Applied Mechanics and Materials Vols. 448-453

Abstract: The preservation conditions of coalbed gas reservoir are one of the most important affecting factors. Coal seam roof and floor of coalbed methane is the most direct emission barrier. That is the direct control of coal seam gas accumulation factor. A coal seam roof lithology prediction method at present more popular is the wave impedance inversion. But the results have multiple solutions. While the technology of stratmagic seismic can be a very good solution to the traditional seismic attributes application problems. It can provide precise results for coal seam roof lithology prediction, providing geological basis for evaluation and development of coal bed gas.

Abstract: In order to improve the resolution of seismic exploration, this paper mainly studied the vibroseis data preprocessing method of metal mining seismic exploration. With the characteristics of vibroseis seismic data, we studied the correlation algorithm of detecting shot gather records, system analyzed the source and classification of noise in copper-nickel detection with Hydraulic sweep source in Jinchang, and chose the denoising method according to the characteristics of noise in the shot gather records. After preprocessing, the SNR of vibroseis seismic data is effectively improved, and then the resolution of seismic section is enhanced.

Abstract: Distribution characteristics of coalbed methane in Huanghebei mining area were studied and influence of geological factors such as faults, lithology of coal seam roof and floor, magmatic activities, burial depth and upper bedrock thickness of coal seam and hydrogeological conditions on occurrence of coalbed methane were deeply discussed in this paper. Coalbed methane content of mining area increased gradually from southeast to northwest. Coalbed methane in deep well points of mining area is dominated by methane and that in shallow parts contained higher content of nitrogen.

Abstract: Controlled-source electromagnetic (CSEM) is an artificial source electromagnetic sounding method. which developed on the basis of magnetotelluric sounding. For showing the CSEM forward modeling result, numerical simulation method must be adopted. A discontinuous Galerkin finite element method is presented to solve problems based on formulation.

Abstract: Geological strata conditions is restriction to the design and construction of projects .The significance of three-dimensional modeling of engineering rock mass is obviously for both construction and monitoring.However,the existing three-dimensional modeling methods have the disadvantages of low productivity and huge amounts of data . Focusing on these problems, a fast modelling method used to build geological model is presented in this paper. Compared with the special geological 3D modeling and analysis software ,VRML has many merits such as flexible visualization method, good transplantation of the visualization achievements , and independent platform . VRML also has the feasibility of low-bandwidth and the real-time visualization and browsing of the models .It is well suited to the visualization requirement of drilling data and cross-sectional data ,and provides a new solution for the realization of the geological visualization.

Abstract: Data mining technology is information from large amounts of data to dig out the unknown can be a practical and effective information, so provide richer information, or to provide decision support. Using data mining techniques handle large amounts of seismic data, analyze data to solve the reservoir characteristics of the intrinsic link scattered distribution problem is not easy to extract, and through Bayesian learning method to extract the hidden reservoir characteristics, based on completion of reservoir parameters of reservoir characterization data accurate modeling. Experimental results show that this method can effectively extract the reservoir characteristics of the data and accurately complete reservoir modeling, and achieved satisfactory results.

Abstract: In isotropic media, P-and SV-waves are coupled. For computational efficiency, we studied a separated pure P-wave VTI wave acoustic approximate equation. And to solve the Pure P-wave equation, we generalized the pseudo-analytical method to isotropic media, which has batter accuracy than conventional pseudo spectral method. Numerical simulation result shows that pure P-wave VTI wave equation not only accurately described the P-wave field characteristics, but also eliminated the pseudo SV-wave artifact in conventional coupled quasi P-wave equation, and made the wave field propagation more stable and less dispersion error.

Abstract: There is the polar distance selection of dipole device, the location determination of recording points, the resolution capability of multiple anomalies and other problems existing in the practical application of transient electromagnetic method in multi-turn minor loop device. Through physical simulation experiments, this paper gives experimental comparisons of polar distance, recording points, and the resolution capability of two anomalies in a certain interval between dipole device and overlapping device. The experimental results show that: the dipole device has the better resolution capability of small polar distance, 1.25 times wire-frame side length is appropriate for general selection of polar distance, and the maximum distance should not exceed 1.5 times wire-frame side length, the recording point is located in the midpoint position of transmitting and receiving coils; while the overlapping device has the obviously higher resolution of double anomalies in a certain interval than dipole device, and the minimum resolution is about 1.5 times wire-frame side length. These characteristics provide the realistic basis for reasonable selections and optimization designs of multi-turn minor loop observation system.

Abstract: The cental Asian orogenic belt (CAOB) which between the North China Craton and the Siberian Craton is one of the tectono-metallogenic belts in the world. The central Inner Mongolia belongs to the eastern part of the CAOB, recently a series of research and exploration work has been done in this region. However, no breakthrough has been made in the exploration of metal ore. In order to research current mineralization issues in the eastern part of the CAOB, a long magnetotelluric (MT) profile was acquired across the central part of Inner Mongolia. The profile starts within the DongUjimqinqi in the northwest, goes southeastward across the Chagan Obo-Arongqi fault, the Erenhot-Hegenshan fault, the Xilinhot fault and the Linxi fault, and ends around the Xar Moron fault in the northern part of Chifeng city; the strike direction of most faults is southeast; the faults have direct control effect to the magmation and mineralization of this region. The model of electrical structure along the profile can be divided into two regions: widely distributed low resistivity is the key feature north of Nianzigou; high resistance is the key feature south of Nianzigou. The Chagan Obo-Arongqi fault, the Erenhot-Hegenshan fault and the Xilinhot fault all present as a southeastward dipping conductor, which reflects their overthrusting process; there are many high conductivity areas along the faults in the region. The electrical structure to the south of Nianzigou is expressed as a mushroom shape, which reflects the tectonic origin of magmatic rock in this region.

Abstract: Dachang ore field is located in the central of Au, Sb, Hg metallogenic belt in the north Bayankela mountain, with the Maduo - Gande deep major fault as its regional guide mineral structure. The gold deposits have grew up in the fracture - fissure system of large share zone in BaYanKaLa mountain group of Triassic strata, and Magmatic activities in Yanshan Period provides favorable conditions for the activation, migration, enrichment and mineralization of gold element. Geophysical - geochemical anomaly and remote sensing of this area have shown that they are related with the mineralization, that means abnormal area with bigger Intensity is often located in the cross area of tectonic alteration and mineralization. Triassic strata, the north - west fault and its secondary structure - rock system and geophysical - geochemical anomaly are the obvious symbols of gold prospecting in the area. Through the metallogenic regularity, obvious symbols and distincting some geophysical - geochemical anomalies, more large and medium-sized gold deposits have been found. We should along the Maduo - Gande fault zone, extending for east - west trend and the depth, and larger scale gold deposits is expected to be found.