Patent ID: 8517692

Claim:
A mud pump system comprising: a pump adapted to pump a pressurized flow of mud through a drillstring in a borehole; pressure sensors disposed in contact with the pressurized flow for detecting a pressure of the pressurized flow; a pressure limiting controller configured to control a motor speed of the pump in response to the pressure detected by the pressure sensors, wherein the pressure limiting controller generates a pressure limiting factor output using a pressure feedback input and a motor speed input to calculate a fluid conductance estimate, wherein the pressure limiting controller maintains the pressure limiting factor output at a maximum value based on a pressure set-point, wherein the pressure limiting controller continuously updates a normal fluid conductance value based on the fluid conductance estimate while the pressure limiting factor output remains at the maximum value, wherein the pressure limiting controller freezes the normal fluid conductance value, if the pressure limiting factor output is less than the maximum value, wherein the pressure limiting controller calculates a change in fluid conductance based on the normal fluid conductance value and the fluid conductance estimate, wherein the pressure limiting controller generates at least one adaptive gain based on the change in fluid conductance, and wherein the pressure limiting controller controls a motor speed of the pump based on the at least one adaptive gain.