湖相泥页岩地球化学参数测井计算方法及应用——以沾化凹陷渤南洼陷沙三下亚段为例

Log calculation method of geochemical parameters of lacustrine shale and its application:a case of lower E s_3 in Bonan subsag,Zhanhua Sag

地球化学指标是烃源岩及非常规页岩储层研究的重要参数,该类型参数对烃源岩的生烃潜力评估及储层有效性评价均具有重要意义。采用Passey经典公式计算济阳坳陷沾化凹陷渤南洼陷沙三下亚段(E s_3)湖相泥页岩地层总有机碳含量(TOC)时误差较大,通过重新分析TOC与测井响应之间的关系,发现TOC与三孔隙度曲线的相关性较好。在此基础上,先分岩性(油泥岩、泥岩和油页岩)建立TOC计算模型,计算精度得到明显提高;再根据TOC和深度(D)间接建立热解烃(S_2)、氢指数(HI)及最高裂解温度(T_(max))等参数的计算模型,利用解释出的连续HI,T_(max)及TOC等数据,定量评价干酪根类型及有机质丰度;最终结合由测井资料计算而得到的矿物组分、物性参数等信息,有效地识别出地层剖面中富含的Ⅰ型和Ⅱ1型有机质泥页岩岩相。该研究成果为济阳坳陷沾化凹陷渤南洼陷沙三下亚段湖相泥页岩有利储层预测提供了理论基础。

The Geochemical index is an important parameter in the study of source rock and unconventional shale oil and gas, and it is of great significance for evaluating hydrocarbon potential of source rocks and reservoir effectiveness. The classic Passey formula was used to calculate the TOC content of lacustrine shale of the lower third member of Shahejie Formation （Es3） in Bonan subsag of Zhanhua Sag, but the error is larger. Through the analysis of the relationship between TOC and log response, it is found that TOC has a good correlation with tripo-rosity curve. The TOC calculation model was established on account of different lithologies （oil mudstone, mudstone and oil shale）, and the calculation accuracy was obviously improved. The calculation models of pyrolysis hy- drocarbon （$2）, hydrogen index （HI） and maximum pyrolysis temperature （Tmax） were established indirectly by TOC and depth variables, and then the kerogen types and organic matter abundance were quantitatively evaluated by using the data of continuous HI, Tmax and TOC. Finally, combining with the information of mineral composi- tion and physical properties obtained from well log data, the shale lithofacies were identified effectively, which is abundant of type I and 11, kerogen. This result provides a theoretical basis for the favorable reservoir prediction of lacustrine shale in Bonan subsag.