页岩气井压力递减分析新方法

A new pressure-decline analysis method suitable for shale gas wells

页岩气井早期生产数据较少,生产状况不稳定,导致数值模拟法与Arps产量递减分析法等经典方法分析生产动态的适用性较差。针对页岩气井实施定产生产、间歇生产等生产控制情况,借鉴页岩气井二项式产能方程建立思路和Arps产量递减分析法,在不稳定渗流数学模型基础上,建立了新的压力递减定量化评价模型,并通过了生产实践的检验。结果表明:①该压力递减分析法可作页岩气井定产量和变产量生产情况下的压力变化分析;②压力递减速度、压力递减率、单位产量压力递减率可作为配产合理性评价指标进行横向对比;③该方法适用性强,还可用于套管或油管生产情况下的压力数据分析。结论认为,压力递减分析法具有简单实用等优点,可作为Arps产量递减分析法的有效补充,适合页岩气井生产动态定量化评价分析。

During an early development stage,many shale gas wells are commonly featured by a little data and unstable operation condition,which may lead to poor adaptability of two classical methods to analyze production performance,such as numerical simulation method and Arps production-decline method.In view that constant-rate and intermittent production were carried out,this study established a new model for shale gas wells to quantitatively evaluate pressure decline based on another mathematical model of unsteady seepage,referring to one thinking to establish a binomial-productivity equation and Arps production-decline analysis method.Furthermore,the model was verified in practices.Results show that(1)this newly established pressure-decline analysis method can be used to analyze pressure change of shale gas wells under working condition of constant or variable rate;(2)pressure-decline velocity(vd),pressure-decline rate(D),and pressure-decline rate of unit production(Dq)can be used as indicators to evaluate proration reasonability for lateral comparison;and(3)this method is of strong applicability and can be also used to analyze both casing or tubing pressure under working condition.In conclusion,the newly established pressure-decline analysis method is simple and practical,and can be used as an effective supplement for Arps method to quantitatively evaluate production performance of shale gas wells.