Analysis of Surface and Downhole Drilling Dynamics High-FrequencyMeasurements Enhances the Prediction of Downhole Drilling Dysfunctionsand Improves Drilling Efficiency

摘要

Drilling rigs in North America are outfitted with Electronic Data Recorder(EDR)systems that acquiremeasurements from rig sensors.These systems typically record surface data at low frequency(0.1-1Hz)which makes it difficult to identify high-frequency events that could be occurring downhole.In an effort tofully understand the transmission characteristics of drilling dynamics signals along the drill string,the top-drive saver sub was embedded with high-frequency drilling dynamics sensors,sampled and continuouslyrecorded at either 800Hz or 1600Hz.Instrumenting the bit,bottom-hole assembly(BHA)and surface saver sub with identical high-frequencydrilling dynamics sensors provided a unique insight into drilling dynamics transmission along the drillstring.The sensors were identical and outfitted with the same hardware,firmware and software to allowdetailed dynamics signal analysis to be undertaken.The signals from the high-frequency surface anddownhole sensors were combined with the low-frequency surface rig measurements for pattern recognitionand correlation analysis.All high-frequency surface/downhole drilling dynamics data and low-frequency EDR data were mergedand over-laid to identify signal patterns that would be beneficial in understanding surface and downholegenerated dysfunction.Vertical,nudge,tangent,curve and lateral sections of the wellbore were analyzedto fully understand the transmission of drilling dynamics from downhole to surface and from surfaceto downhole.It is discovered that at relatively shallow depths,the signatures of at-bit dysfunction wereobserved in the high-frequency lateral vibration channels.Even in deeper wells,certain rotation-speed andshock/vibration signatures were detected at the surface.The novelty of identical high-frequency drilling dynamics sensors at surface and downhole is that thesignals generated by each sensor are produced from the same hardware,firmware and software.There is norisk of signals being mis-interpreted because of the use of different sensors or different signal-processingmethods downhole and on surface.Merging and overlaying of the signal data with rig EDR allows drillingdynamics patterns to be correlated.