Patent ID: 8058882

Claim:
A method of characterizing an electrical cable that is deployed in a well, comprising: applying a voltage input to the electrical cable at an earth surface location, wherein the well extends from the earth surface location; measuring a current response in the electrical cable resulting from the voltage input, wherein the current response is measured at the earth surface location; computing at least one parameter of the electrical cable according to the measured current response; and updating the at least one parameter to account for a change in a characteristic of the electrical cable as a result of operation of a load system connected to the electrical cable; wherein computing comprises computing the resistance of the electrical cable and updating comprises updating the resistance; and wherein computing the resistance comprises computing an exact resistance according to: V 1 , meas = V 2 , meas + I 1 â¢ R exact V 1 , meas = V 2 , set + I 1 â¢ R est â¢ â‡’ R exact = R est - ( V 2 , meas - V 2 , set I 1 ) , wherein, I 1 is the surface current, V 1,meas is the measured surface voltage, V 2,meas is the measured downhole voltage, V 2,set is the target downhole voltage, R exact is the exact resistance of the cable, and R est is the estimated resistance of the cable and wherein the I 1 , V 1,meas , V 2,meas and, V 2,set are steady state voltages and current.