Enhancing the resolution of sparse rock property measurements using machine learning and random field theory

The travel time of rock compressional waves is an essential parameter used for estimating important rock properties,such as porosity,permeability,and lithology.Current methods,like wireline logging tests,provide broad measurements but lack finer resolution.Laboratory-based rock core measurements offer higher resolution but are resource-intensive.Conventionally,wireline logging and rock core measurements have been used independently.This study introduces a novel approach that integrates both data sources.The method leverages the detailed features from limited core data to enhance the resolution of wireline logging data.By combining machine learning with random field theory,the method allows for probabilistic predictions in regions with sparse data sampling.In this framework,12 parameters from wireline tests are used to predict trends in rock core data.The residuals are modeled using random field theory.The outcomes are high-resolution predictions that combine both the predicted trend and the probabilistic realizations of the residual.By utilizing unconditional and conditional random field theories,this method enables unconditional and conditional simulations of the underlying high-resolution rock compressional wave travel time profile and provides uncertainty estimates.This integrated approach optimizes the use of existing core and logging data.Its applicability is confirmed in an oil project in West China.

Hydrodynamic analysis of clastic injection and hydraulic fracturing structures in the Jinding Zn-Pb deposit,Yunnan,China

The Jinding Zn-Pb deposit has been generally considered to have formed from circulating basinal fluids in a relatively passive way, with fluid flow being controlled by structures and sedimentary facies, similar to many other sediments-hosted base metal deposits. However, several recent studies have revealed the presence of sand injection structures, intrusive breccias, and hydraulic fractures in the open pit of the Jinding deposit and suggested that the deposit was formed from explosive release of overpres- sured fluids. This study reports new observations of fluid overpressure-related structures from under- ground workings （Paomaping and Fengzishan）, which show clearer crosscutting relationships than in the open pit. The observed structures include： 1） sand （--rock fragment） dikes injecting into fractures in solidified rocks; 2） sand （~rock fragment） bodies intruding into unconsolidated or semi-consolidated sediments; 3） disintegrated semi-consolidated sand bodies; and 4） veins and breccias formed from hydraulic fracturing of solidified rocks followed by cementation of hydrothermal minerals. The development of ore minerals （sphalerite） in the cement of the various clastic injection and hydraulic fractures indicate that these structures were formed at the same time as mineralization. The development of hydraulic fractures and breccias with random orientation indicates small differential stress during mineralization, which is different from the stress field with strong horizontal shortening prior to miner- alization. Fluid flow velocity may have been up to more than 11 m/s based on calculations from the size of the fragments in the clastic dikes. The clastic injection and hydraulic fracturing structures are interpreted to have formed from explosive release of overpressured fluids, which may have been related to either magmatic intrusions at depth or seismic activities that episodically tapped an overpressured fluid reservoir. Because the clastic injection and hydraulic structures are genetically linked with the mineralizing fluid source, they can be used as a guide for mineral exploration.

Numerical simulation of tectonic stress and strain rate fields in the northeastern margin of the Tibetan Plateau in association with major fault zones

A series of large strike-slip and thrust faults have developed in the northeastern margin of the Tibetan Plateau since the Late Cenozoic,with strong and active tectonic activity and frequent occurrences of large earthquakes.Modulation of regional tectonic stress distribution,strain fields,and seismic hazards has not been well studied.This study introduces a three-dimensional viscoelastic finite element numerical model to calculate crustal stress and strain rate fields under current tectonic loading.The preliminary results show that the direction of the horizontal principal compressive stress rate and compressive horizontal principal strain rate in the northeastern margin of the Tibetan Plateau rotate clockwise as a whole,and this rotation is more significant in the southeast direction because of the block of the Alxa and the Ordos blocks.The NE-SW horizontal principal compressive stress rate and SE horizontal tensile stress rate dominate the entire study region.The maximum value of the horizontal principal compressive strain rate at a depth of 0 km in the model is approximately 4×10^(-8)yr^(-1)near the East Kunlun fault and is smaller in the stable Alxa and Ordos blocks at approximately 1×10^(-8)yr^(-1).The calculated regional stress state is in good agreement with the actual focal mechanism solution,indicating that strike-slip and thrust stress fields dominate the northeastern margin of the Tibetan Plateau.The Altyn Tagh,East Kunlun,and Haiyuan faults demonstrate that the maximum shear strain rate gradually decreases eastward,and the decrease in the maximum shear strain rate value is absorbed by orogenic uplift and crustal shortening at its boundaries.The western section of the Altyn Tagh fault,west-to-middle sections of the East Kunlun fault,and west-to-middle sections of the Haiyuan fault will have high seismic hazards in the future.

Construction of highly dispersed Pt single sites and high-efficiencyheterocatalysis silylation of alcohols with silanes

The construction of silicon-oxygen bonds has been highlighted as an exciting achievement in organosilicon and green chemistry,but their synthetic efficiency has great improvement potential,so it is crucial to explore and achieve an effective approach for synthesizing such compounds.In this study,we successfully prepared the highly dispersed platinum single-atom catalyst(Pt SAC/N-C)through a coordination-assisted strategy with a mixture of ligands(H2bpdc and H2bpydc),which were used for the Osilylation of alcohols with silanes.The strong coordination between Pt2+and the Pyridine N at the skeleton of UiO-67 plays a critical role in accessing the atomically isolated dispersion of Pt sites.Without the assistance of the H2bpydc ligands,the Pt/UiO-67-bpdc precursor is prone to aggregation during the pyrolysis process,resulting in the formation of Pt nanoparticles.Aided by advanced characterization techniques of high-angle annular dark-field scanning transmission electron microscopy(HAADFSTEM)and X-ray absorption fine structure(XAFS)spectroscopy,it has been demonstrated that atomically dispersed Pt was formed on the UiO-67 through a local structure of four-coordinated Pt-N4,exhibiting a high actual Pt loading content(0.6962 wt.%).In the oxidation of silanes,the Pt SAC/N-C catalyst showed a high turnover frequency(TOF)value(up to 9,920 h−1)when the catalyst loading decreased to 0.005%.Excellent performance was maintained during recycling experiments,indicating high stability of the catalyst.

关于我国地震数值预报路线图的设想——汶川地震十周年反思

汶川地震发生已经十年了.汶川地震造成了巨大损失,但是汶川地震未能预测,是中国地震工作者心头永远的痛,对地震预测研究的反思是一个重要课题.中国地震局系统反思报告认为,＂汶川地震未能预测,一是地震成因尚不清楚;二是地震前兆机理尚不清楚;三是经验预报的局限性和不确定性;四是地震前兆时空演化特征尚不十分清楚;五是尚未形成全球地震预测研究机制[1]＂.反思注意到＂地震预测基础性研究落后＂.

Diatomic active sites nanozymes:Enhanced peroxidase-like activity for dopamine and intracellular H2O2 detection

Considering intracellular hydrogen peroxide(H_(2)O_(2))plays pivotal roles in the regulation of serial biological processes,the in-situ detection of intracellular H2O2 has attracted an extensive attention.In the present work,an atomically dispersed diatomic active sites Nanozymes(FeN_(3)/PtN_(4)-single-atom nanozymes(SAzyme))was prepared exhibiting enhanced peroxidase-like activity.The obvious synergistic effect between Fe-Pt heteronuclear diatomic active sites was confirmed by series of characterization and density functional theory(DFT).The peroxidase-like activity of Fe-sites could be substantially enhanced by the bonded Pt-sites via the modulation effect.As a consequence,the gap between the d-band centre(εd)of Fe 3d orbitals and the Fermi energy level was narrowed and the electronic interaction could be strengthened,leading to a lower free energy barrier and a lower activation energy as well as fortified metal-O bonding in the kinetic pathway.Therefore,the constructed FeN3/PtN4-SAzyme exhibited higher peroxidase-like activity than that of FeN4-SAzyme.The FeN3/PtN4-SAzyme-assisted oxidation of 3,3',5,5'-tetramethylbenzidine(TMB)facilitated the colorimetric detection of dopamine(DA),an important biomolecule.The linear detection range and limit of detection(LOD)of DA and H_(2)O_(2) were 1-10 μM,0.01-1.0 mM and 0.109 μM,7.97 μM,respectively.In addition,the constructed SAzymes were also applied for the in-situ detection of intracellular H2O2,expanding the application scope of the newborn SAzymes.

Preliminary analysis of earthquake probability based on the synthetic seismic catalog

The analysis of seismic hazards relies on the statistical analysis of historical seismic data and the instrumental seismic catalog to obtain the regional earthquake recurrence interval and earthquake probability.The accuracy of analysis thus depends strongly on the completeness of the seismic data used.However,available seismic catalogs are too short or incomplete for the reliable analysis of the statistical characteristics of earthquakes.If a long-term synthetic seismic catalog can be generated using a physics-based numerical simulation,and the simulation results match the crustal deformation,seismicity,and other observations,then such a synthetic catalog helps us to further understand the characteristics of seismic activity and analyze the regional seismic hazard.In this paper,taking the northeastern Tibetan Plateau as a case study,we establish a three-dimensional visco-elastoplastic finite-element model to simulate earthquake cycles and the spatiotemporal evolution of earthquakes on the model fault system and obtain a seismic catalog on a time scale of tens of thousands of years.On the basis that the model satisfies the regional geodynamics of the northeastern Tibetan Plateau,we analyze seismicity on the northeastern Tibetan Plateau using the simulated synthetic earthquake catalog.The characteristics of earthquake recurrence at different locations and different magnitudes,and the long-term average probability of earthquake occurrence within the fault system on the northeastern Tibetan plateau are studied.The results are a reference for regional seismic hazard assessment and provide a basis for the physics-based numerical prediction of earthquakes.