关键词: 钻井理论, 数学模型, 井眼轨迹, 定向钻井, 水平钻井

Abstract: From the assumption that within a survey interval the rates of inclination change and azimuth change remain constant, this paper derives formulae for calculating the course coordinates and puts forward to a new mathematical method of modeling and calculating the wellbore trajectory——Natural Parameter Method. The new method has several advantages. First, the model is simple and relatively reasonable. Second, the calculated results are stable. Third, interpolation calculation can be easily achieved for wellbore trajectory. Therefore, it is very convenient for oil field application. The calculated results of two typical curves employed to verify its correctness and advantages above showed that Natural Parameter Method is superior to Cylinder Helix Method (Radius of Curvature Method) and Minimum Curvature Method which are most commonly used today, and it is suitable for both rotary system and steerable system.

Key words: drilling theory, mathematical model, wellbore trajectory, directional drilling, horizontal drilling