大斜度井井眼清洁影响因素及对策研究

INFLUENCING FACTORS AND COUNTERMEASURES OF WELL CLEANING IN HIGH-ANGLE WELLS

为了提高大斜度井井眼清洁效率,降低井下事故复杂率,利用软件模拟分析了井眼清洁影响因素,提出了井眼清洁判断方法和提高井眼清洁效率方法。模拟结果表明,岩屑床厚度和悬浮岩屑浓度与井斜角、机械钻速正相关,与钻井液排量、转盘转速成负相关。分析了井眼清洁程度与大钩载荷变化规律,提出了井眼清洁程度判断方法,当实测值与预测值偏离程度过大时,需要采取相应技术措施,破坏岩屑床,提高井眼清洁效率。在未形成岩屑床之前,可以通过提高钻井液排量和转盘转速等方式提高井眼清洁效率;当形成岩屑床之后,就需要采用机械方式破坏岩屑床,利用水力方式将岩屑携带出井眼,保证井眼清洁。

In order to improve the cleaning efficiency of wells in high-angle wells and reduce the complexity of downhole accidents,the factors affecting wellbore cleaning were analyzed by software simulation.The method of wellbore cleaning judgment and the method of improving wellbore cleaning efficiency were proposed.The simulation results show that the thickness of the cuttings bed and the concentration of suspended cuttings are positively correlated with the inclination angle of the well and the rate of mechanical drilling,and negatively correlated with the displacement of the drilling fluid and the rotational speed of the rotating disc.The cleaning degree of wellbore and the change law of big hook load are analyzed,and the method of judging the cleanliness of wellbore is proposed.When the deviation between the measured value and the predicted value is too large,corresponding technical measures need to be taken to destroy the cuttings bed and improve the cleaning efficiency of the wellbore.Before the formation of the cuttings bed,the well cleaning efficiency can be improved by increasing the drilling fluid displacement,the rotating speed of the rotary disk;after the formation of the cuttings bed,it is necessary to mechanically destroy the cuttings bed and utilize the hydraulic power to carry the cuttings out of the wellbore to ensure that the wellbore is clean.The research in this paper provides powerful technical support for safe and efficient drilling of high-angle wells.