Evaluating characteristics of high-rate hydraulic fractures driven by wellbore energy source

Abstract

Interaction of hydraulic fractures with natural rock fabric that causes fracture growth to deviate from predictable straight geometries defined by stress orientation into complex, branched, and unpredictable ones is a well-known issue. In this numerical modeling study, we evaluate the concept of pumping fractures using localized wellbore energy sources with fast energy release to increase injection rates and propagation pressures and improve fabric crossing and deliver better fracture geometry. The mathematical and numerical model is developed to solve for fully coupled dynamics of fluids in the wellbore and fracture propagation with account of turbulent fluid friction, perforation friction and fluid compressibility. Then, the model is used to study the influence of initial system parameters on the characteristics of the resulting energetic fractures created by a wellbore energy pulse. Energetic fractures are compared with conventional surface pumping to evaluate improvements in fabric crossing efficiency using proxy metrics based on injection rate and fracture volume. Results of this comparison suggest that: (1) fabric crossing efficiency of energetic fractures strongly depends on the loading pressure delivered by the wellbore energy source and weakly depend on the displacement volume generated by the source; (2) in typical scenarios, energetic fracturing can deliver significant improvement in crossing efficiency 5–10 m away from the wellbore and moderate improvement tens of meters away from it; (3) an important factor responsible for improved crossing efficiency with energetic fractures is the smaller volume of fracturing fluid and reduced wellbore compressibility.