Properties Of Strata Research Articles

Research on the Evolutionary Law of Fracture Formation in Loose Seams Under High-Intensity Mining with Shallow Depth

The western mining regions of China, known for shallow-buried and high-intensity mining activities, face significant ecological threats due to damage to loose strata and the surface. The evolution of fissures within the loose layer is a critical issue for surface ecological environment protection in coal mining areas. The study employed field measurements, mechanical experiments, numerical simulations, and theoretical analysis, using the ‘triaxial consolidation without drainage’ experiment to assess the physical and mechanical properties of various strata in the loose layer. Additionally, the PFC2D numerical simulation software was employed to construct a numerical model that elucidates the damage mechanisms and reveals the evolution of loose layer fissures and the development of ground cracks. The research findings indicate that during shallow-buried high-intensity mining loose layer fissures undergo a dynamic evolution process characterized by “vertical extension-continuous penetration-lateral expansion”. As the working face advances, these fissures eventually propagate to the surface, forming ground cracks. The strong force chains within the overlying rock (or soil) layers develop in the form of an “inverted catenary arch”. As the arch foot and the middle of the arch overlap, fissures propagate along these strong force chains to the surface, resulting in ground cracks. The study elucidates the surface damage patterns in shallow-buried, high-intensity mining, offering theoretical insights for harmonizing coal mining safety with ecological conservation in fragile regions.

Study of geomechanical properties of the Pimienta formation with undrained multi-stage triaxial tests, Central-Western Tampico Misantla Basin, Mexico

The Pimienta Formation (J-Pi) of the Tampico Misantla Basin (TMB) in Mexico is known for its potential as unconventional onshore hydrocarbon reserves. The area of interest in this study is located in the western-central part of the TMB, where no significant production has been established from unconventional resources. Given the low permeability and low porosity characteristics of the carbonaceous mudstone in the Pimienta formation, it is necessary to implement techniques to increase the area of flow from the reservoir to the borehole, achieving profitable oil and gas extraction.The geomechanical properties of rock strata are essential inputs for the design and implementation of shale oil and gas production engineering, such as horizontal drilling and hydraulic fracturing. Understanding the capabilities of the rock to yield and contain hydraulic fractures is essential to designing safe and efficient well stimulations. Likewise, the wellbore stability is of critical importance to the successful development of secondary and tertiary recovery systems.In this study, core samples from the Pimienta Formation in the TMB are analyzed through undrained multi-stage triaxial tests, emphasizing the estimated in-situ geo stresses and the effect of the mineral composition of the rock. The geomechanical parameters of compressional strength, Poisson ratio (PR), and Young's modulus of the Pimienta formation are obtained from the analysis of the experimental data and finding correlations to the mineral composition of the samples. A detailed characterization is completed under the conventional rock mechanics methodologies of Mohr-Coulomb and Hoek-Brown failure criterion, as well as Brittleness Index (BI).

Fur flutter in fluid flow fends off foulers.

The fouling of submerged surfaces detrimentally alters stratum properties. Inorganic and organic foulers alike attach to and accumulate on surfaces when the complex interaction between numerous variables governing attachment and colonization is favourable. Unlike naturally evolved solutions, industrial methods of repellence carry adverse environmental impacts. Mammal fur demonstrates high resistance to fouling; however, our understanding of the intricacies of such performance remains limited. Here, we show that the passive trait of fur to dynamically respond to an external flow field dramatically improves its anti-fouling performance over that of fibres rigidly fixed at both ends. We have previously discovered a statistically significant correlation between a group of flow- and stratum-related properties, and the quantified anti-fouling performance of immobile filaments. In this work, we improve the correlation by considering an additional physical factor, the ability of hair to flex. Our work establishes a parametric framework for the design of passive anti-fouling filamentous structures and invites other disciplines to contribute to the investigation of the anti-fouling prowess of mammalian interfaces.

The Impacts of Public Schools on Housing Prices of Residential Properties: A Case Study of Greater Sydney, Australia

Residential property values are influenced by a combination of physical, socio-economic and neighbourhood factors. This study investigated the influence of public schools on residential property prices. Relatively few existing models have taken the spatial heterogeneity of different submarkets into account. To fill this gap, three types of valuation models were applied to sales data from both non-strata and strata properties, and how the proximity and quality of public schools have influenced the prices of different residential property types was examined. The findings demonstrate that an increase of one unit in the normalised NAPLAN score of primary and high schools will lead to a 3.9% and 1.4%, 2.7% and 2.8% rise in housing prices for non-strata and strata properties, respectively. It is also indicated that the application of geographically weighted regression (GWR) can better capture the varying effects of schools across space. Moreover, properties located in the catchment of high-scoring schools in northern Greater Sydney are consistently the most influenced by school quality, regardless of the property type. These findings contribute to a comprehensive understanding of the relationships between public schools and the various submarkets of Greater Sydney. This is valuable for the decision-making processes of home buyers, developers and policymakers.

AdaHRBF v1.0: gradient-adaptive Hermite–Birkhoff radial basis function interpolants for three-dimensional stratigraphic implicit modeling

Abstract. Three-dimensional (3D) stratigraphic modeling is capable of modeling the shape, topology, and other properties of strata in a digitalized manner. The implicit modeling approach is becoming the mainstream approach for 3D stratigraphic modeling, which incorporates both the off-contact strike and dip directions and the on-contact occurrence information of stratigraphic interface to estimate the stratigraphic potential field (SPF) to represent the 3D architectures of strata. However, the magnitudes of the SPF gradient controlling the variation trend of SPF values cannot be directly derived from the known stratigraphic attribute or strike and dip data. In this paper, we propose a Hermite–Birkhoff radial basis function (HRBF) formulation, AdaHRBF, with an adaptive gradient magnitude for continuous 3D SPF modeling of multiple stratigraphic interfaces. In the linear system of HRBF interpolants constrained by the scattered on-contact attribute points and off-contact strike and dip points of a set of strata in 3D space, we add a novel optimizing term to iteratively obtain the optimized gradient magnitude. The case study shows that the HRBF interpolants can consistently and accurately establish multiple stratigraphic interfaces and fully express the internal stratigraphic attribute and orientation. To ensure harmony of the variation in stratigraphic thickness, we adopt the relative burial depth of the stratigraphic interface to the Quaternary as the SPF attribute value. In addition, the proposed stratigraphic-potential-field modeling by HRBF interpolants can provide a suitable basic model for subsequent geosciences' numerical simulation.

Проблемы и перспективы внедрения многостадийной выемки руды при отработке запасов калийных месторождений

Introduction. Most of the potash deposits in the world are mined using room-and-pillar mining method with natural support, which is accompanied by high mineral losses, as well as a high mine accidents due to the destruction of supporting elements, waterproof strata continuity and breakthroughs of oversalt water and brines into the mined-out void. Methods. Generalisation, systematisation and analysis of theoretical and experimental research on increasing the extraction ratio of potash ore to establish the methods degree for increasing extraction of potash reserves, to identify unexplored and problematic issues, to determine directions and approaches. Results. Theoretical justification of the possibility and expediency of several-stage stoping for potash mining implementing the principle of re-extraction of reserves from pillars with the provision of necessary protection measures of aquifer in the form of backfill. Conclusion. The article presents the results of an analysis of the specifics of underground mining of potash deposits. The concept of several-stage stoping for potash mining is formulated. Generalized variants of several-stage stoping are presented. The main problems of several-stage stoping implementation at potash deposits are described: the problem of gap-filling in rooms; prediction of altered physical and mechanical properties of seams and host rocks; the influence of multiple excavation on water-resistant properties of waterproof strata in several-stage stoping; the role of time in geomechanical processes; rational composition and recipe of backfill preparation; organization of stowing and clean-up operations at the site; technical and economic expediency of several-stage stoping. Possible lines of approach are suggested. Resume. The use of several-stage stoping for potash mining will increase the extraction ratio, improve the reliability of the waterproof strata during mining by replacing potash seams with a continuous fill mass, utilize waste from potash ore processing, and extend the service life of potash mines. A competent scientific and methodological foundation on the implementation of such technology at potash deposits needs to be built for a deep evaluation of the mining and geomechanical processes in the operation areas and the technical and economic performance of several-stage stoping. Suggestions for practical applications and future research line. The variants of several-stage stoping presented in the article can be used to develop methods of potash mining considering specific mining and geological conditions. Application of the described and similar variants of several-stage stoping in practice will significantly increase the extraction ratio while maintaining a minimal impact on the seam. Future research line will focus on the underground deposit development plan and the geomechanical justification of the parameters of the several-stage stoping.

Stability Characteristics of Horizontal Wells in the Exploitation of Hydrate-Bearing Clayey-Silt Sediments

The mechanical properties of hydrate-bearing strata in clayey-silt sediments are significantly different from those of either conventional reservoirs or hydrate-bearing sandy sediments, which poses great challenges for wellbore stability analyses. The stability characteristics of a deviated borehole during drilling in hydrate-bearing clayey-silt sediments (HBS-CS) remain to be studied. In this paper, an analysis of the wellbore stability characteristics of a deviated borehole using the Mohr–Coulomb (M-C) criterion and Drucker–Prager (D-P) criterion was carried out based on the elastic stress distribution model of the surrounding strata of the wellbore and the triaxial shear tests of the HBS-CS. The results imply that the collapse pressure and safety density window are symmetrically distributed with deviation angle and azimuth. Considering the effect of hydrate decomposition, the collapse pressure gradient could become higher and the instability risks would be amplified. Considering the combined effects of collapse, fracture pressure gradient, and the safety density window, it is suggested that the borehole be arranged along an azimuth of 60–120°, which could greatly reduce the risk in a drilling operation.

Research on Leakage Mechanism of Underwater Shield Tunnels with Different Soil Layers during Operation Period

Different soil layer properties have great influence on tunnel leakage. In this paper, the finite element software is used to analyze the homogeneous leakage model of different soil layers and different degrees of lining deterioration. The working conditions of different soil layer properties and different degrees of lining deterioration are established by means of soil layer permeability coefficient and lining permeability coefficient, and the law of tunnel leakage under each working condition is analyzed. This paper innovatively explores the relationship between the severity of tunnel seepage caused by different lining deterioration and the soil layer properties of the tunnel. Finally, by comparing the field survey data of Dinghuaimen with the leakage law and mechanism summarized by the model, the reliability and feasibility of the model method to explore the leakage mechanism are verified. The model test results are consistent with the project survey data. In this paper, the seepage law and mechanism of underwater shield tunnel are explored and the result shows: (1) The leakage laws and stress distribution laws of a single homogeneous soil layer with different strata properties are similar. The flow velocity in the lower half of the tunnel lining is greater than the upper half, and the maximum velocity occurs at the arch foot; the velocity inside the lining is much smaller than that inside the soil layer. The maximum absolute value of the axial stress of the lining occurs at the arch waist on the left and right sides, and the minimum values of the axial stress of absolute values all occur at the dome. (2) The leakage of underwater tunnels is related to the properties of soil layers. The larger the soil permeability coefficient is, the more serious the deterioration of the tunnel lining will be, and the more serious the tunnel leakage will be. (3) The leakage of complex strata follows the law of leakage in a single homogeneous stratum. The leakage of the tunnel is the most serious in the fine sand layer with the largest permeability coefficient. Moreover, when the seepage phenomenon occurs, the water flow tends to seep along the fine sand layer to the tunnel.

Machine learning-based automatic control of tunneling posture of shield machine

For a tunnel driven by a shield machine, the posture of the driving machine is essential to the construction quality and environmental impact. However, the machine posture is controlled by the experienced driver of shield machine by setting hundreds of tunneling parameters empirically. Machine learning (ML) algorithm is an alternative method that can let the computer to learn from the driver's operation and try to model the relationship between parameters automatically. Thus, in this paper, three ML algorithms, i.e. multi-layer perception (MLP), support vector machine (SVM) and gradient boosting regression (GBR), are improved by genetic algorithm (GA) and principal component analysis (PCA) to predict the tunneling posture of the shield machine. A set of the parameters for shield tunneling is extracted from the construction site of a Shanghai metro. In total, 53,785 pairwise data points are collected for about 373 d and the ratio between training set, validation set and test set is 3:1:1. Each pairwise data point includes 83 types of parameters covering the shield posture, construction parameters, and soil stratum properties at the same time. The test results show that the averaged R2 of MLP, SVM and GBR based models are 0.942, 0.935 and 0.6, respectively. Then the automatic control for the posture of shield tunnel is illustrated with an application example of the proposed models. The proposed method is proved to be helpful in controlling the construction quality with optimized construction parameters.

Seismic Wave Propagation Characteristics and Their Effects on the Dynamic Response of Layered Rock Sites

To investigate the seismic response of layered rock sites, a multidomain analysis method was proposed. Three finite element models with infinite element boundaries for layered sites were analysed. The results of this multidomain analysis show that stratum properties and elevation have an impact on wave propagation characteristics and the dynamic response of layered sites. Compared with the rock mass, the overlying gravel soil has a greater dynamic amplification effect at the sites. A time domain analysis parameter PGA(IMF) was proposed to analyse the effects of different strata on the seismic magnification effect of layered sites, and its application was also discussed in comparison with PGA. According to the frequency domain analysis, the interface of the rock mass strata has a low impact on the Fourier spectrum characteristics of the sites, but gravel soil has a great magnification effect on the spectrum amplitude in the high-frequency band (≥30 Hz) of waves. Moreover, the stratum properties have a great influence on the shape and peak value of the Hilbert energy and marginal spectrum at layered sites. When waves propagate from hard rock to soft rock, the peak value of the Hilbert energy spectrum changes from single to multiple peaks; then, in gravelly soil, the Hilbert energy spectral peak, its nearby amplitude and the amplitude in the high-frequency band (28–36 Hz) are obviously amplified. The frequency components and amplitude of the marginal spectrum become more abundant and larger from rock to gravelly soil in the high-frequency band (28–35 Hz).

Characterization of gas hydrate systems on the Hikurangi margin (New Zealand) through geostatistical seismic and petrophysical inversion

Quantitative characterization of gas hydrate systems on continental margins from seismic data is challenging, especially in regions where no well logs are available. However, probabilistic seismic inversion provides an effective means for constraining the physical properties of subsurface strata in such settings and analyzing the variability related to the results. We have applied a workflow for the characterization of two deepwater gas hydrate reservoirs east of New Zealand, where high concentrations of gas hydrate have been inferred previously. We estimate porosity and gas hydrate saturation in the reservoirs from multichannel seismic data through a two-step procedure based on geostatistical seismic and Bayesian petrophysical inversion built on a rock-physics model for gas hydrate-bearing marine sediments. We find that the two reservoirs together host between [Formula: see text] and [Formula: see text] of gas hydrate, with the best estimate at [Formula: see text]. This estimate provides a first-order assessment for further gas hydrate evaluations in the region. The two-step statistically based seismic inversion method is an effective approach for characterizing gas hydrate systems from long-offset seismic reflection data.

Mechanical properties of the clayey-silty sediment-natural gas hydrate mixed system

Mechanical properties of hydrate-bearing strata are crucial to evaluate hydrate production related geohazards. However, the mechanical parameters of the hydrate reservoirs in the Shenhu area of the South China Sea have been rarely reported. In this paper, the sediments from the top of the hydrate reservoirs in the Shenhu area are taken to analyze the triaxial shearing behaviors of clayey-silty sediments containing tetrahydrofuran (THF) hydrates. The results indicate that the stress–strain curves of THF hydrate-bearing clayey-silty sediments show strain-hardening failure characteristics under a relatively low hydrate mass fraction (≤16.7%). Triaxial shearing strength, tangent modulus, and cohesion force increase with the increase of hydrate less fraction. However, prime results from pure THF hydrates reveal a brittle failure mode, which is totally different from that when hydrate mass fraction is more than 16.7%. Therefore, hydrate fraction (either mass fraction or volume fraction), rather than hydrate saturation, is strongly recommended to characterize the content of hydrate within clayey-silty sediments. The clayey-silty sediment-hydratemixed system is suggested to be divided into pure sediment, hydrate-bearing sediment (HBS), sediment-bearing hydrate (SBH), and pure hydrate, for which a universally applicable mechanical property evaluation method is thus established.

A conceptual model identifying apartment owners' attitude formation towards solar photovoltaic (PV) adoption

PurposeThis paper addresses the current lack of solar photovoltaic (PV) adoption by Australian apartment dwellers by proposing a conceptual model that identifies and integrates the factors influencing owners' attitudes towards PV adoption.Design/methodology/approachThe conceptual model, which this paper terms the apartment-based solar adoption (ASA) model, is developed by applying motivation–opportunity–ability (MOA) theory to relevant findings in property development, green energy and strata governance literature.FindingsThe ASA model demonstrates the process by which an apartment-owning consumer may progress from considering solar PV adoption to recommending the action to their strata property's Owners' Committee (OC). It incorporates three motivational drivers (pragmatic considerations, perceived values and perceived social norms), three conditional mediators (location accessibility, resource availability and decision-making conditions) and three requirements from the consumer (actual and perceived knowledge, the ability to participate in decision-making and social connections and status).Research limitations/implicationsThis article contributes originality to research on two counts. Firstly, it provides a conceptual framework of specific relevance to issues concerning solar PV adoption, and secondly, it offers a systematic means for research into strata governance decision-making. Further research is required to develop the means with which to utilise the model prescriptively and measure longitudinal effects, such as ongoing trends in apartment owners' motivations. Further research is also recommended into how the ASA model may be utilised to identify generalisable consumer typologies among apartment owners.Practical implicationsThe ASA model may assist building maintenance providers in developing and marketing solar PV services tailored to apartment residents' requirements and enhance strata managers' ability to inform and guide apartment owners. In turn, property developers would be able to review apartment-based solar projects, measure their increased value and decreased energy costs and incorporate this information when planning future developments.Social implicationsThe ASA model may provide a template for apartment owners and owners' corporations considering solar PV for their property. Public policymakers could also refer to the model to incentivise apartment-based solar PV adoption, whether through designing local information campaigns, developing financial incentives or mitigating identified regulatory barriers. By facilitating solar PV adoption in Australian apartment housing, the model may ensure sustainable post-carbon energy consumption for Australia's housing stock and act as an example for high-density housing development internationally.Originality/valueThe ASA model addresses the many drivers and barriers known to affect solar PV adoption by apartment owners, presenting a framework on which to arrange these factors and outline their causal relationships. This framework may inform strata properties' future solar PV adoption initiatives by incorporating their specific physical characteristics, stakeholder dynamics and institutional structure. It also consolidates and provides generalisability to the concepts established in current literature.

A Hybrid Regularization Operator and Its Application in Seismic Inversion

Seismic inversion is an effective tool to estimate the properties of subsurface strata from seismograms. However, the intrinsic ill-posedness of the inversion problem causes the inverted subsurface properties to be easily polluted by inversion errors due to the random noise in the observed data. The inversion errors make it difficult to interpret the geological features of subsurface strata, especially their boundaries and textures. To recover high-fidelity inversion results from noisy observed data, we developed a hybrid total-variation (HTV) regularization operator in this research. Compared with the conventional total-variation (TV) regularization, the HTV regularization has two advantages when applied in seismic inversion. One advantage is that HTV regularization overcomes the typical staircase effect of conventional TV regularization while maintaining the advantage of TV regularization in edge-preserving properties. The determination of regularization parameters is also a difficult problem in seismic inversion with conventional TV regularization. A large regularization parameter may lead to an oversmoothed inversion result, while a small value leads to a noisy inversion result. Another advantage of HTV regularization is that it can generate proper inversion results even if a regularization parameter that is too large is adopted, which makes it easy to set the value of the regularization parameter. Numerical examples demonstrate the performance of the HTV regularization method proposed in this research.

Geodynamic and hydrodynamic conditions of the Urna and Ust‐Tegus oil fields

This paper discusses the productive beds of the Urna and Ust‐Tegus oil fields (West Siberia, Russian) and permeability and capacity properties that are influenced by geodynamic processes. Strong tectonic processes, accompanied by periodic magma intrusions, produced numerous fractures and faults in the Jurassic sediments, which act as conduits for groundwater flows, and thus led to the hydrothermal alteration of rocks and changes in the pore space. The data presented in the paper testify to the manifestation of these processes in the modern hydrogeochemical and geothermal conditions of the Jurassic‐Cretaceous sediments within the two oil fields and their vicinity. The petrophysical studies of the core samples and the hydrodynamic studies in the wells confirm that the reservoir properties of the productive strata are considerably heterogeneous. Despite the significant effect of the geodynamic factors, the analysis of the tracer data has not revealed any apparent spatial consistency of the presence (or absence) of a hydrodynamic connection between the wells and the locations of fractured and dynamically stressed zones. In our study, we have proposed and tested a method based on the analysis of morphotectonic features detectable in the depth maps of reference surfaces. This method is a useful additional tool for discovering and analyzing the relationships between the tectonic and hydrodynamic conditions of oil and gas fields.

Retrofitting strata property - a tool supporting long-term retrofit strategy

Strata property - ownership of apartments or townhouses consisting of private and commonly owned building components and areas - was established in Switzerland in 1965 and since has become very popular. But, well-needed retrofit work of these buildings is often postponed and long-term retrofit strategies are rarely considered. However, the low retrofit rate must increase to meet the global energy goals. Interviews and workshops with relevant actors showed that missing financial means are not the key issues for the low retrofit rate. Major challenges arise from a broad set of issues, such as difficult processes, unclear responsibility, insufficient communication, missing building information or underestimation of the commonly owned building components. “Luzerner Toolbox” provides eight folders that address the key clusters of challenges. Central to this toolbox are Excel-based tools, which transform accurate technical and financial information into a visual format. An ample diagram illustrates the remaining lifetime of the building parts and a graph relates upcoming retrofit costs and the annual payments into the contingency reserve fund with a forecast of the contingency reserve fund. As such, these tools assists in scheduling appropriate retrofit measures and establishing a balanced financial planning. But, various actors have reported that the retrofit timetable is too complex to be used in management firms. Feasibility studies and further research of their specific needs and work processes are needed to refine the tool accordingly. In a further study, interviews with management firms and architects are conducted to determine the key factors of a useful tool.

Transient Pressure and Rate Decline Analysis for Horizontal Well in Stress-Sensitive Composite Reservoir

The existence of stress sensitivity effect made the percolation mechanism of low-permeability reservoirs significantly complex. Further, numerous reservoirs have composite stratum properties in actual development procedure. This paper based on the concept of permeability stress sensitivity presents an unsteady flow model for horizontal well taking both stress sensitivity and composite reservoir into account. Analytic solutions for the transient pressure and the rate decline behaviors are obtained by comprehensive utilization of regular perturbation method, Laplace transformation, orthogonal transformation, and Stehfest numerical inversion. The example analysis verifies that the proposed model is reliable and practical. Likewise, there is a discussion of the influence of permeability modulus and other relevant parameters on the transient pressure and the rate decline for horizontal well in stress-sensitive composite reservoir. The work of this paper improved the previous researches and provided a more accurate basis for transient flow analysis and formation evaluation of this typical reservoir.

서울 오피스 빌딩 매매가격 결정요인 분석 : 부분매매를 중심으로

서울 오피스 빌딩 매매가격 결정요인 분석 : 부분매매를 중심으로

PETROLEUM GEOLOGY: SCIENCE AND PRACTICE IN THE 21TH CENTURY. NEW IDEAS AND PARADIGMS

Nowadays, it is vitally necessary that conceptually new methods be used in petroleum geology. The aim of this paper is to outline new trends and approaches in petroleum geology; to substantiate the necessity for rehabilitation cycles in the process of oilfield development, especially at its active stage; to define the perturbation threshold for equilibrium of a fluid-saturated system. In this paper, an empirical estimation is given of the value of critical perturbation of an equilibrium fluid-saturated system during the oilfield development, equal to formation depression of 5-8 MPa.
 The author’s conclusion is that at present efforts should be focused on the efficient science-based development of the active oilfields in order to produce the residual (hard-to-extract) oil in a soft, sparing and non-damaging way, as well as on discovering new hydrocarbon accumulations, including secondary ones, throughout the whole stratigraphic section, with all depth horizons and various rock-fluid associations, in regions where a well-developed diversified infrastructure is already available. The use of rehabilitation cycles will make it possible to restore the energy potential of the stratum and filtration properties of the rock. In the long run, it will provide for an increased longevity of the object and higher final oil recovery.

论地层性质及其测试方法

论地层性质及其测试方法