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11.
Shixi Bulge of the central Junggar Basin in western China is a unique region that provides insight into the geological and geochemical characteristics of large-scale petroleum reservoirs in volcanic rocks of the western Central Asian Orogenic Belt. Carboniferous volcanic rocks in the Shixi Bulge mainly consist of striped lava and agglomerate, as well as breccia lava and tight tuff. Volcanic rocks differ in porosity and permeability. Striped lava exhibits the highest porosity (average: 14.2%) but the lowest permeability (average: 0.67 × 10−15 m) among the rock types. Primary gas pores are widely developed and mostly filled. Secondary dissolution pores and fractures are two major reservoir storage spaces. Capillary pressure curves suggest the existence of four pore structure types of reservoir rocks. Several factors, namely, lithology, pore structure, and various diagenesis, govern the physical properties of volcanic rocks. The oil is characterized by a high concentration of tricyclic terpane, a terpane distribution of C23 < C21 > C20, and sterane distributions of C27 < C28 < C29 and C27 > C28 < C29. Oil and gas geochemistry revealed that the oil is a mixture derived primarily from P2w source rock and secondarily from P1j source rock in the sag west of Pen-1 Well. The gases are likely gas mixtures of humic and sapropelic organic origins, with the sapropelic gas type dominant in the mixture. The gas mixture is most likely cracked from kerogen rather than oils. The Carboniferous volcanic reservoirs in Shixi Bulge share some unique characteristics that may provide useful insights into the various roles of different volcanic reservoir types in old volcanic provinces. The presence of these reservoirs will undoubtedly encourage future petroleum exploration in volcanic rocks up to the deep parts of sedimentary basins. 相似文献
12.
This paper deals with numerical modeling of the compressive behavior of granite rock under high strain rate dynamic loading and wide range of confining pressure. For this end, a constitutive model based on damage mechanics and viscoplasticity for rock is formulated and implemented in explicit dynamics FEM. The viscoplastic part is based on a simple power law type yield criterion that incorporates the rate-dependency with a linear viscosity term. Moreover, a Rankine type of tensile cut-off is employed. The damage part of the model is formulated with separate scalar damage variables in tension and compression. The model is calibrated for Kuru granite and validated with the experimental data from dynamic compression tests at the strain rate of 600 1/s up to 225 MPa of confining pressure. The numerical simulations demonstrate that, despite the underlying continuum modeling approach, the model captures the correct experimental failure modes, including the transition from single-to-multiple fragmentation, as well as the dynamic compressive strengths at different confining pressures. 相似文献
13.
Reservoir stimulation requires a model to evaluate the fracture path and closure for the simultaneous or sequential propagation of the hydraulic fracture (HF). This paper presents a fluid-solid coupled model to simulate multi-stage HF propagation. A non-linear joint model is proposed to evaluate the fracture closure when the created fractures are elastically propped. HF closure continues until the balance of external stress matches the proppant's resistance. The reservoir along the horizontal wellbore is not stimulated equally by the multi-stage fracturing. The HFs in the subsequent stage are ‘repelled’ and restrained by the HFs in the previous stage. 相似文献
14.
Prediction of Floor Water Inrush: The Application of GIS-Based AHP Vulnerable Index Method to Donghuantuo Coal Mine,China 总被引：6，自引：0，他引：6
Qiang Wu Yuanzhang Liu Donghai Liu Wanfang Zhou 《Rock Mechanics and Rock Engineering》2011,44(5):591-600
Floor water inrush represents a geohazard that can pose significant threat to safe operations for instance in coal mines in
China and elsewhere. Its occurrence is controlled by many factors, and the processes are often not amenable to mathematical
expressions. To evaluate the water inrush risk, the paper proposes the vulnerability index approach by coupling the analytic
hierarchy process (AHP) and geographic information system (GIS). The detailed procedures of using this innovative approach
are shown in a case study in China (Donghuantuo Coal Mine). The powerful spatial data analysis functions of GIS was used to
establish the thematic layer of each of the six factors that control the water inrush, and the contribution weights of each
factor was determined with the AHP method. The established AHP evaluation model was used to determine the threshold value
for each risk level with a histogram of the water inrush vulnerability index. As a result, the mine area was divided into
five regions with different vulnerability levels which served as general guidelines for the mine operations. The prediction
results were further corroborated with the actual mining data, and the evaluation result is satisfactory. 相似文献
15.
前陆冲断带复杂构造解析与建模——以准噶尔盆地南缘第一排背斜带为例 总被引：8，自引：2，他引：6
构造解析应从构造的变形机制、变形过程、变形量和变形时间四个方面入手,合理的构造解释方案是构造解析的基础,论文将等倾角区划分和轴面分析等几何学方法应用到地震解释中,从以上4个方面对准噶尔盆地南缘第一排背斜带做了系统的构造解析。地层结构揭示第一排背斜带深部发育楔状构造,楔状构造由5个古生界—中生界组成的断层转折褶皱叠加而成,是潜在的勘探目标群。在构造楔沿侏罗系西山窑组煤层向北扩展过程中,台阶状逆断层的大部分位移量沿构造楔顶部的反冲断层向南消减,另一部分位移量则沿西山窑组煤层向北传递至第二排背斜带,在总位移量保持稳定的前提下,第一排背斜带和第二排背斜带在走向上的此消彼长,反映位移量在南、北两个方向上的转换。 相似文献
16.
Tanan sub-basin is an active-fault bounded basin. The spatial distribution and temporal evolution of depositional systems were significantly influenced by tectonics. Fault movement and stages of basin development controlled the subsidence rates and the potential for erosion and the rate of sediment supply. Distinct stages of rift evolution during the early Cretaceous can be recognized, namely the early syn-rift, rift climax and late syn-rift stages. Three types of lacustrine sequence, consisting of distinctive depositional systems, are distinguished: (1) the early syn-rift sequences (SQ1 + SQ2), which are composed mainly of fan delta and shallow lacustrine depositional systems; (2) the rift climax sequences (SQ3) which developed in response to rapid and differential tectonic subsidence rates, and consist of fan delta, deep lacustrine and sublacustrine fan depositional systems; and (3) the late syn-rift sequences (SQ4) which are comprised of braided-delta and shallow lacustrine depositional systems. Each of the three lacustrine sequence architectures stands for a particular stage of basin fill and reflects variable rates of basin subsidence. Within each sequence, depositional systems and their stacking patterns are interpreted to have been a function of the interaction between tectonics and sediment supply. Differential subsidence across the basin, related to rotation of fault blocks, resulted in the formation of distinct paleomorphologies in different structural settings. These settings were fault-scarp zones controlling the development of fan-deltas, fault-terrace zones controlling the development of fan-delta and sublacustrine fans, half-graben dip-slope zones controlling the development of braided river and braided deltas, and intra-basinal fault-break zones controlling the development of sublacustrine fans. During the late syn-rift stage, active tectonism, displacement on the boundary faults had ceased. At this stage the depositional systems and their stacking patterns were dominantly related to the sediment supply rates, and not to tectonic activity. 相似文献
17.
Zhi Wang Jian Wang Zhiliang Chen Yuping Liu Runqiu Huang Shunping Pei Qingzhi Zhang Wenqing Tang 《Gondwana Research》2011,19(1):202-212
Seismic imaging together with global positioning system (GPS) and crustal stress data analyses show that the Mw7.9 2008 Wenchuan earthquake occurred within a distinct area of high crustal stress (～ 17.5 MPa) and high Poisson's ratio (7–10%) anomalies centered on the Longmen-Shan (Shan means Mountain in Chinese) tectonic fault belt. Low P-wave and S-wave velocities in the southwest (SW) segment contrast with high-velocity anomalies in the central portion (CP) and northeast (NE) segment within the uppermost ～ 15 km depths along the tectonic fault belt, though a presumably ductile zone with low-velocity anomalies separates the CP and NE segment. The rupture initiated near the southwestern end of the CP at a zone of high Poisson's ratio (σ) which extends down into the lower crust. These low-velocity and high-σ anomalies immediately below the source hypocenter, together with the high crustal stress, indicate the presence of high-pressure fluids from the lower crust, which might have reduced the mechanical strength of the fractured rock matrix and triggered the earthquake. Our study suggests that the structural heterogeneity and high crustal stress played an important role in the nucleation of the Wenchuan earthquake and its rupture process. 相似文献
18.
Geostatistical techniques were used to evaluate the differences in the geochemistry of metals in the marine sediments along the Eastern Brazilian continental margin along the states of Ceará and Rio Grande do Norte (Northeastern sector) and Espírito Santo (Southeastern sector). The concentrations of Al, Fe, Mn, Ba, Cd, Cu, Cr, Ni, Pb, V, Hg, and Zn were obtained from acid digestion and quantified using flame atomic absorption spectrometry (AAS), inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The metals showed a similar order of concentration: Al > Fe > Ba > Mn > V > Ni > Pb > Cr > Zn > Cu, in both the Ceará; and Rio Grande do Norte shelf regions but different in the Espírito Santo shelf (Fe > Al > Mn > Ba > Zn > V > Cr > Ni > Pb > Cu. The concentrations of Hg and Cd were below the detection limit in all areas. A multivariate analysis revealed that the metals of siliciclastic origin on the continental shelf of Ceará are carried by Al. In addition, a large portion of metal deposits is connected to the iron and manganese oxides on the continental margin of Rio Grande do Norte. The metals from the continental supply on the coast of Espírito Santo (Cu, Ni, Ba, and Mn) are associated with Al; whereas Cr, Pb, V, and Zn are associated with iron in this southern area. Geochemical evaluations are needed to distinguish the origin and mineralogical differences of marine sediments within the regions. Scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) applied to the sediments from the coast of Ceará showed the morphological diversity of sediment grains: biological fragments, multifaceted particles, aggregates, and crystals occurred in the three regions analyzed. Among these grains, calcite, Mg-calcite, and aragonite were predominant in the northeastern sector, whereas silicates and other minerals were predominant the southeastern sector. Mg, K, Ti, and Zr as well as the lanthanides La and Ce were identified using SEM/EDS and added to the geochemical analysis of the data. 相似文献
19.
This paper describes application of a fast inversion method to recover a 3D susceptibility model from magnetic anomalies. For this purpose, the survey area is divided into a large number of rectangular prisms in a mesh with unknown susceptibilities. Solving the full set of equations is substantially time consuming, and applying an algorithm to solve it approximately can reduce the time significantly. It is shown that the Lanczos bidiagonalization method can be an appropriate algorithm to solve a Tikhonov cost function for this purpose. Running time of the inverse modeling significantly decreases by replacing the forward operator matrix with a matrix of lower dimension. A weighted generalized cross validation method is implemented to choose an optimum value of a regularization parameter. To avoid the natural tendency of magnetic structures to concentrate at shallow depth, a depth weighting is applied. This study assumes that there is no remanent magnetization. The method is applied on a noise-corrupted synthetic data to demonstrate its suitability for 3D inversion. A case study including ground based measurement of magnetic anomalies over a porphyry-Cu deposit located in Kerman providence of Iran, Now Chun deposit, is provided to show the performance of the new algorithm on real data. 3D distribution of Cu concentration is used to evaluate the obtained results. The intermediate susceptibility values in the constructed model coincide with the known location of copper mineralization. 相似文献
20.
We describe the wave propagation through an irregularly layered, elastic medium for incoming body (SH) and surface (Love) waves. As a result of irregular geometry, each layer generates additional waves by scattering and diffraction. These additional waves modify the input motions and locally may lead to larger motions and concentrations of stresses, strains, and rotations on or below the ground surface. For engineering design, and in particular for analyses of soil-structure interaction, it is important to understand the nature and the consequences of such motions.The scattering and diffraction of Love and SH waves by irregular layers will be investigated by the weighted-residuals method. The scattered and diffracted mode shapes and spectral amplification characteristics at different frequencies will be examined and discussed. 相似文献