水平井冲砂洗井流体流速研究

Research of Fluid Velocity for Sand Washing of Horizontal Well

由于水平井井身结构的特殊性,开发过程中地层砂更易进入井筒,导致产量下降,水平井中冲砂洗井效果直接影响其产能和开发成本。直井冲砂的水力参数设计不适用于水平井水力冲砂洗井,有必要进行水平井冲砂洗井水力参数研究。在分析水平井不同井段内岩屑运移机理的基础上,建立了相应的水力冲砂流体流速数学模型,可以计算砂粒运移时与流体的相对速度以及冲砂洗井所需的临界流速。水平井冲砂洗井中最困难部分为井斜角60°左右的斜井段,临界流速值最大;洗井液黏度适当增大可以降低冲砂洗井所需的临界流速;岩屑尺寸增大,冲砂洗井所需的临界流速也增大。由于未考虑湍流漩涡对于岩屑运移的影响,临界流速计算值略大于实际冲砂洗井中的流速。

Due to the particularly of horizontal well casing program, formation sands more easily come into the wellbore during the exploitation leading to the decline of output. Sand washing results in horizontal well have direct influence on its productivity and development cost. The hydraulic parameters design of sand washing in vertical well cannot be applied in horizontal well ; therefore, it is necessary to study hydraulic parameters of sand washing in horizontal well. Cuttings transport mechanism in different sections of horizontal well was analyzed and then a mathemat- ic model of critical fluid velocity for sand washing in horizontal well was proposed. The relative velocity between cuttings and fluid and the critical fluid velocity for sand washing could be calculated with the model. The most diffi- cult part for sand washing in horizontal well is the deviated segment with inclination angle about 60°and the critical fluid velocity comes to the maximum value at this section. The appropriate increase of flushing fluid viscosity will decline the critical fluid velocity for sand washing. The critical fluid velocity will increase with cuttings size. As the turbulence of flow which will cause the reduction of critical fluid velocity has not been taken into account in the model, the model predictions of critical fluid velocity are slightly higher than that in sand washing Droiect.