关键词: 致密气, 不确定性, 产能预测, 有效渗透率, 解析模型

Abstract: Tight gas productivity prediction involves parameters such as reservoir properties and fracture shape. However, with low permeability, small pore size, strong reservoir heterogeneity, and wide distribution of pore throats, there are uncertainties in predicting reservoir and fracture parameters. Therefore, such productivity prediction is not comprehensive as only by giving one definite value to a parameter. The study shows that there are uncertainties in absolute reservoir permeability, effective permeability, and half lengths of effective induced fractures. In such case, an uncertain productivity prediction technology for tight gas was proposed. First, based on the open flow potentials of single wells, the productivity equation was used to inversely determine the probabilistic distribution of effective gas permeability and the half lengths of effective induced fractures, and the probabilistic distribution of the open flow potential of a block was calculated based on available reservoir and fluid properties; second, the probabilistic distribution of production profiles was predicted based on the parameter probabilistic distribution and an analytical model. This method is applicable for both block and single-well probabilistic productivity prediction, and provides a new way to reduce the uncertainties in tight gas productivity prediction.

Key words: tight gas, uncertainties, productivity prediction, effective permeability, analytical model