Determination method for initial well deviation azimuth angle of three-dimensional horizontal well borehole trajectory

The invention relates to a determination method for an initial well deviation azimuth angle of a three-dimensional horizontal well borehole trajectory and belongs to the technical field of petroleum natural gas drilling. The determination method comprises the following steps: determining a final target-entering deviation angle and a well deviation azimuth angle according to parameters of a target point A and a target point B; determining a minimum stable deviation section length and a well deviation angle behind a twisting direction by using a vertical depth error of the target point A; determining a deviation change rate of a deviation change tool according to a deviation change capability of a drilling tool needing to be used; determining a borehole curve rate needed by a needed entering sleeve according to a sleeve type needing to be adopted; predicating a natural deviation change rate of a stratum according to adjoining well data; determining a first two-dimensional deviation increasing section maximum well deviation rate and a three-dimensional deviation increasing and twisting direction finishing point maximum deviation increasing rate; and combining the parameters to determine the initial well deviation azimuth angle of the three-dimensional horizontal well borehole trajectory. The quantified design is realized, and field drilling and oriented construction are convenient to realize; the oriented working amount is reduced and the drilling engineering cost is reduced.