气体钻井井筒与地层流动耦合分析

气体钻井具有提高机械钻速、降低储层伤害等特点,是开发低压低渗油气田的有效方法。为了分析气体钻井钻开储层时流体的流动规律,基于可压缩流体不稳定流动理论以及地层渗流力学理论,建立了该过程中井筒与地层的耦合流动模型,并结合边界条件与初始条件对模型进行了数值求解。最后,结合钻井实例分析了不同工况下井内流体的流速分布规律和压力分布规律,结果表明,不同的钻井工况在经历一定时间的不稳定流动后都有达到稳定的趋势。

COUPLED ANALYSIS OF FLOW IN THE WELLBORE AND RESERVOIR DURING GAS DRILLING

For being able to increase the rate of penetra ti on and decrease formation damage, gas drilling has become an effective approach for developing the low-pressure and low-permeability reservoir. In order to anal ysis the flow of the fluid when encountering reservoir during gas drilling, the coupled model of wellbore flow and reservoir percolation is established based on the unsteady flow of compressible fluid and the percolation of the formation fl uid. Combined with the boundary conditions and the initial condition, the numeri cal solution of the model has been discussed. In the end, the velocity and the p ressure distribution of different working conditions have been analyzed. The res ults show that after the unsteady stage, both working conditions will become sta ble.