硫酸盐热还原反应蚀变天然气组分热模拟实验对比及意义

通过在烃源岩中加入硫酸盐和不加硫酸盐的热模拟实验，对比分析了实验中气体组分产率的变化特征，对TSR蚀变天然气的变化规律进行了探讨。结果表明:TSR反应使样品的总产气率增大，增大的部分主要为非烃气体，说明当孔隙体积和温度不变的情况下，气藏经过TSR反应改造后，容易形成高压气藏；同时，甲烷气体的产率降低，但由于在实验条件下，有机质可能受高温裂解和氧化还原2种反应共同作用，因此不能确定甲烷产率降低的原因是TSR反应蚀变甲烷引起的，但是可以肯定TSR反应对甲烷产率有较大影响；TSR反应对乙烷气体产率的影响可能和有机质类型有关。发生TSR反应后，Ⅲ型有机质的乙烷产率增加，Ⅰ型和Ⅱ型有机质的乙烷产率减少，这可能是由于Ⅰ型和Ⅱ型有机质比Ⅲ型有机质更容易发生TSR反应，其相对裂解生成乙烷的能力就弱一些。实验中硫化氢的含量低于二氧化碳的含量，而地质实际天然气中硫化氢的含量普遍高于二氧化碳的含量。二氧化碳与钙等金属离子结合形成碳酸氢盐，可能是二氧化碳含量降低的主要原因。二氧化碳分异过程可能是使储层物性明显改善的主要原因。

Comparison and Significance of Thermal Simulation Experiments on Gas Components from Thermochemical Sulfate Reduction (TSR) Alteration

Based on simulation experiments with and without sulfate,the authors comparatively analyze the gas components obtained from experiment,and then investigate the rule of alteration in TSR-altered gases.The result shows: TSR advanced the total gas production rate of samples and the main portions are non-hydrocarbon gases,which refers to that high-pressure gas reservoir can be generated easily because of TSR alteration in the consistent condition of porosity and temperature; production rate of methane is low,and the influence of TSR on production rate of methane is relatively great.Because organic matter may be under joint action of pyrolysis and TSR,it is not sure whether TSR-altered methane can cause of decease of methane production rate or not; the impaction of TSR on production rate of ethane may be related to organic matter type.Ethane production rate of typeⅢorganic matter increases,whereas that of typeⅠ and typeⅡ organic matter deceases due to TSR.The possible cause is that typeⅠand typeⅡ are more prone to TSR than type Ⅲ.In the consequence,the formers′ capability to form ethane is relatively weaker; the content of hydrogen sulfide is less than that of carbon dioxide in experiment,but it is generally converse in geological field.The formation of bicarbonate due to the combination of carbon dioxide and calcium ions may be the main reason for the reduction of carbon dioxide.Fraction process of carbon dioxide probably advances the property of reservoir a lot.