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Fracability Evaluation of Shale of the Wufeng-Longmaxi Formation in the Changning Area, Sichuan Basin

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Acta Geologica Sinica(English Edition) 2019年第4期93卷 996-1004页

作者： HUANG Cheng XU Tianyang JU Yiwen ZHU Hongjian JU Liting LI Wuyang Key laboratory of computational geodynamics Chinese Academy of SciencesCollege of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China

The fracturing technology for shale gas reservoir is the key to the development of shale gas *** makes much sense to study the mechanical properties and deformation characteristics of shale,due to its close relationship with the fracability of shale gas *** paper took marine shale in the Changning area,southern Sichuan Basin of China as the research *** on field profile and hand specimen observation,we analyzed the development of natural fractures and collected samples from Wufeng Formation and Longmaxi *** with the indoor experiment,we investigated the macroscopic and microscopic structural features and the remarkable heterogeneity of shale *** we illustrated the mechanics and deformation characteristics of shale,through uniaxial compression test and direct shear *** shale has two types of fracture modes,which depend on the angular relation between loading direction and the bedding ***,the Wufeng shale has a higher value of brittleness index than the Longmaxi shale,which was calculated using two methods,mechanical parameters and mineral *** the above results,we proposed a fracability evaluation model for shale gas reservoir using the analytic hierarchy *** influence factors,brittleness index,fracture toughness,natural fractures and cohesive force,are ***,under the control of normalized value and weight coefficient of each influence factor,the calculations results indicate that the fracability index of the Wufeng Formation is higher than that of the Longmaxi Formation in Changning area,southern Sichuan Basin.

关键词： marine shale mechanical properties fracability evaluation analytic hierarchy process Sichuan Basin

Numerical simulations on origin of Galilean moons' magnetic anomalies

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Science China Earth Sciences 2011年第12期54卷 1754-1760页

作者： JIAO LiGuo KUANG WeiJia MA ShiZhuang laboratory of computational geodynamics College of Earth Sciences Graduate University of Chinese Academy of Sciences Beijing 100049 China NASA Goddard Space Flight Center Greenbelt MD 20771 USA

Galileo mission detected the magnetic anomalies originated from Galilean *** anomalies are likely generated in the moons' interiors,under the influence of a strong ambient Jovian *** various possible generation mechanisms of the anomalies,we focus on magneto-convection and dynamos in the interiors via numerical *** mimic the electromagnetic environment of the moons,we introduce in our numerical model an external uniform magnetic field B0 with a fixed orientation but varying field *** results show that a finite B0 can substantially alter the dynamo processes inside the *** the ambient field strength B0 increases to approximately 40% of the field generated by the pure dynamo action,the convective state in the core changes significantly:the convective flow decreases by 80% in magnitude,but the differential rotation becomes stronger in much of the fluid layer,leading to a stronger field generated in the *** field morphologies inside the core tend to align with the ambient field,while the flow patterns show the symmetry-breaking effect under the influence of ***,the generated field tends to be temporally more stable.

关键词：卫星磁异常数值模拟伽利略起源磁场强度电磁环境对称性破缺发电机

Studying the viscosity of lower crust of Qinghai-Tibet Plateau according to post-seismic deformation

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Science China Earth Sciences 2009年第3期52卷 411-419页

作者： ZHANG ChaoJun CAO JianLing SHI YaoLin China Earthquake Network Center Beijing 100045China laboratory of computational geodynamics Graduate University of the Chinese Academy of SciencesBeijing 100049China

The viscosity of lower crust of Qinghai-Tibet Plateau on earth should be determined. It has become a predominant problem in quantitative research on geodynamics. Its order of magnitude will have a great influence on the results of quantitative modeling. To obtain the viscosity of lower crust of Qinghai-Tibet Plateau, this parameter was calculated by three methods. The first is based on the estimation on the temperature state of Qinghai-Tibet Plateau in the deep part, and the viscosity of lower crust of northern Plateau was recomputed with strain rate derived from rheology law and GPS observation. Effective viscosity of middle crust in Kunlun region is between 1020 and 1022 Pa·s, and that of lower crust is be- tween 1019 and 1021 Pa·s; the second is based on three kinds of rheological models used to fit the post-seismic deformation recorded by cross-over fault GPS sites set after Ms8.1 Kunlun earthquake in 2001. The viscosity of lower crust obtained by this method is of 1017 Pa·s order of magnitude. However, higher viscosity is required to fit the data of south fault better, and the lower one is required to fit the data of north fault better. The viscosity of lower crust, which was obtained by fitting the cross-over fault post-seismic deformation after Ms7.6 Luhuo earthquake in 1973, is of 1019 Pa·s order of magnitude. Non-linear relationship between effective viscosity and strain rate is ignored in the former research of effective viscosity. This research shows the difference of effective viscosity obtained from laboratory experiment, and shorter and longer time post-seismic deformation after large earthquakes can be explained in phase.

关键词： rheological model strain rate rheological law post-seismic deformation viscosity

Electrical Properties of Hydrous Forsterite Derived from First-Principles Calculations

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Chinese Physics Letters 2011年第5期28卷 289-291页

作者：王多君刘在洋易丽史保平 Key laboratory of computational geodynamics Graduate UniversityChinese Academy of SciencesBeijing 100049 Institute of Earthquake Science China Earthquake AdministrationBeijing 100039

We investigate electrical properties of anhydrous and hydrous forsterite crystalwith 3.2 wt%water by using firstprinciples *** calculation results indicate that the pressure weakly affects the electrical properties of anhydrous *** types of defect configurations involving the two hydrogen atoms in different positions are *** 1 involves the entrapment of two hydrogen atoms in a Mg vacancy,which demonstrates little effect on the electronic density of states(DoS)of the forsterite *** 2 corresponds to the replacement of one hydrogen atom into the Mg vacancy with the other one located in different orientations(free proton model).It is this configuration that can significantly change the DoS of the forsterite *** gap energy of the free proton model derived at different orientations is in the range of 0.693-1.007eV.

关键词： DoS vacancy configuration

Controlled analogue experiments on propagation of seismic electromagnetic signals

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Chinese Science Bulletin 2005年第17期50卷 1956-1961页

作者： HUANG Qinghua computational geodynamics laboratory Department of GeophysicsSchool of Earth and Space Sciences Peking University Beijing 100871China

This study presented a method of laboratory analogue experiments based on a geographical scaling model and a waveguide model to investigate the characteristics of the propagation of seismic electromagnetic signals in the crust and the atmosphere. Some controlled experiments were done to evaluate the possible influence on the experimental results from the background electromagnetic field, geo-graphical conditions, boundary effects, the source of elec-tromagnetic signals (position, magnitude, and frequency), and media conductivity. The reliability and the extensibility of the above analogue experimental method were also inves-tigated. This study indicated that such kind of analogue ex-perimental method provided an intuitionistic way of studying the propagation of seismic electromagnetic signals, which is one of the most difficult research topics in seismo-electro- magnetism.

关键词：地震电磁信号传播方式波导模式震源

Numerical Modeling of Porous Flow in Fractured Rock and Its Applications in Geothermal Energy Extraction

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Journal of Earth Science 2015年第1期26卷 20-27页

作者： Yucang Wang Shimin Wang Sheng Xue Deepak Adhikary Earth Science and Resource Engineering CSIROKenmore Qld 4069BrisbaneAustralia Key laboratory of computational geodynamics University of Chinese Academy of Sciences

Understanding the characteristics of hydraulic fracture, porous flow and heat transfer in fractured rock is critical for geothermal power generation applications, and numerical simulation can provide a powerful approach for systematically and thoroughly investigating these problems. In this paper, we present a fully coupled solid-fluid code using discrete element method （DEM） and lattice Boltzmann method （LBM）. The DEM with bonded particles is used to model the deformation and fracture in solid, while the LBM is used to model the fluid flow. The two methods are two-way coupled, i.e., the solid part provides a moving boundary condition and transfers momentum to fluid, while the fluid exerts a dragging force to the solid. Two widely used open source codes, the ESyS Particle and the OpenLB, are integrated into one code and paralleled with Message Passing Interface （MPI） library. Some preliminary 2D simulations, including particles moving in a fluid and hydraulic fracturing induced by injection of fluid into a borehole, are carried out to validate the integrated code. The preliminary results indicate that the new code is capable of reproducing the basic features of hydraulic fracture and thus offers a promising tool for multiscale simulation of porous flow and heat transfer in fractured rock.

关键词： discrete element method lattice Boltzmann method hydraulic fracturing geothermalenergy extraction multiscale modelling.

Deformation Localization-A Review on the Maximum-Effective-Moment(MEM) Criterion

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Acta Geologica Sinica(English Edition) 2015年第4期89卷 1133-1152页

作者： ZHENG Yadong ZHANG Qing HOU Quanlin School of Earth and Space Sciences Peking University Institute of Geolomechanics Chinese Academy of Geological Sciences Key laboratory of computational geodynamics Chinese Academy of Sciences

The essential difference in the formation of conjugate shear zones in brittle and ductile deformation is that the intersection angle between brittle conjugate faults in the contractional quadrants is acute （usually ～60°） whereas the angle between conjugate ductile shear zones is obtuse （usually 110°）. The Mohr-Coulomb failure criterion, an experimentally validated empirical relationship, is commonly applied for interpreting the stress directions based on the orientation of the brittle shear fractures. However, the Mohr-Coulomb failure criterion fails to explain the formation of the low-angle normal fault, high-angle reverse fault, and the conjugate strike-slip fault with an obtuse angle in the ~1 direction. Although it is ten years since the Maximum-Effective-Moment （MEM） criterion was first proposed, and increasingly solid evidence in support of it has been obtained from both observed examples in nature and laboratory experiments, it is not yet a commonly accepted model to use to interpret these anti- Mohr-Coulomb features that are widely observed in the natural world. The deformational behavior of rock depends on its intrinsic mechanical properties and external factors such as applied stresses, strain rates, and temperature conditions related to crustal depths. The occurrence of conjugate shear features with obtuse angles of -110~ in the contractional direction on different scales and at different crustal levels are consistent with the prediction of the MEM criterion, therefore -110° is a reliable indicator for deformation localization that occurred at medium-low strain rates at any crustal levels. Since the strain-rate is variable through time in nature, brittle, ductile, and plastic features may appear within the same rock.

关键词： anti-Mohr-Coulomb criterion features von Mises Criterion MEM-Criterion,homogeneous deformation deformation localization strain rate

Deep geodynamics of far field interconti- nental back-arc extension: Formation of Cenozoic volcanoes in northeastern China

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Acta Seismologica Sinica(English Edition) 2004年第Z1期17卷 1-8页

作者： SHI Yao-lin(石耀霖) ZHANG Jian(张健) laboratory of computational geodynamics Graduate School of Chinese Academy of Sciences Beijing 100039China Laboratory of Computational Geodynamics Graduate School of Chinese Academy of Sciences Beijing 100039China

There are three cases of variation of trench location possible to occur during subduction: trench fixed, trench ad- vancing, and trench retreating. Retreat of trench may lead to back-arc extension. The Pacific plate subducts at low angle beneath the Eurasia plate, tomographic results indicate that the subducted Pacific slab does not penetrate the 670 km discontinuity, instead, it is lying flat above the interface. The flattening occurred about 28 Ma ago. Geo- dynamic computation suggests: when the frontier of the subducted slab reaches the phase boundary of lower and upper mantle, it may be hindered and turn flat lying above the boundary, facilitates the retreat of trench and back-arc extension. Volcanism in northeastern China is likely a product of such retreat of subduction, far field back-arc extension, and melting due to reduce of pressure while mantle upwelling.

关键词： back-arc basin Cenozoic volcano geodynamics northeastem China

Viscous lithospheric structure beneath Sumatra inferred from post-seismic gravity changes detected by GRACE

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Science China Earth Sciences 2011年第8期54卷 1257-1267页

作者： WANG WuXing SHI YaoLin SUN WenKe ZHANG Jing Institute of Earthquake Science China Earthquake Administration Beijing 100036 China laboratory of computational geodynamics Graduate University of Chinese Academy of Sciences Beijing 100049 China

Satellite gravity data of the regional rheological structure of the lithosphere in the vicinity of Sumatra is used as evidence to enable a better understanding of the regional geodynamic *** data is interpreted using the theory of post-seismic viscoelastic *** post-seismic changes in the gravity field resulting from the 2004 M w 9.3 Sumatra earthquake were calculated from Gravity Recovery and Climate Experiment (GRACE) satellite data.A spatial Gaussian filter,500 km wide,was used in the *** results indicate that there were significant co-seismic jumps in both uplifted and subducted *** magnitude of the jump in the subducted zone was ～9 10 8 m/s 2,more significant than the ～2 10 8 m/s 2 jump observed in the uplifted ***,a positive gravity change occurred in the uplifted zone very soon after the *** rheological structure of the lithosphere has a great effect on deformation and its determination is a fundamental part of developing reliable numerical simulations in *** on the temporally-variable gravity field observed by GRACE,the viscous lithospheric structure of the Sumatra area is investigated with a self-gravitating,half space,viscoelastic earth *** estimated viscosity is of the order of 1.0 10 18 Pa·s and there are differences in the rheological parameters on the two sides of the *** factors that affect the viscosity are discussed in connection with the tectonic structure of the Sumatra area.

关键词：岩石圈结构苏门答腊岛 GRACE 重力变化震后粘性地球动力学环境苏门答腊地震