When the offset distance is smaller on the wellhead, the layer velocity obtained with straight line and the refractionline is matched with that of actual formation velocity.
当井口偏移距较小时，直线法和折线法求取的层速度和地层真速度吻合；
2
Rapidly changing refraction due to turbulence along the line of sight affects different colors of light by different amounts and generally produces a twinkling effect for stars.
Based on the analysis of present methods for atmospheric refraction correction, a new correction model is put forward based on the refraction Angle of the line of sight.