克拉205井岩石变形对产能的影响

Influence of rock deformation on the productivity of Well Kela 205,Kela 2 Gas Field,Tarim Basin,NW China

克拉205井是塔里木盆地克拉2大气田的生产井,在产能测试过程中,由于生产压差的影响,该井储集层发生岩石弹塑性形变,渗透率随着生产压差的增大而减小。利用气井拟稳态产能方程及压力分布方程进行定量分析,结果表明克拉205井岩石渗透率对应力的敏感性不大,因而地层压降所造成的岩石变形对气井产能的影响不明显;测试过程中岩石变形使近井区域形成了一个渗透率下降漏斗,但下降的幅度较小,对气井产量的影响也不大。对克拉205井取样岩心进行的渗透率有效压力增减循环回路试验表明,岩石变形的不可逆性较小,大油嘴放喷损失了渗透率后,再用适当的小油嘴生产,损失的渗透率大部分可得到恢复,因而不会明显影响气井产能。

In the process of potential test of Well Kela 205, Kela2 Gas Field, Tarim Basin, the producing pressure drop resulted in the elastic-plastic deformation of the reservoir rock, and the permeability decreased with the increase of the pressure drop. Quantitative analyses with the pseudosteady productivity equation and pressure distribution equation reveal that the rock permeability of Well Kela 205 is not sensitive to the stress, and that the productivity of the gas well is not seriously affected by the rock deformation caused by the pressure drop. During the test, the rock deformation built up a permeability drawdown cone around the wellbore of Well Kela 205, but the decline scope is small and its effect on productivity is not serious. The permeability experiments of cores from Well Kela 205, with the effective pressure increase and decrease forming a loop, show that the rock deformation irreversibility is small. The production with a proper small choke may generally restore the permeability damaged in the blowout with a large choke, and the well productivity may not be greatly influenced.