力学学报

2015, 47(6): 898-898.

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SENSITIVITY STUDY OF FLOWING GAS COMPOSITION FOR WELLS IN SHALE GAS RESERVOIR

Li Daolun, Zheng Deweny, Fang Chaohe, Zhang Longjun, Zha Wenshu, Lu Detang

Because of the ultra-low permeability of the shale-gas reservoir, the transient flow in these reservoirs can last many years and radial flow is very di cult to reach, which makes the pressure transient analysis impractical. Transientrate-analysis methods as a substitute for pressure transient analysis to determine reservoir parameters have become very popular in recent years. However, due to the absence of the flowing well pressure and low-frequency, low-resolution production data, diagnosis of production data su ers from uniqueness and uncertainty. Composition of di erent gas components change with time has been reported in the gas-condensate reservoirs and the shale-gas reservoirs. In this paper we use a compositional model incorporating extended Langmuir isotherm and apparent permeability to study flowing composition transient response. First, a dry gas compositional model is established to model flow of components in the shale-gas reservoirs. Then, fully implicit linearization of the equation system is employed to solve the nonlinear equation system based on unstructured gridding. Numerical simulation shows that adsorption gas content, porosity and permeability a ect the characteristics of flowing composition, composition change and composition derivative. Adsorption gas content determines drop speed of composition, the value of composition change and composition derivative for CH4 component. Permeability a ects composition transient response during early stage. However, during the medium and late stages, di erent permeabilities have the same influence on the composition transient response. The e ects of porosity and adsorption gas content on composition change and composition derivative are similar. However, small difference exists for the e ects of porosity and adsorption gas content on composition change with time at early stage. The findings in this paper would provide a new way to interpret the shale-gas reservoir parameters.

2015, 47(6): 899-905. doi: 10.6052/0459-1879-15-129

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NUMERICAL SIMULATION OF MULTI-FRACTURED HORIZONTAL WELL IN SHALE GAS RESERVOIR CONSIDERING MULTIPLE GAS TRANSPORT MECHANISMS

Fan Dongyan, Yao Jun, Sun Hai, Zeng Hui

Shale is a typical micro-nano-scale porous media, in which free gas and absorbed gas coexist, so traditional Darcy's law is unable to describe gas transport mechanisms of micro-nano-scale accurately. Based on double porosity model and discrete fracture model, the fractured horizontal well numerical model has been built in shale gas reservoir. Viscous flow, Knudsen di usion and surface di usion have been considered in shale matrix, while viscous flow and Knudsen di usion are considered in the natural fracture. The finite element method is applied to solve the model. The results show that the smaller intrinsic matrix permeability, the greater the e ect of surface di usion and Knudsen di usion. The properties of hydraulic fractures including fracture number, aperture, half-length and spacing, mainly a ect the early production. With the augment of those parameter values, the production rate and cumulative gas of multi-fractured horizontal well increase. Then the development of induced fractures and natural fractures has a significant e ect on the shale gas production and the production will be low when the natural fractures surrounding the horizontal well are closed or not developed.

2015, 47(6): 906-915. doi: 10.6052/0459-1879-15-064

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GAS DESORPTION-DIFFUSION-SEEPAGE COUPLED EXPERIMENT OF SHALE MATRIX AND MATHEMATIC MODEL

Guo Wei, Hu Zhiming, Zuo Luo, Gao Shusheng, Yu Rongze, Zeng Bo

Gas desorption-di usion-seepage coupled experiment was designed and carried out with Longmaxi shale samples collected from South of Sichuan, and both the gas flow characteristics and pressure propagation were then obtained. Shale gas desorption-di usion-seepage coupling mathematical model was derived and numerical solution of the mathematical model using finite difference method was obtained. Numerical simulation results compared with the experimental results show that the model can well describe the gas transport in the shale matrix. And shale matrix permeability, di usion coe cient, desorption constants and other factors can a ect the gas flow through shale matrix as well as pressure propagation, which should be taken into consideration in the development of shale gas reservoir. The presented mathematical model provides a new method to calculate the production capability of shale gas well.

2015, 47(6): 916-922. doi: 10.6052/0459-1879-15-068

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SHALE PERMEABILITY CORRECTION MODELS UNDER DIFFERENT SLIP BOUNDARY CONDITIONS

Zha Wenshu, Li Daolun, Wang Lei, Zhang Longjun, Zeng Yishan, Lu Detang

The scale of shale pore diameter is usually under the magnitude of nanometers, and the gas transport mechanisms existed in the nano-pores make the traditional methods based on Darcy's flow law unsuitable to describe the flow in tight-and shale-gas reservoirs. Navier-Stokes equations with slippery velocity boundary condition are usually used to expand the extent of Darcy's law, which make permeability formulas stress-related (called "apparent permeability"). Therefore, the permeability correction method becomes a hotspot of shale gas research. A general form of permeability correction method is deduced from second-order slip model of equation, and an Ng apparent permeability correlation is proposed based on apparent permeability Ng slip velocity model equations. The Ng formula can describe slip flow, transition flow, and free molecular flow (Kn < 88), and is concise and easy to use. According to the actual shale reservoir parameters and pore distribution system, the Kn range is calculated, which indicates that slip flow, transition flow, and free molecular flow exists in the shale gas flow. Based on the general form of permeability correction model, a comparison run is conducted. The results show that differences of permeability correction factor under di erent slip models increase with the increase of Kn. Beskok model and Ng model can both describe free molecular regime, however, the two models result in di erent well bottom hole pressure with shale of 10nm radius, and the difference becomes more apparent with shale of 1nm radius.

2015, 47(6): 923-931. doi: 10.6052/0459-1879-15-128

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MODEL FOR GAS TRANSPORT IN NANOPORES OF SHALE AND TIGHT FORMATION UNDER RESERVOIR CONDITION

Li Jing, Li Xiangfang, Li Yingying, Shi Juntai, Wu Keliu, Bai Yangai, Xu Min, Feng Dong

The formations of shale gas and tight gas are abundant in the nanopores of shale and tight sandstone, and the pores are partially saturated with water under reservoir conditions, so the evaluation of gas flow capacity by considering water saturation is important to gas production forecast. Based on the thermodynamic equilibrium theory between liquid and vapor in formation nanopores, we quantify the distribution of reservoir pores water under ultra-low water saturation condition, and establish the relation between water saturation and gas phase permeability. Results show that the impacts of water saturation on the gas flow can be divided in two forms: (1)bound water film in large pores will reduce the e ective pore diameter for gas flow; (2)capillary water in small pore will block the entire gas flow channel. And the e ect of water saturation on gas flow capacity cannot be ignored. In case that water saturation is 20%, the gas flow capacity will reduce 10%, compared with the dry conditions. Under the condition that water saturation is 40%, the gas flow capacity will be reduced by about 20%. The results calculated by the models in this paper are in agreement with the experimental results in a newly-published article.

2015, 47(6): 932-944. doi: 10.6052/0459-1879-15-185

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PRESSURE TRANSIENT ANALYSIS OF FRACTURED HORIZONTAL WELL IN SHALE GAS RESERVOIR

Zhu Guangpu, Yao Jun, Fan Dongyan, Zeng Hui

Shale gas reservoirs have received much attention for their potential in satisfying future energy demands. Compared to conventional gas reservoir, Shale gas reservoir is characterized by complicated nonlinear processes, including adsorption and desorption, pressure-dependent permeability and non-Darcy flow. To investigate the e ect of those nonlinear mechanisms, a combined dual-continuum and discrete fracture numerical well test model was developed to analyze the transient pressure. Desorption, pressure-dependent permeability of natural fractures and non-Darcy flow was respectively described by Langmuir isotherm equation, exponential model of permeability and Forchheimer equation. Galerkin finite element method was applied to solve the model. Flow regimes were divided and the e ect of nonlinear factors on pressure response was analyzed according to the well test curve. The results indicate that there are five flow regimes, including fracture linear flow, fracture radial flow, formation linear flow, formation radial flow, pseudo steady state of closed boundary. The shale gas desorption's e ect arising after interporosity flow happened, the bigger Langmuir adsorption volume is, the deeper groove shows on the derivative curve and the later pressure propagate to the border; Bigger pseudo-pressure drop and pseudo-pressure derivative were observed with greater pressure-dependent e ect in the later stage of well test curve; Non-Darcy flow in hydraulic fractures mainly a ecting the early time, the pseudo-pressure drop increased with increasing flow rate. The comparison with analytical solution and field engineering application prove the feasibility of the model.

2015, 47(6): 945-954. doi: 10.6052/0459-1879-15-229

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GAS TRANSPORT BEHAVIOR THROUGH MICRO FRACTURES OF SHALE AND TIGHT GAS RESERVOIRS

Wu Keliu, Li Xiangfang, Chen Zhangxing, Li Junjian, Hu Yuan, Jiang Liangliang

Gas transport mechanism is considerably complex in micro fractures of shale and tight gas reservoirs, which is caused by a fracture with nano-micro scales aperture. A unified model for gas transport in micro fractures of shale and tight gas reservoirs is proposed by coupling slip flow and Knudsen di usion, where, the ratios of the intermolecular collision frequency and the molecule-wall collision frequency to the total collision frequency are the weight coe cients of slip flow and Knudsen di usion, respectively. The present model considers the e ects of micro fracture shape and dimension on gas transport, and is validated with molecular simulation data published. The results show that: (1) the present model can describe all known gas transport mechanisms in micro fractures, including continuous flow, slip flow and transitional di usion; (2) the present model can reasonably describe the process of gradual mass transform for di erent gas transport mechanisms in micro fractures during di erent development stages of gas reservoirs; and (3) The micro fracture shape and dimension significantly impact gas transport, at the same micro fracture aperture, the greater the micro fracture width, the stronger the gas transport capacity, which is more obvious in the case with higher pressure and greater micro fracture aperture.

2015, 47(6): 955-964. doi: 10.6052/0459-1879-15-141

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RESEARCH ON THE GEOSTRESS CHANGE OF SHALE RESERVOIR VOLUME FRACTURING

Zhang Guangming, Liu Yong, Liu Ji, ong, Bao Jinqing, Jin Juan, Cheng Wei

Shale reservoirs have ultra-low porosity and permeability. Without creating complex fracture network, there will be no economical production. Volume fracturing is the primary treatment for shale reservoirs stimulation. The geostress and the di erential stress between the two horizontal principal stresses control the creation of fracture networks. Previous researches have shown that: (1) The small di erential stress between the two horizontal principal stresses eases the development of fracture network and vice versa; (2) The reservoirs geostress can be changed by the creation of hydraulic fractures. The numerical model about volume fracturing in shale gas reservoirs was constructed in which the pore pressure elements were used to simulate the behavior of porous media and the pore pressure cohesive elements were adopted to catch the characters of hydraulic fractures. The Texas Two-Step fracturing method was simulated in the model. The reservoirs stress distribution and change during the process of fracturing were obtained. The simulation results and the theoretical calculation are fit very well. The results of the simulation show that: (1) The generation of the hydraulic fractures reduces the stresses anisotropy; (2) The complex fracture networks could be created by means of the Texas Two-Step fracturing method. For the situation that the initial difference of the two horizontal principal stresses is large and the fracture networks could not be created by adopting the Texas Two-Step fracturing method, the triple and quartic stress "resonance" fracturing model were proposed. The reservoirs stress distribution and change during the process of fracturing were obtained. The area of fracture network was marked. The simulation results show that the triple and quartic stress "resonance" fracturing methods are e ective methods for the high stresses difference shale gas reservoirs.

2015, 47(6): 965-972. doi: 10.6052/0459-1879-15-274

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NUMERICAL SIMULATION OF HYDRAULIC FRACTURING BY A MIXED METHOD IN TWO DIMENSIONS

Wang Lixiang, Tang Dehong, Li Shihai, Wang Jie, Feng Chun

Hydraulic fracturing is widely used in exploitation of shale gas nowadays. It is of great significance to study the mechanism of fracturing process by numerical simulations. We present a mixed numerical model to solve hydraulic fracturing problems based on Continuous-Discontinuous Element Method (CDEM) and Finite Volume Method (FVM). In the mixed model, the CDEM is used for analysis of stress field and fracture propagation, and the FVM is used for analysis of pressure field in fracture. The three fields are all solved by explicit schemes and the coupling of them is implemented through data exchange. The model is verified against the classic KGD analytical solutions. Thereafter, it is validated by the results from a distinct element simulation. Finally, a hydraulic fracturing example related to complex fracture network is studied on the mechanism of fracturing process. The example shows bright future of the mixed numerical model for simulation and mechanism study of hydrauling fracturing.

2015, 47(6): 973-983. doi: 10.6052/0459-1879-15-097

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A ROCK BRITTLENESS EVALUATION METHOD BASED ON ENERGY DISSIPATION

Chen Yun, Jin Yan, Chen Mian

Brittleness evaluation plays an important role in both shale drilling and fracturing design. However, the definition of brittleness is unclear and the method for brittleness evaluation has no reliable theory to support. Based on stress-strain relationship, this paper uses energy method to evaluate rock brittleness. According to nonlinear crack-tip field theory in fracture mechanics, considering frontal zones as special shielding configurations of crack tip to describe energy dissipation during the process of fracturing. The ratio between the intrinsic cohesion energy and the steady-state resistance of frontal zones can be used as rock brittleness index. The study indicates that the more the energy dissipates, the lower the value of rock brittleness, and the plastic property will become even more obvious. This rock brittleness evaluation based on energy dissipation is essential in analyzing rock mechanics and selecting fracturing section.

2015, 47(6): 984-993. doi: 10.6052/0459-1879-15-156

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NUMERICAL MODELING OF FRACTURE NETWORK PROPAGATION IN SHALE RESERVOIRS

Zeng Qingdong, Yao Jun, Sun Zhixue

To investigate the forming mechanism of complex fracture network during the process of hydraulic fracturing in shale gas reservoirs, numerical simulation of fracture network propagation has been carried out. Taking the e ects of stress shadowing and natural fractures into account, coupled mathematical model of fluid flow in the wellbore and fractures is established. The stress and displacement discontinuity are solved by using displacement discontinuity method. New iterative algorithm of pressure and fracture widths has been constructed and solved with Newton iteration method. The mathematical model and numerical algorithm are validated by comparing numerical solutions to analytical solutions with consideration of leak-o e ect. Parameters sensitivity analysis is performed to study the influencing factors of hydraulic fractures propagation. As to simultaneous propagation of multiple cluster fractures: the smaller fracture spacing is, the more unevenly fracturing fluid is distributed to each fracture; the fracture near the heel of wellbore receives more fluid than other fractures and becomes wider; When taking the e ect of natural fractures into account, the smaller approaching angle is or the weaker stress anisotropy is, the more possibly hydraulic fractures change propagation direction and the more complex fracture networks become.

2015, 47(6): 994-999. doi: 10.6052/0459-1879-15-014

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THREE DIMENSIONAL DISCRETE-FRACTURE-CAVITY NUMERICAL WELL TEST MODEL FOR FRACTURED-CAVITY RESERVOIR

Wan Yizhao, Liu Yuewu

The fracture-cavity carbonate reservoir is developed with fractures and cavity in large scale and strongly heterogeneous. The fractures and cavity of large scale play a dominant role in reservoir fluid flow. Therefore, the multimedium models based on continuum theory are not suitable for the description of fluid flow. According to the geological features of the large-scale distribution of fracture and cavity, this paper presents a composite architecture of discretefracture-cavity model to describe the fluid flow in the reservoir. This model describes the fractures with plates, the cavity with irregular polyhedrons of large permeability and high porosity. Then, the fracture faces are discretized with triangle elements of two dimensions, and the cavity and matrix are discretized with tetrahedron of three dimensions. The seepage model of discrete-fracture-cavity is solved by mixed finite element method. The wellbore pressure response curve and pressure fields in three dimensions are obtained. The analysis of log-log type curve of wellbore pressure and pressure fields shows that six flow regimes may appear in the model. The e ects of the di erent parameters to log-log type curve are analyzed. A filed data example is analyzed by the present model.

2015, 47(6): 1000-1008. doi: 10.6052/0459-1879-15-038

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EXPERIMENTAL INVESTIGATION OF THE VIBRATION CHARACTERISTICS OF HYDROFOIL IN CAVITATING FLOW

Gao Yuan, Huang Biao, Wu Qin, Wang Guoyu

Cavitation is a kind of complex and unsteady hydrodynamics phenomenon occurred in hydraulic machinery. The cavity shedding leads to structure vibration which a ects the e ciency, noise and safety of hydraulic machinery, so it is important to study the structure vibration in cavitating flow. The characteristics of the cavity shape around a NACA66 hydrofoil and the vibration response are analyzed experimentally. A high-speed video camera is used to visualize the unsteady cavitating flow patterns and a laser doppler vibration meter is used to measure the vibration velocity. The highspeed video camera and the laser doppler vibration meter can be triggered synchronously by a synchronization system. The characteristics of cavity shape and vibration in di erent cavitation stages are analyzed both in time field and frequency field. Synchronous results of cloud cavitation are studied. It is found that as the cavitation number decreases, four stages of cavitation are visualized in which are non-cavitation, cavitation inception, sheet cavitation and cloud cavitation. The vibration amplitude of the hydrofoil increases as the cavitation number decreases. Cavities shedding leads to vibrations whose dominant frequencies are same with the frequencies of cavities shedding at sheet cavitation and cloud cavitation stages. At the cloud cavitation stage, the vibration is high-frequency and low-amplitude when the attached cavity develops. At the stages of cavity pulsation and cavity shedding, the vibration is low-frequency and high-amplitude.

2015, 47(6): 1009-1016. doi: 10.6052/0459-1879-15-173

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AN EXPERIMENTAL STUDY ON THE INFLUENCE OF THE PHASE DIFFERENCE ON THE MEAN THRUST OF TWO PLUNGING WINGS IN TANDEM

Gong Wuqi, Jia Bobo, Xi Guang

An experimental study is performed to investigate the e ects of phase difference on the mean thrust coe cient of two wings in tandem undergoing a two-dimensional (2-D) plunging motion in a low Reynolds number water tunnel. A 3-D force sensor and a 2-D digital particle image velocimetry (DPIV) are used to measure the wing thrust force and leading edge vortex (LEV) around the wings, respectively. The mean thrust coe cient of the forewing follows a sinusoidal curve when the phase difference changes from 0° to 360°.The increase of the mean thrust coe cient of the forewing is caused by the LEV and stagnation region of the hindwing enhancing the jet velocity behind the forewing and its e ective angle of attack. The curve of the mean thrust coe cient of the hindwing has a V-shaped feature as the phase difference increases. The decreased coe cient in the bottom of the V-shaped curve is caused by the vortex shed from the forewing restraining the LEV formation of the hindwing and reducing its e ective angle of attack. When the spacing distance is half chord and phase difference is 290°, the combined mean thrust coe cient of the forewing and hindwing can reach the maximum value of 0.667, over twice the reference single wing value (2×0.255).

2015, 47(6): 1017-1025. doi: 10.6052/0459-1879-14-378

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A DEFORMATION-INFILTRATION-DISPERSION COUPLING MODEL FOR THE SLURRY INFILTRATION COMPUTATION IN SATURATED SAND

Wu Di, Zhou Shunhua, Li Yaochen

Soil deformation and water seepage are ignored in the computation of slurry infiltration in traditional method. In this paper, the particle dispersion equation coupled with seepage velocity is derived according to the particle mass conversation, which highlights the dynamic properties of the suspended particles transport and deposition. The continuity equation for the suspension is proposed by modifying the water continuity equation in Biot's consolidation theory considering the e ect of particle deposition in slurry. Based on this, non-linear governing equations for slurry infiltration coupling deformation, infiltration and dispersion are derived and the corresponding variational principles are established. Finite element model based on the principles is established and the equations are solved with both incremental and iterative techniques. Computational results are validated by predicting the data from one-dimensional model test, and better agreement with the experimental data is shown compared to the traditional method which only considered particle convection and dispersion. The slurry infiltration in slurry trench is calculated with the method proposed in this paper. The deposition amount of slurry particles grows with the increasing depth, which indicates that a strict vertical degree control is needed during the shallow slurry trench construction. The excavating schedule can be determined considering the filled extent by the slurry particles according to the computation.

2015, 47(6): 1026-1036. doi: 10.6052/0459-1879-15-011

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NUMERICAL MODEL FOR IDENTIFICATION OF INTERNAL DEFECT OR INCLUSION BASED ON EXTENDED FINITE ELEMEMT METHODS

Jiang Shouyan, Du Chengbin

In the traditional structure detection method, it is generally required to sample the structure by drilling, which will lead to the structure with some additional damage. However, the nondestructive testing method will not destroy the structure itself in the detection process. This paper proposes an approach for detecting an internal defect or inclusion by using the extended finite element methods (XFEM) and the artificial bee colony (ABC) algorithm to provide a new way for the nondestructive testing of the structure. The XFEM approximation contains enriched elements in the enriched sub-domain for capturing discontinuities. The method can reflect the location and size of the defect or inclusion by the level set function without re-meshing. Thus, the main advantage of the proposed approach is that at each iteration process, the XFEM alleviates the need for remeshing the domain, and the ABC algorithm can e ectively avoid the appearance of the local optimum by the global and local searching strategy. The XFEM combined with ABC intelligent optimization algorithm can e ectively reduce the amount of calculation for inverse analysis. The results show that the proposed approach can e ectively detect the internal defect or inclusion in materials.

2015, 47(6): 1037-1045. doi: 10.6052/0459-1879-15-134

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DILATED POLYHEDRA BASED DISCRETE ELEMENT METHOD AND ITS APPLICATION OF ICE LOAD ON CYLINDRICAL PILE

Liu Lu, Long Xue, Ji Shunying

With the polyhedron elements with complex geometric shapes, the linear contact force model cannot precisely obtain the contact force and its direction and the contact deformation under various contact patterns. Due that dilated polyhedral element can be generated with superposing one dilating sphere on the surface of one basic polyhedron in the Minkowski sum theory to construct the geometric shape of irregular particle accurately, and then its contact detection between particles can be calculated easily, considering di erent contact patterns between vertices, edges and planes of the dilated polyhedral elements, a unified nonlinear viscoelastic contact force model is developed. In this model, the equivalent radius of curvature is introduced to calculate the elastic contact sti ness in normal direction. Meanwhile, the viscous force and the elastic force in tangential direction are simplified based on the contact force model of spherical element. To simulate the sea ice floes in broken ice region, the sea ice elements are generated randomly with the Voronoi tessellation algorithm. The ice loads on a vertical cylinder pile are simulated with the dilated polyhedral elements considering the buoyancy and drag forces of current. Moreover, the influences of ice velocity and ice floe size on the ice of pile are determined, and the distribution of ice load around the cylindrical pile is obtained. Finally, the limitation of the present dilated polyhedral element and its further modification are discussed.

2015, 47(6): 1046-1057. doi: 10.6052/0459-1879-15-121

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HEMODYNAMIC PARAMETERS ANALYSIS FOR CORONARY ARTERY STENOSIS OF INTERMEDIATE SEVERITY MODEL

Liu Zhaomiao, Nan Siqi, Shi Yi

This paper studies the e ects of coronary artery stenosis of intermediate severity on atherosclerotic process using fluid-structure interaction method. The aim of the study was to analysis the impact of area stenosis (AS = 50%, 65%, 75%) and lesion length (LL = 10 mm, 15 mm, 20 mm) on hemodynamic parameters. Through numerical simulations, it is found that a big margin of oscillating wall shear stress was generated in the branch of coronary artery stenosis and a low wall shear stress was generated in the downstream of stenosis when area stenosis and lesion length increase. The length of the recirculation zone downstream of the stenosis will present with S-shaped growth and the maximum shear rate will grow as parabolic at the same time. In addition, stenosis can bring about a significant decline in pressure. Hemodynamic parameters results show that, intermediate severity area stenosis and lesion length are the factors may cause thrombosis, clinical should attach importance to it.

2015, 47(6): 1058-1064. doi: 10.6052/0459-1879-15-085

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BIOMECHANICAL MODEL OF THE VETIBULE AND SEMICIRCULAR CANALS OF GUINEA PIG

Su Yingfeng, Sun Xiuzhen, Liu Yingxi, Xin Xiaoyan, Shen Shuang, Yan Zhiyong, Yu Shen

The vestibular system, the most important organ to maintain the human body balance, involves three systems, including the vestibular, visual and proprioception. Because of its fine structure and deep location of the vestibule and the three semicircular canals, the traditional method was di cult to meet the positioning, qualitative and quantitative research of modern vestibular medicine, while biological numerical simulation has the advantages in modern otology, in which it is important to establish an accurate biological numerical model. Based on two-dimensional anatomical data of guinea pig inner ear by serial tissue sections, three-dimensional biological numerical model of the vestibular system containing the vestibule and the three semicircular canals was established and the spatial structure and size of the model was consistent with the anatomic observation. Furthermore, numerical simulation of the caloric test was carried out on the model and biomechanical characteristics of top of semicircular canal crest were described quantitatively with the parameters including displacement, velocity and pressure under the di erent environment temperature excitation and the results were in agreement with the clinical observation. In short, it was feasible to reconstruct a biological numerical model of the vestibular system based on the two-dimensional anatomical data by continuous tissue slicing technique and the biological model meets the needs of positioning, qualitative and quantitative research of the vestibular and semicircular canals balance function.

2015, 47(6): 1065-1072. doi: 10.6052/0459-1879-15-140

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CHARACTERIZATION OF ROCK MICROSTRUCTURE USING 3D X-RAY COMPUTED TOMOGRAPHY

Xue Huaqing, Xu Ruina, Jiang Peixue, Zhou Shangwen

The investigation on microstructure of rock is critical to the basic geology research in unconventional oil and gas reservoir, such as evolution, occurrence state of oil and gas, migration patterns and seepage characteristics. The advantages of pore structure characterization by computed tomography (CT) are multi-scale and without damage. The tar sand, tight sand and shale were scanned by the CT, and the results were compared between CT scan characterizations and normal measurements to show that the mineral total components are really close and the size distributions of mineral are overall small difference, and large difference in the mineral size less than 96 1m between CT scan and the sieving method on tar sand. The pore structure of tight sand was observed by the CT images. Due to the di erent measurements and sample size, the porosity tested by CT scan, is a little more. The layer structure of shale can be found by micro CT images, but the microstructure of pore are not distinguished by the micro CT. Compared with normal methods, the TOC and pyrite mineral are measured by the Nano CT scan, but the porosity test is smaller. It is due to the resolution of Nano CT is not high enough and the grey value between organic matter and pore are not easily separately.

2015, 47(6): 1073-1078. doi: 10.6052/0459-1879-15-102

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REVIEW OF THE NINTH NATIONAL SYMPOSIUM ON DYNAMICS AND CONTROL FOR YOUNG SCHOLARS

Shen Jianwei, Sun Zhongkui, Zhan Shige, Zhang Panfeng, Xu Jian

This paper brief introduced the ninth national symposium on dynamics and control for young scholars, Reports of this symposium were reviewed, and some constructive suggestions were put forward.

2015, 47(6): 1079-1083. doi: 10.6052/0459-1879-15-366

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