A method can include, during drilling operations at a wellsite, receiving operational data, where the data include hookload data, surface rotation data and block position data; training a controller using the hookload data, the surface rotation data and the block position data for determination of one or more transition thresholds, where the transitions thresholds include an in-slips to out-of-slips transition threshold and an out-of-slips to in-slips transition threshold; during the drilling operations, receiving additional operational data that include additional hookload data; and storing at least a portion of the additional operational data in association with slips state as determined based at least in part on a comparison of at least a portion of the additional hookload data and at least one of the determined transition thresholds.