鄂尔多斯盆地东部太原组页岩气吸附特征及影响因素

鄂尔多斯盆地东部太原组在绥德地区发育一套潜在的烃源岩,总有机碳(Total Organic Carbon,TOC)含量为0.75%~5.71%(平均2.75%); 镜质体反射率(R_o)为1.43%~2.12%(平均1.80%),处在高成熟—过成熟阶段,具有很好的生气潜力。为了探讨鄂尔多斯盆地东部太原组泥页岩的吸附特征,选取了研究区SSD1井10个泥页岩样品进行等温吸附、总有机碳含量、镜质体反射率、X-射线衍射和比表面积等测试分析,在此基础上探讨了盆地东部太原组富有机质泥页岩的吸附能力及其影响因素。结果表明: 研究区SSD1井太原组10个泥页岩样品的兰氏体积为1.11~2.41 m³/t,随着压力的增加,吸附能力迅速增加,当达到一定压力后达到饱和; 泥页岩的吸附能力与总有机碳含量和黏土矿物含量有正相关关系; 页岩比表面积与兰氏体积相关性不明显,推测样品孔隙大小及形态对气体的扩散和吸附有一定的影响。综合评价认为,总有机碳含量、黏土矿物含量是影响太原组泥页岩吸附能力的重要因素,这为盆地东部页岩气勘探提供参考。

Shale gas adsorption characteristics and influencing factors of Taiyuan Formation in Eastern Ordos Basin

Taiyuan Formation in Eastern Ordos Basin develops a set of potential hydrocarbon source rocks in Suide area of the study area. Its total organic carbon content is between 0.75% and 5.71%, with an average content of 2.75%, and its organic maturity (R_o) is mainly between 1.43% and 2.12%, with an average of 1.80%. It is in the stage of high maturity to over maturity and has a good gas potential. In order to study the adsorption characteristics of shale from Taiyuan Formation in Eastern Ordos Basin, 10 shale samples from well SSD1 in the study area were selected for isothermal adsorption, total organic carbon content, vitrinite reflectance, X-ray diffraction and specific surface area test. On this basis, the adsorption capacity and the influencing factors of organic-rich shale from Taiyuan Formation in Eastern Ordos Basin were discussed. The results show that the Langmuir volume of 10 shale samples from Taiyuan Formation of well SSD1 in the study area is 1.11-2.41 m³/t. With the increase of pressure, the adsorption capacity increases rapidly and reaches saturation at a certain pressure. The adsorption capacity of shale is positively correlated with the total organic carbon content and clay mineral content, while the specific surface area of shale is not significantly correlated with Langmuir volume. It is possible that the pore size and morphology of the sample have some influence on gas diffusion and adsorption. The comprehensive evaluation shows that the total organic carbon content and clay mineral content are important factors affecting the adsorption capacity of shale in Taiyuan Formation, which can provide some reference for shale gas exploration in the eastern part of the basin.