江汉盆地潜江凹陷古近系潜江组盐间可动页岩油赋存空间多尺度表征

Multi-scale characterization of the spatial distribution of movable hydrocarbon in intersalt shale of Qianjiang Formation,Qianjiang Sag,Jianghan Basin

为更精细地刻画可动页岩油赋存的孔隙空间特征,通过对比抽提前后样品在低温氮气吸附实验的吸附量变化、高压压汞实验的进汞量变化以及场发射扫描电镜中的孔径变化特征,来表征可动页岩油赋存的孔隙空间。研究表明,江汉盆地潜江凹陷古近系潜江组Eq34-10韵律可动页岩油主要赋存在微、纳米级的白云石晶间孔、粒间孔以及黏土矿物层间孔中,纹层状发育的页岩可动页岩油较为富集。以孔径80 nm为界拼接低温氮吸附和高压压汞测试孔径,结果表明,可动页岩油主要赋存在孔径小于200nm的范围内,微米级孔隙内也有赋存,90~200 nm孔径范围内可动页岩油赋存相对较多。黏土矿物含量较低的样品,在孔径小于等于5 nm的范围内抽提出可动页岩油。孔隙度越高,平均孔径越大,可动页岩油越富集。

Pore space containing mobile shale oil was more precisely characterized by comparing the change of adsorption volume of low-temperature nitrogen experiments and the change of mercury intake volume in high-pressure mercury injection experiments and the change of pore diameter using field emission scanning electron microscopy.The Eq34-10 rhythmic mobile hydrocarbon mainly occurs in dolomitic intercrystalline/intergranular pores and clay mineral interbedded pores,and movable hydrocarbon is relatively rich in lamellar shale.Low temperature nitrogen adsorption and high-pressure mercury injection measurements of pore size were spliced with pore size of 80 nm,and the results showed that movable hydrocarbon mainly occurs in the range of pore size less than 200 nm,and also occurs in the micron sized pores.Relatively more movable shale oil occurs in pores from 90 nm to 200 nm.The samples with low clay mineral content can yield movable hydrocarbon within the pores of≤5 nm.The higher the porosity,the larger the average pore size,and the richer the movable shale oil.