基于高压压汞法的泥页岩储层分形研究——以松辽盆地青山口组湖相泥岩为例

Fractal Characteristics of Shale Based on the Mercury Injection Method

基于高压压汞数据,以松辽盆地青山口组湖相泥岩为例,首次利用分形理论研究泥页岩孔隙结构分形特征.根据毛管压力曲线和J函数曲线的分形几何公式获得泥页岩过渡孔（10~100 nm）分形维数.过渡孔分形维数与泥页岩组成、结构（有机地球化学参数TOC、S1、S2,孔隙结构）之间关系分析表明：过渡孔分形维数随TOC含量增加而呈现先降低后趋于平缓的趋势;中值孔径相比较平均孔径、最可几孔径,与过渡孔分形维数相关性最强;黏土矿物中不同组分对孔隙的影响不同,从而泥页岩过渡孔分形维数与黏土矿物含量相关关系均较差;石英受自身脆性、溶蚀作用及次生加大等作用的影响,与过渡孔分形维数相关性较差;过渡孔孔隙结构越复杂,非均质性越差,汞越容易滞留其中,退汞效率越低.

Based on the high pressure mercury injection data,with the example of the lacustrine shale fromQingshankou Formation in the Songliao basin for the first time by using fractal theory we studed the fractalcharacteristics of pore structure of the shale. According to the capillary pressure curve and fractal geometry formulaof＂J＂function curve,we got the fractal dimension value of the transition hole（10-100 nm）. By analyzing therelationship between the transition pore fractal dimension and the composition,structure（organic geochemicalparameters TOC,S1,S2,pore structure）,we got the following conclusions. With the increase of the TOC content,Transition pore fractal dimension will reduce first and then keep smooth. The median pore diameter has a strongercorrelation than the average aperture and the most probable aperture. The different components of clay mineralshave different influence on the pore,so the transition pore fractal dimension has a poor correlation with the claymineral content. Because of the dissolution and secondary increase effect,the transition pore fractal dimension has apoor correlation with the quartz content. The more complex pore structure shale has,the stronger heterogeneity ofthe shale will be,and the mercury is easier to detain,with lower mercury withdrawal efficiency.