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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。
Through the thermal simulation experiment of adding sulphate and without sulphate to the source rock, the changing characteristics of the gas component yield in the experiment were compared and the variation regularity of TSR altered natural gas was discussed. The results show that TSR increases the total gas yield and increases the non-hydrocarbon gas, indicating that when the pore volume and temperature are unchanged, the gas reservoirs are easily transformed to high-pressure gas reservoirs after being reformed by TSR At the same time, the yield of methane gas decreased. However, due to the interaction of the two reactions of pyrolysis and redox under the experimental conditions, the reason for the decrease of methane yield could not be confirmed by the TSR reaction of methane alteration, but It can be affirmed that the TSR reaction has a great influence on the methane yield; the effect of the TSR reaction on the ethane gas yield may be related to the organic matter type. After the TSR reaction, the yield of ethane of type III organic matter increased and the yield of ethane of type I and type II organic matter decreased. This may be due to the fact that type I and type II organic matter are more prone to TSR than type III organic matter, The ability to crack to produce ethane is weaker. In the experiment, the content of hydrogen sulfide is lower than the content of carbon dioxide, while the actual content of hydrogen sulfide in geology natural gas is generally higher than the content of carbon dioxide. The combination of carbon dioxide with metal ions such as calcium to form bicarbonate may be the main reason for the reduction in carbon dioxide. The carbon dioxide differentiation process may be the main reason for the obvious improvement of reservoir physical properties.