高含硫气藏气—液硫渗流规律研究

发布时间：2018-01-02 09:38

本文关键词：高含硫气藏气—液硫渗流规律研究　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：高含硫气藏在我国四川盆地分布广泛。在高含硫气藏的开发过程中,由于地层压力的下降,元素硫在含硫气体中的溶解度降低,元素硫从气体中析出并沉积,且在高温条件下以液态的形式存在于地层孔隙中,液硫的沉积会增大渗流阻力,降低地层孔隙介质的渗流能力,当液硫饱和度达到并超过其临界流动饱和度时,地层中就会形成气-液硫两相渗流,最终影响高含硫气藏的开采效率。目前国内外学者对于高含硫气藏中硫的析出主要集中在固态硫对地层孔隙的伤害理论模型研究上,而对于液硫的沉积运移研究较少,考虑液硫沉积对产能的影响的研究更少。因此,本文在分析了高含硫气体与液硫物性参数、液硫的沉积运移机理以及对气相渗透率的伤害的基础上,建立了高含硫气藏液硫饱和度计算模型,并根据实例计算进行了影响因素分析。在现有的实验设备基础上改进研发了一套高温高压气-液硫渗流实验装置,测定了气-液硫相对渗透率曲线并分析了温度和应力敏感对相对渗透率的影响。根据液硫从含硫气体中的析出运移机理,推导建立了气-液硫渗流数学模型并求解。基于上述研究得到以下几点结论:(1)高含硫气藏气体物性参数由于酸性气体的存在而需要校正,建立的硫饱和度预测模型考虑了非达西流与应力敏感的影响,使液硫饱和度计算结果更准确。(2)对实例气井岩心进行了应力敏感性实验,实验结果表明:基质岩心应力敏感为中等偏弱。实验测定了气-液硫两相相对渗透率曲线,结果表明:液硫临界流动饱和度较高,气-液硫两相共渗区较窄。(3)研究了温度与应力敏感对相渗曲线的影响,结果表明:温度与应力敏感对气相相对渗透率的影响比较明显,气相渗透率降低,等渗点左下移。温度和应力敏感对液硫相对渗透率影响大不。(4)根据元素硫从含硫气体中析出并以液态的形式与含硫天然气形成气液两相渗流的情况,推导建立了气-液硫渗流数值模型并求解,通过编程模拟研究发现:液硫沉积使气井稳产年限缩短、累产气量下降,液硫流动能力越差对气井产能影响越大。
[Abstract]:High sulfur gas reservoirs are widely distributed in Sichuan Basin of China. During the development of high sulfur gas reservoirs, the solubility of elemental sulfur in sulfur gas decreases due to the decrease of formation pressure, and elemental sulfur is precipitated and deposited from gases. At high temperature, liquid state exists in the formation pore, the deposition of liquid sulfur will increase the percolation resistance and reduce the percolation ability of the formation pore medium, when the liquid sulfur saturation reaches and exceeds its critical flow saturation. The gas-liquid sulfur two-phase percolation will be formed in the formation. At present, domestic and foreign scholars mainly focus on the theoretical model of the formation pore damage caused by solid sulfur. However, there are few researches on the deposition and migration of liquid sulfur, even less on the effect of liquid sulfur deposition on productivity. Therefore, the physical properties of high sulfur gas and liquid sulfur are analyzed in this paper. On the basis of sedimentary migration mechanism of liquid sulfur and damage to gas permeability, a calculation model of liquid sulfur saturation in high sulfur gas reservoir is established. On the basis of the existing experimental equipment, a set of high-temperature and high-pressure gas-liquid sulfur seepage experimental equipment was developed. The relative permeability curves of gas-liquid sulfur were measured and the effects of temperature and stress sensitivity on the relative permeability were analyzed. The mathematical model of gas-liquid sulfur percolation is established and solved. Based on the above research, the following conclusions are obtained: 1) the gas physical properties of high sulfur gas reservoirs need to be corrected because of the presence of acid gas. The influence of non-Darcy flow and stress sensitivity is taken into account in the prediction model of sulfur saturation, which makes the calculation results of liquid sulfur saturation more accurate. The experimental results show that the stress sensitivity of matrix core is moderately weak. The relative permeability curves of gas-liquid sulfur phase are measured experimentally. The results show that the critical flow saturation of liquid sulfur is high. The effect of temperature and stress sensitivity on the phase permeability curve is studied. The results show that the influence of temperature and stress sensitivity on gas phase relative permeability is obvious and the gas phase permeability decreases. The influence of temperature and stress sensitivity on the relative permeability of liquid sulfur is not. 4) according to the condition that elemental sulfur is precipitated from sulfur-containing gas and formed in liquid form with sulfur-bearing natural gas, gas-liquid two-phase seepage is formed. The numerical model of gas-liquid sulfur percolation is established and solved. It is found that liquid sulfur deposition shortens the stable production life of gas wells, decreases the cumulative gas production, and the worse the flowing capacity of liquid sulfur, the greater the effect on gas well productivity.
【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】：TE312

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