Non-Klinkenberg slippage phenomenon at high pressure for tight core floods using a novel high pressure gas permeability measurement system

Klinkenberg slippage theory has been widely used to predict the percolation rules at high pore pressure for conventional core floods. However, recent studies have shown deviations to applications of Kinkenberg slippage theory at low back pressure for tight cores. A novel phenomenon of deviation to apparent gas permeability by Klinkenberg slippage theory as pressure differential increase for tight core is reported. To overcome problems of measuring apparent gas permeability for tight core accurately, a system of three novel equipment is invented composed of a high pressure micro flow meter, a high pressure micro flow experimental pressure control system, and a high pressure dynamic micro differential pressure gauge. Nitrogen permeability as a function of pressure gradient in tight core at high pressure differed than that at atmospheric pressure where nitrogen permeability varied inversely with pressure gradient according to Klinkenberg slippage theory. A novel phenomenon observed in this study was that as pore pressure increased passed an inflection pressure point, nitrogen permeability became directly related to pressure gradient contrary to the trend predicted by Klinkenberg slippage theory. As pore pressure became greater, the magnitude of nitrogen permeability enhancement is enhanced.