Directional well using MWD as its working tools to get directional well data. The reliability of directional tools is very important. Describing the directional well hole space location and the shape of the method, is measuring borehole. There are three borehole datum to each point, namely Depth, Inclination, Azimuth. We called it is the basic elements of directional well.
1）Measure depth: Any point in the well to the well hole axis’s length, known as the point of sounding, also known as the measuring point inclined depth. Usually indicated as the letter L, the unit of measure is meter or feet.
2）Hole inclination or Hole angle: Well point of borehole directional line (tangent) and by that point of the angle between the gravity line known as the point at which Angle. Hole direction of line and line of the gravity is directed straight line. Usually indicated ad the Greek letter α(alpha), its unit of measurement is the degrees.
3）Hole Azimuth: Due north bearing line as beginning, clockwise to bearing line around the hole deviation angle. Usually expressed as Ø, unit is degree. It also can use the quadrant value, point to it and it is the angle between the orientation or line with south orientation, quadrant value between 0-90 ° change, and to indicate the quadrant.