大位移井岩屑床厚度预测模型与现场应用： 以CH1-1-XX井钻井为例

大位移井钻井过程中，岩屑极易在斜井段及水平段环空底部积聚成床，导致憋泵、卡钻等事故，严重影响钻井施工安全和钻井时效。现有的岩屑运移及岩屑床清除模型均针对标准圆球状岩屑，与实钻中返出的岩屑形状差异较大，导致模型应用范围受限，无法提供更准确的现场指导。为探究大位移井非标准圆球状岩屑运移规律，本文通过可视化岩屑运移实验与CFD数值模拟结合的方法，建立了一套大位移井岩屑床厚度预测经验模型，并在CH1-1-XX井开展了现场应用，对不同开次下的钻进参数进行了优化，取得了良好效果。结果表明：利用模型预测岩屑床厚度并进行钻进工艺参数优化后，一开与二开钻井时最高岩屑床厚度分别为40.6 mm、33.9 mm，均低于同井深处的岩屑床厚度安全线，表明井眼清洁程度高，无憋卡风险。本文建立的岩屑床厚度预测经验模型对提高大位移井井眼净化效率，保障大位移井安全高效钻进具有重要意义。

Prediction model and field application of cuttings bed thickness in extended reach well

During the drilling process of extended reach wells, cuttings are easy to accumulate and form a bed at the bottom of the inclined section and horizontal section of the annulus, leading to accidents such as overpressure pumping and sticking, which seriously affect the safety of drilling construction and drilling efficiency. The existing cuttings migration and cuttings bed removal models are all aimed at standard spherical cuttings. They are quite different from the shape of actual cuttings returned in drilling, resulting in limited application range of the model and unable to provide more accurate on-site guidance. In order to explore the migration law of non-standard spherical cuttings in extended reach wells, this paper proposes a set of empirical models for predicting the thickness of cuttings bed in extended reach wells by combining visual cuttings migration experiments and CFD numerical simulation methods. The model was applied in CH1-1-XX Well to optimize the drilling parameters under different openings, and good results were achieved. The results show that by using the model to predict the thickness of the cuttings bed and optimizing the drilling process parameters, the maximum cuttings bed thickness during the primary and secondary spuds is 40.6 mm and 33.9 mm, respectively. They are both lower than the safety line of the thickness of the cuttings bed at the same well depth. It indicates the wellbore is highly clean and there is no risk of sticking. The empirical model of cuttings bed thickness prediction established in this paper is of great significance to improve the wellbore purification efficiency of extended reach wells and ensure the safe and efficient drilling of extended reach wells.