基于渗流特征的低渗透致密砂岩气藏气井生产规律

Production law based on percolation for a gas well in tight sandstone gas reservoirs with low permeability

低渗透致密气藏的气井存在井底或井口压力、产量随开采生产时间延长而快速下降的特征,掌握其随开采生产时间变化的规律,可在开发早期准确预测气井稳产年限和递减规律,测算经济可采储量,指导气井工作制度的合理调整和气田合理开发。以渗流理论为指导,以气井长期生产过程中取得的大量生产动态数据为基础,以不同生产阶段进行的压力恢复试井成果为检验手段,借鉴不稳定试井资料解释方法,研究了此类气井压力、产量与开采生产时间等参数间的关系,并在气井生产历史拟合、生产动态预测等方面进行了实际应用。通过研究,认为具有人工裂缝的气井压力响应特征多符合地层线性渗流模型,且地层线性流动期持续时间较长,这对同类气藏的开发具有指导意义。

There is a characteristic for low permeability tight gas reservoirs that wellhead pressure or bottom hole pressure and production will reduce rapidly with the increase of development time. So, to master the rule of these factors changing with the production time can help predict stable production life and decline law for a gas well in the early development period, estimate economic recoverable reserve, and instruct to readjust working system of a gas well rationally and develop gas well reasonably. Instructed by percolation theory and based on large amounts of dynamic production data obtained in the long production period, this paper takes the achievement of pressure buildup test data as examining approaches and uses the interpretation method of unstable well testing data as reference to study the relationship between parameters of such kind of gas well such as pressure, productivity and production time, which is applied in production history matching and production performance prediction actually. The study shows that the pressure response characteristics of a gas well with artificial fracture is coincidence with formation linear percolation model and that linear flow period in formation lasts a relatively longer period, which is of guidance in development for such kind of gas reservoir.