Geological Properties Research Articles

Excavatability Classification of Rocks around Haroglu Mountain in Northeast of Baskil in Elazig According to Engineering Geology Properties

Knowledge of the geology of the ground to be excavated in surface mines and foundations, especially in civil engineering works, is very important to decide on the appropriate excavation method and equipment and ensure human and equipment safety with time and cost savings. For this purpose, the engineering geological properties and excavatability classification of rocks around the Haroglu Mountain located in the northeast of Baskil in Elazig were studied. The research started with a desktop study and then continued with a walkover, the determination, and mapping of lithostratigraphic units outcropping in this study area. Yuksekova Formation, Kuscular Formation, Seske Formation, Kirkgecit Formation, and surficial deposits are the lithostratigraphic units in order of occurrence from old to young. Yuksekova Formation, the oldest unit between them, makes up of a group of plutonic, hypabyssal, volcanic, and pyroclastic rocks. After Yuksekova Formation occurs which is magmatic, the sedimentary sequence begins to form with Middle Paleocene-aged rocks. Sedimentary rocks are divided into three formations according to their stratigraphic properties. In order of occurrence from old to young, these sedimentary formations are composed of Kuscular conglomerate, Seske Formation, Kirkgecit Formation. Also, surficial deposits as the youngest unit are formed occasionally over other formations. The structural geological properties of the formations, one of the most important parameters of the excavability, were mapped. The set number, roughness, magnitude of the angle of dip, azimuth of strike or dip of discontinuities or joints, and the block volume are the significant parameters that are influenced excavatability. The azimuths of strikes of discontinuities were measured and carried out the rose diagrams from them. As a result of these measurements, the discontinuities or fractures in Yuksekova Formation have been usually found in the azimuth of a strike having NNE and a 45-90 SW of angle and azimuth of dip. It was determined that the orientation of K60W of excavation is the orientation of a very favorable excavation based on the discontinuity attitudes in the study area. It was established that the orientation of a very unfavorable excavation also is in the azimuth of the strike of fracture, namely N30E. Excavatability of the rocks was determined by assessment of lower and upper discontinuity spacing index and point load strength values. Yuksekova Formation requires methods that can be excavated from very hard to extremely hard ripping (D 9)–blasting by taking into consideration formations exposed in the study area. Kuscular Formation can be excavated by methods of easy ripping (D 6-D 7) to hard ripping (D 8) and Seske Formation also easy ripping (D 6-D 7)-very hard ripping (D 9). Kirkgecit Formation has the capabilities of being excavated by methods of hard digging (CAT 245) to very hard ripping (D 9). As a result of this study, the order of excavatability as the rocks from hard to easy can be expressed as the micro-diorite, granite, andesite, and diorite of Yuksekova Formation, the conglomerate of Kırkgecit Formation and the conglomerate of Kuscular Formation. Finally, the limestone and shale of Kirkgecit Formation would be also excavated the easiest respectively. Additionally, it has been revealed that surficial deposits can be also excavated optimally by easy digging method. Keywords: blasting, digging, discontinuity spacing index, excavatability, formation, ripping, DOI: 10.7176/JSTR/7-02-03

Introduction to this special section: Basin exploration

Originally, explorers relied on hydrocarbon seeps and 2D seismic lines to define a basin's petroleum potential and to identify its best part. Due to dramatic improvements in seismic technology, today's explorers have access to a vast seismic tool kit, from basin-scale regional 3D seismic surveys to neural network techniques that directly derive reservoir properties from seismic volumes. However, in frontier or mature exploration, geoscientists are often limited by the amount of well data and rock properties information available, and they may deal with poor(er) seismic that makes seismic calibration difficult. Successful explorers will require a lot of knowledge-based creativity to derive meaningful geologic and reservoir properties models to reduce exploration risk. By embracing uncertainties, explorers develop “outside-the-box” thinking to help them chase the hydrocarbon molecules and unlock the prize. With their knowledge in rock physics, subsurface deformation, and wave propagation, geoscientists are deploying new methodologies and tools to fill the data gap and produce an improved description of the subsurface.

Creating Forecast Maps of the Spatial Distribution of Dangerous Geodynamic Phenomena Based on the Principal Component Method

Subject matter of the research is mining and geological subsurface objects use in the conditions of the DGDE possibility. Scope of research is the regularities of spatial distribution of geological objects properties, causing DGDE in the mining enterprise. The purpose of research is to map the mining enterprise territory subject to DGDE using the method of objective determination of weight coefficients and influencing factors. The main tasks: establish the size of the operational territorial units (OTU) and discretization of the research area; determination of the weight coefficients of the factors influencing the process of the DGDE occurrence formation on the subsurface territory; create a mathematical expression for a generalizing value determining that characterizes the degree of adverse factors coincidence, and therefore the risk rank of the DGDE occurrence.

Rescaling Method for Improved Machine-Learning Decline Curve Analysis for Unconventional Reservoirs

Summary Decline curve analysis (DCA) has been widely applied in production forecasting of wells in unconventional hydrocarbon reservoirs. However, traditional curve-fit-based methods fall short of forecast accuracy due to three weaknesses: first, they cannot capture the reservoir signals not modeled by the underlying DCA model formulas; second, when predicting the production of a target well, the production history of other wells in the geologic formation (which is valuable information) is not considered; third, the wells’ geographic, geologic, wellbore, well spacing, and completion properties, which are highly relevant to production capability, are not used. More recent approaches have begun replacing traditional DCA with machine-learning methods [e.g., random forest (RF), support vector regression (SVR), etc.] for production forecast. Nevertheless, these methods are still suboptimal in detecting similar production trends in different wells, leading to large forecast error. A new and simple method called dynamic production rescaling (DPR) is developed to improve the accuracy of machine-learning DCA (ML-DCA). By combining DPR with common ML-DCA methods, we observe that the error mean, deviation, and skewness can be significantly reduced by 15 to 35% compared with ML-DCA without DPR. The error reduction is 30 to 60% compared with automatic curve fit of the traditional modified Arps DCA model. DPR has been tested successfully on monthly production data of over 20,000 unconventional horizontal wells in the Permian and Appalachian basins for both long- and short-term forecasts. The significant error reduction is consistent across different basins and formations. DPR is computationally efficient, so a large number of wells can be analyzed automatically and quickly. Moreover, the effectiveness and efficiency of DPR is independent of the underlying machine-learning algorithm, further demonstrating its robustness.

Forecasting Landslides Using Mobility Functions: A Case Study from Idukki District, India

Catastrophic landslides and associated destructions are increasing every year, because of the change in climatic conditions and land-use patterns. The ecologically sensitive zones of Western Ghats are highly susceptible to landslides and require scientific attention in developing an efficient early warning system. Definition of empirical rainfall thresholds on local, regional or global scales is the most commonly followed method of forecasting rainfall induced landslides. The limitations associated with such thresholds demands for better forecasting performance, incorporating the effect of physical processes in the initiation of landslides. This study is an attempt to forecast landslides in Idukki district, using mobility functions. The function separates the impossible and certain mobilisation parts and forecasts whether landslides can occur or not. Based on the critical value of mobility function, two different warning levels are proposed for four different reference areas in the district. The study shows that the model is 97% efficient in smaller areas with uniform topographical and geological conditions, and the performance is reduced as the area becomes larger, with varying topographical and geological properties. The model proves to be an effective landslide forecasting tool that can be integrated with a rainfall forecasting system, to develop an early warning system for the region.

Evaluating the influence of engineering geological parameters on TBM performance during grinding process in limestone strata

The chipping and grinding processes are the basis for understanding rock cutting during TBM excavation in hard rock conditions. The chips are produced when tensile fractures created by adjacent cutters propagate parallel to the tunnel face and coalesce whereas grinding occurs when fractures do not fully propagate through the rock and only fines are generated. Chipping is the normal and efficient boring process using machines equipped with disc cutters. Consequently, almost all of the models proposed for predicting the TBM penetration have been developed by the assumption that chipping is the dominant mode. It is obvious that these models are unable to predict correctly TBM performance when grinding is dominated in the rock cutting process. In this study, the relationships between engineering geological properties of the rock units (Cretaceous limestones) and operating and performance parameters of a refurbished EPB-TBM, employed for completion of SEL6 (the Southern Extension of Line 6, Tehran Metro) tunnel, were evaluated and analyzed. In this project due to limitations in the load capacity of the employed cutters and insufficient initial penetration in rock, the excavation was mostly carried out on grinding-dominated mode. So, the suitable data for establishing a special database and consequent analyses were provided. The established database composed of actual operating and performance parameters of the machine (i.e., cutterhead penetration and RPM and cutter load) and also engineering geological properties (i.e., UCS, alpha angle, GSI, and RQD) of limestone strata. Finally, by statistical analyses performed on collected and screened data (41 data sets), some simple, site-specific, empirical equations were developed to predict the TBM performance on grinding mode. In addition, according to the multivariate regression method, a significant relationship between the cutterhead penetration (PRev), the cutter load (Fn), intact rock strength (UCS), and geological strength index (GSI) was established, statistically. The obtained results demonstrate that this engineering geological-based model could provide a new applicable equation for accurately predicting TBM performance for similar geological conditions where grinding is dominant.

Uncertainty quantification for uranium production in mining exploitation by In Situ Recovery

Uranium In Situ Recovery (ISR) is based on the direct leaching of the uranium ore in the deposit by a mining solution. Fluid flow and geochemical reaction in the reservoir are difficult to predict due to geological, petrophysical and geochemical uncertainties. The reactive transport simulation code used to model ISR is very sensitive to the spatial distribution of physical and chemical properties of the deposit. Stochastic geostatistical models are used to represent the uncertainty on the spatial distribution of geological properties. The direct propagation of geological uncertainties by multiple ISR mining simulations is intractable in an industrial context. The CPU time needed to perform one ISR numerical simulation is too heavy. This work presents a way to propagate geological uncertainties into uranium production uncertainties at a reduced computational cost, thanks to a scenario reduction method. A subset of geostatistical simulations is built to approximate the variability of a larger set. The selection is obtained using a proxy of reactive transport simulation. The main contribution of this work is the development of the proxy, which is based on an artificial mineral exploitation that has common properties with uraninite. It allows the discrimination of geostatistical realizations in terms of potential uranium production. Then, the ISR simulation carried out with the selected geostatistical realizations gives a good approximation of the uranium production variability over the whole set of geostatistical simulations. This approximation is then used to quantify the uncertainties on the uranium production. The proposed approach is assessed on real case studies.

Grain size variation in two lakes from margin of Asian Summer Monsoon and its paleoclimate implications

A wealth of research has demonstrated that polymodal grain/particle size distributions (GSD or PSD) in lake sediments can be mathematically decomposed to serve as a more precise tool for paleoenvironmental reconstructions. However, linking grain size subcomponents to specific environmental parameters is sometimes ambiguous, as grain size in lake sediments depends on local characteristics of individual lakes. In view of this, illustrative case studies with widespread practical significance are needed. Here, GSD datasets of two lake sediments from the Asian Summer Monsoon (ASM) marginal zone were decomposed and compared with nearby surficial lacustrine/eolian sediments with clear geological origins, to study the dominant sedimentary processes-grain size regimes of these two representative lakes. The decomposition and comparison clarify the geologic properties of certain grain size parameters and minimizes extraneous signals. Based on this information, we interpret certain size fractions as regional climate indicators associated with ASM intensity changes. We also consider centennial-timescale climate variability during the last half of the Holocene, and discuss the driving forces controlling centennial moisture variability in the studied area.

Estimating Watershed Subsurface Permeability From Stream Discharge Data Using Deep Neural Networks

Subsurface permeability is a key parameter in watershed models that controls the contribution from the subsurface flow to stream flows. Since the permeability is difficult and expensive to measure directly at the spatial extent and resolution required by fully distributed watershed models, estimation through inverse modeling has had a long history in subsurface hydrology. The wide availability of stream surface flow data, compared to groundwater monitoring data, provides a new data source to infer soil and geologic properties using integrated surface and subsurface hydrologic models. As most of the existing methods have shown difficulty in dealing with highly nonlinear inverse problems, we explore the use of deep neural networks for inversion owing to their successes in mapping complex, highly nonlinear relationships. We train various deep neural network (DNN) models with different architectures to predict subsurface permeability from stream discharge hydrograph at the watershed outlet. The training data are obtained from ensemble simulations of hydrographs corresponding to an permeability ensemble using a fully-distributed, integrated surface-subsurface hydrologic model. The trained model is then applied to estimate the permeability of the real watershed using its observed hydrograph at the outlet. Our study demonstrates that the permeabilities of the soil and geologic facies that make significant contributions to the outlet discharge can be more accurately estimated from the discharge data. Their estimations are also more robust with observation errors. Compared to the traditional ensemble smoother method, DNNs show stronger performance in capturing the nonlinear relationship between permeability and stream hydrograph to accurately estimate permeability. Our study sheds new light on the value of the emerging deep learning methods in assisting integrated watershed modeling by improving parameter estimation, which will eventually reduce the uncertainty in predictive watershed models.

Land use, geology and soil properties control nutrient concentrations in headwater streams

Nutrient losses from headwater catchments (<50 km2) cause eutrophication problems downstream. Catchment properties are strongly reflected in the levels of nutrient concentrations in headwater streams. Based on measurements of total and dissolved nitrogen (TN, DN) and phosphorus (TP, DP) in 235 small headwater streams, we showed that proportion of arable land in a catchment had the strongest positive effect on nutrient concentrations, with coefficient of determination (R2) of 0.54, 0.64, 0.45, and 0.51 for TN, DN, TP, and DP, respectively. In contrast, increased proportion of forest and wetland led to lower nutrient concentrations in streams. The geological composition of catchments had a major influence on the soil properties. In turn, certain soil properties, such as clay content and content of aluminum (Al), an important binding agent of P, influenced losses of particulate P (PP) and DP, respectively. Consequently, by using soil properties as a link between geology and water quality, areas potentially sensitive to nutrient losses were identified by classifying bedrock categories into three geological groups. Approximately 25% of Swedish arable land was identified as potentially sensitive. Sensitive catchments were found in regions with sedimentary bedrock and showed higher concentrations of dissolved nutrient fractions even when the proportion of agricultural land was small, indicating higher background concentrations.

Scientific and methodological basic principles for determining design of clay acid treatments applied to wells

A new methodological approach is presented in determining design of current clay acid treatments of wells. The proposed scientific and methodological approach allows differentiating for different groups of objects in the Langepass region to determine certain technological parameters of impact on the bottom hole zone of formations, taking into account the features of geological and physical properties of formations and fluids saturating them. In special cases, it is suggested to use acid retarders for reaction with rock. The authors proposed algorithm for determining wells where the maximum effect can be obtained at a specific time.

An Adaptive Inverse-Distance Weighting Interpolation Method Considering Spatial Differentiation in 3D Geological Modeling

The inverse-distance weighting interpolation is widely used in 3D geological modeling and directly affects the accuracy of models. With the development of “smart” or “intelligent” geology, classical inverse-distance weighting interpolation cannot meet the accuracy, reliability, and efficiency requirements of large-scale 3D geological models in these fields. Although the improved inverse-distance weighting interpolation can basically meet the requirements of accuracy and reliability, it cannot meet the requirements of efficiency at the same time. In response to these limitations, the adaptive inverse-distance weighting interpolation method based on geological attribute spatial differentiation and geological attribute feature adaptation was proposed. This method takes into account the spatial differentiation of geological attributes to improve the accuracy and considers the first-order neighborhood selection strategy to adaptively improve efficiency to meet above requirements of large-scale geological modeling. The proposed method was applied to an area in eastern China, and the results of the proposed method, compared to the results of classical inverse-distance weighting interpolation and improved inverse-distance weighting interpolation, suggest that the problems encountered above in large-scale geological modeling can be solved with the proposed method. The method can provide effective support for large-scale 3D geological modeling in smart geology.

Quantitative analysis of geological attributes for reservoir heterogeneity assessment in carbonate sequences; a case from Permian–Triassic reservoirs of the Persian Gulf

This study integrates quantitative analysis of reservoir properties with geological parameters to discriminate the reservoir heterogeneities in the Permian–Triassic sequences of the Persian Gulf. To achieve this goal, geological analysis of core samples and thin sections were integrated with petrophysical logs and porosity–permeability data. For quantitative assessment of reservoir heterogeneity, Coefficient of Variation (CV), Dykstra-Parsons Coefficient (VDP) and Lorenz Coefficient (VLC) were used along with the concept of Hydraulic Flow Units (HFU). Depositional facies, diagenetic alterations and sequence stratigraphic framework of the reservoir were used as a basis for the interpretation of geological heterogeneities. Accordingly, 14 microfacies types and 5 facies belts have been defined and indicate a low-angle (homoclinal) ramp model. Complex diagenesis history of these sequences includes marine, hypersaline and shallow to deep burial diagenesis that considerably altered the primary distribution of reservoir properties. A comparison of tested methods revealed that the CV is the best approach for quantification of heterogeneity in targeted reservoir. Consequently, the K4 and K2 are proposed as the most homogeneous units with a dominance of grain-supported facies of shoal setting, intense effects of hypersaline dissolution and lesser effect of compaction and cementation. The K3 and K1 units show high levels of heterogeneity resulting from the combined facies changes and diagenetic alterations (dolomitization, cementation and compaction). Finally, sequence stratigraphic framework of reservoir heterogeneities is discussed for all reservoir units and can be used as a basis for ongoing reservoir studies of the Permian–Triassic sequences in the Persian Gulf and the Middle East.

Analytical Modeling of a Synthetic VMS Deposit Data: a Proxy Tool for Education and Initial Research

Freely accessible and non-confidential real-life geological data sets from mineral deposits are desirable for the wide range of applications in research and education. However, publicly available statistical data are limited in their number and quality—they contain reduced information about geological, geophysical, geotechnical, chemical, mineralogical, and other relevant properties of deposits. This makes such data insufficient for scientific purposes. However, the amount of geological knowledge obtained for a variety of deposits in the past allows the construction of an idealized synthetic ore body model using analytical approach. Such a model could be used for education purposes and testing basic scientific theories, e.g., visualization of deposit structure; teaching sampling strategies; testing new algorithms for mine planning; or comparing geostatistical modeling methods. This paper presents an analytical approach to simulate volcanic massive sulfide (VMS) deposits and shows how synthetic deposit model can be constructed and further used for studying sampling with drilling and simulating folding and faulting.

Research on the Vertical Stratification Characteristics and Dielectric Constant Calculation of Geological Bodies Based on Structural Plane Information of Borehole GPR Image and Digital Panoramic Image Fusion

For Ground-penetrating radar (GPR) image and the digital panoramic image obtained from single-hole measuring, a novel and noncooperative measuring method for quantitatively calculating the relative dielectric constant of geo-bodies based on information fusion of the two types of image is proposed. Structural plane tilt angle in borehole optical image and GPR image is extracted to calculate the permittivity and quantify the geological medium properties. The vertical stratification characteristics of geo-bodies can be obtained through the analysis of changing dielectric constant. Experiment with borehole optical and GPR images in this letter reveals the continuity and discontinuity of medium change. It confirms that there are many kinds of layered structures in shallow geology, such as soil, clay, sand with different water content, crushed stone, shale, and solution cracks with varying degrees of development. On the contrary, the values of permittivity of materials in deep geology have slight variation, and it indicates that the deep geological vertical stratification characteristic is relatively simple. The method provides a new and efficient means of dielectric constant calculation and vertical stratification characteristics analysis, especially for complex shallow geology in engineering applications.

Seismic microzoning of Guwahati metropolitan area, Assam, India

Seismic microzonation maps for Guwahati metropolitan area are presented based on the Uniform-Hazard-Spectrum (UHS) methodology. UHS method satisfies the performance-based design (PBD) criteria, which are based on two sets of spectral amplitudes, one for which the structure will remain linear, and the other for which it may undergo nonlinear response. The UHS method also considers contributions from large distant earthquakes and includes simultaneously the effects of site geology and of site soils. The maps presented include in a balanced way the effects of near and distant large earthquakes, spatial distribution of seismic activity, the site geology and site soil properties. The results also show that scaling design spectra by peak acceleration to which a standard spectral shape is anchored is not conservative.

Geological Properties of Güney Formation (Ereğli-Ulukışla Basin, Niğde)

Geological Properties of Güney Formation (Ereğli-Ulukışla Basin, Niğde)

Insights into Unloading Relaxation Mechanism of Columnar Jointed Basalt at the Baihetan Left Dam Foundation

Columnar jointed basalt (CJB), characterized by unique geometric and geological properties, poses a great challenge for geotechnical designs due to its unloading relaxation and damage during excavation. In this paper, the geometrical structure and field failures of the CJB exposed on Baihetan left dam foundation were briefly presented. A systematic field test was conducted to study the excavation damage zone of the CJB on the dam foundation using ultrasonic P wave measurements. The excavation damage zone of the CJB not only showed time‐dependent damage in depth but also showed spatially inhomogeneous distribution in depth. Corresponding three‐dimensional numerical analysis was also carried out to analyze the unloading relaxation mechanism of CJB. The unloading relaxation of CJB on dam foundation was mainly caused by the joint opening under tension stress during excavation. The difference of excavation damage zone of the CJB located in different test zones was also discussed in this article.

Geological interpretation using multivariate K-means and robust factor analysis in Dezak area, SW Iran

The Dezak limestone area, located SW Iran, is a potential site for industrial survey project of Precipitated Calcium Carbonate (PCC). Economic geology studies and geochemical implications of the area involve a high-risk level given the high purity of the limestone and the amount of penalty elements in the deposit. Generally, considering the compositional properties of geochemical data and using multivariate methods for a total of 527 composite samples showed that the data can be classified into five classes based on geological characteristics. According to K-means analysis, the grades of CaCO3 and SiO2 were 96.066% and 1.4754% within the second zone, and 94.5914% and 2.3278% within the fifth zone, respectively. Therefore, these zones were recognized as the first and second highest priorities having in common 165 and 133 samples on the specific geological units of Kdl and Kdld, respectively. Geochemical classification confirmed the geological units and variations. The priorities may preferably change depending on the time, place, plant requirements, access position, and the concentration of MgO and SiO2. Results from the robust factor analysis indicated that CaCO3 enrichment was mainly associated with depletion of SiO2 and Fe2O3 as well as P2O5 and, to some extent, MgO. This indicates the suitability of the selected study area, as major penalties are in contrast to CaCO3 enrichment. Geological and geochemical studies suggest different types of crystallized limestone and micritic limestone as the best zones for extraction. Therefore, geological properties were verified using multivariate K-means and factor analysis in the Dezak area.

Evaluation of exploiting barite, the critical raw material in Slovakia, and benefits of its mining

Purpose. There are several deposits of critical raw materials in the Slovak Republic, but currently only one is mined. This is a barite deposit in Spiš, which shows an ever-lower volume of exploited raw material year-on-year. However, this area is rich in several confirmed barite veins, which represent potential strategic raw materials. The presented article analyzes in detail and describes the Jaklovce I. deposit, which is located in the Gelnica district in north-east of Slovakia. Despite the fact that Slovakia, as well as most EU countries, is dependent on imports of raw materials, the new deposits represent new potential. Determination of the economic value of these deposits creates a promising potential for the investor, but also, secondarily, a potential for the socio-economic development of regions, as well as for the state. Methods. Based on the evaluation of dynamic economic variables, the article predicts the benefits which mining in this deposit would bring, which are also supported by SWOT analysis of barite exploitation. Findings. According to the methods used during the financial evaluation of the single mined deposit of CRM in Slovakia, which was developed because of CRM criticality in EU, we showed, based on § 14 of the Mining Act no. 44/1988 Coll. the necessity of CRM mining from the view of regions, the state and investors. The present article summarizes impacts of exploiting the barite from Jaklovce I. deposit for the investor, as well as for the state, which is also underlined through SWOT analysis. Originality. This study attempts to point out that mining critical raw materials is economically suitable not only for the state, but also for investors. SWOT analysis also pinpoints most threats, opportunities and some forecasts which should be taken into account while designing the investment project. Practical implications.I nvestment project in mining area is one of the most critical and challenging decisions that experts have to make mainly based on geological, economical and geotechnical properties of the deposit, which are very specific. The same is true for the investment project which represents huge investments and rate of risk