Hydraulic Fracturing Propagation in Naturally Fractured Reservoirs Based On Leak-Off Rate

Hydraulic Fracturing Propagation in Naturally Fractured Reservoirs Based On Leak-Off Rate

Fluid leak-off phenomenon plays a critical role in hydraulic fracturing operation. This phenomenon can be very impressive in successful operation of hydraulic fracturing. This operation is very complex in fractured reservoirs due to the reaction between induced fracture and natural fractures. In this study, using cohesive element method, the effect of presence of natural fracture on the magnitude of hydraulic fracturing fluid leak-off is investigated. First of all, cohesive element and extended finite element methods are described. The fluid flow inside hydraulic fractures and the effective parameters on leak-off of this fluid in the adjacent environment are analyzed. Then, effects of natural fractures on hydraulic fracturing direction such as deviation, leak-off and the mutual influences (which includes the changes of stress regime around the natural fractures), and also changes in pore pressure are processed. The results indicate that presence of natural fractures will cause reduction in aperture of hydraulic fractures. This decrease will lead to extension of fluid lag and eventually delaying of leak-off phenomenon. However, this effect is negligible in comparison with the positive impact due to shear and normal displacement on increasing leak-off