An Analytical Model for Production Estimation from Hydraulically Fractured Tight-Gas Reservoirs

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn relatively high-permeability reservoirs, the pseudo-steady state (PSS) flow condition dominates the production life of a well, and therefore modeling of production profile considering this flow condition only is found adequate. In tight-gas reservoirs, however, the early production period is dominated by the transient flow condition whereas the later period by the PSS condition. Neither of these conditions alone can be used to adequately model the production profile during the entire production life of a tight-gas reservoir. The creation of hydraulic fracture also influences the flow conditions and thus the production profile. This paper presents an analytical method, which combines both the flow conditions and account for the effect of hydraulic fracture and non-Darcy components for computationally efficient estimation of production from tight-gas reservoirs. An algorithm is then presented to couple these two different models by a production rate matching technique, which has resulted in a hybridized transientpseudo-steady-state (TPSS) model to predict the production profile during the whole production life. The production profiles and resulting pressure profiles for both TPSS and PSS models are verified by a reservoir simulator for a range of reservoir permeability. The TPSS model is found to be closer to the results from simulation for low-permeability reservoirs.