Apparatus and methods for controlling drilling

A control system for drilling operations, the control system comprising:

• a computer system comprising a hardware processor coupled to a memory, the memory storing instructions executable by the processor to:
• receive a target value corresponding to a drilling parameter for drilling a wellbore during drilling of the wellbore;
• receive data corresponding to a measured value of the drilling parameter during drilling of the wellbore;
• calculate an error between the target value and the measured value;
• provide the target value and the error to a first controller, wherein the first controller generates a first controller output;
• responsive to the calculated error, calculate an adjustment to the drilling parameter;
• responsive to the adjustment, calculate a model error between the target value and the measured value and based on the calculated adjustment;
• provide the model error to a second controller, wherein the second controller generates a second controller output;
• determine a difference between the first controller output and the second controller output;
• apply a filter to the difference between the first controller output and the second controller output to generate updated coefficients;
• responsive to the updated coefficients, determine whether to adjust the first controller or the second controller or both;
• responsive to the model error, adjust the drilling parameter for drilling the wellbore based on the calculated adjustment and the updated coefficients, wherein the drilling parameter comprises at least one of:
• spindle position, toolface orientation, weight-on-bit, and differential pressure;
• and
• controlling the drilling of the wellbore based on the adjusted drill parameter.

A method of controlling drilling operations, the method comprising:

• receiving, by a first controller comprising a proportional integral derivative controller or a proportional integral controller, a target value corresponding to a drilling parameter for a well being drilled;
• receiving, by the first controller, data corresponding to a measured value of the drilling parameter;
• receiving, by the first controller during drilling of a wellbore, data corresponding to a measured value of the drilling parameter;
• calculating, by the first controller, an error between the target value and the measured value;
• provide the target value and the error to a first controller, wherein the first controller generates a first controller output;
• calculating, by the controller, an adjustment for the drilling parameter based on the calculated error;
• calculating, by the first controller, a model error between the target value and the measured value and based on the calculated adjustment;
• providing, by the first controller, the model error to a second controller and generating a second controller output therefrom;
• determining a difference between the first controller output and the second controller output;
• applying a filter to the difference between the first controller output and the second controller output to generate coefficients;
• responsive to the generated coefficients, determining whether to adjust the first controller or the second controller or both;
• implementing, by the first controller, the calculated adjustment for the drilling parameter based on the calculated adjustment and the updated coefficients when the calculated adjustment is outside a target error margin;
• adjusting the drilling parameter during drilling in accordance with the calculated adjustment based on the calculated adjustment and the updated coefficients;
• and
• controlling the drilling of the wellbore based on the adjusted drilling parameter.

A non-transitory, computer-readable medium comprising instructions that when executed by a processor, causes the processor to:

• receive a target value corresponding to a drilling parameter from a first controller;
• receive data corresponding to a measured value of the drilling parameter during drilling of a wellbore from the first controller;
• calculate an error between the target value and the measured value, wherein the first controller generates a first controller output;
• calculate an adjustment to a drilling parameter based on the calculated error;
• calculate a model error between the target value and the measured value and based on the adjustment;
• provide the model error to a second controller and generating a second controller output therefrom;
• determine a difference between the first controller output and the second controller output;
• apply a filter to the difference between the first controller output and the second controller output to generate coefficients;
• responsive to the generated coefficients, determine whether to adjust the first controller or the second controller or both;
• deploy the calculated adjustment to the drilling parameter during drilling based on the calculated adjustment and the updated coefficients, when the calculated adjustment exceeds a threshold error margin therefor;
• and
• control the drilling of the wellbore based on the calculated adjustment to the drilling parameter.