Dynamics of Pressure in a Well During Treatment of its Face Zone by a Thermal Gas Generator

An analysis of the pressure wave field that appears in a well as a result of combustion of a powder charge of a thermal gas generator is presented. Based on the solution of the problem obtained by the spectral method, it is shown that in the case under consideration the well represents a resonator that implements wave perturbations of discrete spectrum. Four types of possible pressure fluctuations in the well are determined, which correspond to the implementation of various combinations of periodic, aperiodic, and resonant modes. For the case of realizing only periodic modes, a comparison with experiment was made, which indicates the predominant contribution of the zero mode. From this it also follows that approximation of oscillations only by the zero mode is possible at both small and large amplitudes. The value of the apparent damping coefficient is approximately twice higher for high-amplitude processes, while the circular frequency remains unchanged. It has been established that the attenuation of pressure waves occurs mainly due to elastic losses into the medium surrounding the well. The contribution of dissipative processes caused by the viscous friction of the fluid in the well is relatively small.