Method for analysing a completion system

Abstract

The present invention provides a method for analysing a well completion system, wherein the method includes receiving data representative of physical characteristics of the completion system and calculating a first change in length of a tube string resulting from a helical buckling effect. The method further includes calculating a second change in length of the tube string resulting from a ballooning effect and calculating a third change in length of the tube string resulting from a slackoff force effect. Upon completion of the calculating steps, the method may output predetermined results therefrom.

1 . A method for analysing a well completion system, the method comprising the steps of: 
 receiving input data representative of physical and environmental characteristics of the completion system;    determining a change in length for each individual tube section of a tube string;    determining a total change in length of the tube string through summing the change in length determined for each individual tube section of the tube string; and    outputting results of the determining step to the user.    
     
     
         2 . The method of  claim 1 , wherein the step of determining the change in length for each individual tube section further comprises the steps of: 
 calculating a first change in length as a result of temperature gradient;    calculating a second change in length as a result of helical buckling;    calculating a third a change in length as a result of a piston effect;    calculating a fourth change in length as a result of a ballooning effect; and    calculating a fifth change in length as a result of a slackoff force.    
     
     
         3 . The method of  claim 2 , wherein the step of calculating the first change in length as a result of temperature gradient further comprises the steps of: 
 calculating a change in length for each individual tube section in the tube string as a result of temperature gradient; and    summing the calculated change in length for each individual tube section to generate the first change in length as a result of temperature gradient.    
     
     
         4 . The method of  claim 2 , wherein the step of calculating the second change in length further comprises the steps of: 
 determining the location of a neutral point in the tube string;    calculating a change in length due to partial helical buckling for a section of tubing having the neutral point located therein;    calculating a change in length due to complete helical buckling for each individual section of tubing positioned below the section of tubing having the neutral point located therein; and    summing the calculated change in length due to partial helical buckling for the section of tubing having the neutral point therein and the calculated change in length due to complete helical buckling for each individual section of tubing positioned below the section of tubing having the neutral point located therein to generate the second change in length as a result of helical buckling.    
     
     
         5 . The method of  claim 2 , wherein the step of calculating the third change in length further comprises the steps of: 
 calculating hydraulic forces acting on each individual tube section in the tube string;    determining a change in length for each individual tube section as a result of the calculated hydraulic forces; and    summing the determined change in length for each individual tube section to determine the third change in length as a result of piston effect.    
     
     
         6 . The method of  claim 2 , wherein the step of calculating the fourth change in length further comprises the steps of: 
 calculating a density effect term for each individual tube section in the tube string;    calculating a pressure effect term for each individual tube section in the tube string;    summing the density effect term and the pressure effect term for each individual tube section in the tube string to determine a change in length for each individual tube section as a result of the ballooning effect; and    summing the chance in length determined for each individual tube section to determine the fourth change in length as a result of the ballooning effect.    
     
     
         7 . The method of  claim 2 , wherein the step of calculating the fifth change in length further comprises the steps of: 
 calculating a pure elastic term for each individual tube section in the tube string;    calculating a buckling term for each individual tube section in the tube string;    summing the pure elastic term and the buckling term for each individual tube section to determine a change in length for each individual tube section resulting from the slackoff force; and    summing the determined change in length for each individual tube section resulting from the slackoff force in order to generate the fifth change in length as a result of the slackoff force for the tube string.    
     
     
         8 . The method of  claim 1 , wherein the method further comprises the step of calculating the longest wireline tool that may be passed through the tube string.  
     
     
         9 . A signal bearing medium containing a completion system analysis program, that when executed by one or more processors, performs a method for analysing a completion system comprising the steps of: 
 receiving data representative of physical characteristics of the completion system;    calculating a first change in length of a tube string resulting from a helical buckling effect;    calculating a second change in length of the tube string resulting from a ballooning effect;    calculating a third change in length of the tube string resulting from a slackoff force effect; and    outputting predetermined results from the calculating steps.    
     
     
         10 . The signal bearing medium of  claim 9 , wherein the method for analysing further comprises the steps of: 
 calculating a fourth change in length resulting from a temperature gradient; and    calculating a fifth change in length resulting from a piston effect.    
     
     
         11 . The signal bearing medium of  claim 9 , wherein calculating the first change in length further comprises the steps of: 
 calculating a change in length resulting from helical buckling for each tube section in the tube string;    summing the calculated change in length resulting from helical buckling for each tube section in the tube string to generate the first change in length of the tube string resulting from the helical buckling effect.    
     
     
         12 . The signal bearing medium of  claim 11 , wherein the step of calculating a change in length resulting from helical buckling further comprises the steps of: 
 determining a tube section having a neutral point therein;    calculating a change in length due to partial helical buckling for the tube section having the neutral point therein; and    calculating a change in length due to complete helical buckling for each tube section positioned below the tube section having the neutral point therein.    
     
     
         13 . The signal bearing medium of  claim 9 , wherein the step of calculating a second change in length further comprises the steps of: 
 calculating a density change effect term for a tube section in the tube string;    calculating a pressure change effect term for the tube section in the tube string;    summing the density change effect term and the pressure change effect term to determine a change in length for the tube section resulting from ballooning effects; and    summing a change in length resulting from the ballooning effect for each tube section in the tube string to determine the second change in length of the tube string resulting from the ballooning effect.    
     
     
         14 . The signal bearing medium of  claim 9 , wherein the step of calculating the third change in length further comprises the steps of: 
 calculating a pure elastic term for a tube section in the tube string;    calculating a buckling term for the tube section in the tube string;    summing the pure elastic term and the buckling term to determine a change in length for the tube section resulting from the slackoff force effect; and    summing a change in length resulting from slackoff force for each tube section in the tube string to determine the third change in length of the tube string resulting from the slackoff force effect.    
     
     
         15 . The signal bearing medium of  claim 10 , wherein the step of calculating a fourth change in length further comprises the steps of: 
 calculating a change in length due to temperature gradient for each tube section in the tube string; and    summing the calculated change in length for each tube section to generate the fourth change in length resulting from temperature gradient.    
     
     
         16 . The signal bearing medium of  claim 10 , wherein the step of calculating a fifth change in length further comprises the steps of: 
 calculating a change in length due to piston effect for each tube section in the tube string; and    summing the calculated change in length for each tube section to generate the fifth change in length resulting from the piston effect.    
     
     
         17 . The signal bearing medium of  claim 9 , wherein the method of analysing further comprises the step of calculating a longest wireline tool to pass through the tube string.  
     
     
         18 . A signal bearing medium containing a program for analysing a completion system that when executed by a processor performs a method for analysing characteristics of a completion system comprising the steps of: 
 receiving input data representative of physical and environmental characteristics of the completion system;    determining a change in length for each individual tube section of a tube string;    determining a total change in length of the tube string through summing the change in length determined for each individual tube section of the tube string; and    outputting results of the determining step to the user.    
     
     
         19 . The signal bearing medium of  claim 18 , wherein the step of determining the change in length for each individual tube section further comprises the steps of: 
 calculating a first change in length as a result of temperature gradient;    calculating a second change in length as a result of helical buckling;    calculating a third a change in length as a result of a piston effect;    calculating a fourth change in length as a result of a ballooning effect; and    calculating a fifth change in length as a result of a slackoff force.    
     
     
         20 . The signal bearing medium of  claim 19 , wherein the step of calculating the first change in length as a result of temperature gradient further comprises the steps of: 
 calculating a change in length for each individual tube section in the tube string as a result of temperature gradient; and    summing the calculated change in length for each individual tube section to generate the first change in length as a result of temperature gradient.    
     
     
         21 . The signal bearing medium of  claim 19 , wherein the step of calculating the second change in length further comprises the steps of: 
 determining the location of a neutral point in the tube string;    calculating a change in length due to partial helical buckling for a section of tubing having the neutral point located therein;    calculating a change in length due to complete helical buckling for each individual section of tubing positioned below the section of tubing having the neutral point located therein; and    summing the calculated change in length due to partial helical buckling for the section of tubing having the neutral point therein and the calculated change in length due to complete helical buckling for each individual section of tubing positioned below the section of tubing having the neutral point located therein to generate the second change in length as a result of helical buckling.    
     
     
         22 . The signal bearing medium of  claim 19 , wherein the step of calculating the third change in length further comprises the steps of: 
 calculating hydraulic forces acting on each individual tube section in the tube string;    determining a change in length for each individual tube section as a result of the calculated hydraulic forces; and    summing the determined change in length for each individual tube section to determine the third change in length as a result of piston effect.    
     
     
         23 . The signal bearing medium of  claim 19 , wherein the step of calculating the fourth change in length further comprises the steps of: 
 calculating a density effect term for each individual tube section in the tube string;    calculating a pressure effect term for each individual tube section in the tube string;    summing the density effect term and the pressure effect term for each individual tube section in the tube string to determine a change in length for each individual tube section as a result of the ballooning effect; and    summing the change in length determined for each individual tube section to determine the fourth change in length as a result of the ballooning effect.    
     
     
         24 . The signal bearing medium of  claim 19 , wherein the step of calculating the fifth change in length further comprises the steps of: 
 calculating a pure elastic term for each individual tube section in the tube string;    calculating a buckling term for each individual tube section in the tube string;    summing the pure elastic term and the buckling term for each individual tube section to determine a change in length for each individual tube section resulting from the slackoff force; and    summing the determined change in length for each individual tube section resulting from the slackoff force in order to generate the fifth change in length as a result of the slackoff force for the tube string.    
     
     
         25 . The signal bearing medium of  claim 18 , wherein the method further comprises the step of calculating the longest wireline tool that may be passed through the tube string.  
     
     
         26 . A method for analysing a string of tubulars in a wellbore, comprising: 
 calculating a first change in length of a section of a tube string resulting from a helical buckling effect, wherein calculating the first change in length comprises:    determining a location of a neutral point in a tube string section; and    selecting one of a partially buckled change in length equation and a completely buckled change in length equation in accordance with the determined location of the neutral point to calculate the first change in length; and    summing calculated changes in lengths for each tube string section to determine a total change in length as a result of helical buckling.    
     
     
         27 . The method of  claim 26 , further comprising: 
 calculating a second change in length of the tube string resulting from a ballooning effect; and    calculating a third change in length of the tube string resulting from a slackoff force effect.    
     
     
         28 . The method of  claim 26 , further comprising: 
 calculating a fourth change in length resulting from a temperature gradient; and    calculating a fifth change in length resulting from a piston effect.    
     
     
         29 . The method of  claim 26 , wherein calculating the first change in length further comprises: 
 calculating a change in length resulting from helical buckling for each tube section in the tube string;    summing the calculated change in length resulting from helical buckling for each tube section in the tube string to generate the first change in length of the tube string resulting from the helical buckling effect.    
     
     
         30 . The method of  claim 26 , wherein of calculating the first change in length resulting from helical buckling further comprises: 
 determining a tube section having a neutral point therein;    calculating a change in length due to partial helical buckling for the tube section having the neutral point therein; and    calculating a change in length due to complete helical buckling for each tube section positioned below the tube section having the neutral point therein.    
     
     
         31 . The method of  claim 27 , wherein calculating a second change in length further comprises the steps of: 
 calculating a density change effect term for a tube section in the tube string;    calculating a pressure change effect term for the tube section in the tube string;    summing the density change effect term and the pressure change effect term to determine a change in length for the tube section resulting from ballooning effects; and    summing a change in length resulting from the ballooning effect for each tube section in the tube string to determine the second change in length of the tube string resulting from the ballooning effect.    
     
     
         32 . The method of  claim 27 , wherein calculating the third change in length further comprises the steps of: 
 calculating a pure elastic term for a tube section in the tube string;    calculating a buckling term for the tube section in the tube string;    summing the pure elastic term and the buckling term to determine a change in length for the tube section resulting from the slackoff force effect; and    summing a change in length resulting from slackoff force for each tube section in the tube string to determine the third change in length of the tube string resulting from the slackoff force effect.