System and method for monitoring and controlling underground drilling
A system and method for monitoring underground drilling in which vibration is monitored by creating a model of the drill string using finite element techniques or finite difference techniques and (i) predicting vibration by inputting real time values of operating parameters into the model, and then adjusting the model to agree with measured vibration data, (ii) predicting the weight on bit and drill string and mud motor speeds at which resonance will occur, as well as when stick-slip will occur, so that the operator can avoid operating regimes that will result in high vibration, (iii) determining vibration and torque levels along the length of the drill string based on the measured vibration and torque at one or more locations, (iv) determining the remaining life of critical components of the drill string based on the history of the vibration to which the components have been subjected, and (v) determining the optimum drilling parameters that will avoid excessive vibration of the drill string.
1. A system configured to monitor operation of a drill string having a drill bit configured to drill a borehole into an earthen formation, the system comprising:
a plurality of sensors configured to obtain drilling data associated with operation of the drill string, at least one of the plurality of sensors configured to measure a vibration at at least one predetermined location along the drill string while rotating the drill bit at a first speed and applying a first weight on the drill bit, wherein the vibration at the at least one predetermined location is a measured vibration; and
a processor configured for communication with the plurality of sensors, the processor configured to, in response to receiving the drilling data:
a) determine a value of a first rotary speed at which the drill bit rotates;
b) determine a value of a first weight on the drill bit;
c) determine a value of a first diameter of the borehole;
d) predict a first vibration of the drill string at the at least one predetermined location with a finite element model of the drill string, wherein the first vibration is based on the value of the first rotary speed of the drill bit, the value of the first weight on bit, and the value of a first borehole diameter;
e) determine a difference between the measured vibration and the first vibration predicted by the finite element model;
f) generate a revised finite element model that reduces the difference between the measured vibration and the vibration predicted by the finite element model;
g) determine a value of a second rotary speed at which the drill bit rotates;
h) determine a value of a second weight on the drill bit;
i) determine a value of a second diameter of the borehole; and
j) predict a second vibration of the drill string with the revised finite element model of the drill string, wherein the second vibration is based on the value of the second rotary speed of the drill bit, the value of the second weight on bit, and the value of a second borehole diameter.
2. The system of claim 1 , wherein said finite element model of said drill string predicts vibration is based on a set of operating parameters, wherein the set of operating parameters comprise a rotary speed of the drill bit, a weight on the drill bit, and a diameter of the drill bit,
wherein the processor is configured to identify the value of a plurality of operating parameters in the set of operating parameters that reduces the difference between the measured vibration and first vibration to below a predetermined threshold.
3. The system of claim 1 , wherein the plurality of operating parameters are adjusted one at a time so as to identify an adjustment that reduces the difference between the measured vibration and first vibration to below a predetermined threshold.
4. The system of claim 1 , wherein the plurality of operating parameters are adjusted by adjusting two or more parameters at a time so as to identify an adjustment that reduces the difference between the measured vibration and first vibration to below a predetermined threshold.
5. The system of claim 1 , wherein the first and second borehole diameters are approximately equal.
6. A system configured to monitor operation of a drill string having a drill bit configured to drill a borehole into an earthen formation, the system comprising:
a plurality of sensors configured to obtain drilling data associated with operation of the drill string, the plurality of sensors configured to measure vibration of the drill string when operating at a first set of operating parameters, wherein the vibration of the drill string when operating at the first set of operation parameters measured by the plurality of sensors is a measured vibration; and
a processor configured for communication with the plurality of sensors, the processor configured to, in response to receiving the drilling data:
a) determine values of parameters in a first set of operating parameters, wherein the first set of operating parameters comprises a speed at which the drill bit rotates;
b) in response to input of the values of parameters in the first set of operating parameters, determine at least a portion of a vibratory mode shape of the drill string with a finite element model when the drill string operates at the first set of operating parameters;
c) determine a relationship between a first amplitude of vibration at a first location to a second amplitude of vibration at a second location when operating the drill string at the first set of operating parameters, wherein the relationship between the first amplitude of vibration at the first location to the second amplitude of vibration at the second location is based on the at least a portion of the vibratory mode shape; and
d) predict an amplitude of vibration of the drill string based on the relationship between the first amplitude of vibration at the first location to the second amplitude of vibration at the second location determined from the at least a portion of the vibratory mode shape.
7. The system of claim 6 , wherein using said portion of said vibratory mode shape to determine the relationship between the amplitude of vibration at the first location to the amplitude of vibration at the second location comprises determining a ratio of the amplitude of vibration at the first location to said amplitude of vibration at the second location.
8. The system of claim 7 , wherein applying to, at the second location to the relationship comprises multiplying the amplitude of vibration measured at the second location by the ratio.