高含硫气藏储层井筒一体化模拟研究

发布时间：2018-01-14 21:08

本文关键词：高含硫气藏储层井筒一体化模拟研究　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：在我国四川盆地地区有许多高含硫气藏,与常规气藏相比,该类气藏天然气成分中包含有H2S,CO2等酸性气体,同时还溶解有元素硫,酸性气体的存在必然影响气体性质。随着开采的进行,储层压力的降低造成元素硫的析出使得流动变成复杂的气固两相流,同时元素硫的沉积对储层的孔隙度渗透率产生影响。在高含硫气井井筒中,酸性气体的存在以及从储层中携带出的硫以及井筒压力条件下析出的硫也会影响气井井筒温度和压力的分布。储层和井筒的流动是一个连续的过程,储层条件的改变也会造成井筒温度压力分布的变化。建立能够描述高含硫气藏渗流和井筒流体流动的数学模型并求解计算,实时反映储层和井筒动态参数的变化,能够为高含硫气藏的高效开发提供参考依据,具有重要的指导意义。本文以实现高含硫气藏储层井筒一体化模拟为目标,主要开展了以下一些研究,并取得了以下一些认识:(1)高含硫气藏流体的流动特征研究,包括H2S的来源与性质,元素硫的溶解析出特征,以及元素硫在储层中的运移、沉降、吸附特征,高含硫气体物性参数特征等;高含硫气体物性参数如偏差因子,粘度,密度等需要进行酸性校正。(2)基于Warren-Root双重介质模型建立了用于描述高含硫气藏储层流体流动的气固两相渗流数学模型,对模型进行数值求解,并通过与文献中的模拟数据结果进行对比,验证模型的可靠性,并分析了井底压力曲线发生陡降的原因。(3)建立高含硫气井井筒单相流动的温度压力模型以及考虑析出硫为固态时的气固两相流动的井筒温度压力模型,给出井筒温度压力耦合计算算法;通过与商业软件Pipesim的计算结果进行对比,保证模型的正确性。运用所建立的模型对比单相流和气固两相流的井筒温度压力计算结果,发现气固两相流计算的温度压力比单气相时偏低,说明两相流能量损失,热量损失更大一些。并发现在井筒流体中硫较少时,两相流对温度压力计算结果影响并不大。(4)在储层渗流模型和井筒温度压力模型的基础上,将两部分以井底压力为衔接点进行连续求解,从而实现一体化计算。(5)建立机理模型分别对比了考虑硫析出沉积和不考虑硫析出沉积对储层和井筒的影响,以及通过改变初始含硫量来分析硫的析出沉积量的多少对储层和井筒的影响,结果发现硫沉积降低了稳产时间,并且初始含硫量越大,稳产时间越短;井筒中析出的硫降低井筒温度,但析出较少时影响并不大,甚至可以忽略。(6)通过生产实例对高含硫气藏进行储层井筒一体化模拟,模拟计算该区块储层硫沉积,孔隙度,渗透率等参数及井筒温度压力剖面随时间的变化,为高含硫气藏的动态预测分析提供参考。
[Abstract]:There are many high sulfur gas reservoirs in Sichuan Basin area of China. Compared with conventional gas reservoirs, these gas reservoirs contain acid gases such as H _ 2S _ 2 _ 2 and dissolved elemental sulfur. The existence of acid gas will inevitably affect the gas properties. With the development of production, the reduction of reservoir pressure leads to the release of elemental sulfur, which makes the flow into a complex gas-solid two-phase flow. At the same time, the deposition of elemental sulfur has an effect on the porosity and permeability of the reservoir. The presence of acid gas, sulfur from reservoir and sulfur from wellbore pressure will also affect the distribution of wellbore temperature and pressure. The flow of reservoir and wellbore is a continuous process. The change of reservoir condition will also cause the change of wellbore temperature and pressure distribution. The mathematical model which can describe the percolation and wellbore fluid flow in high sulfur gas reservoir is established and solved. Reflecting the change of dynamic parameters of reservoir and wellbore in real time can provide reference basis for the high efficiency development of high sulfur gas reservoir and has important guiding significance. The aim of this paper is to realize the integrated well bore simulation of high sulfur gas reservoir. The following researches have been carried out, and some understandings have been obtained as follows: 1) the fluid flow characteristics of high sulfur gas reservoirs, including the source and properties of H 2S and the characteristics of elemental sulfur dissolution and precipitation. And the migration of elemental sulfur in the reservoir, sedimentation, adsorption characteristics, physical properties of high sulfur gas, etc. High sulfur gas physical parameters such as deviation factor, viscosity. Based on the Warren-Root dual medium model, the mathematical model of gas-solid two-phase percolation is established to describe the fluid flow in high-sulfur gas reservoirs. The model is solved numerically, and the reliability of the model is verified by comparing the results with the simulation data in the literature. The reason of the steep drop of bottom hole pressure curve is analyzed.) the temperature and pressure model of single phase flow in high sulfur gas well and the temperature and pressure model of gas-solid two-phase flow with sulfur precipitation as solid state are established. The calculation algorithm of wellbore temperature and pressure coupling is given. By comparing the calculation results with commercial software Pipesim to ensure the correctness of the model, the established model is used to compare the wellbore temperature and pressure calculation results of single-phase flow and gas-solid two-phase flow. It is found that the temperature and pressure calculated by gas-solid two-phase flow is lower than that of single gas phase, which indicates that the energy loss and heat loss of two-phase flow are higher than that of single gas phase flow, and it is found that when sulfur is less in wellbore fluid. The effect of two-phase flow on the calculation results of temperature and pressure is not great.) on the basis of reservoir percolation model and wellbore temperature and pressure model, the two parts are solved continuously with bottom hole pressure as the junction point. Thus, the mechanism model is established to compare the effects of sulfur deposition and no sulfur deposition on reservoir and wellbore, respectively. By changing the initial sulfur content to analyze the influence of the amount of sulfur deposition on the reservoir and wellbore, the results show that sulfur deposition reduces the stable production time, and the higher the initial sulfur content, the shorter the stable production time; The sulfur emitted from the wellbore reduces the wellbore temperature, but when the precipitation is less, the influence is not great, even can be ignored. 6) through the production example to carry on the wellbore integration simulation to the high-sulfur gas reservoir. The parameters such as sulfur deposition porosity permeability and wellbore temperature and pressure profile in this block are simulated and calculated with time which provides a reference for the performance prediction and analysis of high sulfur gas reservoirs.
【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】：TE37

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