Method and System for Directional Drilling

Abstract

A method for wellbore directional drilling includes selecting a starting and stopping spatial position of at least one portion of the wellbore. A sequence of sliding and rotary drilling operations within the portion is determined to calculate a wellbore trajectory. The sequence has at least one drilling operating parameter. The operations include a constraint on the drilling operating parameter or the calculated trajectory. The calculated trajectory includes a projected steering response of a steerable motor in response to the at least one drilling operating parameter. Drilling the portion of the wellbore is started. A spatial position of the wellbore during drilling is determined at at least one point intermediate the starting and stopping positions. Using a relationship between the projected steering response and the drilling operating parameter, the drilling parameter and/or the constraint are adjusted based on the measured spatial position and the stopping spatial position.

What is claimed is: 
     
         1 . A drilling system comprising:
 a steerable motor;   a sensor for measuring orientation of the wellbore;   a sensor for measuring toolface orientation of the steerable motor;   a drill bit at a distal end of a drill string coupled to the steerable motor;   a processor in signal communication with the orientation sensor and the toolface sensor, the processor having instructions to cause the processor to compute one or more of, (i) a steering response of the steerable motor, (ii) measured depths of slide drilling intervals, (iii) a change in tool face orientation with respect to weight applied to the drill bit, and (iv) parameters related to variation in measurements made by the toolface sensor; and   a user interface in signal communication with the processor, the interface providing an output of one or more of the computed parameters or values derived therefrom, the output provided to at least one of a user interface and an automatic drilling unit controller.   
     
     
         2 . The system of  claim 1 , wherein the steering response is extrapolated from one or more prior measured steering responses. 
     
     
         3 . The system of  claim 2 , wherein the extrapolation of the steering response is estimated from a weighted average of prior steering responses, wherein weights for the average are based on one or more of temporal proximity, depth proximity, fractional or absolute amount of slide drilling included in an associated directional survey interval, tool-face scatter in the associated directional survey interval, relationship to change-points estimated from any combination of prior steering responses or drilling parameters and outlier measurements. 
     
     
         4 . The system of  claim 1 , wherein the processor is programed to cause the user interface to display a warning to replace one or more components of the drill string when the steering response or toolface variation fails to meet threshold criteria either predetermined or based on a current well status and at least one target well spatial location. 
     
     
         5 . The system of  claim 1 , wherein measurements of the toolface orientation change with respect to reactive torque of the steerable motor is used by the processor to compute outputs displayed on the user interface that assist determining a zero reactive torque toolface measurement that will result in a desired toolface orientation when a selected reactive torque is determined. 
     
     
         6 . The system of  claim 1 , further comprising:
 instructions for the processor to receive as input a target spatial position of a wellbore; and   instructions for the processor to calculate one or more drilling parameters which when applied enable the steerable motor to cause the wellbore trajectory to reach the target spatial position.   
     
     
         7 . The system of  claim 1 , wherein toolface orientation measurements are used by the processor to determine measured depth intervals that were slide-drilled and rotary drilled. 
     
     
         8 . The system of  claim 3 , wherein scatter properties of the toolface orientation measurements are used by the processor to determine measured depth intervals that were slide drilled and rotary drilled, the scatter properties including any combination of a difference between successive toolface measurements, an absolute deviation, a variance, a range, a norm of an average of vectors representing the toolface orientations, a modulus of an average of complex numbers representing the tool-face orientations. 
     
     
         9 . The system of  claim 1 , in which virtual survey points beyond a measured depth of directional surveying equipment or values derived therefrom are calculated by the processor and are output to at least one of a user interface and an automatic drilling controller. 
     
     
         10 . The system of  claim 9 , in which a virtual survey point at or near a bottom of the wellbore is used as a starting point for a well path and wherein an orientation of the virtual survey point is used to constrain tangent vectors at or near the beginning of the well path.