SEGJ Technical Conference


Brittleness Prediction based on Mechanical Properties: Application to Longmaxi shale


Abstract
Differentiating brittle from ductile in low permeability formation is key to success for the development of shale gas and tight gas reservoirs. In the first part of the study, two commonplace brittleness estimation techniques, brittleness average (BIave) using log based elastic properties (Young's modulus, Poisson's ratio, and brittleness index based on mineralogy (BImin) are applied to the quartz rich Longmaxi shale, Sichuan Basin China. However, these two measures correlate reasonably well but provide a critical assessment of brittleness. In the second part, we compute mechanical properties (compressive strength, minimum horizontal stress, overburden pressure, and fracture index) using elastic logs and hydraulic fracture data to establish a link between elastic and mechanical properties via mineralogy, and design the brittleness templates. Our proposed brittleness templates are empirical and differentiate the brittle-ducti le zones in a field or basin.