天然气井产能方程研究

发布时间：2018-08-09 11:18

【摘要】：本文从分析天然气不稳定渗流数学模型入手。利用拟压力函数和拟时间函数将非线性的天然气渗流方程化简为线性的方程,然后利用“拟稳态”阶段的特点,将不稳态渗流方程化简为稳态方程,再求解稳态方程得到天然气井的产能方程,最后对产能方程进行分析计算,并且分析对比了另外三种改善的气井产能方程。根据拟函数的定义,本文给出了常规储层、压敏储层拟压力函数和普通拟时间、物质平衡拟时间函数的计算方法和计算结果。在直角坐标图中展示了拟压力函数曲线、压敏拟压力函数曲线、采出程度与物性参数(μgcg)关系曲线、采出程度与拟时间函数关系曲线。针对圆形均质气藏偏心气井的不稳定渗流模型,利用Laplace变换和Bessel函数加法定理求解,然后通过渐近分析得到了晚期拟稳态产能方程,计算分析了偏心距对气井产能的影响。计算结果表明:偏心距的存在使得边界影响提前,平面径向流动持续时间相对变短,无量纲压力导数后期产生上翘,这种上翘类似于单一直线断层的影响,但本质上是不同的,在压力导数曲线上不能产生半径向流直线段;对于给定的储层,大偏心距的井产量递减相对较快,在弹性开采条件下,拟稳态生产阶段的中后期偏心距大的井弹性产量其实是小的,只是在末期相对大些。针对矩形均质压敏气藏不稳定渗流模型,利用点源函数结合Newman乘积方法给出了其解析解式,通过重新定义压敏拟压力函数和压敏拟时间因子,应用渐近分析给出了晚期拟稳态产能方程。计算结果表明:随着渗透率敏感性的增加,定流量生产过程中井壁压力下降增大,定流压生产则井产量下降幅度增加,表明渗透率的下降引起地层渗流阻力相对增大。本文的研究结果可用于产能分析和预测,为天然气井的生产方案设计提供基础数据。
[Abstract]:In this paper, the mathematical model of gas unstable seepage is analyzed. The nonlinear natural gas seepage equation is simplified to linear equation by using quasi pressure function and quasi time function, and the unsteady seepage equation is simplified to steady state equation by using the characteristic of "quasi steady state" stage. The productivity equation of natural gas well is obtained by solving the steady-state equation. Finally, the productivity equation is analyzed and calculated, and the other three improved gas well productivity equations are analyzed and compared. According to the definition of quasi function, this paper gives the calculation methods and results of the pseudo pressure function, the general pseudo time function and the material balance pseudo time function of conventional reservoir, pressure sensitive reservoir and general pseudo time function. The pseudo pressure function curve, pressure sensitive pseudo pressure function curve, recovery degree and physical property parameter (渭 gcg) curve and extraction degree and quasi time function curve are shown in the Cartesian coordinate diagram. In view of the unstable percolation model of eccentric gas wells in circular homogeneous gas reservoirs, Laplace transform and Bessel function addition theorem are used to solve the problem, and then the late quasi-steady productivity equation is obtained by asymptotic analysis, and the effect of eccentricity on gas well productivity is calculated and analyzed. The calculation results show that the existence of eccentricity makes the boundary effect advance, the duration of plane radial flow is relatively shorter, and the dimensionless pressure derivative produces upwarping at the late stage, which is similar to the effect of a single linear fault, but it is different in nature. For a given reservoir, the production decline of the well with large eccentricity is relatively fast, and under the condition of elastic exploitation, the radial flow line can not be produced on the pressure derivative curve. The elastic production of wells with large eccentricity in the middle and late stage of quasi-steady production is small, but relatively large at the last stage. In view of the unstable percolation model of rectangular homogeneous pressure-sensitive gas reservoir, the analytical solution of point source function combined with Newman product method is given. By redefining the pressure-sensitive quasi-pressure function and pressure-sensitive pseudo-time factor, The late quasi steady state productivity equation is given by asymptotic analysis. The calculation results show that with the increase of permeability sensitivity, the wellbore pressure decreases and the well production decreases with the constant flow pressure production, which indicates that the decrease of permeability leads to the relative increase of percolation resistance. The results of this paper can be used for productivity analysis and prediction, and provide basic data for the production scheme design of natural gas wells.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE328

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