焦石坝页岩声学、气体吸附和孔渗特性实验研究

发布时间：2018-04-09 03:01

本文选题：页岩　切入点：纵波波速　出处：《华南理工大学》2016年硕士论文

【摘要】：页岩气是一种主要以吸附和游离态赋存于页岩层中的非常规天然气。页岩气在美国等国家的成功开采使得页岩气越来越受到世界各国的关注。中国拥有世界第一的页岩气资源储量,开采前景巨大。在未来的一段时间,页岩气将成为缓解我国能源危机的一种非常重要的非常规天然气资源。由于不同地区页岩的物性差异较大,需要对页岩的物性做进一步的研究。四川盆地涪陵焦石坝地区页岩气储量丰富,是我国第一个具有工业化页岩气的产能地区。本文以四川盆地焦石坝地区某露头页岩为研究对象,采用测量页岩中的纵波速度的方法研究了页岩的声学特性,分析了影响页岩声学特性的影响因素;采用静态体积法测量了页岩的气体吸附特性,考察了影响页岩吸附的因素;分析测试了页岩的孔隙结构,并采用实验手段,运用达西定律研究了气体在页岩中的渗流规律。结果显示页岩中纵波速度主要受温度、轴压、含水率和含气饱和度的影响。温度越高,纵波速度越小;轴压越大,纵波速度越大;含水率越高,纵波速度越大,含气饱和度越大,纵波速度越大。页岩对气体吸附量受压力、温度、页岩粒径、含水率、气体种类和有机碳的影响。在等温条件下,随着压力的增大,气体的吸附量先增大后趋于稳定;气体吸附量随温度的升高而减小;页岩粒径越小,对气体吸附量越大;含水率越高,气体的吸附量越小;氮气、甲烷和二氧化碳在页岩中的吸附量依次增大;气体在页岩的吸附和解吸存在滞后,其中二氧化碳的滞后程度最大;有机碳含量越高,气体的吸附量越大。该页岩中主体孔径以小于50纳米的中孔和微孔为主,孔隙结构分为:粒间孔、粒内孔、有机质孔和裂缝。甲烷、二氧化碳和氮气在页岩中的表观渗透率都随着气体渗透压的增大而减小,即存在滑脱效应;相同渗透压条件下,表观渗透率大小为CO2CH4N2;经滑脱校正后页岩中的气体的绝对渗透率结果为:KN2=0.274mD,KCH4=0.182mD,KCO2=0.165mD;页岩所受围压越大,表观渗透率越小;该页岩具有一定的塑性。
[Abstract]:Shale gas is a kind of unconventional natural gas which mainly exists in shale bed by adsorption and free state.Shale gas has attracted more and more attention in the world due to its successful exploitation in the United States and other countries.China has the world's largest shale gas reserves, the prospect of exploitation is huge.In the future, shale gas will become a very important unconventional natural gas resource to alleviate the energy crisis in China.Because the physical properties of shale vary greatly in different regions, it is necessary to further study the physical properties of shale.There are abundant shale gas reserves in Fuling Jiaoshiba area of Sichuan Basin, which is the first productive area of industrial shale gas in China.In this paper, the acoustic characteristics of shale are studied by measuring the longitudinal wave velocity in a outcrop shale in Jiaoshiba area of Sichuan Basin, and the influencing factors on the acoustic characteristics of shale are analyzed.The gas adsorption characteristics of shale were measured by static volume method, the factors affecting shale adsorption were investigated, the pore structure of shale was analyzed and tested, and the percolation law of gas in shale was studied by using Darcy's law.The results show that the longitudinal wave velocity in shale is mainly affected by temperature, axial pressure, water content and gas saturation.The higher the temperature, the smaller the velocity of the P-wave, the greater the axial pressure, the greater the velocity of the P-wave, the higher the water content, the greater the velocity of the P-wave, the greater the gas saturation and the greater the velocity of the P-wave.The amount of gas adsorbed by shale is affected by pressure, temperature, shale particle size, moisture content, gas species and organic carbon.Under isothermal conditions, with the increase of pressure, the adsorption capacity of gas increases first and then tends to stabilize; the amount of gas adsorption decreases with the increase of temperature; the smaller the particle size of shale is, the larger the adsorption capacity of gas is, the higher the moisture content is, the smaller the adsorption capacity of gas is.The adsorption capacity of nitrogen, methane and carbon dioxide in shale increased in turn; the adsorption and desorption of gas in shale had hysteresis, and the lag degree of carbon dioxide was the largest; the higher the content of organic carbon was, the greater the adsorption capacity of gas was.The main pore size of the shale is less than 50 nm mesoporous and micropore. The pore structure can be divided into intergranular pore, intragranular pore, organic pore and fracture.The apparent permeability of methane, carbon dioxide and nitrogen in shale decreases with the increase of gas osmotic pressure.The apparent permeability is CO _ 2CH _ 4N _ 2, and the absolute permeability of the gas in shale is 0.274mDX 0.274mDX 0.182mDX 0.165mD. the larger the confining pressure is, the smaller the apparent permeability is, and the shale has a certain plasticity.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TE31

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