| With the growing concerns for resources and environmental issues in our society, the exploitation of fluid resources including petroleum, natural gas, coal bed methane, ground water atc, also the disposal of hazardous wastes including radioactive wastes, greenhouse gases etc, have become problems which are of considerable importance recently and will become increasingly significant in future years. Fluids and dissolved materials permeate through crustal rocks by processes of seepage and diffusion. However, the permeability of the geomaterials is, in many cases, the controlling factor in the above engineered exploitation and subsurface migration of hazardous wastes. The major problem encountered in the safety evaluation and construction design of the above engineering, however, is that the permeability of engineered materials distribute in a large range, probably well over 10 orders of magnitude and vary significantly so far as to several orders of magnitude, due to the changes in various kinds of environmental conditions and man-made disturbances including hydro-mechanical, temperature, chemical, biological reactions etc. However, the existing laboratory permeability measurement methods cannot meet the needs of measuring the coefficients of permeability of the above porous media materials completely. According to be capable of flexibility in testing situations of large-range-changing and changing quickly, a new kind of permeability measurement method, which is rapid, large range, high efficient and steady-going, will be required. It will provide an effective means to measure the permeability of reservoir or stratum or caprock materials, which are much accounted of fluid mineral storages exploitation and wastes underground storage stratum evaluation. In this dissertation, previous research results have been summarized, then, storage-variable transient pulse permeability measurement method has been proposed, which is a new kind of flexible testing technique. The new advanced testing method is based on traditional transient pulse method, but no limitations of narrow measuring range. Furthermore, the storage-variable transient pulse permeability testing device has been developed successfully. The storage-variable transient pulse permeability measurement method has been worked over systematically, involving theory deduction, system design, device manufacture, laboratory tests, error analysis and stretch of application. Meanwhile, referred to many research fields, the research work has been combined with rock hydraulics, permeation mechanics, FEM numerical simulation and laboratory tests.The errors of permeability testing results for porous media materials in laboratory experiment are related to qualities of specimen itself, the design of testing system, the constitution and performance of testing device and so on. Therefor, the testing results for the same specimen are different by using different permeability measurement methods or devices. Moreover, the testing results for the same sample are still different even by the same permeability measurement method and device if during different periods or under different conditions. Presently, there is no standard sample, the permeability of which is known, and can be able to be regarded as reference. So that, the accuracy of permeability testing results is difficult to describe definitely. Some engineering geological phenomena will also be difficult to explain, even the laboratory experiment seems making no sense, if the testing results are inaccuracy. It will be demanded urgently to establish a series of unified standards for calibrating permeation experiments. In this dissertation, the right demanded standard samples of porous media have been developed. Many more development researches have been made on the standard samples, including the proposal of the idea of standard sample for calibrating permeation experiments; the design of Li's samples and their preparation, preservation, maintenance, transportation and application; the calibration method for permeation experiments. In the same meantime, referred to many research fields, this part research work is involved of powder metallurgy, hydromechanics, porous media mechanics and laboratory experiments.The main researches of this dissertation are as follows:The theory and application of various kinds of laboratory permeability measurement methods have been summarized. The advantages and disadvantages of various kinds of laboratory permeability measurement methods have been analysed. In order to meet the needs of spacial permeability measurements, which is required to be flexibility in situations of multi-time-scale, large-range-changing, high efficiency and steady-going, a new kind of permeability measurement method has been proposed, which is remarkable for its features of rapid, large-range and high accuracy. This new method is based on the advantages of unsteady flow and testing fast of the traditional transient pulse technique. (Chapter 2 and 3)The development history of the traditional transient pulse method theory and its related parameters have been analysed. The key points and matters needing attention for the transient pulse permeability measurement experimental design have been summarized when the permeability parameter solved by using approximate solution. The experimental system and device structure design for storage-variable transient pulse method have been outlined. (Chapter 3 and 4)Based on inspiring from the theory of the traditional transient pulse method, breaking through the limitation of the narrow testing range, combining with the key points for experimental design with a great deal of testing experiences, the storage-variable transient pulse permeability measurement method and its testing device have been developed successfully. The new method has been proved availably and steadily by theory and practice. (Chapter 4)In view of the advanced permeability measurement method, named storage-variable transient pulse method, there has been conceived another kind of measurement method for testing ultra low permeability and also its matched system and device design trends. The ultra-low permeability measurement method can measure 10-10D materials, such as halite, argillite and so on, moreover, it can make tests under high pore-pressure situations even more than 20MPa, so as to simulate complex geological processes in situ, under which it can be capable to obtain the permeability parameter of rock materials and its changing ragularities.(Chapter 4)13 kinds of the methodological and technological error sources have been discussed for storage-variable transient pulse technique permeation experiment. All the error sources have been classified to 6 kinds of error factors which make a great impact on measurement testing results. The impactions have been analysed categorically and systematically by using FEM numerical simulation method. It will help to optimize the testing operation, improve the testing device and supply an available reference to calibrate error influences. (Chapter 4)The influences, effected by the properties of rock specimen, the components of experimental system, the machinery and performance of testing device on the permeability measuring accuracy, have been analysed comprehensively. Presently, the accuracy of permeation experiment testing results cannot be illuminated definitely. In order to filling the gap of calibrating the accuracy and range availably for permeation measurement techniques, the conception of calibrating permeation experiment has been proposed, the conception of the standard sample for calibrating permeation experiment has been proposed and the detail design plan has been made. (Chapter 5)Applying the powder sintering technique to make porous media specimen by using powder sintering method, and considering the relations among various physical characteristics parameters of porous media materials, Li's samples have been designed and manufactured successfully. The permeabilities of Li's samples are constant and changeless under long-period and many different loading conditions permeation experiment testing. According to the permeabilities of Li's samples, which are regarded as references, will help to supply a convincing check platform for permeation measurement fields. (Chapter 5)The calibration method for evaluating permeation experiments has been drafted up within Li's samples applications. It will help to establish the unified standards and checking platform for permeability measurement techniques. (Chapter 5)... |
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