As information is assessed while drilling, the planned path may change with respect to remaining wellbore to be drilled.The planned well path defines the preferred location and tangent orientation of the wellbore in 3D space.Four THD components address hole deviation in the "vertical" sense and four address it in the "horizontal" sense.
By design their definitions convey High/Low and Left/Right and match directional-driller common sense regardless of 3D complexities at play.
The terminology and equations apply to all curvilinear and linear well plans.
Consider two examples of technical hole deviation in the vertical sense where for purpose of discussion only RCVD differs, as sketched below.
Current VD is identical in both cases, that is, the wellbore is low of the plan by the same amount.
RCVD/RCHD provide insight as to how VD/HD are changing.
The signs and magnitudes of RCVD and RCHD help to guide directional tool-setting adjustments.
Joshua served as technical reviewer on several Tableau titles and is the author of the book Learning Tableau.
) quantifies spatial differences between actual and planned well paths. From a mathematical point of view differentiating "noisy" data to assess "change" is useless.
This point along the plan is called MD* ("measured depth star").
Associated with MD* is N*, E*, TVD*, Inc*, and Azi*; respectively, planned values North, East, True Vertical Depth, Inclination, and Azimuth. A description and mathematical definition of each THD component follows.
Eight components collectively define Technical Hole Deviation (THD).