气体钻井过程中的瞬态流动分析

ANALYSIS OF TRANSIENT FLOW DURING AIR DRILLING

气体钻井过程中,调整钻井参数或者钻遇储层都会引起井内流体的瞬态流动。基于可压缩流体不稳定流动理论及地层流体渗流理论,建立了气体钻井过程中井筒瞬态流动的数学模型。针对井内水动力体系的复杂特点,讨论了模型的定解条件,并对模型进行了数值求解。最后,文章对气体钻井中改变钻井参数以及钻遇储层两种情况井内气体的流动进行了计算,结果表明,增加注气量时井内压力波动不大,但钻遇储层会引起井内压力和流速的大幅度波动。

During gas drilling, both the alteration of the drilling parameters and encountering the reservoir will cause the transient flow of wellbore fluid. Based on the theory of unsteady flow of compressible fluid and the seepage theory of formation fluid, the mathematical model of the gas transient flow in the wellbore has been established. In view of the hydrodynamic complexity of the wellbore, the definite condition of the model has been discussed, and the numerical solution has been presented. In the end, the gas flow of adjusting the drilling parameters and encountering the reservoir has been simulated. The results show that the alteration of the drilling parameter will not cause a strong change of the pressure in the wellbore, but when encountering the reservoir, the pressure and flow velocity in the wellbore will fluctuate strongly.