Logging evaluation of the engineering quality of the Paleogene Funing Formation oil shales in the Subei Basin

Shale oil reservoirs, characterized by no productivity, are developed by horizontal drilling and volume fracturing, and it is very important to optimize shale fracable intervals based on engineering quality logging evaluation. The Paleogene Funing Formation shale in the Subei Basin is taken as a typical example in this study. A sonic scanner is used to calculate the elastic parameters, including Poisson's ratio and Young's modulus. Dynamic and static parameters are converted through core analysis data. The brittleness index and in situ stress are calculated according to Poisson's ratio and Young's modulus. In addition, a one-dimensional rock mechanics model was constructed with the shear slowness in a single well to calculate three components of in situ stress. Finally, considering the difference in the brittleness index and horizontal stress differences between different layers, brittleness index (BI) and (BI/(σH-σh)) were selected to describe the engineering quality. According to oil test data, the larger t