Abstract:

Formation pressure distribution of non-Darcy flow in low permeability reservoir differs from Darcy flow in custom reservoir, and there are non-startup regions uncontrolled by single well. Based on mass conservation and momentum equations in theory of fluid mechanics in porous medium, the non-Darcy flow mathematic model considering threshold pressure gradient is established, which derives analytic solution of non-Darcy radial flow and deliverability equation. A new calculation method of formation pressure is presented, which provides theoretical foundation for reservoir evaluation and development design of low or ultra-low permeability reservoir. The calculation results demonstrate that there is not exciter response everywhere of non-Darcy flowing in low permeability reservoir which differs from Darcy flowing in custom reservoir. Energy decay rate of non-Darcy flowing in low permeability reservoir is faster than Darcy flowing in custom reservoir. Because of small spreading range, it exists reasonable employing radius.

Key words: low permeability, non-Darcy flow, pressure distribution, effective startup, threshold pressure gradient(TPG)