Abstract：An ordinary horizontal well consists of vertical section,curve section and horizontal section.Radial horizontal well is the most complicated one in horizontal well series,it has a major horizontal section and one or several branch sections.The design of a horizontal well includes the steps:1)designing the horizontal section in the light of drilling target and reservoir configuration,which involves determination of the coordinates of starting point,ending point and control points;2)using the starting-point parameters to calculate well-head coordinate and curved-section parameters:locus coordinates,curvature,vertical and horizontal displacements.Branch sections are designed to ascertain oil-water contact in slant reservoir.Control point parameters of branch sections are designed in the same way for the horizontal section.
