Quantitative Brittleness Prediction Method Driven by Rock Physics

Brittleness is a key evaluation parameter for the fracturability of unconventional shale oil and gas. By analyzing the Poisson's ratio-Young's modulus brittleness index and the mineral composition brittleness index, it is pointed out that the conventional elastic parameter based brittleness index is easily affected by factors such as porosity, which in turn affects the accuracy of brittleness prediction. Regarding the issue of conventional elastic parameter based brittleness index, a rock physics driven brittleness indicator factor construction method is proposed to address the issue. On the basis of constructing a rock physics model, the response characteristics of brittle elastic parameters were clarified by changing the content of brittle minerals, and high-precision brittle indicator factors were constructed through coordinate rotation, reducing the impact of porosity and other factors on brittleness evaluation. The feasibility and accuracy of the proposed brittleness indicator factor have been verified through actual data, providing a new prediction method for the characterization of brittleness in unconventional reservoirs.