为查明鄂尔多斯盆地古生界二叠系山西组页岩生烃过程中产物的变化规律及影响因素,揭示页岩生烃潜力,选取了鄂尔多斯盆地东缘山西组地层低成熟度富有机质页岩样品,采用密封黄金管—高压釜体系,在50 MPa围压下,以20℃/ h和2℃/ h的升温速率进行生烃热模拟实验,测定气态烃和液态烃的产量及气态烃的碳同位素组成,分析不同升温速率下实验产物的演化规律,探讨碳同位素特征及成因,并建立了山西组页岩生烃模式.研究表明:(1)相对低的升温速率有利于烃类气体的生成;(2)相对低的升温速率下,液态烃产率和最大产率对应的温度都较低;(3)温度对热解气碳同位素有明显影响,而升温速率对热解气碳同位素并无明显影响.建立了鄂尔多斯盆地山西组页岩生烃模式.生烃热模拟结果显示鄂尔多斯盆地山西组页岩生烃潜力较好.
Low-maturity organic-rich shale from the Paleozoic Shanxi Formation in the eastern margin of Ordos Basin was chosen for pyrolysis simulation in order to find out hydrocarbon generation laws and its influencing factors,and to reveal the hydrocarbon generation potential of shale. A pyrolysis system of sealed gold tubes in high pressure vessels was employed to conduct pyrolysis experiments at two heating rates of 20℃/h and 2℃/h under a constant confining pressure of 50 MPa. The yields of gaseous hydrocarbons and liquid hydrocarbons,and the carbon isotopic compositions of gaseous hydrocarbons were measured. The experimental products at different heating rates were analyzed, the carbon isotope characteristics and genesis were discussed, and a hydrocarbon generation model of Shanxi group was established. The research demonstrated that(1)the relatively low heating rate was favorable for the generation of hydrocarbon gas;(2)at the relatively low heating rate, both yield of liquid hydrocarbon and temperature of maximum yield were low;(3)the temperature had a significant effect on the carbon isotope of pyrolysis gas. However,the effect of heating rate on the carbon isotope of pyrolysis gas was not obvious. A shale hydrocarbon generation model was established according to the thermal simulation experi-ment. The results of hydrocarbon generation simulation indicated that the shale in the Shanxi Formation in the Ordos Basin had a good potential of hydrocarbon generation.