Revised inflow performance relationship for productivity prediction and energy evaluation based on stage characteristics of Class III methane hydrate deposits

Productivity prediction and energy evaluation can reduce the economic risk of hydrate development. Meanwhile, the study of conventional resources provides useful reference and guidance. Therefore, this paper aims to establish Inflow Performance Relationship (IPR) formulas for the multiphase, non-isothermal flow in Class III methane hydrate deposits. The production process is divided into ascent and decline stage based on production characteristics. Fetkovich's formula and Vogel's formula are selected respectively for these stages. To revise these formulas, new index and pressure value are introduced to reflect the complexity and variability of hydrate production. New index called pseudo-pressure describes the compound effect of multi-driven forces. New value of minimum production pressure can avoid the adverse impact of ice block. Coefficients in these formulas are quantitatively characterized by selected key factors. The coefficient in Fetkovich's formula is characterized by layer thickness and gas flowablity. The coefficient in Vogel's formula is characterized by hydrate saturation, layer thickness and salinity. The verified results indicate that the average errors of the revised Fetkovich's formula is around 8% and under 11% for the revised Vogel's formula. This means these revised IPR formulas can provide guidance for the productivity prediction and evaluation of Class III methane hydrate deposits.