Hot Non-condensable Gas Stimulation Mechanism And Parameters Optimization Of Huff And Puff Process

The hot non-condensable gas is a mixture of N₂ and CO₂ that carries heat.The hot non-condensable gas（HNCG）stimulation combines thermal oil recovery and gas injection development,which could be regarded as a replacement technology in heavy oil reservoir and low-permeability reservoirs.At present,few experimental studies,mathematical calculations,numerical simulation studies and field tests for this technology are conducted.In this paper,a systematic study of the HNCG huff and puff is carried out,including stimulation mechanism,reservoir adaptability,physical and chemical characteristics,thermodynamic characteristics and parameters optimization of HNCG.Some conclusions can be concluded.According to the experimental study of the physical and chemical properties of the HNCG-heavy oil mixture system,the 2-D visualization experimental study of the NCG stimulation process,and the analysis of the stimulation characteristics based on the numerical model,it is shown this technology can significantly improve oil recovery and the production can increase 2.36 times for single well;the key mechanisms of HNCG stimulation could be summarized as pressurization,viscosity reduction by heating and gas dissolution,light hydrocarbons extraction and water-inhibiting effects;the thermodynamic analysis of the HCNG multiphase flow in wellborethe couled be conducted based on the coupled calculation model of temperature-pressure-physical properties;the HNCG stimulation productivity could be estimated based on the three-zone composite model based on the thermal-hydrological process in the reservoir;the reservoir adaptability of this technology are determined as oil viscosity less than26100m Pa·s,oil saturation greater than 0.43,range less than 10,reservoir depth less than2350m,reservoir thickness greater than 4m,and reservoir permeability greater than420×10^-3μm²,the porosity is greater than 0.135;the optimal injection and production parameters are determined as the cycle injection volume of 150000m³,the injection velocity of 15000m³/d,the soaking time of 5 days,and the CO₂ ratio of 0.5.Using the optimization results of gas injection intensity under different reservoir parameters,the periodic gas injection intensity plate can be obtained.The research in this paper can determine the feasibility and effectiveness of the HNCG stimulation,and clarify the adaptability and stimulation mechanism.This technology owns important application prospects under the background of exploring new methods for thermal recovery of heavy oil reservoirs and enhancing oil recovery.