Geological Bodies Research Articles

A method to construct a main hole structural plane model based on advanced parallel adit geological body

The advanced parallel adit of tunnel refers to the adit parallel to the direction of the main hole. Generally it is spaced tens of meters from the axis of the positive hole. During the tunnel construction, the parallel adit is driven before the main hole. Main function of it is to provide geological reference for the subsequent excavation of the main hole. At the same time, it can also help improve the long-term construction and operation and maintenance efficiency of the main tunnel. In terms of providing geological prediction information for the main tunnel, the surrounding rock information disclosed in the advanced parallel adit excavation is mainly used for surrounding rock classification and geological sketch, so as to qualitative analysis the possible geological conditions when the positive tunnel is excavated near the distance where the advanced parallel adit is located. However, the above methods cannot accurately and quantitatively analysis the geological conditions that the main tunnel will face. The lack of research on the correlation between the main tunnel and the advanced parallel adit geological conditions results in the waste of the key factor of the horizontal geological information.In this paper, the improved DBSCAN clustering algorithm is used to group the dominant structural planes according to the attitude of rock and other information. Some non-primary structural planes are screened out. The average distance between the same group of structural planes is calculated according to the average attitude of the dominant structural plane. The structural planes that are close enough are fused. Then, the axial and radial projection was carried out to form a larger range of surrounding rock fracture models. When the main tunnel is excavated to the relevant area, the situation of the surrounding rock in front can be predicted according to the model, so that the countermeasures can be made in advance. The method in this paper is applied to a tunnel project with bidirectional single line and advanced parallel adit. The prediction results after tunnel excavated show that the method in this paper is reasonable and effective.

Fracture network characterisation of the Balmuccia peridotite using drone-based photogrammetry, implications for active-seismic site survey for scientific drilling

The presence of discontinuities (e.g. faults, fractures, veins, layering) in crystalline rocks can be challenging for seismic interpretations because the wide range of their size, orientation, and intensity, which controls the mechanical properties of the rock and elastic wave propagation, resulting in equally varying seismic responses at different scales. The geometrical characterisation of adjacent outcrop discontinuity networks allows a better understanding of the nature of the subsurface rocks and aids seismic interpretation. In this study, we characterise the discontinuity network of the Balmuccia peridotite (BP) in the Ivrea–Verbano Zone (IVZ), northwestern Italy. This geological body is the focus of the Drilling the Ivrea–Verbano zonE (DIVE), an international continental scientific drilling project, and two active seismic surveys, SEismic imaging of the Ivrea ZonE (SEIZE) and high-resolution SEIZE (Hi-SEIZE), which aim to resolve the subsurface structure of the DIVE drilling target through high-resolution seismic imaging. For fracture characterisation, we developed two drone-based digital outcrop models (DOMs) at two different resolutions (10−3–10 m and 10−1–103 m), which allowed us to quantitatively characterise the orientation, size, and intensity of the main rock discontinuities. These properties affect the seismic velocity and consequently the interpretation of the seismic data. We found that (i) the outcropping BP discontinuity network is represented by three more sets of fractures with respect to those reported in the literature; (ii) the discontinuity sizes follow a power-law distribution, indicating similarity across scales, and (iii) discontinuity intensity is not uniformly distributed along the outcrop. Our results help to explain the seismic behaviour of the BP detected by the SEIZE survey, suggesting that the low P-wave velocities observed can be related to the discontinuity network, and provide the basic topological parameters (orientation, density, distribution, and aperture) of the fracture network unique to the BP. These, in turn, can be used for interpretation of the Hi-SEIZE seismic survey and forward modelling of the seismic response.

Viscoacoustic VTI media reverse time migration method in the complex-domain based on the staining algorithm

Underground media exhibit characteristics of viscosity and anisotropy, with vertical transversely isotropic (VTI) media being a common example of anisotropic media. Consequently, it is crucial to address the viscoacoustic VTI wave equation during forward modeling and migration imaging processes to attain highly precise imaging outcomes. However, conventional subsalt imaging techniques yield low accuracy and suffer from a low signal-to-noise ratio. To overcome this challenge, this study proposes a staining algorithm-based viscoacoustic vertical transversely isotropic reverse time migration (VTI RTM) in the complex-domain method by deriving the complex-domain viscoacoustic VTI equation. This method requires both the traditional real velocity field and the imaginary velocity field as inputs. The imaginary velocity field contains stained geological bodies and significant areas without data. Seismic waves propagate normally in the real wavefield, while in the imaginary wavefield, reflections occur only when the wavefront encounters stained geological bodies. The proposed method is assessed through testing on both a horizontally layered model and a salt model. Through comparative analysis, it has been verified that the method fully incorporates reflected waves with distinct structural features into the imaginary wavefield. Numerical experiments demonstrate that this method can accurately image subsalt structures.

Study on the Influence of Geological Structure on Gas Occurrence and Gas Outburst

Gas is a gaseous geological body and a product of geological genesis. The geological structure and the historical evolution of coal bearing strata control the generation conditions of coal-bed gas and the preservation conditions of coal-bed gas subjected to depression, uplift, compression and tension in previous tectonic movements. The geological conditions that control the occurrence of gas disasters determine the state of gas occurrence, gas content, gas pressure, gas emission and the risk of coal and gas outburst in coal seams. There are obvious characteristics of zoning and zoning. Gas occurrence and gas outburst are controlled by various geological factors, and geological structure plays a decisive role in coal and gas outburst. Studying the influence of geological structure on gas occurrence law and gas outburst and mastering gas geological law can achieve the purpose of gas prediction and gas control. This paper discusses the influence of fold, fault and sliding structure on gas occurrence, and discusses the influence of geological structure on gas outburst from three aspects of coal seam gas pressure, in-situ stress and coal body structure. It can provide a basis for the prediction of gas outburst and has important significance for the prevention and control of gas accidents in coal mines.

Assessment of health risks posed by toxicological elements of the food chain in a typical high geologic background

Enrichment of toxicological elements in soils of high geologic background has a significant effect on toxicity. The aim of this study was to assess the health risks associated with the transfer of toxicological elements in the food chain in a typical high geologic background. We systematically collected data on rocks, soils and food crops belonging to a typical black rock system geological body and at the same time belonging to the main grain-producing areas in Hunan Province, and analyzed the exposure and health threat of toxicological elements Cr, Cd, Pb, Hg, As and Se in cucumber, rape, soybean, peanut and ginger. Based on the JISEVM method to establish the spatial contamination constitutive relationship between rock-soil-food, we deduced the conclusions from the bioconcentration factor (BCF), integrated crop contamination index (P) and hazard index (HI). Our results showed that Cr, Cd, Pb, Hg, and Se were exceeded in agricultural soils, with Hg and Se levels severely exceeding the standard Se was most bioconcentrated in soybean (BCF = 0.5855), followed by Cd (BCF = 0.5603) and Se (BCF = 0.3800) in peanut and Se (BCF = 0.4255) in rape, and the BCFs of all the BCF of crops were less than 1, and the enrichment of these six elements in the food chain did not reach a dangerous level; the overall spatial distribution of radioactive contamination was centered on the black rocky geologic body; and the contamination and absorption levels of foods in the study area were: leafy vegetables (oilseed rape) > legumes (soybeans and peanuts) > stem vegetables (ginger) > fruit vegetables (cucumber). The intake of Cd and Se through consumption of oilseed rape was the most important source of health risk among foods in the study area. This study, since it can fill the gap in risk assessment due to endogenous factors in a high geologic background, can also guide studies in other specialized contexts or in a multi-media background.

A unified model for frost wedging in an open fissure under unidirectional freezing

The propagation of joints and fissures, included by the frost heaving pressure arising from the water-ice phase transition is considered as frost wedging. This process is widely observed and plays a crucial role in weathering of jointed hard rocks in cold regions. Despite some fundamental results achieved in former experimental studies, a unified theoretical model is still absent, hindering a thorough understanding of this process. To further explore the mechanism of frost wedging during the freezing process, this paper firstly carries out a frost heave test on a rock block bearing a single open fissure. The results indicate that the evolution of frost heaving pressure in the fissure can be divided into four stages: sealing of the open fissure by ice wedge, ice wedge slipping, crack propagation, as well as stabilization of the ice-filled fissure. Based on the laboratory test results, a unified model for the frost heaving pressure in a single open fissure is established, which comprehensively takes into account the mechanical interaction between ice, water and rock. The model is validated by the test result, and it can reasonably describe the formation of the sealing conditions and the process of crack propagation. Fracture of the ice-rock interface near the free surface increases the likelihood of ice wedge slip, while frost wedging mainly damages geological bodies during crack propagation.

Transient electromagnetic perspective technology in the ultra-long coal mining face

The ultra-long coal mining face has the advantages of high recovery efficiency and low production cost; however, the widening of the coal face poses the difficulty of detecting the hidden geological bodies inside the coal face, and using conventional geophysical methods gives rise to imprecise detection results. Therefore, this paper proposes a transient electromagnetic perspective technology based on the conventional mining transient electromagnetic method. A long rectangular loop is used as the transmitting source in one coal mining tunnel of the coal mining face, and it is received in the opposite coal mining tunnel. This method is characterized by a long detection distance and high construction efficiency. Firstly, the paper used numerical simulation to investigate the spread of the transient electromagnetic field from the long rectangular loop source in both a uniform full-space model and a full-space laminated model. This showed the transient electromagnetic field propagation law and the effect of the coal seam thickness. Then, we analyzed the transient electromagnetic perspective signal characteristics of typical geological structures and gave the all-time apparent resistivity calculation method. Conclusively, the feasibility of this method is ultimately confirmed by the analysis of the measured data. Also, the research results provide a new technological approach to detecting hidden geological structures in the ultra-long coal mining faces.

Fluoritites Produced by Crystallization of Carbonate–Fluoride Magma

Abstract Fluorite-dominated rocks are occasionally found in association with carbonatites, but their geologic and petrologic relations are rarely reported. The Dunkeldyk area of the Pamir mountains in south-eastern Tajikistan contains dikes of distinctive rocks composed of calcite, fluorite, celestine-barite, sulfides, apatite, with minor quartz, biotite, and REE fluorcarbonates. The dikes have sharp contacts with the host (meta-)sedimentary rocks and layering with ribbons, ranging from fluorite-bearing calcite carbonatites to fluoritites (rocks with >50% fluorite). The fluoritites are characterized by high Ca, F, Ba, Sr, REE, and S coupled with anomalously low O. The geologic relations and textures suggest a magmatic origin of the dikes from melts close to calcite–fluorite eutectic that experienced nucleation-controlled differentiation during the crystallization of dikes and the formation of fluoritite cumulates in larger intrusions. The Dunkeldyk dikes demonstrate that sizable geological bodies of fluorite-dominated rocks could form from carbonate–fluoride melts originating from the differentiation of alkaline silicate magmas.

Discovery of Eclogite Facies Kyanite Quartzite in Central Jilin Province:Evidence of Ultra-high-pressure Metamorphism

The work area is located in the convergence domain of the Siberian plate and North China plate. The Jilin Province of the Soren-Xilamnlun river-Changchun-Heilog jiang plate collision zone. Before 2000, there was no empirical evidence of high-ultrahigh pressure transformation in the middle Jilin section. For this reason, the Changchun-Panshi-Jiaohe area was selected as the primary geological survey area. After comprehensively analysing the previous regional geological and mineral exploration data, we drew on the experience and achievements of studying the collision between the Suiu-dabie plate. Jiaohe blueschist origin was concerned. After fine field investigation, collecting fresh and representative samples, conducting microscopic identification, electron probe analysis and other work, the key identification and measurement results were obtained. Comprehensive results proved that the geological body producing kyanite undergoes high-pressure kyanite-quartzite was a metamorphic rock of gernet pgroxenite facies. This discovery is of fundamental importance for the establishment of the Jihei high pressure human ultra-high-pressure collision subduction zone. The discovery was briefly reported in 2000 and is now being published in detail. The garnet-phase blueschist quartzite is massive, laminated, ienticular, and rootless hook like bodies occur in within the luoguangou Dashihu narrow ductile shear zone. The rock being sheared is late paleozoic Early perntian Daheshan formation and late variscan Granite Porphyry, which were deformed and metamorphosed to form. blueschist dolomite quartz schist and dolomitic blueschist quartzite. The Peak mineral combination is Ky2+Qz2+Ms2 (Phn2) +Zt+Rt+Miss, without Sili and Pl, which basically meets the constraining charactenstics of eciogite facies. The peak metamorphic temperature reaches 700-750℃, indicating the Si (pfu) =3. 440-3. 535 of phengite, and indicated metamorphic pressure reaches p=2. 75-3. 30GPa, which shows that the rock has undergone ultra-high pressure metamorphic process, and its temperature and pressure conditions have been comparable to those formed by coesite. The temperature of secondary peak period of is about 550℃-600℃ and the pressure is about 1. 6-1. 7GPa. The multi-phase nature of the blueschist, muscovite and quartz indicates that the rock is subjected to prosess of subduction exhumation, and exhumation suffering from strong progressional and retrograde metamorphism. The temperature and pressure numbers of the metamorphism indicate that the paths are successively hornblende and green schist phases, with temperatures of about 500℃-450℃ and pressures of about 0. 5-0. 7GPa, and temperatures of about 300℃-350℃ and pressures of about 0. 3-0. 4GPa, respectively.

Three-dimensional finite-memory quasi-Newton inversion of the magnetotelluric based on unstructured grids

Abstract Simulation optimization of complex geological bodies is a necessary means to improve inversion accuracy and computational efficiency; thus, inversion of magnetotelluric (MT) based on unstructured grids has become a research hotspot in recent years. This article realizes the three-dimensional (3D) finite element forward modeling of MT based on the magnetic vector potential-electric scalar potential method, using unstructured grids as the forward modeling grid, which improves computational efficiency. The inversion uses the limited-memory Broyden–Fletcher–Goldfarb–Shanno (LBFGS) method, and in the process of calculating the objective function gradient, the quasi-forward method is used to avoid solving the Jacobian matrix, which has the advantages of requiring small storage space and fast computational efficiency. Finally, the 3D LBFGS inversion algorithm of MT based on unstructured grids was realized, and the inversion studies of classic and complex models verified the effectiveness and the reliability of the algorithm proposed in this article.

Study on Coordinated Deformation Failure Mechanism and Strength Prediction Model of Rock-lining Concrete

Shotcrete has been widely used in the excavation of caverns and tunnels as a key load-bearing element in the support system. However, the interfacial stresses and bond strengths within the composite structures formed by the interaction of geologic bodies and tectonic formations are not well understood, which can lead to safety accidents and excessive wastage of support materials in engineering. To address this gap, rock-concrete composite specimens were created using six distinct types of surrounding rocks. The strength law of composite specimens was analyzed, and the uniaxial compressive strength prediction model of composite specimens was derived based on Mohr−Coulomb strength yield criterion. The results show that the uniaxial compressive strength of the composite specimen changes with the change of rock type, which is between the strength of rock and concrete. The uniaxial peak strength and elastic modulus of composite specimens are linearly positively correlated with the ratio (Y) of concrete-rock elastic modulus, which is easily affected by concrete properties. However, the peak strain is linearly and negatively correlated with Y, which is greatly influenced by rock. The rock-concrete interface of the composite specimen plays an important role in the failure of the specimen, which changes the stress transfer state of the composite specimen, produces uncoordinated deformation, and finally causes the failure of the specimen. The theoretical and test value error of the derived composite specimen uniaxial compressive strength prediction model are –1.19%~12.20%, and the theoretical calculation model can be used to predict the uniaxial compressive strength of rock-concrete composite specimens.

Application of biopolysaccharide green foam fluid to enhance CO2 sequestration in high-temperature and high-salinity saline aquifer

Saline aquifer, a geological body, is widely distributed in the world and has high CO2 sequestration potential. Due to the large differences in viscosity and density between the CO2 and brine and the micro-heterogeneity of the saline aquifer, CO2 override, and viscous fingering may occur in strata, resulting in low CO2 sequestration efficiency. Following the concept of green chemistry, this study formulated CO2 foam using biopolysaccharides and a green surfactant alkyl polyglycosides (APG), to enhance the CO2 sequestration efficiency in saline aquifers. The ability of three biopolysaccharides (diutan gum, welan gum and xanthan gum) to stabilize CO2 foam was explored. According to the foam drainage activation energy and the Ostwald ripening rate, the CO2 foam with diutan gum as the stabilizer and APG as the foaming agent exhibited the favorable performance. The mechanism of diutan gum stabilizing CO2 foam was analyzed through studies on intermolecular interactions, interfacial properties, rheology, and micromorphology studies. We then investigated the effects of foam quality and flow rate on the CO2 foam rheology in sandstone cores by analyzing the changes in CO2 saturation, the matching relationship between bubble diameters under different conditions and sandstone core pore size, and the variation in foam rheology was explained. Furthermore, the ability of CO2 foam to enhance CO2 sequestration was explored in saline aquifers using core-nuclear magnetic resonance techniques. CO2 foam largely reduces the water saturation of macropores and establishes high-seepage resistance to facilitate CO2 foam diversion to the meso- and micropores. This fully leverages the space in these pores to store CO2 and greatly improves CO2 sequestration in saline aquifers.

ABOUT WATERFLOODING OF LOW-PERMEABILITY RESERVOIRS

The purpose of this work is to analyze the effectiveness of the flooding system on low-permeable reservoirs of the Achimovian formation and optimize its operation taking into account the facial model. Due to the depletion of hydrocarbon reserves in traditional formations with good reservoir properties, interest in hard-to-recover reserves is currently increasing. And the main difficulty in the development of such reservoirs is the efficiency of waterflooding systems. When developing low-permeability reservoirs, various mechanisms of oil displacement during flooding can be identified. When flooding reservoirs with a permeability of less than 1 mD, there is no need to keep a high wellhead pressure. Moreover, with a large accumulated compensation, stopping water injection for up to six months does not lead to a drop in production, which creates prerequisites for the organization of cyclic flooding. This will solve a number of problems that appear in injection wells when working in such conditions. The facial structure of reservoirs sometimes has a decisive influence on wells operation and their mutual influence. The transition to the field development with a complex geological structure, low filtration characteristics of the formation, the existence of geological bodies with different properties, requires not only thoroughness in the formation of a conceptual understanding of the oilfield, but also the creation of detailed digital facial maps taking into account the existence of zones with different sedimentation, as a consequence, creating zones with different filtrationcapacitance properties, requiring different approaches to development.

Neogene carbonate platform development in the southern South China Sea: Evidence from calcareous microfossils

Biogenic reefs are unique geologic bodies that are the products of biological activity in tropical and subtropical oceans and critical to global carbon cycling. The South China Sea (SCS) has developed largest carbonate platforms in the Western Pacific. The fully-cored Well NK-1, which is drilled through the reef complex on the Meiji Atoll, Nansha Islands, offers good opportunity for assessing the long-term evolutions of biogenic reefs in the SCS. The stratigraphic ages based on palaeomagnetic and Sr isotopic data are controversial in some intervals of core NK-1. To reveal the evolution history of Nansha Islands and their controlling factors, more credible age constraints on core NK-1 are needed. This research presents new records of calcareous microfossils (calcareous nannofossil and foraminifer) abundances and diversities in the biogenic reef carbonates of core NK-1. Based on the assemblages of the calcareous microfossils, seven biostratigraphic datums are recognized from the sequence of core NK-1, revealing a general continuous succession of the earliest Miocene to Pleistocene age. By combining with the magnetostratigraphic data, the development and evolution of carbonate platform in Nansha Islands are reconstructed. The bottom age of the biogenic reef sequence of NK-1 is estimated for 23.03 ± 1.06 Ma, close to the Oligocene/Miocene boundary. The new chronology highlights three short hiatuses of 3.6–2.4 Ma, 11.1–10.0 Ma, and 13.5–11.9 Ma, which are well correlated with the prominent exposed surfaces at 210.3 m, 464.6 m and 561.6 m, respectively. It reveals remarkably similar evolution history of carbonate platforms in the SCS since Neogene by comparing with records of stratigraphy and growth rate from deep drilling cores on isolated coral reefs in Nansha and Xisha Islands. The results showed that the SCS carbonate platform developments, which go through Late Oligocene / Early Miocene initiation phase, Early-Middle Miocene rapid growth phase, Middle-Late Miocene erosion phase, Miocene-Pliocene stable development phase and Quaternary growth phase, are mainly influenced by global sea level changes, environmental factors and regional tectonism such as the SCS basin spreading, Sabah Orogeny Movement and Dongsha Movement.

Application of second order multi-synchrosqueezing transform for seismic data analysis

Time-frequency methods, which allow us to observe the seismic signal in time and frequency domains simultaneously, can efficiently discern the seismic response features of geological bodies in different frequency bands. In this paper, a newly developed time-frequency method named second order multi-synchrosqueezing transform (SMSST) is introduced to analyze seismic data. SMSST combines the second-order instantaneous frequency estimation and the iterative idea of multi-synchrosqueezing transform to approximate the true instantaneous frequency trajectory. It solves the problems of non-reassignment points and the sensitivity to noise at the same time. Synthetic example is employed to validate the superiority of SMSST in time-frequency analysis. Results obtained from four different methods show that SMSST offer the best performance in terms of energy-concentration and noise robustness. Applications on field data further demonstrate that SMSST-based method is suitable and effective to highlight geological information and stratigraphic features compared to the previous techniques. The capabilities of SMSST for accurate reservoir localization with high resolution, making it a promising and potential tool in seismic interpretation.

Geoelectrical and Remote Sensing in the Characterization of the Pan-African Meta-sedimentary Basement Aquifer Systems: A Case Study at Nkoteng-Elap, Central Region of Cameroon

Abstract Nkoteng-Elap, a hamlet in the Central Region of Cameroon (Central Africa), has water issues, particularly with access to drinking water. The current study aims at (1) mapping the fracture networks of aquifers in the conceptual hydrogeological model and (2) delimiting the groundwater potential zones of the study area. A study combining remote sensing and geoelectrical measurements was carried out along profiles sub-perpendicular to the elongation of the geological bodies. Borehole and field geology data were used to validate the results obtained. The findings point to more than 300 linear structures about 0.065-74.89 km long, with two main directions: N80-100°E and N30-50-70°E. According to the Electrical Resistivity Tomography approach, there are three (03) geoelectric levels: conductive (less than 500 Ωm), semi-resistive (6500-12500 Ωm). resistive (more than 12500 Ωm), and resistant intrusive body (2050 Ωm). Existing drillings display three main lithological formations: the alteration zone, the fissured/altered zone, and micaceous quartzite. The correlation between the ERT data and drilling data reveals that the fissured or altered zone observed at 50 m is potentially aquifers. This structure is characterized by medium resistivity values (6500 Ω.m), flow rates of 1 to 3 m3/h for positive boreholes, and by low resistivity values (500 Ω.m), flow rates less than 1 m3/h for negative boreholes. The final map is categorized into five classes: very good, good, moderate, poor, and very poor groundwater potential zones. These results can help find basement aquifers and be useful in the planning and management of groundwater resources in a meta-sedimentary context.

3D Reverse-Time Migration Imaging for Multiple Cross-Hole Research and Multiple Sensor Settings of Cross-Hole Seismic Exploration

The two-dimensional (2D) cross-hole seismic computed tomography (CT) imaging acquisition method has the potential to characterize the target zone optimally compared to surface seismic surveys. It has wide applications in oil and gas exploration, engineering geology, etc. Limited to 2D hole velocity profiling, this method cannot acquire three-dimensional (3D) information on lateral geological structures outside the profile. Additionally, the sensor data received by cross-hole seismic exploration constitute responses from geological bodies in 3D space and are potentially affected by objects outside the well profiles, distorting the imaging results and geological interpretation. This paper proposes a 3D cross-hole acoustic wave reverse-time migration imaging method to capture 3D cross-hole geological structures using sensor settings in multi-cross-hole seismic research. Based on the analysis of resulting 3D cross-hole images under varying sensor settings, optimizing the observation system can aid in the cost-efficient obtainment of the 3D underground structure distribution. To verify this method’s effectiveness on 3D cross-hole structure imaging, numerical simulations were conducted on four typical geological models regarding layers, local high-velocity zones, large dip angles, and faults. The results verify the model’s superiority in providing more reliable and accurate 3D geological information for cross-hole seismic exploration, presenting a theoretical basis for processing and interpreting cross-hole data.

About flooding of low-permeable formations

Due to the depletion of hydrocarbon reserves in traditional reservoirs with good filtration and reservoir properties, there is currently increasing interest in hard-to-recover reserves, and the main difficulty in developing such reservoirs is the efficiency of reservoir pressure maintenance systems. When developing low-permeability reservoirs, various mechanisms of oil displacement during flooding can be distinguished. For reservoirs with permeability less than 1 mD, there is no need to maintain high wellhead pressure; moreover, with a large accumulated compensation, stopping the maintenance of reservoir pressure for up to six months does not lead to a drop in production, which creates the prerequisites for organizing cyclic flooding. This will solve a number of problems that arise while maintaining reservoir pressure when working in such conditions.
 The facies structure of reservoirs sometimes has a decisive influence on the performance of wells and their interinfluence. The transition to the development of fields with a complex geological structure, low filtration characteristics of the formation, the existence of geological bodies with different properties requires not only careful formation of a conceptual understanding of the field, but also the creation of detailed facies digital maps taking into account the existence of zones with different sedimentation, which, as a consequence, creates zones with different filtration and capacitance properties, requiring different approaches to development.

Subsurface Qualitative Investigation for Mineral Exploration using Aeromagnetic Data

This research investigated the subsurface qualitative investigation for mineral exploration of Ibadan Southwest Nigeria, using high resolution aeromagnetic data. The data acquired from Nigeria Geological Survey Agency (NGSA) were subjected to different filtering processing techniques to produce magnetic anomaly maps which were analyzed to detect the subsurface geologic features that are indicative of the potential mineral deposits in the study area. The processing techniques applied in this study to delineate the magnetically active regions were Total Horizontal Derivative (THD), Analytic Signal Amplitude (ASA) and Upward Continuation (UP) method at 150 m and 250m. The results obtained show THD values ranged between 0.002 nT and 0.039 nT connoting regions between non-magnetic body region and high magnetic anomaly regions. The ASA technique revealed susceptibility contrast region between 0.0022 and 0.1472 nT/m; these depict region of geologic body housing the mineralized zones. Thus, there is potential for mineral exploration in the study area.

Generation of 3D finite element mesh of layered geological bodies in intersecting fault zones.

As the geological fault surface divides the 3D space of stratified ores and rocks into complex spatial surface domains, it is necessary to fully consider the spatial relationship between intersecting fault zones and geological bodies in the process of 3D modeling, and how to accurately establish the 3D finite element mesh of geological bodies in intersecting fault zones is a difficult point in modeling complex geological structure. The laminated geological body in intersecting fault zone is a multifaceted domain grid model consisting of a ground-level grid, a geological fault plane grid, and a range grid. By analyzing the spatial relationship between the geological interfaces of the intersecting fault zones, a closed manifold processing method is proposed to establish the closed manifold spatial surface model of the intersecting fault zones, based on which the closed spatial surface model is tetrahedrally divided to establish a 3D solid model. Finally, the 3D solid model is imported into Ansys to generate a 3D finite element mesh. VC++ is used as the development platform for programming, to realize the generation and closed manifold processing of ground level and geological fault surfaces, and use TetGen library to generate finite element mesh based on irregular tetrahedron. Taking an intersecting fault zone in an open-pit mine as an example, the 3D finite element mesh of laminated geological bodies in the intersecting fault zone is established successfully. This method provides an effective and feasible solution for generating accurate 3D finite element meshes in complex stratigraphic spaces based on closed manifold processing.