呼图壁储气库合理生产压差数值分析

气井出砂是一个带有普遍性的复杂问题。出砂不仅会导致气井减产或停产,地面和井下设备磨蚀,而且会使油管损坏,最终导致油井报废。对于储气库而言,出砂问题关系着储气库设备寿命的长短、配产的大小、完井方式等重要问题。由于储气库采取强注强采开发方式,并且要求长期安全运行,因此,迫切需要解决好合理生产压差的大小问题。目前,常用的判断地层是否出砂的方法为现场观测法、经验计算法等,这些方法只能给出储气库正常生产情况下定性的判断。针对呼图壁储气库强注强采的特殊生产模式,在详细分析出砂的影响因素、出砂机理、出砂原因的基础上,以三轴地应力实验、测井资料求取最大主应力、最小主应力为基础,采用数值计算的方法,给出5种数值计算模型,综合分析后,最终给出了呼图壁储气库气井在不同地层压力下的合理生产压差。计算结果表明,地层压力越高,地层越稳定,越不容易出砂。参考合理生产压差进行合理配产,可以避免储气库出砂。

The Numerical Analysis of Reasonable Producing Pressure Drop in Hutubi Gas Storage

Sand production of the gas well is a universal and complex problem.Sand production will lead to not only production reduction or shutting-down of the gas well,and abrasion of the equipments ground and underground,but also tubing deterioration and even abandonment of the oil well.For the gas storage,sand production is concerned with many important matters such as the life of the equipments,allocation volume,well completion system.The problem of reasonable producing pressure drop needs to be resolved urgently because of intensive injection and production and requiring long-term safe operation.Now common methods used for judging whether sand production or not are the field observation method,experiment calculation method and so on,but they can only give the gas storage a qualitative judgment in normal production.According to the special production mode of intensive injection and production in Hutubi gas storage,influencing factors,mechanisms and reasons of the sand production are analyzed in detail.Maximum and minimum principal stress is evaluated through the experiment of triaxial ground stress and log information.Based on that,the method of numerical calculation is applied,and five numerical models are given for comprehensive analysis.Finally reasonable producing pressure drop at different formation pressures of the gas well in Hutubi gas storage is gained.The results show that higher formation pressure brings more stable formations and less sand production.Reasonable allocation at the reasonable producing pressure drop may avoid sand production of the gas storage.