Geological Section Research Articles

Sequence stratıgraphıc analysıs of the Galmaz field based on well loggıng data


 
 
 It is known that over 90% of oil, gas and gas condensate in Azerbaijan is produced from Productive Series (PS) of the Early Pliocene. In this respect, the detailed study of Pro- ductive Series deposits and their evolution conditions has a special value. Currently in most sedimentary basins of the world the latest highly informative methods of stratigraphic analysis are applied and one of these methods is sequence-stratigraphy, which is used in this study. The application of the concept of sequence stratigraphy enables an in-depth analysis of the study area to be conducted from a geological point of view. Despite the fact that the search for oil and gas deposits in the basins of Azerbaijan Republic has been going on for many years, there is a limited understanding of the distribution of elements associated with the oil system within the sequence stratigraphic structure. This is evidenced by the small number of scientific publications that exist in this area at the moment. To study in more detail the sedimentation process of PS of the Pliocene in the Galmaz field the genetically tied facies have been outlined and correlated within the framework of chronostratigraphic boundaries. As the study targets we have chosen the stages of Absheron, Akchagyl and PS of Pliocene in the Galmaz field. New data acquired by well logging techniques were re-examined in detail. To analyze and interpret the data , NeuralogTM and PetrelTM software were applied. From positions of the sequence-stratigraphy and taking into account the curve features (gamma ray log) predictions of the sedimentation environment of PS have been made. In the study process the sequences and system tracts have been outlined and studied, the sedimentation periods of the outlined sequences have been defined. It has been suggested to apply stratigraphic surfaces for tracing changes in regression and transgression surfaces. Clay and sand fractions of rocks were evaluated with further lithological analysis. On the gamma-ray curves, the intervals with intensity values less than 3.5 mR/h were considered as reservoir layers. At the same time, the normalized value of αSP, calculated from the curve of Spontaneous Polarization, was assumed to be greater than 0.6. Based on the sequence-stratigraphy analysis of oil-field geophysical data it has been established that the geological section of the Galmaz area was developing at various rates and in frequently changing energy mode. It has been also made clear that parasequences of the Absheron stage and Productive Series were formed in progradation mode by detritus brought by river flows. Akchagyl sediments play the role of the regional major cap in the basin.
 
 

An aeromagnetic denoising-decomposition-3D inversion approach for mineral exploration

Reduction of aeromagnetic noise and extraction of mineralization-related residual anomalies are critical for aeromagnetic data processing in mineral exploration. This study introduced a multifractal singular value decomposition (MSVD) method to remove the noise and improved the bi-dimensional empirical mode decomposition (BEMD) algorithm to extract residual magnetic anomalies. It is shown that MSVD and improved BEMD could effectively reduce the noise and extract residual magnetic anomalies. Then, a wavenumber–domain iterative approach is applied in 3D imaging of magnetic anomalies and gradients with depth constraints, which is a rapid tool for qualitative and quantitative interpretation of magnetic data and is suitable for rapidly imaging large-scale data. The 3D inversion result is verified by four geological sections along the regional tectonic directions and some drilling holes on the deposits. It is revealed that this proposed approach is practical and effective in dealing with aeromagnetic data interpretation and inversion for mineral exploration.

Yeraltı Raylı Sistem İnşaatlarındaki Jeoteknik İncelemeler ve Geoteknik Uygulamalar: Halkalı-Yeni Havalimanı Metro Hattı Örneği

In this study, geological researches carried out before the construction of underground rail systems and geotechnical application methods preferred during the construction were examined within the scope of Halkalı-İstanbul Airport metro project. The metro line consists of a total of 66.2 km long underground tunnels, 31.3×2 km main line and 1.8×2 km repertorium connection line. 1006 soil and 1230 rock samples were collected for the main line whose geological research was carried out with 198 core drillings with a total length of 9588.5 m. The results of the laboratory tests on the samples and the field tests carried out in the boreholes were obtained. In addition, a total of four two-dimensional inverted solution resistor underground sections were obtained by using the Multiple Electrode Electrical Resistance Tomography measurement method in the middle of two lines (Line-1 Km. 61+440 – 61 +660 /Line-2 Km: 61 +400 - 61+620), in the Olympic Stadium station (Km: 62+215 – 62 +490) and in the TBM route (Line-2 Km: 62 +835 – 63+050). The geological sections obtained from the drillings and the geophysical sections obtained by the electrical resistivity method were compared.

Safety evaluation of buildings adjacent to shield construction in karst areas: An improved extension cloud approach

To accurately evaluate the safety risk status of buildings adjacent to karst shield construction areas, a safety evaluation standard for buildings adjacent to shield construction in karst areas and a safety risk assessment method based on optimal cloud entropy are proposed. Comprehensive consideration of the tunnel characteristics, geological conditions, building conditions, construction, management and other influencing factors, a risk evaluation index system including 4 level-II indicators and 15 level-III indicators and evaluation criteria are established for buildings adjacent to shield construction in karst areas. The traditional extension cloud theory is improved based on the optimal cloud entropy calculation method for adaptive evaluation objects, and the clarity and fuzziness of index classification are considered. To verify the applicability of the proposed approach, it was applied to ten adjacent buildings in a karst geological section of Guiyang Rail transit Line 3. The results show that (a) the evaluation standard and the improved extended cloud safety risk assessment method proposed can effectively consider the uncertainty of risk events and that the evaluation results are consistent with the actual building safety risk status information with the calculated reliability factor of each building is close to 1. (b) The key risk factors are identified through sensitivity analysis. According to the key risk factors and risk statuses, effective measures can be taken, and high-risk buildings can be monitored to maintain a safe control state. Thus, the proposed approach can be feasibly used in various applications and can provide guidance for other similar projects.

Environmental and Technological Problems for Natural Gas Production in Permafrost Regions

Russia has unique technical and technological experience of gas field development in permafrost regions. According to this experience, different environmental and geocryological conditions require different technical solutions. Such problems as considerable subzero temperatures in geologic sections, great ice saturation of subsurface sediments, and gas and gas hydrate accumulations inside permafrost and immediately below it cause a series of dangerous consequences when gas production wells are in operation. These include back freezing, breaking well casings, well site subsidence when in production; movement and deformation of the wellhead caused by thawing of the rock massif around the well column when in operation; sudden and strong gas blowouts during well drilling, completion, and operation. To prevent possible accidents, different technical and technological solutions are applied: zoning of the field area according to the degree of complexity of geocryological conditions and the correction of future gas well cluster locations to avoid zones with extremely complex conditions; preliminary degassing of permafrost zones by shallow slim wells in places of future production well clusters; mechanical support of unstable production wells; installation of passive and active heat-isolation systems to the well construction and inside ground around wellheads. Key messages received during the development of gas fields at complex geocryological conditions are (consistently): preliminary careful geological engineering surveys and zoning of the field area, well clusters placed in areas with relatively soft geocryological conditions, preliminary degassing of permafrost depth intervals, passive and active heat isolation installation to the sub-wellhead part of the production well and around wellhead, and mechanical strengthening of unstable wells. Current plans are underway to utilize this experience for new gas discoveries in the Russian Arctic.

The spatial coordinates projection method for generating digital geologic cross sections from the multi-source terrain and geologic data

The spatial coordinates projection method for generating digital geologic cross sections from the multi-source terrain and geologic data

Numerical Investigation of the Evolution Process of an Open-Pit Mine Landslide Using Discrete-Element Method

Because of the complexity of geological conditions and disturbance of external factors, the process of instability of open-pit landslides is very complicated. To illustrate this complex process, taking an open-pit coal mine landslide as an example, an accurate landslide geological section was established via detailed field investigation, remote sensing image interpretation, and field borehole data, in this study. A two-dimensional discrete-element model was established by the Fast CPU Matrix Computing of Discrete-Element Method (MatDEM, Version 1.60). The failure evolution of the landslide was investigated; then, the deformation behavior and dynamic characteristics of the landslide were systematically studied. The analyses of the failure process, velocity, displacement, and heat showed that the evolution of the landslide could be divided into the stages of initial deformation, accelerated deformation, and deceleration and stabilization. During the movement of the landslide, the gravitational potential energy of the landslide gradually converted into kinetic energy, heat, and elastic potential energy. The kinetic energy in the initial stage was small but rapidly increased and occupied the dominant position in the second stage. The kinetic energy gradually decreased and tended to be stable in the third stage. The final geometry and accumulation characteristics of the landslide obtained by numerical simulation were consistent with the corresponding field investigation and remote sensing interpretation. This work can provide a reference for the study of the evolution and prevention of open-pit mine landslides.

Intelligent tunnelling robot system for deep-buried long tunnels

Existing tunnel boring machine (TBM) construction presents certain shortcomings. These include difficulty in comprehensive perception of information, poor timelines of information transmission and storage systems, significant effects of traditional data processing methods on the timeless of intelligent decision-making, and poor applicability of decision-making models and control strategies. In addition, the integration level of perception, decision-making, and control should be further improved. Therefore, a cross-platform deployable intelligent tunnelling robot system with closed-loop intelligent control functions of a “comprehensive perception, dual-driven decision-making, and composite intelligent control” is developed. Based on fieldbus, communication, database, cloud computing, and advanced exploration technologies, a multi-source information perception and integrated management platform based on a two-layer architecture is built to achieve the comprehensive perception of tunnelling information. In addition, an optimal decision-making method of the particle swarm optimisation (PSO) algorithm is simultaneously proposed for the minimum decision-making of tunnelling specific energy for scientific analyses and decision-making. A composite intelligent control strategy comprising multimodal and expert experienced learning control strategies is designed to achieve the control of conventional and unfavourable geological sections, respectively. Engineering cases verified the effectiveness and reliability of the intelligent tunnelling robot system. The research results not only provide new ideas and technical means for achieving the less-manned, unmanned, and intelligent tunnelling construction of deep-buried long tunnels but can also be promoted owing to its universality.

Anomalous position of Paleozoic faults of Western Donbas

Statement of the general problem. The oil and gas-bearing province of Eastern Ukraine is located in the Dnipro-Donetsk Basin (DDB). It covers the Paleozoic structural floor and is buried under younger sediments. The Paleozoic structural floor of the territory is represented as a long rift graben. The maximum thickness of the sedimentary cover in the graben is 15–17 km. According to geophysical data, the thickness of the earth's crust is 31–32 km under the axial part of the DDB and increases towards the sides. But according to the maximum thickness and facies characteristics of the Paleozoic deposits, the thickness of the Earth's crust below them could not exceed 20 km. The modern thickness is 1.5 times higher. Therefore, such a geological-geophysical model of the structure of the DDB is contradictory. Analysis of recent research and publications. The removal of the contradiction is possible due to the detection of a series of Hercynian thrusts with total amplitude of thrusts of the order of 50 km. Such thrusts began to be established on the northern and southern flanks of the DDB. Hercynian thrusts have a southwestern vergence. In the north, the Voronezh crystalline massif is pushed onto the DDB along the Noviy thrust with an amplitude of 9–10 km. In the south, the South Donbas melange zone is established, which pushes the folded Donbas onto the Ukrainian shield. On its continuation to the northwest is the southern side of the DDB - the so-called Southern monocline. The well-studied Pavlograd-Petropavlovsk coal mining district of Western Donbass with operating coal mines is located within its borders. An unsolved part of the overall problem. Numerous faults with relatively small amplitudes are established within the Paleozoic Southern Monocline. Together, they form a system of horsts and grabens with a north-western extension. But the bottom parts of the grabens are 1–3 km higher than the tops of the horsts. Such a geological situation is anomalous. This indicates the post-fault dislocation of the horst-graben system as a whole. The purpose of the article is identification of the causes of the anomalous structural position of the graben-horst system in the modern geological structure of the Southern Monocline and in the general model of the geological structure of Eastern Ukraine. Research materials and methods. Were involved more than 390 geological sections, constructed based on the data of more than 10,000 wells. Of them, 265 wells revealed the folds that are being analyzed. In addition, were used data of catagenetic transformations of the sedimentary section. Presentation of the main research material. The South Donbas mélange zone falls to the northeast and continues under the Southern Monocline. It is located in the upper block of this regional thrust structure and is in an allochthonous setting. According to geological data, the true amplitude of the thrust of Western Donbas on the Ukrainian shield is 15–20 km, and the vertical component of this amplitude exceeds 3 km. Such spatial parameters explain the abnormality of the structural position of the horsts and grabens of Western Donbass - their southwestern flanks were significantly raised relative to the northeastern flanks during thrusting. Scientific novelty. Therefore, in the modern geological structure, the Dnipro-Donetsk "basin" is not a rift, but a post-rift Hercynian folded region. It is formed by high-amplitude thrusts on the northern and southern flanks. The Hercynian fold region is buried under Mesozoic and Cenozoic sediments and is further complicated by Laramian and Attic fold-thrust dislocations of lesser intensity. Conclusions. The thrust model brings the geophysical parameters into the correspondence with the geological data and is confirmed by the actual material.

APPLICATION OF PHASE-ENERGY ANALYSIS OF SEISMIC WAVES FOR GEOLOGICAL SECTION PREDICTION

Link for citation: Kochegurov A.I., Kochegurova E.A., Orlov O.V. Application of phase-energy analysis of seismic waves for geological section prediction. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.54-62.In Rus. Relevance. One of the main tasks in predicting a geological section is the task of determining the type of the section and mapping types over the area under study, as well as assessing the absorbing and dispersive properties of geological media. To solve these problems, specialized software-algorithmic complexes for processing and interpreting seismic data are currently widely used. In most modern complexes for forecasting a geological section, the information extracted from the kinematic and dynamic characteristics of seismic waves is used. Based on the information received and the data on the geophysical survey of wells, ideas are formed about the material composition of sediments, the presence of productive strata in the study area. This approach made it possible in a number of regions of Russia, including Western Siberia, to obtain interesting and important results related to the discovery of productive sedimentary strata and the assessment of their oil and gas content, which was confirmed by practice. At the same time, the results of practical activities have shown that when conducting studies of many areas, there are areas where the percentage of identifying false anomalies in geological environments and making erroneous decisions in the forecast is still quite large. This is due, among other things, to the fact that in the analysis of the recorded seismic field, for predicting geological section, the energy characteristics of the reflected waves are mainly used, and changes in the phase spectra are practically not taken into account. Thus, the integrated use of the characteristics of reflected seismic waves (amplitude and phase) in the prediction of a geological section is a very urgent task. The aim of the work is to carry out phase-energy analysis for various models of seismic fields based on the method of phase-frequency deconvolution for predicting the geological section. Methods: computational experiment, inverse filtering, discrete Fourier transform. Results. The authors developed the algorithm for phase-energy analysis of seismic waves, which is based on the results of phase-frequency deconvolution. The algorithm was studied on various models of geological environments, and phase-energy sections were constructed, which make it possible to identify zones with anomalously low energy values for subsequent oil and gas potential diagnostics. The paper introduces the example of constructing a phase-energy section based on real data in the interval of Upper Jurassic deposits.

RESULTS OF STUDYING THE PLEISTOCENE IN THE VILGORT SECTION (CHERDYN DISTRICT, PERM TERRITORY)

Link for citation: Plyusnin A.V., Sulima A.I., Marinov V.A., Vdovichenko S.I., SamodurovS.A. Results of studying the Pleistocene in the Vilgort section (Cherdyn district, Perm territory). Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.148-158.In Rus. The relevance. The study of glacial deposits, which is one of the main components of most continental sedimentary formations of all ages, makes it possible to identify the features of its structure and formation, as well as to establish the facies-genetic confinement. This is especially true for Quaternary geology, since makes it possible to carry out stratigraphic comparisons and identify paleogeographic settings for the formation of deposits. This paper presents the results of a comprehensive lithological and biostratigraphic study of the Vilgort section of the Kolva river valley, Cherdyn district of the Perm Territory. The main aim of the research is to study the geological section and substantiation of the age of the Mesozoic deposits according to the fauna complex. Objects: continental deposits of the Middle Pleistocene, exposed in the right side of the river Kolva. The deposits of this region are poorly studied. References are sown in the literature about the Mesozoic fauna found in the Vilgort section. Methods: geomapping, layered lithological description, layer-by-layer sampling, biostratigraphic studies. Results. These studies made it possible to carry out a detailed layer-by-layer description and stratigraphic subdivision of the Vilgort section. The Permian carbonate deposits are overlain by eluvial-deluvial deposits of the Likhvin horizon, they are overlain first by lacustrine-glacial, and then by glacial deposits of the Dnieper horizon of the middle Pleistocene with erratic blocks of Mesozoic repeatedly redeposited terrigenous rocks. Due to the neotectonic activity of the right-bank block part of the Vilgort area, which underwent uplift in the Late Pleistocene, most of the Upper Pleistocene deposits were eroded, which explains the stratigraphic unconformity, when modern deposits lie on glacial deposits of the Middle Pleistocene. According to the results of micropaleontological studies, foraminifers were identified from samples taken in the fifth layer: the Middle Volgian substage of the Volgian stage (sample 1); distributed in the interval of the Ryazanian Stage of the Lower Cretaceous (sample 3) and the middle and upper substages of the Volgian Stage (sample 4).

Application of a Modular Dynamic Formation Tester on a Wire Line to Refine the Filtration Characteristics of the Production Formations of the Magovsky Oil and Gas Condensate Field

An important task in monitoring the development of hydrocarbon fields is to obtain data on the filtration characteristics of reservoirs and the properties of fluids in reservoir conditions. When using standard logging in the complicated conditions of low-permeability formations, poorly consolidated rocks and eroded wellbores, it is very difficult to perform reservoir pressure measurements, sampling with a detailed analysis of fluid properties. A study was carried out in order to clarify the filtration properties of the rocks of the geological section by the method of hydrodynamic logging with testing of the formations by a tester on a MDT logging cable (modular dynamic tester). This problem was solved using the example of carbonate production formations of the Magovskoye oil and gas condensate field, which are generally characterized by a complex heterogeneous structure. An analysis of the effectiveness of using a modular dynamic reservoir tester made it possible to clarify the boundaries of permeable rock intervals with an assessment of their saturation. At the same time, working intervals of the geological section were established, which, with standard logging, were interpreted as dense rocks.

CURRENT STATUS AND WAYS TO IMPROVE THE EFFICIENCY OF THE DEVELOPMENT OF "KALMAZ" UNDERGROUND GAS STORAGE FACILITIES (UGSF)

Geological structure of the "Kalmaz" oil and gas field, that is being studied since 1930, is located 100 km south-west of Baku, in the north-eastern part of the lower Kura depression. Information on geological structure, stratigraphy, tectonics, oil and gas content of the field etc. has been collected as a result of the search and exploration works carried out and structural and research wells drilled. The "Kalmaz" field was formed from the brachianticlinal fold with south-east direction from north-west. The structure is divided into separate blocks by tectonic faults, and the blocks are not interconnected. Data on stratigraphic affiliation, lithology and thickness of stratigraphic units of sediments participating in the geological section of the site were obtained on the basis of deep wells drilled here. Upper Miocene-Pont, Pliocene and Quaternary sediments are involved in the geological section of the site. Tectonically, Kalmaz brachianticlinal is located in the north-eastern part of the lower Kura depression, over the Kalameddin-Bandovan anticline zone, between Mishovdag in the West and Khidirli folding in the East. The Kalmaz structure is mainly stretched in the north-west – south-east direction, however in the western part the axis of elongation of the structure takes a close direction to the latitude circle. The structure is asymmetrical. North-east wing is upright (lying angle is 35-400) and short, the south-west wing is relatively low-leaved (22-300) and being extensive passes to the south-east Shirvan syncline. The geological aspects of the structure was complicated by a fault that cuts its elongation at a certain angle. In the western part, tectonic fault passes through the north-east wing of the structure and through the south-west wing in the eastern part. As a result of the change in the direction of the axis of the fault structure, which is being talked about, cuts off the north-eastern wing in the western part, almost perpendicular to its lengthway and passes to the neighboring Navahi syncline. As a result of the fracture, the north-eastern wing of the Kalmaz structure and the south-western pericline were broken and dropped due to other parts of the fold. It's worth to note, that the Kalmaz structure has a very complex structure. This is also denoted by the Kalmaz mud volcano located in the central part of the fold. Despite the study of the geological aspects of the site by various methods and the numerous wells drilled here, its deep tectonics and connection with neighboring Mishovdagh and Khidirli structures have not been sufficiently studied. Numerous natural oil and gas manifestations are found in the site due to mud volcano springs. The mud volcano, located in the arch part of the fold, is related to a disruption that cuts its north-east wing. There is an active oil and gas flow from the mud springs arranged on a line in the direction of this disruption. Gas discharge related to Absheron sediments was detected in the structural mapping wells No. 39, 40, 41, 42, 44, 46 drilled on this strip. In most of these wells, the gas discharge passed into the gas fountain and lasted for a long time. 40000 m3/day gas and oil was obtained from the bottom Absheron sediments in the search well No. 87/2 located in the research site. In the well No. 15, drilled in a tectonic block in the south-eastern part of the fold, oil with a daily output of 38-39 t was obtained from the IV horizon of the productive layer (PL). Gas with daily production of 22 200 thousand m3 was obtained from the upper horizon of the PL in the search and operation well No. 22, and of 180 thousand m3 was obtained from the IV horizon of the PL in the well No. 40. As a result of research and exploration drilling, the I, II, III, IV, V, VI horizons of Kalmaz site have been proven to contain oil and gas. These facts show that the Kalmaz site has great oil and gas prospects. It should be noted that the presence of rich oil and gas underground gas storage facilitiess in the not yet opened and insufficiently studied lower horizons of the productive layer is beyond doubt. For this reason, information on geological study, stratigraphy, oil and gas characteristics, development, well fund of Kalmaz field, the first underground gas storage facilities in Azerbaijan, was analyzed in the article and due to the fact that a number of problems arose during the joint exploitation of wells, it was proposed to develop the well by dividing it into horizons. Keywords: gas, underground gas storage facilities, horizon, well, gas injection.

Sedimentary Evolution and Geological Characteristics of the Jurassic in the South Qiangtang Basin, China

Based on the analysis of lithology, lithofacies combinations, sedimentary structures, and fossil types in five geological sections measured through fieldwork, this paper comprehensively elucidates the sedimentary evolution characteristics of the Jurassic period in the South Qiangtang area. The South Qiangtang Basin is renowned for preserving the most complete Jurassic marine sedimentary strata in China, and it primarily consists of a mixed platform environment of carbonate and clastic rocks. The Jurassic strata in the South Qiangtang Basin range from the Quse Formation at the base to the Suowa Formation at the summit, with sedimentary facies evolving from the outer shelf to the subtidal zone, and seawater depth gradually becoming shallower. This trend may be associated with the division and expansion of the Bangong–Nujiang suture zone during the Late Triassic, subduction in the Middle Jurassic, and the suture and splicing of the Qiangtang–Lhasa plate during the Late Jurassic tectonic movements. In conclusion, this research presents a comprehensive analysis of the sedimentary evolution of the Jurassic period in the South Qiangtang Basin for the first time. The findings offer significant contributions to the understanding of the region’s geological history and serve as a valuable foundation for future investigations.

Joint Inversion of Geodetic and Strong Motion Data for the 2012, Mw 6.1–6.0, May 20th and May 29th, Northern Italy Earthquakes: Source Models and Seismotectonic Interpretation

AbstractWe present the first rupture models of the two mainshocks of the 2012 northern Italy sequence, determined by jointly inverting seismic and geodetic data. We aim at providing new insights into the mainshocks for which contrasting seismotectonic interpretations are proposed in literature. Sources' geometric parameters were constrained by seismic reflection profiles, 3‐D relocations and focal mechanisms of mainshocks/aftershocks. Site‐specific velocity profiles were used to model accelerograms affected by strong propagation effects related to the Po basin. Our source models differ significantly from previous ones relying on either seismic or geodetic data. Their comparison against geological sections and aftershock distribution provides new insights about the ruptured thrust faults. The May 20th Mw6.1 mainshock activated the Middle Ferrara thrust‐ramp dipping ∼45° SSW‐wards, breaking a main eastern slip patch 4–15 km deep in Mesozoic carbonates (maximum slip 0.7–0.8 m) and Paleozoic‐Triassic basement rocks, and a small western patch in the basement. The May 29th Mw6.0 mainshock featured two separated asperities along the Mirandola thrust‐ramp dipping ∼42° S‐wards: an eastern asperity 4–15 km deep in Mesozoic carbonates and basement rocks (maximum slip 0.7 m) and a deeper western one (7–16 km depth) mainly in the basement (slip peak 0.8 m). On‐fault aftershocks were concentrated within the basement and Mesozoic carbonates, devoiding high‐slip zones. Slip and aftershock distribution was controlled by the rheological transition between Mesozoic carbonates and Cenozoic sediments. Unlike previous thin‐skinned tectonic interpretations, our results point to a complex rupture process along moderately dipping (40°–45°) thrust‐ramps deeply rooted into the Paleozoic crystalline basement.

A Three-Dimensional Geological Model of the R’Mel Aquifer, Northwestern Morocco

One of the challenges of 3D geological modelling is the spatial representation of heterogeneous sedimentary rocks. The R’Mel coastal basin located in northwestern Morocco is a very suitable area for the modelling of sedimentary rock formations. This basin is part of the external Pre-Rif area and is composed of rocks of Miocene to Quaternary age (principally sand, marl, sandstone, silt, and alluvia). Due to the impact of climate change, any increase in the abstraction of groundwater can accentuate its vulnerability to marine water intrusion. Therefore, understanding of geometry of this aquifer is so important. To achieve this, a 3D geological model was developed to determine the different HydroGeological Units (HGUs) of the R’Mel aquifer. The processing and the construction of a GIS database including a detailed geological map, 125 boreholes, and 50 vertical electrical soundings (VESs), as well as the development of five geological cross-sections, helped build this model using 3D modelling software. The model provides a detailed visualization of the spatial distribution of the eight HGUs. HGUs 3 and 6 consist of marly-clayey lenses and five HGUs of Plio-Quaternary age are composed of: sand or/and sandstone (HGU 1), calcarenites and lumachelles (HGU 2), sandstone and/or shelly marine sand (HGU 4), gravel with a sandy-clayey matrix (HGU 5), and shelly sandstone and gravelly sand (HGU 7). The eighth layer (HGU 8) is composed of marls and clays of Miocene age. The generation of several geological sections from the model made it possible to identify anticlines, synclines and faults trending NNW–SSE and NNE–SSW. Theses, support the tectonics of the Gharb basin during the Mio-Plio-Quaternary. Finally, a conceptual model of the R’Mel aquifer was developed.

3-D imaging of the Balmuccia peridotite body (Ivrea–Verbano zone, NW-Italy) using controlled source seismic data

SUMMARY We provide new results from a controlled-source seismic experiment on the deepest part of the Val Sesia crust–mantle section of the Ivrea–Verbano zone (IVZ) in the Italian Alps. The IVZ is a tilted, almost complete section through the continental crust and exposes gabbros and peridotites in the structurally deepest level, coinciding with high-resolution gravity anomalies imaging the Ivrea geophysical body. The seismic experiment SEIZE (SEismic imaging of the Ivrea ZonE) was conducted along two crossing profiles: an NNE-SSW profile of ∼11 km length and an E-W profile of ∼16 km length. 432 vibration points were recorded with 110 receivers resulting in 24 392 traveltime picks. Inversion methods using Markov chain Monte Carlo techniques have been used to derive an isotropic 3-D P-wave velocity model based on first break traveltimes (refracted phases) from controlled source seismic data. Resulting seismic P-wave velocities (Vp ) range from 4.5 to 7.5 km s−1, with an expected general trend of increasing velocities with depth. A sharp velocity change from low Vp in the West to high Vp in the East marks the Insubric Zone (ISZ), the Europe–Adria plate boundary. The most prominent feature of the 3-D tomography model is a high-velocity body (Vp increases from 6 to 7.5 km s−1) that broadens downwards. Its pointy shape peaks the surface East of Balmuccia at a location coincident with the exposed Balmuccia peridotite. Considering rock physics, high-resolution gravity and other geophysical data, we interpret this high-velocity body as dominantly composed of peridotite. The dimension of this seismically imaged peridotite material is far bigger than interpreted from geological cross-sections and requires a revision of previous models. The interpretation of ultramafic bodies in the IVZ as fragments of mantle peridotites interfingered in the crust during pre-Permian accretion is not supported by the new data. Instead, we revive a model that the contact between the Balmuccia peridotite and the Permian mafic magmas might represent a fossil continental crust–mantle transition zone.

Instrumental monitoring for the location of endogenous fires in the coal mine wall

Introduction. Endogenous fire is a fire initiated by the process of self-ignition of coal. Detection of this type of fire is carried out visually by fire and smoke or by the results of temperature, gas or geophysical control. The occurrence of endogenous fires in coal mines leads to serious consequences, such as pollution of the environment and deterioration of sanitary and hygienic working conditions. It also leads to economic losses due to the suspension of technological processes and burnout of coal reserves. The prevention of endogenous fires includes measures to prevent the possible development of self-ignition processes in the identified areas of potential fire hazard. Research objective is to investigate areas of fire in active coal mines in order to determine the center of the profile of geophysical sounding, as close as possible to the epicenter of endogenous fire, to perform its binding to the mine plan and geological section. Methods of research. In order to achieve this goal, it is necessary to carry out a visual inspection of the areas of fire, to take photographs, as well as to carry out a thermal imaging survey with specialized equipment. Results. The results of photo- and thermal imaging surveys were recorded, the assessment of mining and geological conditions of formation of endogenous fires was carried out, and plans of the location of endogenous fires were presented. Conclusions and scope of results. After implementation of measures on inspection and survey in areas close to the centers of endogenous fires, as well as analysis of the results, we can conclude that direct visual inspections and thermal imaging measurements do not allow to fully determine the boundaries of fire zones in plan and depth. This is due to the fact that noticeable temperature anomalies are recorded only when the focus is directly on the ground surface due to the low thermal conductivity of coal and host rocks.

Fast stratification of geological cross-section from CPT results with missing data using multitask and modified Bayesian compressive sensing

Since cone penetration test (CPT) is reasonably rapid, affordable, and repeatable, it has been widely used in situ for subsurface soil stratification and classification in geological and geotechnical engineering practice. When used for soil stratification across a 2D geological cross-section, however, it is often observed that some CPTs probe deeper than others, and that some CPT soundings may contain missing data due to presence of gravel-sized particles or intentional bypassing of gravelly soil layers. Arguments above and frequently encountered problem of a small number of CPT soundings in practice pose a great challenge for 2D soil stratification, especially for nonstationary CPT within multilayers. While certain methods have been proposed hoping to address these concerns, they are frequently constrained by either stationary assumption of data, autocorrelation function forms, or computational issues. This study introduces a data-driven multitask Bayesian compressive sensing (MT-BCS) method to estimate missing data for CPT sounding of interest, and then develops a modified 2D BCS method for fast interpolation for horizontal locations without CPT soundings. The proposed method is demonstrated and validated using both numerical and real-world CPT data. Results show that proposed method is both efficient and robust in terms of missing data estimation in each CPT sounding and soil stratification for a 2D geological cross-section.

Comparative Analysis of Application of Seismic Wave Reflection Method in Advanced Geological Prediction

Seismic wave reflection method is an advanced geophysical detection method in tunnel geological prediction. It is more sensitive and effective in detecting geological anomalies such as fault fracture zone and karst. In order to verify the prediction efficacy and accuracy of the seismic wave reflection method with different instruments and equipment (tunnel geological prediction [TGP]/tunnel seismic prediction [TSP]) and different vibration modes (hammering, explosives), a comparison test was carried out in Jinping Tunnel. The test results showed that the time-consumption of the hammering source was short, which can greatly reduce the impact on the construction site; different vibration sources methods of seismic wave reflection can predict the unfavorable geological sections accurately.