Devices, systems, and methods for mitigating downhole motor dysfunction
AssigneeSchlumberger Technology Corporation
InventorAshley Bernard Johnson
Life of this patent
Estimating the term…
Abstract
A drilling system may determine a change in motor torque and/or a pressure drop of a downhole motor based on a flow of a drilling fluid through the downhole motor. The drilling system may determine a change in bit torque of a bit with respect to a change in a weight on bit of the bit. Based at least in part on the change in motor pressure and the change in bit torque of the bit with respect to the change in the weight on bit of the bit, the drilling system may adjust a flow rate of the drilling fluid through the downhole motor to reduce a frequency of motor stalls of the downhole motor.
Claims20
A method for mitigating motor stall, comprising:
- determining a sound speed of a drilling fluid;
- determining a motor speed based on at least one of a motor change in torque or a motor pressure drop of a downhole motor using a flow of the drilling fluid through the downhole motor;
- determining a bit aggressivity based on a change in bit torque of a bit with respect to a change in a weight on bit of the bit;
- determining a stability metric as a function of at least the sound speed of the drilling fluid, the motor speed, and the bit aggressivity;
- determining that the stability metric is above a threshold stability metric, and decreasing a flow rate of the drilling fluid through the downhole motor to reduce the stability metric and reduce a frequency of motor stalls of the downhole motor;
- and
- determining that the stability metric is below the threshold stability metric, and increasing the flow rate of the drilling fluid through the downhole motor.
A method for mitigating motor stall, comprising:
- flowing a drilling fluid through a motor with a flow rate;
- determining a stability metric as a function of at least the flow rate, a motor change in torque with respect to a change in pressure of the motor, a change in bit torque of a bit with respect to a change in a weight on bit of the bit, a sound speed of the drilling fluid, and a density of the drilling fluid;
- comparing the stability metric with a threshold stability metric to obtain a comparison indicating an instable condition or a stable condition of the motor;
- and
- adjusting the flow rate of the drilling fluid through the motor in response to the comparison, wherein adjusting the flow rate comprises:
- decreasing the flow rate through the motor in response to the comparison indicating the instable condition of the motor;
- and
- increasing the flow rate through the motor in response to the comparison indicating the stable condition of the motor.
Dependencies are inferred from the claim text.