| Today, with international oil price rises violently and the global energy demand is increasing constantly, petroleum resources shortage already is the great difficult problem of restricting global economic development, develop the petroleum and substitute is the main subject for research of various countries, the opportunity of developing oil shale mineral deposit already come. Oil shale, as a kind of important supplement and substitute petroleum energy, with its enormous reserves and abundant comprehensive use level , have aroused the attention from whole world. The majority verified oil field of our country has already entered the later stage of old well developing, the future output of crude oil of our country is difficult to increase, the imbalance between supply and demand of the energy is conspicuous day by day. So, base on our country, seeking effective and economic utilization route of oil shale, for relieving the imbalance between supply and demand of energy of our country and promoting the development of society have great realistic meanings.This text takes oil shale in-situ steam drive technology as the background, combine macroscopic and detailed view experiment, method of the theoretical research combines with numerical simulation, with the aid of new experiment means, experimental facilities and Instrument, further study the weightless characteristic, permeability characteristic, change of density and porosity, development and evolvement law of fissures and pore of oil shale under different temperatures. Use superheated steam as the carrier of heat transmit, studied the oil and gas producing law of oil shale under its heating condition. Set up the coupled mathematical model of heat, fluid flow and solid deformation for oil shale in-situ steam drive, work out the corresponding computer program, carry on the numerical simulation, it offer theoretical foundation and project reference for carrying on extensive oil shale in-situ steam drive. The following is main research contents and research results:1. The oil shale pyrolysis weightlessness mainly display in 3 temperature sections. From room temperature to 300℃, weightlessness of this stage mainly caused by moisture appear, weightlessness is about 3%. 300℃～600℃, a large amount of organic matter in the oil shale turn into shale oil and pyrolysis gas in this relatively smaller temperature block, weightlessness is about 20%. 600℃～900℃, weightlessness of this stage mainly caused by the breaking out of calcite, dolomite and carbon particle, weightlessness is about 3%.2. Determine the density, proportion and porosity of the Fushun oil shale under different temperature using the specific gravity bottle. The experiment result shows: from normal atmospheric temperature to 200℃, the density, proportion, porosity of the oil shale do not change much, after temperature exceeds 200℃, the density of the oil shale drops rapidly with the rising of temperature, at the same time, proportion and porosity increase by a wide margin with the rising of temperature.3. The permeability coefficient of distilled oil shale under three dimension stress state is measured through the 3D permeable experimental machine (MDS-200) devised by Taiyuan University of Technology. Result of study show the permeability coefficient of distilled oil shale attenuates with the increase of volume stress and increases with the rise of pore pressure, and follows the formula:4. Utilized theμCT225kVFCB micro-CT experimental system (μm grade), which was newly co-designed by Taiyuan University of Technology, and Applied Electronics Institute, Academy of Engineering Physics of China, carried on the no damaged triaxial micro-observation and analysis on thermal cracking of oil shale of square body of 7.0mm to be long under different temperatures. The experiment shows: Under 300℃, it was observed that certain few micro-fissures in the specimen which mainly evolved from the raw original bedding and the border of hard mineral particle, the fissure surfaces were basically all parallel with each other, and there is little quantity, the width is relatively small. After temperature exceeded 300℃, due to the influence of chemical reaction of the oil shale pyrolysis, the quantity, length and width of the fissures had seen a violent increase, all fissure surfaces were still parallel with each other, At the same time, formed a lot of micro-fissures perpendicular to the bedding direction, caused the connection between small fissures and large fissures, so formed a huge connecting network structure, fundamentally improved the influent ability of the oil shale. Start with fractal theory, analyzed the thermal cracking course of the oil shale, quantized distribution state and complexity of the fissures. Studies have suggested: The thermal fissures have strong self-similarity, according with fractal law.5. Carry on CT scan experiment to the oil shale standard ofφ0.82mm×7mm under different temperatures, aim to study the development rule of theμm grade pore structure within the oil shale at high temperature. The study show: From room temperature to 300℃, pore quantity, pore area, average of pore diameter and porosity do not change much in the study area. After temperature exceeded 300℃, the above-mentioned parameters all increase sharply and reach the maximum at 500℃, subsequently fall a little, so, confirm 300℃as the boundary point of the pore structure parameters changes. After 300℃, a large number of new pores emerge within the oil shale because of pyrolysis chemical reaction, cause the increase of quantity of medium-sized pores and large pores, secondly, Because a large number of little pores are joined under the high temperature, promote the increase of quantity of medium-sized pores and large pores, at the same time, cause the little pores quantity to reduce relatively. As a whole, no matter in which temperature section, little pores and medium-sized pores are main pore structure within oil shale, the sum of the two should account for more than 90% of the total pore number. Start from pore medium percolation theory, calculate percolation probability of 3D data oil shale under different temperatures. The result of calculation indicates: As temperature is in 300℃- 400℃, the percolation threshold of oil shale is between 8﹪-12﹪.6. Utilized the high temperature and high pressure superheated steam boiler devised by Taiyuan University of Technology carried on pyrolysis experiment to two kinds of oil shales are separately produced in Liaoning and Neimeng. The experimental result shows:The oiliness rate keep about 0.30% of two kinds of oil shale residue after the superheated steam heated,have achieved very high oil and gas recovery ratio. At the same time, the output of H2 and CO is obviously improved in the pyrolysis gas under the participation of superheated steam. The driving oil mechanism of superheated steam mainly embody: The convection heat way, lower viscosity by heating, boiling and denudation effect of high-temperature steam, function of thermal expansion, solve stop up function and take off gas function.7. On the foundation of analyzing of the theory, set up the coupled mathematical model of heat, fluid flow and solid deformation for oil shale in-situ steam drive, work out the corresponding program using Fortran computer language and carry on the numerical simulation to nine point wells disposal. The numerical simulation result show:1) Within the same exploitation time, temperature is relatively high near the hot injection well. In the system runs for one year, the majority oil shale stratum temperature is low at 400℃between hot injection well and oil adopting well, after running for 2.5 years, temperature has already reached 500℃. So, among 1-2.5 years, the shale oil and gas are produced in a large amount and confirm operation cycle of this model as 2.5 years.2) Fluid pressure regard hot injection well as peak value to reduce gradually all around, and as time lengthens, the range that the pressure involves expands to the area beyond the oil adopting well gradually, the pressure gradient is very large and the velocity of flow is very fast near the area of hot injection well and oil adopting well, and the pressure gradient of middle area is relatively low, the velocity of flow is steady. At the same time, because the permeabilities of roof, baseplate rock are weaker than the oil shale, so the fluid pressure slowly rises, obviously lag behind the oil shale stratum. By about one year, the two press difference already very small. 3) With the rising of the stratum temperature, reach from pressure stress change tensile stress progressively, and the extension with time, the area of tensile stress regard hot injection well as the centre to expand outwards constantly. The improvement of the tensile stress, while making the hole volume expand, have increased the width of the fissure, creating the advantage for the furtherly pouring into of high-temperature fluid.4) With the running into constantly of heat, the stratum has presented obvious inflation between hot injection well and oil adopting well, and is up to the extension of time, the heaving amount is increasing constantly. By 2.5 years, The heaving amount in the earth's surface of hot injection well is 1.29cm and the oil adopting well is 0.51cm.
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