水侵气藏水侵量与地层压力预测方法研究

The prediction method of water influx and formation pressure for a water drive gas reservoir.

天然水侵气藏水侵量的计算和预测是水侵气藏动态分析和预测的一项重要内容，它直接关系到气藏的开发效果。根据水侵气藏的压降方程和非稳态水侵量的计算模型，提出了在未来不同开采时间和累积产气量的情况下，预测侵入气藏的水量和对应的气藏压力的方法和步骤。采用据此编制的计算机程序，进行了实例计算和分析。对比计算结果发现，天然水侵气藏的累积水侵量不仅取决于天然气的采出程度和气藏压力，而且在气藏开发一段时间后还与开采时间有关。对于均质气藏，在同一采气程度下，采气速率越高，累积水侵量越少。因此，为了提高气藏的最终采收率，应尽可能提高采气速率。

For a water drive gas reservoir, the calculation and prediction of water influx are the important work of the performance analysis and prediction, which directly influences the effect of he gas reservoir development. Consequently, this paper presents a prediction method of the water influx based on the material balance equation and unsteady water influx flow model. Given a future time and cumulative gas production, the method can predict the formation pressure and water influx of a water drive gas reservoir. By means of example calculations and contrast analyses , it can be seen that as soon as a gas reservoir is developed, the cumulative water influx depends on not only the cumulative gas production, but also the production time. In addition, it is also shown that for a homogeneous water drive gas reservoir, on condition that the cumulative gas production is equal, the greater the gas production rate, the less the cumulative water influx. Consequently, in order to enhance the ultimate gas recovery of a homogeneous water drive gas reservoir, it is helpful to increase gas production rate as greatly as possible.