Normalized Pressure Integral（NPI） Production Analysis is a kind of modern production decline analysis method which defines new parameters by integral. It can not only reflect the pseudo-steady state flow stage influenced by outer boundary

but also can reflect the unsteady state flow stage. In order to study the NPI production decline analysis method of carbonate reservoir

we established triporate-uniphase parallel inter-porosity flow model. In this model

fracture is the main flow channel and inter-porosity flow happens from cave to fracture and matrix to fracture. The bottom hole pseudopressure solution with considering the effect of skin factor of this model was obtained by Laplace transform and Duhamel principle. The NPI method curves were plotted by using normalized pressure integral method and Stehfest numerical inversion. And the curves can reflect the production performance of this model accurately. The storage ratio

inter-porosity flow coefficient

and dimensionless outer boundary radius were chosen to be sensibility parameter for sensibility analysis. The result shows that the storage ratio mainly influences the depth of depression on derivative curve and the inter-porosity flow coefficient mainly influences the time when inter-porosity flow stages happen. The skin factor just influences the dimensionless pseudopressure and dimensionless pseudopressure integral curves

while the dimensionless outer boundary radius will also influence the unsteady state flow stage of derivative of dimensionless pseudopressure integral curve.