Unitization of horizontal well 's target window with directional well target area

Key words:  directional well  horizontal well  path  target area  target window  mathematical model

Abstract:

Horizontal well can be considered as a special case of directional wells, but the target window of a horizontal well is not included in the target area of the directional well. In fact, the target window of the horizontal well is in conflict with the target area of the directional well using the current well-design method. The basis for the unitization of the target area and the target widow is the redefinition of the relationship between the directional-horizontal well borehole axis and the target plane, namely the target plane should always be vertical to the borehole axis, and the target area in the target plane should vary with the increase of the inclination angle, gradually changing from a circular shape for a vertical well to a rectangle or oval shape for a horizontal well. In this paper, mathematical models of the target area with oval and rounded rectangle shapes were established respectively, and calculation software was formulated for mapping the safe boundary of the elliptic cone and rounded corner pyramid in the target area. The results show that the target plane should be perpendicular to the borehole axis, and the transition of the vertical well target area to the horizontal well target window along with the inclination angle is one of the effective methods to resolve the conflict.