Method for calculating working fluid level of heavy oil well

The invention provides a method for calculating the working fluid level of a heavy oil well. The method for calculating the working fluid level of the heavy oil well comprises the steps that 1, a plurality of test samples are taken; 2, sound waves of a plurality of wells are measured through a nitrogen sound wave method, and the working fluid level depth is calculated with a plurality of tubing couplings as the reference and recorded; 3, a regression decision tree model is established; 4, an overfitting test is carried out; and 5, the liquid level is pre-estimated through the generated regression decision tree, and the pre-estimated liquid level is compared with the actually measured working liquid level. According to the method for calculating the working fluid level of the heavy oil well, a large amount of data serves as an input end to be input into an algorithm, the algorithm is trained through the data, the potential relation between the data is found out, a data model is established, therefore the worki