高含硫气藏元素硫颗粒运移规律研究

发布时间：2018-04-23 00:05

本文选题：高含硫气藏 + 硫沉积　；参考：《西南石油大学》2017年硕士论文

【摘要】：高含硫气藏在世界分布广泛,在气井开采过程中,随着温度和压力的变化,会发生相变,气体中析出单质硫,当单质硫不能被气体携带走时,就会产生硫沉积现象,堵塞孔喉,伤害地层,严重影响高含硫气井产能。目前关于硫沉积机理研究主要采用宏观实验和理论手段,对元素硫颗粒的微观运移沉积机理认识不清,有必要采用微观尺度研究方法。因此,从微观角度利用气固耦合方法模拟研究元素硫颗粒微观运移沉积机理,重点考虑元素硫颗粒运移过程中受到的重力、曳力、浮力以及硫颗粒碰撞聚团过程中受到的粘结力,分析硫颗粒的析出方式,探究不同流速、粒径、孔喉条件下元素硫颗粒微观运移沉积规律。通过研究,取得了以下相关认识:(1)应用扫描电镜观测析出的硫颗粒微观形态,其粒径分布主要在0-2μm之间,类比冰晶的分布规律,认为硫颗粒粒径在地层中服从Log-Normal分布;应用扫描电镜和压汞法实验手段,研究了高含硫气藏岩心孔喉分布特征,孔隙半径大小主要分布在1～20μm,平均中值半径16μm。(2)在经典的Hertz-Mindlin(no-slip)模型基础上,建立考虑粘结力的接触模型来描述元素硫颗粒的结晶、团聚过程,模拟结果表明:元素硫颗粒之间粘结数量随时间增大而增加,元素硫颗粒平均粒粒径会增大,其分布曲线的概率密度函数峰值会变小。(3)单个硫颗粒在多孔介质中的运移主要受重力、浮力、曳力控制,低气流速度条件下,硫颗粒的沉积主要为重力沉积和碰撞沉积;高速条件下,硫颗粒的运移主要受到流体曳力控制,随气流流出多孔介质而不产生沉积。(4)元素硫颗粒运移沉积规律:对于同一粒径的硫颗粒而言,其沉积率随着气流进口速度增大而减小;对于同一气流进口速度而言,其沉积率随着颗粒直径增大而增大,因为较小粒径硫颗粒基本处于悬浮状态,沉积率一般都很小,而大粒径硫颗粒受重力作用影响比较大,更易发生沉积现象。还发现颗粒直径对沉积率影响的程度大于气流进口速度对沉积率影响的程度。(5)模拟研究不同多孔介质物理模型发现,相同条件下,单孔双喉的沉积率大于单孔孔三喉;双孔三喉中,前一个孔隙比后一个孔隙沉积多;复杂多孔介质沉积率最大;沉积元素硫颗粒的运移渗流通道越曲折复杂,其元素硫颗粒在运移过程其沉积率会明显增大。
[Abstract]:The gas reservoirs with high sulfur content are widely distributed in the world. With the change of temperature and pressure, phase change will take place in the gas well production, and simple sulfur will be released from the gas. When the simple sulfur can not be carried away by the gas, the phenomenon of sulfur deposition will occur and the pore throat will be blocked. Damage formation, seriously affect the productivity of high sulfur gas wells. At present, the mechanism of sulfur deposition is mainly studied by macroscopical experiments and theories. The microscopic migration and deposition mechanism of elemental sulfur particles is not well understood, so it is necessary to adopt micro-scale research methods. Therefore, the mechanism of microscopic migration and deposition of elemental sulfur particles is simulated by gas-solid coupling method from a microscopic perspective, with emphasis on the gravity and drag force in the transport of elemental sulfur particles. The buoyancy and the adhesion of sulfur particles in the process of colliding clusters are analyzed, and the microcosmic migration and deposition of elemental sulfur particles under different velocity of flow, particle size and pore throat are studied. Through the research, the following relative knowledge is obtained: 1) the microscopic morphology of sulfur particles is observed by scanning electron microscope. The particle size distribution is mainly between 0 and 2 渭 m. Compared with the distribution law of ice crystal, it is considered that the particle size of sulfur particles is distributed from Log-Normal in the strata. The characteristics of pore throat distribution in high sulfur gas reservoirs are studied by means of scanning electron microscope and mercury injection method. The pore radius is mainly distributed in 1 ~ 20 渭 m and the mean median radius is 16 渭 m 路m ~ (-2) based on the classical Hertz-Mindlinno-slip model. A contact model considering adhesion is established to describe the crystallization and agglomeration process of elemental sulfur particles. The simulation results show that the amount of bonding between elemental sulfur particles increases with time, and the average particle size of elemental sulfur particles increases. The peak value of probability density function of its distribution curve will become smaller. (3) the migration of single sulfur particles in porous media is mainly controlled by gravity, buoyancy, drag force, and the deposition of sulfur particles is mainly gravity deposition and collision deposition under the condition of low airflow velocity. At high speed, the transport of sulfur particles is mainly controlled by fluid drag, and no deposition of sulfur particles is produced by flowing out of porous media with the flow: for sulfur particles of the same diameter, the sulfur particles of the same size are transported and deposited. For the same inlet velocity, the deposition rate increases with the increase of particle diameter, because the smaller sulfur particles are suspended, and the deposition rate is generally very small. However, the large diameter sulfur particles are affected by gravity more easily. It is also found that the influence of particle diameter on deposition rate is greater than that of airflow inlet velocity. (5) the physical models of different porous media show that the deposition rate of single pore and double throat is higher than that of single pore triple throat under the same conditions. In the twin-pore three-throat, the former pore is more than the latter; the deposition rate of complex porous media is the largest; the more complicated the migration and percolation channel of the deposited elemental sulfur particles, the higher the deposition rate of elemental sulfur particles in the migration process.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE31

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