Developing a novel model for predicting geomechanical features of carbonate rocks based on acoustic frequency processing during drilling

Abstract

The drilling operation is one of the significant phases in geosciences. Analyzing this function assists investigators to determine the correct standpoint on the drilling process itself. The drilling operation generates acoustic frequencies as a beneficial derivative output, which could facilitate achieving this standpoint. On the other hand, determining the properties of rocks plays a critical role in all downstream stages of the operation. Determining rock characteristics using direct geomechanical methods is time-consuming and expensive, and requires excessive accuracy. The dvelopment a frequency-based technique for predicting the geomechanical functions of rocks would solve these problems. Here, we discuss the logical relations between rock characterization and the first five dominant acoustic frequencies of the drilling operation, as determined by first recording and then analyzing the frequencies of the acoustic signals generated during the drilling operation, using Fast Fourier Transform. For providing a comparable condition, we developed a novel rotary drilling device. Eight carbonate rock samples were collected that covered a wide range of geomechanical features and used in the geomechanical and drilling tests. The results show there are reliable mathematical relations between various characteristics of carbonate rock samples (uniaxial compressive strength, tensile strength, S-wave and P-wave velocity, hardness) and diverse dominant frequencies of the drilling acoustic signals.