The Establishment of a Novel Deliverability Equation of Abnormal Pressure Gas Reservoirs Considering a Variable Threshold Pressure Drop.

In abnormal pressure gas reservoirs, a traditional binomial deliverability equation is insufficient to accurately describe the gas filtration theory, but only the trinomial deliverability equation considering non-Darcy flow effect and ripple effect can be reasonable to some extent. When gas reservoirs are characterized by low porosity and permeability, strong heterogeneity, and high water saturation, gas flow, similar to liquid flow, is featured in significant threshold pressure gradient effect. Therefore, a threshold pressure gradient is added to the trinomial deliverability equation, and it is derived that the pressure drop caused by the pressure gradient is a variable related to production but not a constant. Consequently, a novel deliverability equation of abnormal pressure gas reservoirs considering variable threshold pressure drop has been established, providing theoretical guidance for determining reasonable gas production in abnormal pressure gas reservoirs. [ABSTRACT FROM PUBLISHER]