底水驱基岩气藏全生命周期产能预测方法

Full life-cycle productivity forecast for bedrock gas reservoir with bottom-aquifer drive

采用传统的无阻流量经验配产方法对储层物性复杂的底水驱基岩气藏进行产能预测时,存在稳产难、产能递减速度大,气井见水快等问题。为了能够延长气井的开采寿命,提高气藏采收率,提出一种针对底水驱基岩气藏的全生命周期产能预测方法。该方法利用气井的气水两相垂直管流方程、水驱物质平衡方程和二项式产能方程的相互影响和制约关系,预测气井从投产初期稳产阶段到中期递减阶段,再到生产末期增压阶段的整个生命周期内的产量、地层压力、井底流压、井口压力变化规律。采用该方法对东坪气田基岩气藏的15口气井进行产能预测,预测结果与实际生产曲线相吻合,说明该方法适用于底水驱基岩气藏的长期产能预测,可以有效控制底水锥进速度。

The productivity forecast with empirical production allocation of traditional absolute open flow for the bedrock gas reservoir with complex reservoir properties and bottom-aquifer drive is usually challenged by no stable production,rapid production decline,water breakthrough in advance and other problems.A full life-cycle productivity forecast method for the bed rock gas reservoir with bottom-aquifer drive was proposed to extend the gas well production life and enhance gas reservoir recovery.This method can forecast the full life-cycle gas well production,formation pressure,bottom-hole flowing pressure and wellhead pressure from the initial stable production stage to the mid-term production decline stage and the late pressurization stage by making use of the mutual interaction and restriction between gas-water two-phase vertical pipe flow equation in gas well,the waterflooding material balance equation and the binomial productivity equation..The productivities of 15 gas wells in the bedrock gas reservoir of Dongping gas field were forecasted by this new method and the forecast results are consistent with the actual production history.Therefore,it verifies the validity in the long-term productivity forecast for bedrock gas reservoir with bottom-aquifer drive and could effectively control the bottom-aquifer coning rate.