产量不稳定法评价水平气井动态储量

水平井技术作为提高气田采收率的一项重要技术,已开始在各大气田广泛应用。动态储量是确定气井合理产能和井网密度的重要依据,是编制气田整体开发方案的基础。因此,对水平气井动态储量进行评价,对于高效开发气田、优化井网、缩短开发周期至关重要。为此,提出了一种评价水平气井动态储量的新方法——产量不稳定法。采用该方法只需要日常的生产历史数据就可以简单、直接、快速地计算动态储量,并且可以免去昂贵的试井测试。该方法是在建立圆形封闭气藏水平井不稳态流数学模型的基础上,应用积分变换等方法求得模型的Laplace空间解,再通过Steh-fest反演算法绘制水平气井的产量递减典型曲线图版。最后用实例说明了水平气井递减典型曲线图版的应用过程。结果表明:产量不稳定法可以很好地计算水平井的动态储量且精度较高。

Rate Transient Analysis: A method to evaluate dynamic reserves of horizontal gas wells

As an important method to increase the recovery ratio of gas fields, horizontal well technology has been widely used all over the gas fields in China. The dynamic reserve for a horizontal well is of great significance for gas field development, being the basis not only for determining the reasonable productivity and the well pattern density, but for the integral field development scenarios. Therefore it is necessary to study the dynamic reserves of horizontal wells. In this paper, we present a new method named Rate Instability Method to evaluate the dynamic reserves of horizontal wells. It only needs the production history data to obtain the dynamic reserves simply, directly and fast, and also it can avoid expensive well tests. Based on the horizontal well non steady flow mathematical model in a cylindrical gas reservoir, the model's solution is obtained by means of Laplace transforms. And also a typical plot of decline type curve for a horizontal well is drawn by using Stehfest inversion. An example is given to illustrate the application of horizontal well decline type curve. The results show that it can evaluate the dynamic reserves of a horizontal well with a high accuracy. This method is of great significance for the efficient development of gas reservoirs with low permeability, the evaluation of horizontal well reserves and the development of program design.