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

摘要

In relatively high-permeability reservoirs, the pseudo-steadyrnstate (PSS) flow condition dominates the production life of arnwell, and therefore modeling of production profile consideringrnthis flow condition only is found adequate. In tight-gasrnreservoirs, however, the early production period is dominatedrnby the transient flow condition whereas the later period by thernPSS condition. Neither of these conditions alone can be usedrnto adequately model the production profile during the entirernproduction life of a tight-gas reservoir. The creation ofrnhydraulic fracture also influences the flow conditions and thusrnthe production profile. This paper presents an analyticalrnmethod, which combines both the flow conditions and accountrnfor the effect of hydraulic fracture and non-Darcy componentsrnfor computationally efficient estimation of production fromrntight-gas reservoirs. An algorithm is then presented to couplernthese two different models by a production rate matchingrntechnique, which has resulted in a hybridized transientpseudo-rnsteady-state (TPSS) model to predict the productionrnprofile during the whole production life. The productionrnprofiles and resulting pressure profiles for both TPSS and PSSrnmodels are verified by a reservoir simulator for a range ofrnreservoir permeability. The TPSS model is found to be closerrnto the results from simulation for low-permeability reservoirs.