A novel model for dynamic temperature distribution in heavy oil reservoirs is derived from and axial difference equations and then integrated. Taking into account the coupling of temperature and pressure in the reservoir and wellbore, models for calculating distributions of the reservoir temperature, reservoir pressure, and water saturation are also developed. The steam injected into the wellbore has a that the reservoir temperature and pressure decrease exponentially with increasing distance

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... om the as that of the temperature field, and both variation ranges decrease from the wellbore heel to the toe. variation ranges of the reservoir temperature and pressure increase with steam injection time, but rate of increase diminishes gradually.