Transient pressure analysis is a crucial tool to forecast the production performance during the exploration and production process in gas reservoirs. Usually, a regular shaped outer boundary is assumed in previous studies for well-testing analysis, which is just a simplification of practical cases and cannot reflect the actual boundaries of reservoirs. In this paper, a mathematical model is established to analyze the transient pressure behaviors of a horizontal well in an arbitrarily shaped gas reservoir. Dimensionless treatment, Laplace transformation, and boundary element method are applied in solving the model, which is verified by comparing with the results from the source function method. Based on the Stehfest numerical inversion method, the models of single-porosity media and dual-porosity media are solved respectively. Then, the time-domain curves of pseudo pressure and its derivative are obtained, and the flow regimes are identified. Finally, the impacts of some critical parameters on pressure transient behaviors are analyzed, including storativity ratio, interporosity coefficient, well length, and well orientation. This paper presents an effective way to handle complex external boundary problems in gas reservoirs.

中文翻译：

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任意边界气藏水平井瞬态压力特性

瞬态压力分析是预测气藏勘探和生产过程中生产动态的重要工具。在以往的试井分析研究中，通常假设外边界为规则形状，这只是实际案例的简化，并不能反映储层的实际边界。本文建立了一个数学模型来分析任意形状气藏中水平井的瞬态压力行为。采用无量纲处理、拉普拉斯变换和边界元法求解模型，并与源函数法的结果进行比较验证。基于Stehfest数值反演方法，分别求解了单孔介质和双孔介质模型。然后，获得了伪压力及其导数的时域曲线，并确定了流态。最后，分析了一些关键参数对压力瞬态行为的影响，包括储量比、孔隙度系数、井长和井向。本文提出了一种有效处理气藏复杂外边界问题的方法。