Rop optimization

Abstract

A system for optimizing a rate of penetration (ROP) in real-time in a subterranean operation that can include a rig, a tubular string extending from the rig into a subterranean formation, wherein the tubular string comprises a bottom hole assembly (BHA) with a drill bit; and a rig controller configured to determine, via a rock strength simulator, an equivalent confined compressive rock strength (ECCRS) profile along a future wellbore, receive the ECCRS profile at an ROP optimizer of the rig controller, receive physical parameters of the bottom hole assembly (BHA) at the ROP optimizer, and simulate in real-time, via the ROP optimizer, a simulated ROP of the drill bit of the BHA through a portion of the subterranean formation based on the ECCRS profile, the physical parameters of the BHA, and drilling parameters of the rig.

What is claimed is: 
     
         1 . A system for optimizing a rate of penetration (ROP) in real-time in a subterranean operation, the system comprising:
 a rig;   a tubular string extending from the rig into a subterranean formation, wherein the tubular string comprises a bottom hole assembly (BHA) with a drill bit; and   a rig controller configured to:   determine, via a rock strength simulator, an equivalent confined compressive rock strength (ECCRS) profile along a future wellbore;   receive the ECCRS profile at an ROP optimizer of the rig controller;   receive physical parameters of the bottom hole assembly (BHA) at the ROP optimizer; and   simulate in real-time, via the ROP optimizer, a simulated ROP of the drill bit of the BHA through a portion of the subterranean formation based on the ECCRS profile, the physical parameters of the BHA, and drilling parameters of the rig.   
     
     
         2 . The system of  claim 1 , wherein the ROP optimizer simulates the BHA as a discretized BHA with rigid and flexible beam elements interconnected via viscoelastic connections. 
     
     
         3 . The system of  claim 1 , wherein the rig controller is further configured to receive a well plan at the ROP optimizer, wherein the future wellbore is defined by the well plan. 
     
     
         4 . The system of  claim 1 , wherein the rock strength simulator is a statistical model that is configured to receive historical parameter data from historical wells and determine the ECCRS profile along at least a portion of the future wellbore based on the historical parameter data. 
     
     
         5 . The system of  claim 1 , wherein the rock strength simulator is a real time simulator that is configured to receive real-time parameter data from the rig and determine the ECCRS profile along at least a portion of the future wellbore based on the real-time parameter data. 
     
     
         6 . The system of  claim 1 , wherein the rock strength simulator is a real time simulator that is configured to receive real-time parameter data from the rig and historical parameter data from historical wells, and wherein the rock strength simulator is further configured to determine the ECCRS profile along at least a portion of the future wellbore based on the real-time parameter data and the historical parameter data. 
     
     
         7 . The system of  claim 1 , wherein the rig controller is further configured to:
 vary the simulated ROP of the drill bit by adjusting one or more of the drilling parameters; and   determine an optimum simulated ROP by comparing various simulated ROPs.   
     
     
         8 . The system of  claim 7 , wherein the rig controller is further configured to predict, via the ROP optimizer, dysfunctions of the optimum simulated ROP, and wherein the dysfunctions comprise at least one of:
 vibrations;   stick-slip;   whirl;   stall;   bit bounce;   factors that affect mechanical specific energy (MSE); or   combinations thereof.   
     
     
         9 . The system of  claim 1 , wherein the rig controller is further configured to select, via the rock strength simulator, one or more previously drilled wellbores from a rock strength database. 
     
     
         10 . The system of  claim 9 , wherein the rig controller is further configured to retrieve, via the rock strength simulator, historical rock strength properties associated with the one or more previously drilled wellbores. 
     
     
         11 . The system of  claim 1 , wherein the rig controller is further configured to:
 simulate a plurality of ROP simulations;   rank each of the plurality of ROP simulations; and   select from the plurality of ROP simulations the simulated ROP with a highest ranking.   
     
     
         12 . The system of  claim 11 , wherein the rig controller is further configured to simulate the plurality of ROP simulations while the rig is drilling along a roadmap of the future wellbore defined by a well plan. 
     
     
         13 . The system of  claim 11 , wherein the plurality of ROP simulations comprise:
 at least one of:
 simulation of sensitivity of ROP to changes in weight on bit (WOB); 
 simulation of sensitivity of ROP to changes in revolutions per minute (RPM) of a tubular string; 
 simulation of sensitivity of ROP to changes in differential pressure (DP) across a mud motor; or 
 combinations thereof. 
   
     
     
         14 . The system of  claim 1 , wherein the rig controller is further configured to:
 receive a well plan for the future wellbore at the ROP optimizer; and   simulate the simulated ROP based on the well plan.   
     
     
         15 . The system of  claim 14 , wherein the well plan comprises a roadmap of the future wellbore through the subterranean formation and simulation of the simulated ROP predicts ROP along at least a portion of the roadmap. 
     
     
         16 . The system of  claim 15 , wherein the rig controller is further configured to determine the ECCRS profile for the roadmap of the future wellbore defined by the well plan. 
     
     
         17 . The system of  claim 15 , wherein the rig controller is further configured to:
 simulate, via the ROP optimizer, a plurality of ROP simulations for the portion of the roadmap;   select one of the plurality of simulated ROPs with associated drilling parameters; and   recommend the associated drilling parameters for drilling the portion of the roadmap of the future wellbore.   
     
     
         18 . The system of  claim 17 , wherein the rig is further configured to drill the portion of the future wellbore through a subterranean formation based on the associated drilling parameters. 
     
     
         19 . The system of  claim 18 , wherein the rig controller is further configured to score performance of the rig to drill the portion of the future wellbore by comparing one of the plurality of ROP simulations associated with the associated drilling parameters to an actual ROP of the portion of the future wellbore. 
     
     
         20 . The system of  claim 1 , wherein the rig controller is further configured to predict, via the ROP optimizer, an ROP along the future wellbore prior to and during drilling of the future wellbore.