Applied Mechanics and Materials Vols. 295-298

Abstract: The ground movement laws due to wide strip mining under deep-lying seams has been studied with the experiment of similar material model, and the results of experiment could analysis qualitatively that it is feasible for wide strip mining under deep-lying seams. Taking 25 mining area of Hemei 9th mine as geologic background, the model of wide strip mining under deep seams has been made, which was used to study on the deformation of overburden and the ground movement laws. The results of experiment show that the properties and thickness of strata play a control role on the deformation, and the key strata play a core role; the deformation was dispersed with wide strip mining. When the width of strip mining and protective coal pillar are scientific and reasonable, the purpose of increasing the width of strip mining under the condition of controlling deformation could be achieved, and the entire mining area would be formed a flat subsidence basin. These achievements provide a scientific basis for solving the problem for the ground buildings protection in the conditions of wide strip mining under deep-lying seams, and that also provide some references for further studying on the method of wide strip mining under deep-lying seams.

Abstract: In order to optimize the gathering system and reduce the energy consumption in the production, single-pipe concatenation process has been widely used after the tertiary oil recovery technique is applied and development enters into high water cut stage in the oilfield. Aiming at condensate oil in gathering pipeline and obvious increase of the high circle pressure wells in the operation of the process, the adaption relationship between oil gathering pipeline size and flow, as well as the temperature limit of the gathering system start are studied, through the hydraulic and thermodynamic calculations of oil-gas-water multiphase flow. It has directive function for making effective schemes to solve the production problems caused by the high back pressure of wells.

Abstract: Daniudi gas field is a tight sandstone gas field in the northeast of Ordos Basin. How to use the successful experience in developing area to predict favorable gas-rich area in other areas in this gas field is very important to the next exploration and development in this field. This paper proposes a multi-information integrated method to predict favorable gas-rich area. Firstly describe sedimentary microfacies by integrating seismic, logging and geological information; and then summarize and analyze the seismic reflection patterns of medium-high productivity wells; finally determine the favorable gas-rich area with the distribution of storage coefficient based on the previous analysis. The welltest of newly drilled wells shows that the coincidence rate of favorable gas-rich area predicted by this method could be up to 90%,and this method could be extended to use in the other tight sandstone gas reservoirs.

Abstract: Most current optimization methods could not take engineering and economical factors into account at the same time. A theoretical optimization method, which could obtain a simultaneous optimization of engineering and economy, has been proposed on horizontal injection-production patterns with net present value (NPV) and cumulative production as its target organisms. The theory of wave frontal movement has been utilized to limit the pattern scope and the pressure drawdown has its constraint from 0 to three quarters of the formation fracture pressure. The method is finally tried out in a certain field in Oman, and the optimized results are as below: for the face to face pattern and crisscross pattern, well spacing densities are 15/sq. mi. and 29/sq. mi., while the length of the wellbores are 3 300 feet and 2 600 feet. The results are pretty closed to the real data in situ and the simulation by reservoir numerical simulator.

Abstract: Based on the gas analysis results of coalbed methane (CBM) wells in the Weibei CBM field, two main recoverable target seams (Nos. 5 and 11) were evaluated for the potential of exploration and exploitation by using the grey correlation analysis method. The main influnce factors on the CBM potential by increasing importance are gas content, gas saturation, buried depth, methane concentration, critical desorption pressure,reservoir pressure and coal thickness for the No.5 coal seam; while they are gas saturation, gas content, critical desorption pressure, methane concentration, buried depth, reservoir pressure and coal thickness for the No.11 coal seam. The exploration potential of No.5 coal seam is better than that of No.11. The favorable area for CBM exploration are the areas including Well block W2, W3, W4 and W8 in the middle of Weibei CBM field.

Abstract: This paper discusses the structural characteristics and tectonic evolution, as well as the accumulation history and preservation conditions of coalbed methane (CBM) in Zhengzhuang block located in southeastern Qinshui basin. Deformed by the Hercynian, Indo-China, Yanshan and Himalayan four tectonic movements, the study area emerges the structure pattern that folds developed in northwest of the block, while faults in the southeast. The area near the syncline axis is the favorable region of CBM accumulation with good sealing condition. The Sitou fault has an effect on the diffusion of CBM. The geological controls of gas accumulation were concluded by a conceptual model, which provides a basis for further exploration and development.

Abstract: This paper discusses how sedimentary controls on accumulation of coal and coalbed methane in Hancheng CBM field. Two major coal-bearing strata include the Upper Carboniferous Taiyuan formation (a marine and terrestrial sedimentation) and the Lower Permian Shanxi formation (a terrestrial sedimentation). The favorable sedimentary environments for accumulation of coalbed methane by decreasing order are the shallow marine and barrier island system, the delta system, and the shallow marine and plane coast system.

Abstract: From the basic conditions of Chinese Coal Mine Methane (CMM) emission, the thesis studies the CMM discharge coefficient of different types of mines in china after establishing the “the output - emission regression function model” by the means of raw coal production. Besides, according to CMM’ distribution in different provinces’ (areas) of China, interprovincial emission factors will be calculated, laying foundation for the calculation of the CMM’s emission and reduction.

Abstract: Analysis and research on the reasons for abnormal methane emission in local coal seams were given through Gas-geology Theories in this article, considering the practical conditions in Yitang Mine and the current situation that low gas emission while frequent occurrence of disastrous gas accidents in some mines. Geological tectonism was mainly responsible for the mass storage of free form gas in fracture, for it crushed and broke the original reservoir and contributed to fracture development in roof limestone. The centralized release of free form gas caused abnormal methane emission in local when these fractures were disturbed by mining activities. Hereby, feasible measures for gas prevention were taken to ensure safety production. The results had provided constructive guidance for gas prevention and control in similar coal seams or mines.