Abstract: Researches show that the fluid flow in low permeability media needs a start-up pressure gradient. That is, the drive pressure must be greater than a certain threshold pressure if the fluid is to flow. Such a flow feature cause that the pressure drops at the locations with different distances from the well are obviously different from each other. Therefore, the pressure drops for different locations can not be approximately thought as the same. However, these pressure drops are treated as the same one by using the conventional material balance method. The domain material balance method is presented for this case, and used to determine the elastic drive recovery of low permeability reservoir. The principle, usage and case study of this method are introduced in this paper. The calculated result by the method is more accordant with real conditions of low permeability reservoirs.

Key words: depletion drive, low permeability reservoir, recovery factor, material balance method