The relationships between the solubility of the two gases and temperature , pressure as well as the salinity of formation water were studied based on the solubility data of methane gas( CH4 ) and carbon dioxide gas( CO2) in sodium bicarbonate type water at different temperature and pressure. The results show that the different dissolution mechanism in the formation water results in solubility values of two gases with the different evolution characteristics as temperature and pressure changing. Connecting with the predecessors' experimental results under low-temperature condition( less than 90 ℃ ) , the relationships of the solubility of methane gas and temperature were divided into three stages of slowly descending phase(0-80 ℃ ) , rapidly increasing phase( 80-150℃ ) and slowly increasing phase ( greater than 150℃ ). The solubility of carbon dioxide gas dissolving in formation water gradually decreases with temperature increasing and gradually increases with pressure mcreasing, so it is obviousthat the pressure controls the dissolution and exsolution of carbon dioxide gas in formation water. The differential evolutioncharacteristics of the solubility between two kinds of gases affect the spatial distribution of natural gas.%根据不同温度和压力条件下测得的甲烷和二氧化碳两种气体在碳酸氢钠型水中的溶解度数据,对两种气体的溶解度与温度、压力及地层水矿化度之间的关系进行研究.结果表明:在地层水中的溶解机制不同,导致两种气体的溶解度值随温度、压力条件的变化具有不同的演变特征;综合前人低温(小于90℃)测试的溶解度数据,可将甲烷溶解度与温度之间的演变关系划分为缓慢递减(0～80℃)、快速递增(80～150℃)和缓慢递增(大于150℃)3个阶段;二氧化碳溶解度随温度的升高而逐渐降低,随压力升高而逐渐增大,其溶解与析离能力受压力影响更为明显;实际地层中,两种气体间溶解度的差异演变影响了天然气的空间分布.
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