页岩含油率多种测试方法对比

页岩含油率是页岩油资源评价的基本参数,但其测定方法尚无统一认识,制约了页岩油资源潜力的评估准确率。选取松辽盆地页岩油井的密闭取心页岩样品,依次开展二维核磁共振(T₁—T₂ NMR)、有机溶剂蒸馏萃取(Dean Stark)、热解气相色谱(PY-GC)和岩石热解(Rock-Eval)4种页岩含油率测定实验。对比分析表明,T₁—T₂ NMR法与Dean Stark法的页岩含油率测试结果相近,均高于PY-GC法,Rock-Eval法测试结果最低。样品处理方式对页岩含油率的测试结果具有重要影响,块状样品的测试含油率明显高于粉碎样品。综合分析认为,T₁—T₂ NMR法测试页岩含油率结果的可靠性高,具有时间短、样品无损、样品非均质性影响小等特点,是分析页岩含油率的最优手段,具有良好的推广应用前景。建立了不同热演化成熟度页岩的含油率恢复系数、轻烃恢复系数及校正图版,对于湖相I型有机质页岩发育区开展页岩含油率分析具有重要参考价值。

Comparative analysis of test methods for shale oil content

At present, there is still not a unified understanding about the determination of shale oil content, the most important parameter for shale oil resource evaluation, which restricts the accuracy of shale oil resource evaluation. Using the sealed coring shale samples from a shale oil well in Songliao Basin, this paper successively conducts the four experiments of nuclear magnetic resonance (T₁-T₂ NMR), organic solvent distillation and extraction (Dean Stark), pyrolysis-gas chromatography (PY-GC) and rock pyrolysis (Rock-Eval) to determine the shale oil content. The results show that the oil content value determined by the T₁-T₂ NMR method is similar with that determined by the Dean Stark method (per gram of rock), both above that determined by the PY-GC method, and that determined by the Rock-Eval method is the lowest. Besides, sample preparation method has an important influence on the test results for shale oil content, and the oil content of block samples is significantly higher than that of crushed samples. Through a comprehensive analysis, it is considered that among the aforesaid test methods for shale oil content, the T₁-T₂ NMR method can obtain more reliable results within a short period of time, with no sample damage and little effect on sample heterogeneity. Thus, it is deemed as the best method for analyzing shale oil content and possesses a broad prospect for promotion and application. In addition, the oil content recovery coefficient and light hydrocarbon recovery coefficient for the shales with different thermal evaluation maturities and the corresponding correction chart have been established, which is of important reference value for the analysis of shale oil content in the development area of Type I lacustrine shale oil with organic matter.