Method and System For Calculating Extension Length of Main Fracture In Hydraulic Fracturing, and Medium

A method for calculating an extension length of a main fracture in hydraulic fracturing, comprising the following steps:

• S10:
• acquiring a water hammer wave signal at a wellhead after pump shutdown during hydraulic fracturing using a high-frequency pressure gauge;
• S20:
• converting the water hammer wave signal into a complex cepstrum and performing cepstrum analysis on the water hammer wave signal;
• S30:
• calculating a minimum period between positive pulse extremum points in a curve of the complex cepstrum and taking half of the minimum period as a time for a water hammer wave to travel from the wellhead to a bridge plug;
• S40:
• calculating an average velocity of the water hammer wave in a well based on the time for the water hammer wave to travel from the wellhead to the bridge plug and a distance from the wellhead to the bridge plug;
• S50:
• performing linear trend removal on a local signal of the water hammer wave during an ascending phase or a descending phase of the water hammer wave along a wellbore;
• S60:
• performing a Fourier transform on the local signal with linear trend removed, to obtain a frequency spectrum of the local signal of the water hammer wave;
• S70:
• extracting a fundamental frequency corresponding to maximum value points in the frequency spectrum of the local signal of the water hammer wave as a response frequency in a main fracture;
• S80:
• calculating a propagation time of the water hammer wave in the main fracture based on the response frequency in the main fracture;
• and
• S90:
• calculating an extension length of the main fracture based on the average velocity of the water hammer wave in the well and the propagation time of the water hammer wave in the main fracture.