Workflow to directly relate rate of penetration (rop) to hole cleaning based on real-time density and rheology of drilling fluids

Abstract

A method includes performing a drilling operation using a drilling fluid; determining pressure losses of the drilling fluid in the drilling operation; updating non-linear regression coefficients to model the drilling operation; and performing gel strength tests on the drilling fluid. The method also includes determining optimal drilling parameters and the non-linear regression coefficients and determining optimal hole cleaning energy by balancing a mechanical energy level of the drilling fluid based on a maximum pump pressure of the mud pump and the optimal drilling parameters. The maximum pump pressure is determined based on the pressure losses and a range. The method further includes determining pressure changes created by the drilling operation using the optimal hole cleaning energy and results of the gel strength tests; determining an estimated equivalent circulating density based on the pressure changes; and modifying or maintaining the drilling operation based on the estimated equivalent circulating density.

What is claimed is: 
     
         1 . A method, performed iteratively and repeatedly, comprising:
 obtaining real-time drilling data from drilling equipment, including a mud pump, performing a drilling operation using a drilling fluid;   determining, using a computer processor, pressure losses of the drilling fluid in the drilling operation using the real-time drilling data;   updating, using the computer processor, non-linear regression coefficients to model the drilling operation using results obtained during field experiments;   performing, using the computer processor, gel strength tests on the drilling fluid;   determining, using the computer processor, optimal drilling parameters based on the real-time drilling data and the non-linear regression coefficients;   determining, using the computer processor, optimal hole cleaning energy by balancing a mechanical energy level of the drilling fluid based on a maximum pump pressure of the mud pump and the optimal drilling parameters, wherein the maximum pump pressure is determined based on the pressure losses and a range;   determining, using the computer processor, pressure changes created by the drilling operation using the optimal hole cleaning energy and results of the gel strength tests;   determining, using the computer processor, an estimated equivalent circulating density based on the pressure changes; and   modifying or maintaining the drilling operation based on the estimated equivalent circulating density.   
     
     
         2 . The method of  claim 1 , wherein performing the gel strength tests on the drilling fluid comprises modifying or maintaining a rheology of the drilling fluid. 
     
     
         3 . The method of  claim 1 , wherein the range comprises a first range and a second range, the first range comprising a maximum operating capacity of the mud pump and the second range comprising a maximum energy of the mud pump. 
     
     
         4 . The method of  claim 3 , wherein balancing the mechanical energy level of the drilling fluid using the first range comprises assuming rate of penetration is linearly related to the maximum operating capacity of the mud pump. 
     
     
         5 . The method of  claim 3 , wherein balancing the mechanical energy level of the drilling fluid using the second range comprises assuming rate of penetration is a function of bottom hole cleaning. 
     
     
         6 . The method of  claim 1 , wherein determining the pressure changes comprises estimating an annular velocity of cuttings in the drilling fluid. 
     
     
         7 . The method of  claim 6 , wherein estimating the annular velocity of the cuttings in the drilling fluid comprises estimating an average size of the cuttings using the drilling equipment. 
     
     
         8 . The method of  claim 1 , wherein the drilling equipment further comprises a drill string and modifying the drilling operation comprises pulling the drill string out of hole and changing parameters and composition of the drilling fluid. 
     
     
         9 . The method of  claim 1 , wherein maintaining the drilling operation comprises updating the non-linear regression coefficients based on progression of the drilling operation. 
     
     
         10 . The method of  claim 1 , wherein determining the optimal drilling parameters comprises optimizing the drilling parameters with respect to change in axial force on the drilling equipment and torsional force. 
     
     
         11 . A system comprising:
 a drilling system comprising drilling equipment, including a mud pump, configured to perform a drilling operation using a drilling fluid and   a computer processor configured to, iteratively and repeatedly:
 obtain real-time drilling data from the drilling equipment; 
 determine pressure losses of the drilling fluid in the drilling operation using the real-time drilling data; 
 update non-linear regression coefficients to model the drilling operation using results obtained during field experiments; 
 perform gel strength tests on the drilling fluid; 
 determine optimal drilling parameters based on the real-time drilling data and the non-linear regression coefficients; 
 determine optimal hole cleaning energy by balancing a mechanical energy level of the drilling fluid based on a maximum pump pressure of the mud pump and the optimal drilling parameters, wherein the maximum pump pressure is determined based on the pressure losses and a range; 
 determine pressure changes created by the drilling operation using the optimal hole cleaning energy and results of the gel strength tests; 
 determine an estimated equivalent circulating density based on the pressure changes; and 
 modify or maintain the drilling operation based on the estimated equivalent circulating density. 
   
     
     
         12 . The system of  claim 11 , wherein performing the gel strength tests on the drilling fluid comprises modifying or maintaining a rheology of the drilling fluid. 
     
     
         13 . The system of  claim 11 , wherein the range comprises a first range and a second range, the first range comprising a maximum operating capacity of the mud pump and the second range comprising a maximum energy of the mud pump. 
     
     
         14 . The system of  claim 13 , wherein balancing the mechanical energy level of the drilling fluid using the second range comprises assuming rate of penetration is linearly related to the maximum operating capacity of the mud pump. 
     
     
         15 . The system of  claim 13 , wherein balancing the mechanical energy level of the drilling fluid using the second range comprises assuming rate of penetration is a function of bottom hole cleaning. 
     
     
         16 . The system of  claim 11 , wherein determining the pressure changes comprises estimating an annular velocity of cuttings in the drilling fluid. 
     
     
         17 . The system of  claim 16 , wherein estimating the annular velocity of the cuttings in the drilling fluid comprises estimating an average size of the cuttings using the drilling equipment. 
     
     
         18 . The system of  claim 11 , wherein the drilling equipment further comprises a drill string and modifying the drilling operation comprises pulling the drill string out of hole and changing parameters and composition of the drilling fluid. 
     
     
         19 . The system of  claim 11 , wherein maintaining the drilling operation comprises updating the non-linear regression coefficients based on progression of the drilling operation. 
     
     
         20 . The system of  claim 11 , wherein determining the optimal drilling parameters comprises optimizing the drilling parameters with respect to change in axial force on the drilling equipment and torsional force.