Research On Drilling Parameter Optimization Based On Mechanical Specific Energy

China ’s deep strata are rich in oil and gas resources,but deep strata have problems such as high rock hardness,strong abrasiveness,poor drillability,and complex downhole environment,resulting in increased difficulty and cost of drilling operations.Drilling parameter optimization is one of the important methods to improve drilling efficiency and reduce drilling cost.In view of the above problems,this paper adopts the research method of combining theoretical modeling and data analysis.Based on the mechanical specific energy model,an intelligent algorithm is established to solve the drilling parameter optimization method.The main research work is as follows :Firstly,aiming at the missing values and outliers in drilling data,a data fusion processing method based on Savitzky-Golay filtering is proposed,which integrates random forest missing value filling method,integrated outlier detection method and Savitzky-Golay filtering technology.The missing values are accurately filled and the outliers are effectively filtered,which provides accurate and effective training data for drilling speed prediction and parameter optimization.Secondly,the mechanical specific energy model of PDC bit considering the influence of hydraulic energy is established,and the key parameters in the model are obtained,including the comparison of the prediction accuracy of the classical three-dimensional drilling speed prediction equation and the machine learning algorithm.The BP neural network prediction model is used to calculate the drilling speed.The measured data of the sliding friction coefficient and the drilling pressure are used to calculate the torque of the drill bit.The mechanical specific energy baseline is established by using the logging data to calculate the rock compressive strength,and the drilling parameter optimization objective equation is determined.Then,the correlation analysis heat map of each parameter of drilling data is constructed,and the main influencing factors of mechanical specific energy are drilling pressure,rotational speed and flow rate.The specific influence law of drilling pressure,rotational speed and flow rate on mechanical specific energy is further analyzed,and the adjustable drilling parameters are determined.Finally,using the constructed target equation and the determined adjustable drilling parameters,the simulated annealing algorithm is used to solve the optimal drilling parameter combination.The sliding window mechanism is used to realize the segmented selection of drilling parameter combination and guide the actual drilling.