Adaptive drillstring condition determination

Abstract

A method can include identifying a threshold value for a drillstring off-bottom condition determination; filtering time series surface data of a post-connection drilling state of the drillstring using the threshold value to generate filtered time series surface data; and statistically determining a drillstring off-bottom condition value using the filtered time series surface data.

What is claimed is: 
     
         1 . A method comprising:
 identifying a threshold value for a drillstring off-bottom condition determination;   filtering time series surface data of a post-connection drilling state of the drillstring using the threshold value to generate filtered time series surface data; and   statistically determining a drillstring off-bottom condition value using the filtered time series surface data.   
     
     
         2 . The method of  claim 1 , wherein the drillstring off-bottom condition value comprises a torque loss value. 
     
     
         3 . The method of  claim 2 , comprising determining a downhole torque value based at least in part on the torque loss value. 
     
     
         4 . The method of  claim 3 , wherein the determining comprises utilizing a difference between surface torque and torque loss. 
     
     
         5 . The method of  claim 3 , wherein the downhole torque loss value is indicative of amount of cuttings adjacent to at least a portion of the drillstring. 
     
     
         6 . The method of  claim 5 , wherein the drillstring is disposed in a deviated bore. 
     
     
         7 . The method of  claim 1 , wherein the drillstring off-bottom condition value comprises a hook load value. 
     
     
         8 . The method of  claim 7 , wherein the hook load value comprises a hook load free rotate weight value, a hook load pick-up value or a hook load slack-off value. 
     
     
         9 . The method of  claim 7 , comprising determining a downhole weight on bit based at least in part on the hook load value. 
     
     
         10 . The method of  claim 9 , wherein the determining the downhole weight on bit comprises utilizing a difference between the hook load value as a hook load free rotate value and at least one measured hook load value. 
     
     
         11 . The method of  claim 1 , comprising determining a friction factor based at least in part on the drillstring off-bottom condition value. 
     
     
         12 . The method of  claim 11 , comprising utilizing a broomstick model. 
     
     
         13 . The method of  claim 1 , wherein the drillstring off-bottom condition value comprises a pressure value. 
     
     
         14 . The method of  claim 1 , wherein the drillstring off-bottom condition value comprises a median value. 
     
     
         15 . The method of  claim 1 , wherein the identifying the threshold value comprises utilizing time series surface data acquired during drilling by the drillstring. 
     
     
         16 . The method of  claim 1 , wherein the filtering comprises utilizing a filter model that includes a parameter value determined via offset well data. 
     
     
         17 . The method of  claim 16 , wherein the offset well data comprise downhole sensor-based data. 
     
     
         18 . The method of  claim 1 , comprising identifying a plurality of different threshold values for a plurality of different drillstring off-bottom condition determinations; filtering time series surface data of a post-connection drilling state of the drillstring using the plurality of different threshold values to generate filtered time series surface data; and statistically determining a plurality of different drillstring off-bottom condition values using the filtered time series surface data, wherein the plurality of different drillstring off-bottom condition values comprise at least one member selected from a group consisting of a torque value, a weight value and a pressure value. 
     
     
         19 . A system comprising:
 a processor;   memory accessible by the processor;   processor-executable instructions stored in the memory and executable to instruct the system to:
 identify a threshold value for a drillstring off-bottom condition determination; 
 filter time series surface data of a post-connection drilling state of the drillstring using the threshold value to generate filtered time series surface data; and 
 statistically determine a drillstring off-bottom condition value using the filtered time series surface data. 
   
     
     
         20 . One or more computer-readable storage media comprising processor-executable instructions to instruct a computing system to:
 identify a threshold value for a drillstring off-bottom condition determination;   filter time series surface data of a post-connection drilling state of the drillstring using the threshold value to generate filtered time series surface data; and   statistically determine a drillstring off-bottom condition value using the filtered time series surface data.