System and method for monitoring and controlling underground drilling

Abstract

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 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, and when stick-slip will occur, to 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, and (v) determining the optimum drilling parameters that will avoid excessive vibration of the drill string.

What is claimed: 
     
         1 . A method of monitoring the operation of a drill string drilling into an earthen formation so as to form a bore hole using a drill bit located in a bottom hole assembly, comprising the steps of:
 a) determining the values of a plurality of operating parameters associated with said underground drilling operation by taking measurements from a plurality of sensors, at least a portion of said sensors located in said bottom hole assembly;   b) determining from said determined values of said operating parameters whether each of a plurality of predetermined symptoms of lost drilling performance are present in said drilling operation;   c) identifying the probability that each of said parameters determined to be present in said drilling operation are caused by each of a plurality of predetermined causes of lost drilling performance;   d) combining said identified probabilities for each of said predetermined causes of lost drilling performance so as to determine the most likely cause of lost drilling performance present in said drilling operation.   
     
     
         2 . The method according to  claim 1 , further comprising the step of:
 e) adjusting at least one operating parameter associated with said drilling operation based on said cause of lost drilling performance determined to be most likely present in said drilling operation.   
     
     
         3 . The method according to  claim 1 , wherein said plurality of operating parameters comprises the vibration of said drill string. 
     
     
         4 . The method according to  claim 3 , wherein said plurality of operating parameters comprises the amplitude of vibration of said drill string in the axial and lateral and torsional vibratory modes. 
     
     
         5 . The method according to  claim 1 , wherein said plurality of operating parameters comprises the frequency of the vibration of said drill string. 
     
     
         6 . The method according to  claim 1 , wherein said plurality of operating parameters comprises the weight on said drill bit and the rotary speed of said drill bit. 
     
     
         7 . The method according to  claim 1 , wherein the plurality of predetermined symptoms of lost drilling performance comprises vibration of said drill string. 
     
     
         8 . The method according to  claim 1 , wherein the plurality of predetermined symptoms of lost drilling performance comprises stick-slip. 
     
     
         9 . The method according to  claim 1 , wherein the step of combining said identified probabilities for each of said predetermined causes of lost drilling performance comprises summing said identified probabilities. 
     
     
         10 . The method according to  claim 1 , wherein the step of identifying the probability that each of said parameters determined to be present in said drilling operation are caused by each of a plurality of predetermined causes of lost drilling performance comprising retrieving said probabilities from a data base in which said probabilities are stored. 
     
     
         11 . A non-transitory computer-readable storage medium having stored thereon computer-executable instructions for performing a method of monitoring the operation of a drill string drilling into an earthen formation so as to form a bore hole using a drill bit, the method comprising the steps of:
 a) determining the values of a plurality of operating parameters associated with said underground drilling operation by taking measurements from a plurality of sensors, at least a portion of said sensors located in said bottom hole assembly;   b) determining from said determined values of said operating parameters whether each of a plurality of predetermined symptoms of lost drilling performance are present in said drilling operation;   c) identifying the probability that each of said parameters determined to be present in said drilling operation are caused by each of a plurality of predetermined causes of lost drilling performance;   d) combining said identified probabilities for each of said predetermined causes of lost drilling performance so as to determine the most likely cause of lost drilling performance present in said drilling operation.   
     
     
         12 . The computer-readable storage medium according to  claim 11 , wherein the step of identifying the probability that each of said parameters determined to be present in said drilling operation are caused by each of a plurality of predetermined causes of lost drilling performance comprising retrieving said probabilities from a data base in which said probabilities are stored. 
     
     
         13 . A method of monitoring the operation of a drill string drilling into an earthen formation so as to form a bore hole using a drill bit, comprising the steps of:
 a) operating said drill string at a first set of operating parameters, said first set of operating parameters comprising the speed at which said drill bit rotates;   b) determining the values of said parameters in said first set of operating parameters;   c) inputting said determined values of said parameters in said first set of operating parameters into a finite element model of said drill string;   d) using said finite element model of said drill string with said inputted values of said parameters to determine at least a portion of the vibratory mode shape of said drill string when operating at said first set of operating parameters;   e) using said portion of said vibratory mode shape to determine the relationship between the amplitude of vibration at said first location to the amplitude of vibration at a second location when operating at said first set of operating parameters;   f) measuring the amplitude of vibration of said drill string at said second location when operating at said first set of operating parameters;   g) determining the amplitude of vibration of said drill string at said first location by applying to said measured vibration at said second location said relationship between the amplitude of vibration at said first location to said amplitude of vibration at a second location determined from said portion of said vibratory mode shape.   
     
     
         14 . The method according to  claim 13 , wherein using said portion of said vibratory mode shape to determine the relationship between the amplitude of vibration at said first location to the amplitude of vibration at a second location comprises determining the ratio of said amplitude of vibration at said first location to said amplitude of vibration at said second location. 
     
     
         15 . The method according to  claim 14 , wherein the step of applying to said measured vibration at said second location said relationship comprises multiplying said amplitude of vibration measured at said second location by said ratio.