The Effect of Sand Plug at the Gas Well Bottom-hole on its Productive Characteristics

Abstract

The reasons that lead to the destruction of the bottomhole zone during the operation of wells with unstable reservoirs are considered. The negative effects of the sand carry-over from the formation into the wellbore are shown. The review of scientific and technical literature on the effect of the sand plug on well productivity is presented. It indicates that the studies have mainly considered oil wells, but the effect of the sand plug on well productivity has not been studied sufficiently. For most gas wells, Darcy's law is primarily violated while filtering gas to the bottom-hole of the well, especially at high gas flow rates. The authors have studied theoretically the effect of a sand plug at the bottom of a gas well with permeability variations on the productive characteristics. According to the results of theoretical studies, the authors construct and analyze graphical dependencies in the form of the ratio of gas flow with and without a sand plug to the ratio of the reservoir permeability and the plug, on condition that the plug blocks the reservoir completely and the plug height exceeds the reservoir thickness. The scientists work a formula for indicating the flow rate of a gas well with a sand plug at the well bottom, on condition that the plug blocks the reservoir completely and the plug height exceeds the reservoir thickness while filtering gas in the reservoir according to the binominal law. On the basis of the research, it is established that on condition of the identical height of the sand plug and the identical ratio of reservoir permeability and the plug, the productivity of the gas well with the sand plug increases with the increase of the reservoir permeability. If the height of the plug exceeds the reservoir thickness, the flow rate of the gas well will be the smaller, the greater is the height of the sand plug compared to the reservoir thickness.