| There are abundant acidic gas reservoirs with CO2 and H2S in the world,and the effective development of unconventional natural gas such as acid gas reservoirs is of great significance for alleviating the contradiction between natural gas supply and demand.In the original state of gas reservoir,natural gas and formation water contact each other to reach the equilibrium of hydrocarbon water mutual dissolution.The existence of CO2 and H2S may aggravate the mutual dissolution of gas phase and formation water.Therefore,the study of hydrocarbon water solubility law between CO2 and H2S gas and formation water is of guiding significance to the calculation of reserves of such gas reservoirs,the production law of condensate and the preparation of development plans.Based on the high temperature and high pressure reaction kettle indoors was carried out by 80 ? and 144 ? of natural gas in formation water solubility test,formation water saturation of gas multistage degassing experiment and the competition of formation water and hydrocarbon gas dissolved CO2 experiment.On this basis,the PR equation of state is used to verify and fit theoretically.Finally,the solubility and condensate water content were simulated by PR equation.The main conclusions and understandings of the study are as follows:(1)PR equation of state can well simulate the solubility and condensate watercontent of the gas containing CO2 and H2S and the formation water.(2)Under the condition of 80 ? and 14MPa,II gas group gas dissolved gas water ratio is about 1.72 m3/m3.Under the condition of 144 ? and 54MPa,dissolved gas water ratio is about 5.65 m3/m3.(3)Degassing process for many times,as the pressure drop,gas dissolved gas water ratio decreases,and close to the pure CH4 dissolved gas water ratio,also illustrates the components of natural gas are mainly composed of CH4.It also indicates that the initial gas production of water-soluble gas reservoir is large and the later gas production is small.(4)The competitive dissolution of natural gas with high CO2 content is significant.Dissolved gas(45%)or higher content of CH4 in significantly higher than the high CO2 content in natural gas(27.5%),the content of CH4 in CH4 content of a dissolved gas(40%)or less significantly below the CH4 content in natural gas(74%),and the content of CO2(45%or higher)is significantly higher than CO2 content in the gas(0).(5)The simulation of the co-solubility phase states of natural gas hydrocarbon water containing CO2 and H2S shows that the content of condensate water is mainly determined by the content of carbon dioxide,and the content of hydrogen sulfide has little influence on the content of condensate water.The influence of temperature pressure on the content of condensate is greater than that of acid gas.(6)The gas-water ratio of natural gas containing carbon dioxide always increases with the increase of pressure,that is,the solubility of natural gas in water increases with the increase of pressure.With the same carbon dioxide content,the higher the hydrogen sulfide content,the higher the solubility of natural gas.The influence of acid gas composition on solubility is greater than the effect of temperature and pressure on solubility. |
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