Mathematical Model for Flow of High-pressure Gas in Microscale

Abstract

Fused silica micro-tubes, whose size is similar to the pore throat in a low permeability reservoir, simplify the complex and tortuous of channels and throats and are used in this study to stimulate the flow pattern with micro-scale methods. A high-pressure micro-tube holder (designed and developed independently with a patent for invention) has been used to study gas flow patterns within the pressure range of 0.1MPa-30MPa. Moreover, we establish a gas flow equation and analysis the applicability of different inlet pressure based on the experiment result. The result shows: First, the pressure drop in the micro-tube is predominantly induced by friction resistance at low inlet pressure. While under relatively high inlet pressure, the impact of kinetic energy conversion and throttling effect on pressure drop shall be considered. Second, we build up a gas-flow equation in a micro-tube considering friction resistance, kinetic energy loss, and throttling effect. We also analyze the applicability for different diameters and inlet pressure. These research achievements were enriched in microtubule flow; different conditions have been identified for a different equation which has significant meaning to gas flow regulation in tight sandstorm reservoirs.