Fracture closure and flowback optimization for fractured wells considering dynamic fluid loss coefficient

Key words:  gas well  fracturing  dynamic fracturing fluid loss  fracture closure

Abstract:

According to the core filtration experiment and introducing the dynamic filtration coefficient, a theoretical model of forcing fracture closure and a dynamic filtration coefficient model were developed for post fracturing tight gas well based on percolation mechanics theory, by which the fracturing fluid loss, the filtrate invasion mechanism and the formation pressure profile near the fracture were dynamically analyzed during the sand fracturing and the shut in period after fracturing. The results indicate that the dynamic filtration coefficient model could better describe the dynamic process of the fracturing fluid loss. The filter loss rate is high in the early stage, and becomes low with time and is almost a fixed value in the late stage. The fracturing fluid loss decreases from fracture start to fracture end, and the invasion damage zone mainly concentrates on the fracture start. The invasion depth is related to the reservoir petrophysical parameters, the fracturing fluid parameters and the construction scale. For gas well, the pressure drop mainly occurs in the undisturbed formation, and the energy for flowback mainly comes from the additive energy resulting from formation gas compression during the fracturing and the shut in period.