Characterize fracture geometry and propagation with low frequency distributed acoustic sensing strain data

Abstract

Low-frequency distributed acoustic sensing (LF-DAS) strain data from offset wells are widely used to characterize hydraulic fracture geometry. In this paper, we propose a new optimization model for DAS interpretation. The model quantifies the fracture propagation trajectory and fracture geometry variation with time from low-frequency DAS strain data of offset wells. First, the optimization model is developed by combining the Green function and the Sneddon fracture width function to correlate parameters such as fracture width distribution, fracture length and fracture location with the far-field strain distribution. Second, the optimization model is solved by the Levenberg-Marquardt nonlinear least squares algorithm. The model was validated by generating cases. In addition, the model was applied to the interpretation of fracture propagation characteristics for the fiber optic well case of HFTS-2 offset wells. The interpretation results can visually determine the fracture modification effect and help to improve the production efficiency.