System and method for drilling a borehole

Abstract

A system and method for drilling are provided. Responsive to receipt of information, the system determines an estimated position of a drill bit in a borehole and whether the estimated position is within a defined margin of error on the planned path. If the estimated position is not within the defined margin of error, the system calculates a first plurality of convergence plans, each defining a path from the estimated position to the planned path or from a projected position of the drill bit. The system defines a second plurality of convergence plans defining a subset of the first plurality, each falling within a window of correction. The system selects a convergence plan from the second plurality that optimizes target parameters and produces control parameters associated with drilling the selected plan. The system drills at least a portion of the borehole based on the produced control parameters.

What is claimed is: 
     
         1 . A method for drilling comprising:
 receiving, by a computer system coupled to a drilling rig, a plurality of inputs including a planned path for a borehole, formation information for the planned path of the borehole, drilling rig equipment information for equipment associated with the drilling rig, wherein the drilling rig equipment information comprises bottom hole assembly (BHA) information for a BHA coupled to the drilling rig, and cost information;   receiving, by the computer system, feedback information received from the drilling rig during drilling of the borehole;   determining, by the computer system, responsive to the feedback information, an estimated position of a drill bit located in the borehole;   determining, by the computer system, whether the estimated position of the drill bit is within a defined margin of error of a point on the planned path;   calculating, by the computer system, a first plurality of convergence plans if the estimated position of the drill bit is not within the defined margin of error, wherein each of the first plurality of convergence plans defines a path from the estimated position of the drill bit to a point on the planned path, or from a projected position of the drill bit based on a trajectory of the drill bit, wherein the point on the planned path is different for each of the first plurality of convergence plans;   defining a second plurality of convergence plans that each fall within a window of correction and together define a subset of the first plurality of convergence plans;   selecting, by the computer system, a convergence plan that optimizes a set of target parameters from the second plurality of convergence plans;   producing, by the computer system, a set of control parameters associated with drilling the selected convergence plan; and   drilling, by the drilling rig, at least a portion of the borehole based on the set of control parameters.   
     
     
         2 . The method of  claim 1 , wherein calculating each of the first plurality of convergence plans further includes determining, by the computer system, a drift of the drill bit based on at least one of the formation information and the feedback information. 
     
     
         3 . The method of  claim 1 , wherein the cost information includes financial cost information and time cost information, and wherein calculating each of the first and second plurality of convergence plans includes identifying an optimal value of financial cost versus time cost. 
     
     
         4 . The method of  claim 3 , wherein one of the optimal value of financial cost and the time cost is weighted more heavily than the other. 
     
     
         5 . The method of  claim 4 , wherein the optimal value of financial cost has a lower bound defined by a most aggressive possible correction that is limited by a maximum dogleg severity. 
     
     
         6 . The method of  claim 1 , further comprising outputting the set of control parameters to at least one drilling rig control system. 
     
     
         7 . The method of  claim 6 , wherein the at least one drilling rig control system is at least one of: a differential pressure control system, a positional control system, and a fluid circulation control system. 
     
     
         8 . The method of  claim 1 , wherein the window of correction is bounded on one side by a maximum radius of curvature. 
     
     
         9 . The method of  claim 1 , wherein calculating the second plurality of convergence plans includes calculating a delay associated with each of the second plurality of convergence plans that defines a period of time during which the drill bit is allowed to continue from the estimated position prior to a change in direction of the drill bit in accordance with each of the second plurality of convergence plans. 
     
     
         10 . A method for drilling a borehole comprising:
 receiving, by a computer system, a well plan for drilling a borehole, wherein the well plan comprises a planned path for the borehole;   receiving, by the computer system, feedback information from a drilling rig drilling the borehole;   calculating, by the computer system, an estimated position of a drill bit based on the feedback information;   comparing, by the computer system, the estimated position of the drill bit to a desired position of the drill bit along the planned path of the borehole;   calculating, by the computer system, a plurality of convergence paths if the comparison indicates that the estimated position is outside a defined margin of error relative to the desired position, wherein each of the plurality of convergence paths defines a path from the estimated position of the drill bit to a point on the planned path or from a projected position of the drill bit based on a trajectory of the drill bit to a point on the planned path, wherein the point on the planned path is different for each of the plurality of convergence paths;   calculating, by the computer system, a cost of each of the plurality of convergence paths;   selecting, by the computer system, a first convergence path from the plurality of convergence paths based at least partly on the cost of the first convergence path;   producing, by the computer system, control information for drilling the first convergence path; and   drilling, by the drilling rig, at least a portion of the borehole in accordance with the first convergence path based on the control information.   
     
     
         11 . The method of  claim 10 , wherein calculating the cost of each of the plurality of convergence paths includes identifying a plurality of cost elements applicable to each convergence path and applying a weight factor to at least one of the cost elements. 
     
     
         12 . The method of  claim 11 , wherein selecting the first convergence path includes identifying the cost of the first convergence path as a minimum of the cost of the plurality of convergence paths. 
     
     
         13 . The method of  claim 11 , wherein one of the plurality of cost elements comprises a time cost and another of the plurality of cost elements comprises a financial cost. 
     
     
         14 . The method of  claim 10 , wherein calculating the plurality of convergence paths further comprises calculating a drift responsive to the feedback information or formation information. 
     
     
         15 . The method of  claim 10 , wherein calculating the plurality of convergence paths includes calculating a slide start time and slide end time for each of the convergence paths. 
     
     
         16 . The method of  claim 15 , wherein calculating the plurality of convergence paths further includes calculating a start time and an end time for pumping lubricants into the borehole prior to the slide start time for each of the convergence paths. 
     
     
         17 . The method of  claim 10 , further comprising calculating, by the computer system, a second plurality of convergence paths if the comparison indicates that the estimated position is outside a defined margin of error relative to the desired position, wherein each of the second plurality of convergence paths defines a path from a projected position to the planned path, and wherein each projected position is determined by extending a current trajectory of the drill bit from the estimated position. 
     
     
         18 . The method of  claim 17 , wherein calculating each of the second plurality of convergence paths includes calculating a delay that defines a period of time during which the drill bit is allowed to continue along a current trajectory from the estimated position prior to the currently trajectory being altered according to a first solution. 
     
     
         19 . The method of  claim 18 , wherein calculating each of the second plurality of convergence paths includes calculating a delay that defines a period of time during which the drill bit is allowed to continue along a straight-line path after the current trajectory is altered by a first solution. 
     
     
         20 . A non-transitory computer-readable medium comprising processor-executable instructions configured to cause one or more processors to:
 receive a plurality of inputs, wherein the inputs include a well plan comprising a planned path for a borehole, formation information for the borehole, drilling rig information, bottom hole assembly (BHA) information, and cost information;   responsive to feedback information received from a drilling rig during drilling of the borehole, determine whether an estimated position of a drill bit is within a defined margin of error of a desired point along the planned path;   calculate a plurality of convergence paths if the estimated position of the drill bit is outside the defined margin of error, wherein each of the plurality of convergence paths defines a path from the estimated position of the drill bit to a point on the planned path based at least in part on the feedback information, wherein the point on the planned path is different for each of the plurality of convergence paths;   select a first convergence path of the plurality of convergence paths;   produce a set of control parameters for drilling the first convergence path; and   transmit instructions to a control system coupled to a drilling rig, wherein the drilling rig is adapted to drill a portion of the borehole in accordance with the set of control parameters.   
     
     
         21 . The non-transitory computer-readable medium of  claim 20 , further comprising a regional database, wherein the regional database includes data representing a plurality of planned paths, formation information for a plurality of geographic regions, drilling rig equipment information for a plurality of drilling rigs, BHA equipment information for a plurality of BHAs, a set of financial cost parameters, and a set of reliability parameters. 
     
     
         22 . The non-transitory computer-readable medium of  claim 20  further comprising instructions for a guidance control loop and an autonomous control loop, wherein the guidance control loop calculates the plurality of convergence paths and the autonomous control loop outputs a set of revised control parameters for the drilling rig. 
     
     
         23 . The non-transitory computer-readable medium of  claim 20 , further comprising instructions for optimizing the set of control parameters. 
     
     
         24 . The non-transitory computer-readable medium of  claim 23 , wherein the instructions for optimizing the set of control parameters include instructions for iteratively modifying the set of control parameters while maintaining a target parameter. 
     
     
         25 . The non-transitory computer-readable medium of  claim 20 , further comprising instructions for calculating the cost information of each of the plurality of convergence paths. 
     
     
         26 . The non-transitory computer-readable medium of  claim 25 , wherein the instructions for calculating the cost information of each of the plurality of convergence paths further comprise instructions for identifying a plurality of cost elements applicable to each convergence path and applying a weight factor to at least one of the cost elements. 
     
     
         27 . The non-transitory computer-readable medium of  claim 20 , wherein selecting the first convergence path further comprises identifying a cost of the first convergence path as a minimum of the cost of the plurality of convergence paths. 
     
     
         28 . The non-transitory computer-readable medium of  claim 20 , further comprising instructions for calculating a second plurality of convergence paths if the calculation indicates that the estimated position of the drill bit is outside a defined margin of error relative to the desired point along the planned path, wherein each of the second plurality of convergence paths defines a path from a projected position to the planned path, and wherein each projected position is determined by extending a current trajectory of the drill bit from the estimated position. 
     
     
         29 . The non-transitory computer-readable medium of  claim 28 , wherein the calculating each of the second plurality of convergence paths includes calculating a delay that defines a period of time during which the drill bit is allowed to continue along a current trajectory from the estimated position prior to the current trajectory being altered according to a first solution.