气体钻井井径扩大环空气固动态流动研究

发布时间：2018-05-08 14:56

本文选题：气体钻井 + 井径扩大　；参考：《西南石油大学》2017年硕士论文

【摘要】：气体钻井技术因其钻速快、成本低和对储层伤害低的特点受到广泛关注和应用。气体钻井在薄弱地层、高构造应力地层等井段容易造成井眼坍塌扩径。扩径会影响井筒内的流场二次分布,改变井眼净化工况从而引起卡钻等钻井事故,尤其是深井气体钻井。因此,需要针对气体钻井井径扩大环空气固动态流动展开研究。本文在管内气体流动理论、颗粒动力学理论、气固两相流动理论的基础上,结合气体钻井实际工况,建立了气体钻井井径扩大环空气固动态流动数学模型,利用CFD模拟、数值模拟及室内可视化扩径井段岩屑运移实验等方法,开展气体钻井井径扩大环空气固动态流动研究,得到以下研究成果:(1)结合BZX井气体钻井实际工况,对该井进行数值模拟,获得BZX井井筒流动参数。采用数值模拟手段,分析BZX井井径扩大不同形式(不同扩径率、不同扩径形态)条件下的环空流场动态分布规律。(2)基于环空流场动态分布规律的研究,加载固相岩屑颗粒并进行了受力分析,建立了岩屑颗粒运动方程。同时,建立了扩径段环空气固仿真模型,通过CFD软件模拟,得到了不同扩径工况下环空气固动态流动。(3)在分析岩屑运移方式基础上建立了岩屑运移模型,并提出了一种基于气体钻井立压变化反演井眼扩径率的方法,通过BZX井实际工况进行实例分析,计算结果与实际工况基本吻合。结合BZX井气体钻井实际工况,利用CFD模拟,得到不同井深条件下:井底沉砂厚度～井眼尺寸～注气量之间的三维图版;并且分析不同含水量条件下的井底沉砂运移效果,得到含水量越高,沉砂运移越困难。(4)自主研制了气体钻井扩径井段岩屑运移可视化实验架,开展岩屑运移可视化室内实验,得到了岩屑颗粒在扩径井段产生动态悬浮现象的临界注气量与井底沉砂厚度0.1m时启动运移临界注气量,并且通过实验分析验证了三维图版的准确性。(5)针对BZX井扩径段进行环空携岩规律的研究。通过数值模拟计算,得到了不同注气量条件下环空气体安全携岩的最大岩屑粒径,并提供了推荐施工参数,为气体钻井现场施工提供重要理论指导。本文研究能够为气体钻井施工参数优化设计提供理论支持,同时为气体钻井风险控制工艺的改进提供技术指导。
[Abstract]:Gas drilling technology has been widely concerned and applied because of its rapid drilling speed, low cost and low damage to reservoir. Gas drilling is easy to cause hole collapse and dilatation in weak formation and high structural stress formation. The diameter expansion will affect the secondary distribution of the flow field in the wellbore and change the condition of borehole purification resulting in drilling accidents such as drilling jam especially in deep well gas drilling. Therefore, it is necessary to study the dynamic flow of annular air-solid in gas drilling. On the basis of gas flow theory, particle dynamics theory and gas-solid two-phase flow theory in pipe, combined with the actual condition of gas drilling, a mathematical model of expanding annulus air-solid dynamic flow in gas drilling is established and simulated by CFD. Numerical simulation and experimental study of cuttings migration in extended diameter section are carried out. The following research results are obtained: 1) combined with the actual conditions of BZX well gas drilling, the numerical simulation of this well is carried out. The wellbore flow parameters of BZX well are obtained. By means of numerical simulation, the dynamic distribution law of annulus flow field in different forms of BZX well diameter expansion (different expanding rate and different expanding shape) is analyzed based on the dynamic distribution law of annulus flow field. The motion equation of cuttings was established by loading solid-phase cuttings and analyzing the stress. At the same time, the simulation model of annulus air solid in expanding section is established. By CFD software, the dynamic flow of annulus air solid under different expanding working conditions is obtained. (3) based on the analysis of cuttings migration mode, the cuttings migration model is established. A method based on the vertical pressure change of gas drilling to invert the hole diameter expansion rate is proposed. The actual working conditions of BZX well are analyzed and the calculated results are in good agreement with the actual working conditions. Combined with the actual condition of gas drilling in BZX well, using CFD simulation, the three-dimensional chart between bottom hole sand-sinking thickness and borehole size ~ gas injection rate is obtained under different well depth conditions, and the effect of bottom-hole sand sinking migration under different water content conditions is analyzed. The results show that the higher the water content, the more difficult the sand migration is.) the visual experimental frame of cuttings migration in expanding section of gas drilling has been developed independently, and the visualization laboratory experiment of cuttings migration has been carried out. The critical gas injection rate for dynamic suspension of cuttings in the expanded well section and the critical gas injection rate for starting migration at 0.1 m bottom sand thickness are obtained. The accuracy of 3D plate is verified by experimental analysis. (5) the law of carrying rock in annular space is studied in view of the expanding section of BZX well. Through numerical simulation calculation, the maximum cuttings diameter of the ring air body safely carrying rock under different gas injection rate is obtained, and the recommended construction parameters are provided, which provide important theoretical guidance for the field construction of gas drilling. The research in this paper can provide theoretical support for optimization design of gas drilling construction parameters and provide technical guidance for the improvement of gas drilling risk control technology.
【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】：TE21

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