Monitoring of Hydraulic Fractures Using Tube Waves in a Well Generated by Krauklis Wave Coming from Fracture Tips

In previous publications of the authors (Derov&Maximov, 2008, Maximov&al, 2011) the new active method for estimation of hydraulic fracture parameters was grounded. This approach is based on registration of the primary and the secondary tube waves in a well at incidence of external seismic wave on a well with fracture. The primary tube waves are generated when incident seismic wave intersect cross point of fracture and a well. The secondary tube waves are the result of interaction of Krauklis wave with a well. The Krauklis wave propagates along fluid filled fracture and is generated on fracture tips under action of incident seismic wave. The time delay between the primary and the secondary tube waves allows us to estimate the linear size of hydraulic fracture. The key question of this approach is amplitude of the secondary tube waves to detect them among other arrivals and noise. The developed mathematical model and numerical calculations represented in the report show that amplitudes of the secondary tube waves have the same order as amplitudes of the primary tube waves and hence they can be detected by VSP technique for both cases of subhorizontal and vertical hydraulic fractures for general 3D statement of the problem.