气体钻开气层井筒压力波动机理研究

发布时间：2018-01-28 16:56

本文关键词： 气体钻井井筒流动地层渗流耦合流动瞬态模型　出处：《西南石油大学》2015年硕士论文　论文类型：学位论文

【摘要】：气体钻井因其具有机械钻速快、克服井漏、成本低、保护储层等优势被视为解决难动用油气资源开发的有效途径,并在四川盆地和塔里木盆地得到了较多应用,取得了良好效果。但是气体钻开产层时由于地层气体产出引起的井筒不稳定高速流动会引发一系列安全风险,目前尚未清楚认识地层产气后井筒压力波动规律,缺乏定量计算模型,对风险的准确评估和有效控制缺乏科学理论基础。因此,本文对气体钻开气层井筒压力波动机理展开了系统的研究,具体研究内容和取得的主要成果如下： (1)建立气体钻井井筒流动基本控制方程,采用特征线法和有限差分法联合求解了气体钻井井筒瞬变流动模型,分析了注气和停气两个典型气体钻井井筒瞬变流工况,并对其影响因素进行了分析。 (2)结合现场实测甲烷浓度曲线,分别建立了基质产层、裂缝组产层、单裂缝产层的瞬态渗流模型,采用有限差分法对其直接求解,分析了不同类型产层的瞬态渗流特征及影响因素。 (3)设计了一维岩心瞬态渗流实验装置,利用该装置模拟了定压边界和封闭边界条件下的一维岩心瞬态渗流,实验结果与理论计算吻合较好,一定程度上说明了地层瞬态渗流模型的准确性。 (4)基于地层-井筒耦合瞬态流动计算方法,结合现场实例分析了气体钻开裂缝组产层后井筒压力波动规律,研究发现气体钻开裂缝组产层后,井底压力迅速增大,井底流量激增至峰值后衰减,立管和环空出口的响应分别为立管压力增大和环空出口流量增大,这一响应可用于在气体钻井时及时识别持续产气能力较强的产层。 (5)分析了气体钻开单裂缝产层后井筒压力波动规律,研究发现气体钻开单裂缝产层后,井底会产生较大的压力扰动,井底流量和井底压力均迅速激增至峰值后逐渐衰减,呈现出先增长后减小的波动变化,但是立管压力和环空出口流量变化非常微弱。本文研究成果对于深入认识气体钻开产气层井筒流动机理及加强井筒安全风险控制具有重要意义。
[Abstract]:Gas drilling has been widely used in Sichuan Basin and Tarim Basin because of its advantages such as quick mechanical drilling, low cost, low cost and reservoir protection, which is considered to be an effective way to solve the problem of exploitation of oil and gas resources in Sichuan Basin and Tarim Basin. But the unstable and high velocity flow of wellbore caused by formation gas production will lead to a series of safety risks. At present, there is no clear understanding of wellbore pressure fluctuation law after formation gas production. Lack of quantitative calculation model, the accurate assessment of risk and effective control of the lack of scientific theoretical basis. Therefore, the mechanism of pressure fluctuation in gas drilling well bore is systematically studied in this paper. The specific contents of the study and the main results achieved are as follows: 1) the basic governing equation of wellbore flow in gas drilling is established, and the transient flow model of gas drilling wellbore is solved by using the characteristic line method and the finite difference method. The transient flow conditions of two typical gas drilling wells, gas injection and gas stoppage, are analyzed, and the influencing factors are analyzed. 2) combined with the measured methane concentration curve in the field, the transient seepage models of the matrix layer, the fracture group layer and the single fracture layer are established, and the finite difference method is used to solve them directly. The characteristics and influencing factors of transient seepage in different types of production layers are analyzed. An experimental device for transient seepage of one-dimensional core is designed. The transient seepage of one-dimensional core under the condition of constant pressure boundary and closed boundary is simulated by the device. The experimental results are in good agreement with the theoretical calculation. To a certain extent, the accuracy of the formation transient seepage model is explained. 4) based on the coupled transient flow calculation method of formation and wellbore, combined with field examples, the pressure fluctuation law of wellbore after gas drilling fracture formation is analyzed, and it is found that gas drilling fracture group produces layer. The bottom hole pressure increases rapidly, the bottom hole flow increases to the peak value, and the response of riser and annular outlet is the increase of riser pressure and annular outlet flow, respectively. This response can be used to identify gas producing layers with strong continuous gas production ability in time during gas drilling. (5) the pressure fluctuation law of wellbore after gas drilling has been analyzed, and it is found that there will be a big pressure disturbance in the bottom hole after gas drilling. The bottom hole flow rate and bottom hole pressure rapidly surge to the peak and gradually decrease, showing a fluctuation change of first increase and then decrease, but the variation of riser pressure and annulus outlet flow rate is very weak. The research results in this paper are of great significance for further understanding the wellbore flow mechanism and enhancing the wellbore safety risk control.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE24

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