising type of filler for construction materials industry., Alexander O. Konstantinov, Pavel V. Smirnov, Olga B. Kuzmina, Irina V. Khazina, Georgii A. Batalin and Bulat I. Gareev., and Obsahuje bibliografii
Based on experimental studies using the “integral velocity index of the vertical displacement of the territory” and criterion of generalized seismicity, a close functional relationship was found between two parameters of different physical nature: seismic activity and altitude displacements of the Earth’s surface in Europe. The mathematical correlation between the generalized parameters of the velocity altitude displacements on the territory and seismic activity is established according to seismic and GNSS stations for the period from 2000-2011 for the areas in Europe with close correlation between seismicity and velocity of vertical movements of the Earth’s surface. and Tretyak Kornyliy, Romaniuk Volodymyr.
For companies doing business in mining mineral deposits, ensuring safe work is one of the key tasks (Safety First!). One of the important trends in this area is prevention and endeavour to forestall risk situations. Risks need to be searched, technically described, spatially defined, evaluated and categorized by degree of risk. Complex geological and stability conditions can be one of the sources of persistent and significant risks, which are mainly landslides and rockslides threatening both mining equipment and employees. The problem described in this article and its solution concerns the Most Basin (formerly the North Bohemian Lignite Basin). This is a tertiary basin that was founded in the Oligocene. The main mineral is lignite and mining takes place on the surface. The main excavating machinery in the surface lignite quarries in Europe (Czech Republic, Germany, Poland) is the bucket wheel excavator., Roman Kapica, Dana Vrublová and Martin Vrubel., and Obsahuje bibliografii
Dynamic soil properties are important parameters for the design of structures subjected to various dynamic/cyclic loading such as earthquake which can be obtained by in situ and laboratory measurements. Numerous empirical and mathematical models have been proposed to predict the dynamic properties of soils, including maximum shear modulus (Gmax), normalized shear modulus (G/Gmax - γ) curve, reference shear strain (γr), minimum damping ratio (Dmin) and damping ratio (D - γ) curve. However, the majority of the existing models were proposed for specific soil types, loading characteristics, initial soil fabrics and strain ranges. This paper proposes five universal models to estimate the Gmax, γr and Dmin values, and also G/Gmax - γ and D - γ curves using a database that contains 117 tests on 5 different granular soils. The proposed models include the effect of grading characteristics, void ratio, mean effective confining pressure, consolidation stress ratio (KC) and specimen preparation method. The models are validated using experimental data from previous studies for granular soils. The results indicate that the proposed models are capable of evaluating the dynamic properties of granular soil., Meysam Bayat., and Obsahuje bibliografii