Abstract:Barrier hydrocarbon sealing mainly results from membrane,water power and pressure. Anyhow,displacement pressure plays an important role in hydrocarbon sealing. The barrier sealing ability is relative;even the high displacement pressure barrier only stops free hydrocarbon at a certain level, without obstruction to diffuse bydrocarbon and water solution hydrocarbon, Less-poor barrier also stops hydrocarbon when it is very thick or there is abundant hydrocarbon resources. It is theoretitally and practically shown that barrier sealing is controlled by many factors. By comprehensively analysing these factors,we can make a reasonable mathematic model to work out fluid flux in unit areaJunit time,whose reciprocal is defined as fluid sealing coefficient for sealing ability evaluation of the barrier. The experiment shows the method feasible.